Input Output Reference — EnergyPlus 8.7

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Input Output Reference

Group – Plant Equipment[LINK]

Equipment Types[LINK]

In each PlantEquipmentList described using the above syntax, various equipment types and names must be given. Each type-name pair must then have a corresponding equipment definition. This subsection lists the various equipment types that are available and examples from an IDF. Where appropriate, notes and comments on the input structure are provided.

Generic Chiller Outputs[LINK]

Many output variable names are common across all chiller types. These generic chiller output names all begin with the word “Chiller”. Certain chiller types have additional output variables which are specific to that type of chiller. Chiller energy use is added to the appropriate plant-level meters as a cooling end-use.

  • HVAC,Average,Chiller Electric Power [W]

  • HVAC,Sum,Chiller Electric Energy [J]

  • Zone,Meter,Electricity:Plant [J]

  • Zone,Meter,Cooling:Electricity [J]

  • HVAC,Average,Chiller Evaporator Cooling Rate [W]

  • HVAC,Sum,Chiller Evaporator Cooling Energy [J]

  • Zone,Meter,EnergyTransfer:Plant [J]

  • Zone,Meter,Chillers:EnergyTransfer [J]

  • HVAC,Average,Chiller Evaporator Inlet Temperature [C]

  • HVAC,Average,Chiller Evaporator Outlet Temperature [C]

  • HVAC,Average,Chiller Evaporator Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller Condenser Heat Transfer Rate [W]

  • HVAC,Sum,Chiller Condenser Heat Transfer Energy [J]

  • Zone,Meter,HeatRejection:EnergyTransfer [J]

  • HVAC,Average,Chiller COP [W/W]

The following output is applicable only for air-cooled or evap-cooled chillers

  • HVAC,Average,Chiller Condenser Inlet Temperature [C]

The following outputs are applicable only for evap-cooled chillers

  • HVAC,Average,Chiller Basin Heater Electric Power [W]

  • HVAC,Average,Chiller Basin Heater Electric Energy [J]

The following three outputs are only available for water-cooled chillers

  • HVAC,Average,Chiller Condenser Inlet Temperature [C]

  • HVAC,Average,Chiller Condenser Outlet Temperature [C]

  • HVAC,Average,Chiller Condenser Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller Drive Shaft Power [W]

  • HVAC,Sum,Chiller Drive Shaft Energy [J]

  • Zone,Meter,HeatRecovery:EnergyTransfer [J]

  • HVAC,Average,Chiller Lube Recovered Heat Rate [W]

  • HVAC,Sum,Chiller Lube Recovered Heat Energy [J]

  • HVAC,Average,Chiller Jacket Recovered Heat Rate [W]

  • HVAC,Sum,Chiller Jacket Recovered Heat Energy [J]

  • HVAC,Average, Chiller Exhaust Recovered Heat Rate [W]

  • HVAC,Sum,Chiller Exhaust Recovered Heat Energy [J]

  • HVAC,Average,Chiller Total Recovered Heat Rate [W]

  • HVAC,Sum,Chiller Total Recovered Heat Energy [J]

  • HVAC,Average,Chiller Exhaust Temperature [C]

  • HVAC,Average,Chiller Heat Recovery Inlet Temperature [C]

  • HVAC,Average,Chiller Heat Recovery Outlet Temperature [C]

  • HVAC,Average,Chiller Heat Recovery Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller Effective Heat Rejection Temperature [C]

The following blocks of outputs are for steam and fuel-driven chillers

  • HVAC,Average,Chiller Gas Rate [W]

  • HVAC,Sum,Chiller Gas Energy [J]

  • HVAC,Average,Chiller Gas Mass Flow Rate [kg/s]

  • HVAC,Sum,Chiller Gas Mass [kg]

For steam absorption chillers:

  • HVAC,Average,Chiller Source Steam Rate [W]

  • HVAC,Sum, Chiller Source Steam Energy [J]

  • HVAC,Average,Chiller Steam Mass Flow Rate [kg/s]

For hot water absorption chillers:

  • HVAC,Average,Chiller Source Hot Water Rate [W]

  • HVAC,Sum,Chiller Source Hot Water Energy [J]

  • Zone,Meter,Steam:Plant [J]

  • Zone,Meter,Cooling:EnergyTransfer [J]

  • HVAC,Average,Chiller Hot Water Mass Flow Rate [kg/s]

The following output is applicable only for indirect absorption chillersHVAC,Average,Chiller Part Load Ratio

  • HVAC,Average,Chiller Cycling Ratio []

  • HVAC,Average,Chiller Propane Rate [W]

  • HVAC,Sum,Chiller Propane Energy [J]

  • HVAC,Average,Chiller Propane Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller Diesel Rate [W]

  • HVAC,Sum,Chiller Diesel Energy [J]

  • HVAC,Average,Chiller Diesel Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller Gasoline Rate [W]

  • HVAC,Sum,Chiller Gasoline Energy [J]

  • HVAC,Average,Chiller Gasoline Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller FuelOil#1 Rate [W]

  • HVAC,Sum,Chiller FuelOil#1 Energy [J]

  • HVAC,Average,Chiller FuelOil#1 Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller FuelOil#2 Rate [W]

  • HVAC,Sum,Chiller FuelOil#2 Energy [J]

  • HVAC,Average,Chiller FuelOil#2 Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller OtherFuel1 Rate [W]

  • HVAC,Sum,Chiller OtherFuel1 Energy [J]

  • HVAC,Average,Chiller OtherFuel1 Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller OtherFuel2 Rate [W]

  • HVAC,Sum,Chiller OtherFuel2 Energy [J]

  • HVAC,Average,Chiller OtherFuel2 Mass Flow Rate [kg/s]

Chiller Electric Power [W] [LINK]

Chiller Electric Energy [J] [LINK]

These outputs are the electric power input to the chiller. In the case of steam or fuel-powered chillers, this repesents the internal chiller pumps and other electric power consumption. Consumption is metered on Cooling:Electricity, Electricity:Plant, and Electricity:Facility.

Chiller Evaporator Cooling Rate [W] [LINK]

Chiller Evaporator Cooling Energy [J] [LINK]

These outputs are the evaporator heat transfer which is the cooling delivered by the chiller. Chiller Evaporator Cooling Energy is metered on Chillers:EnergyTransfer, EnergyTransfer:Plant, and EnergyTransfer:Facility.

Chiller Evaporator Inlet Temperature [C] [LINK]

Chiller Evaporator Outlet Temperature [C] [LINK]

Chiller Evaporator Mass Flow Rate [kg/s] [LINK]

These outputs are the evaporator (chilled water) inlet and outlet temperatures and flow rate.

Chiller COP [W/W] [LINK]

This output is the coefficient of performance for the chiller during cooling operation. It is calculated as the evaporator heat transfer rate (Chiller Evaporator Cooling Rate) divided by the “fuel” consumption rate by the chiller. For the constant COP and electric chillers, the “fuel” is electricity so the divisor is Chiller Electric Power [W]. For the absorption chiller, the “fuel” is steam so the divisor is Steam Consumption Rate [W].

Note that this variable is reported as zero when the chiller is not operating. When reported for frequencies longer than “detailed” (such as timestep, hourly, daily, monthly or environment), this output will only be meaningful when the chiller is operating for the entire reporting period. To determine an average COP for a longer time period, compute the COP based on total evaporator heat transfer divided by total electric or fuel input over the desired period.

Chiller Part Load Ratio[LINK]

This output is the operating part-load ratio of the indirect absorption chiller. This output may fall below the minimum part-load ratio specified in the input. For this case, the Chiller Cycling Ratio is used to further define the performance of the indirect absorption chiller.

Chiller Cycling Ratio[LINK]

This output is the fraction of the timestep the indirect absorption chiller operates. When the chiller operates above the minimum part-load ratio, a Chiller Cycling Ratio of 1 is reported. When the chiller operates below the minimum part-load ratio, the Chiller Cycling Ratio reports the fraction of the timestep the indirect absorption chiller operates.

Chiller Condenser Heat Transfer Rate [W] [LINK]

Chiller Condenser Heat Transfer Energy [J] [LINK]

These outputs are the condenser heat transfer which is the heat rejected from the chiller to either a condenser water loop or through an air-cooled condenser. Chiller Condenser Heat Transfer Energy is metered on HeatRejection:EnergyTransfer, EnergyTransfer:Plant, and EnergyTransfer:Facility.

Chiller Condenser Inlet Temperature [C] [LINK]

This output is the condenser (heat rejection) inlet temperature for air-cooled or evap-cooled chillers. For an air-cooled chiller, this output would be the dry-bulb temperature of the air entering the condenser coil. For an evap-cooled chiller, this output would be the wet-bulb temperature of the air entering the evaporatively-cooled condenser coil.

Chiller Basin Heater Electric Power [W] [LINK]

Chiller Basin Heater Electric Energy [J] [LINK]

These outputs are the electric power input to the chiller’s basin heater (for evaporatively-cooled condenser type). Consumption is metered on Chillers:Electricity, Electricity:Plant, and Electricity:Facility

Chiller Condenser Inlet Temperature [C] [LINK]

Chiller Condenser Outlet Temperature [C] [LINK]

Chiller Condenser Mass Flow Rate [kg/s] [LINK]

These outputs are the condenser (heat rejection) inlet and outlet temperatures and flow rate for water-cooled chillers.

Chiller Drive Shaft Power [W] [LINK]

Chiller Drive Shaft Energy [J] [LINK]

For engine-driven and turbine-driven chillers, these outputs are the shaft power produced by the prime mover and transferred to the chiller compressor.

Chiller Lube Recovered Heat Rate [W] [LINK]

Chiller Lube Recovered Heat Energy [J] [LINK]

Chiller Jacket Recovered Heat Rate [W] [LINK]

Chiller Jacket Recovered Heat Energy [J] [LINK]

Chiller Exhaust Recovered Heat Rate [W] [LINK]

Chiller Exhaust Recovered Heat Energy [J] [LINK]

Chiller Total Recovered Heat Rate [W] [LINK]

Chiller Total Recovered Heat Energy [J] [LINK]

For chillers with heat recovery, such as engine-driven chillers, these outputs are the components of recoverable energy available. For a given chiller type, one or more of the following components may be applicable: Lube (engine lubricant), Jacket (engine coolant), Exhaust (engine exhaust), and Total. Chiller Lube Recovered Heat Energy, Chiller Jacket Recovered Heat Energy, and Chiller Exhaust Heat Recovery Energy are metered on HeatRecovery:EnergyTransfer, EnergyTransfer:Plant, and EnergyTransfer:Facility.

Chiller Exhaust Temperature [C] [LINK]

This is the exhaust temperature leaving an engine chiller.

Chiller Heat Recovery Inlet Temperature [C] [LINK]

Chiller Heat Recovery Outlet Temperature [C] [LINK]

Chiller Heat Recovery Mass Flow Rate [kg/s] [LINK]

These outputs are the heat recovery inlet and outlet temperatures and flow rate for chillers with heat recovery such as engine-driven and gas turbine chillers.

Chiller Effective Heat Rejection Temperature [C] [LINK]

This output variable is available for heat recovery chillers that model split bundle condenser. The condenser fluid temperatures used to characterize chiller performance are modified to account for the temperature of the heat recovery fluid. This output is the resulting temperature used for characterizing chiller performance and is a blend of the temperatures in the condenser and heat recovery fluid streams. For the Chiller:Electric and Chiller:Electric:EIR models, this is an effective inlet temperature while for the Chiller:Electric:ReformulatedEIR model, this is an effective outlet temperature.

Chiller <Fuel Type> Rate [W] [LINK]

Chiller <Fuel Type> Energy [J] [LINK]

Chiller <Fuel Type> Mass Flow Rate [kg/s] [LINK]

Chiller Gas Mass [kg] (Gas Turbine Chiller only)[LINK]

These outputs are the steam or fuel input for steam or fuel-fired chillers. Valid fuel types depend on the type of chiller. <Fuel Type> may be one of: Gas (natural gas), Steam, Propane, Diesel, Gasoline, FuelOil#1, FuelOil#2, OtherFuel1 and OtherFuel2. Consumption is metered on Cooling:<Fuel Type>, <Fuel Type>:Plant, and <Fuel Type>:Facility.

Chiller Source Hot Water Rate [W] [LINK]

Chiller Source Hot Water Energy [J] [LINK]

Chiller Source Steam Rate [W] [LINK]

Chiller:Absorption[LINK]

Inputs[LINK]

Field: Name[LINK]

This alpha field contains the identifying name for the absorption chiller.

Field: Nominal Capacity[LINK]

This numeric field contains the nominal cooling capability of the chiller in Watts.

Field: Nominal Pumping Power[LINK]

This numeric field contains the nominal pumping power of the absorber in Watts.

Field: Chilled Water Inlet Node Name[LINK]

This required alpha field contains the identifying name for the absorption chiller plant side inlet node.

Field: Chilled Water Outlet Node Name[LINK]

This required alpha field contains the identifying name for the absorption chiller plant side outlet node.

Field: Condenser Inlet Node Name[LINK]

This required alpha field contains the identifying name for the absorption chiller condenser side inlet node.

Field: Condenser Outlet Node Name[LINK]

This required alpha field contains the identifying name given to the Heat Recovery Loop Component Outlet Node.

Field: Minimum Part Load Ratio[LINK]

This numeric field contains the absorption chiller’s minimum part load ratio. The expected range is between 0 and 1. The minimum part load is not the load where the machine shuts off, but where the amount of power remains constant to produce smaller loads than this fraction.

Field: Maximum Part Load Ratio[LINK]

This numeric field contains the absorption chiller’s maximum part load ratio. This value may exceed 1, but the normal range is between 0 and 1.1.

Field: Optimum Part Load Ratio[LINK]

This numeric field contains the absorption chiller’s optimum part load ratio. This is the part load ratio at which the chiller performs at its maximum COP.

Field: Design Condenser Inlet Temperature[LINK]

This numeric field contains the absorption chiller’s condenser inlet design temperature in Celsius.

Field: Design Chilled Water Flow Rate[LINK]

For variable volume chiller this is the maximum flow and for constant flow chiller this is the design flow rate. The units are in cubic meters per second.

Field: Design Condenser Water Flow Rate[LINK]

This numeric field contains the absorption chiller’s design condenser water flow rate in cubic meters per second.

Generator Heat Input Part Load Ratio Curve[LINK]

The Generator Heat Input Part Load Ratio Curve is a quadratic equation that determines the Ratio of the generator load on the absorber to the demand on the chiller. The defining equation is:

SteamInputRatio=C1PLR+C2+C3PLR

The following three fields contain the coefficients for the equation.

Field: Coefficient 1 of the Steam Use Part Load Ratio Curve[LINK]

C1 in the Generator Heat Input Part Load Ratio Curve. This value is obtained by fitting manufacturers’ performance data to the curve.

Field: Coefficient 2 of the Steam Use Part Load Ratio Curve[LINK]

C2 in the Generator Heat Input Part Load Ratio Curve. This value is obtained by fitting manufacturers’ performance data to the curve.

Field: Coefficient 3 of the Steam Use Part Load Ratio Curve[LINK]

C3 in the Generator Heat Input Part Load Ratio Curve. This value is obtained by fitting manufacturers’ performance data to the curve.

Pump Electric Use Part Load Ratio Curve[LINK]

The Pump Electric Use Part Load Ratio Curve is a quadratic equation that determines the Ratio of the actual absorber pumping power to the nominal pumping power. The defining equation is:

ElectricInputRatio=C1+C2PLR+C3PLR2

The following three fields contain the coefficients for the equation.

Field: Coefficient 1 of the Pump Electric Use Part Load Ratio Curve[LINK]

C1 in the Pump Electric Use Part Load Ratio Curve. This value is obtained by fitting manufacturers’ performance data to the curve.

Field: Coefficient 2 of the Pump Electric Use Part Load Ratio Curve[LINK]

C2 in the Pump Electric Use Part Load Ratio Curve. This value is obtained by fitting manufacturers’ performance data to the curve.

Field: Coefficient 3 of the Pump Electric Use Part Load Ratio Curve[LINK]

C3 in the Pump Electric Use Part Load Ratio Curve. This value is obtained by fitting manufacturers’ performance data to the curve.

Field: Chilled Water Outlet Temperature Lower Limit[LINK]

This numeric field contains the lower limit for the evaporator outlet temperature. This temperature acts as a cut off for heat transfer in the evaporator, so that the fluid doesn’t get too cold.

Field: Generator Inlet Node Name[LINK]

This alpha field contains the identifying name given to the Generator Inlet Node. A steam or hot water loop is not required to simulate an absorption chiller. If a steam/hot water loop is used, enter the name of the generator inlet node.

Field: Generator Outlet Node Name[LINK]

This alpha field contains the identifying name given to the Generator Outlet Node. A steam or hot water loop is not required to simulate an absorption chiller. If a steam/hot water loop is used, enter the name of the generator outlet node.

Field: Chiller Flow Mode[LINK]

This choice field determines how the chiller operates with respect to the intended fluid flow through the device’s evaporator. There are three different choices for specifying operating modes for the intended flow behavior: “NotModulated,” “ConstantFlow,” and “LeavingSetpointModulated.” NotModulated is useful for either variable or constant speed pumping arrangements where the chiller is passive in the sense that although it makes a nominal request for its design flow rate it can operate at varying flow rates. ConstantFlow is useful for constant speed pumping arrangements where the chiller’s request for flow is stricter and can increase the overall loop flow. LeavingSetpointModulated changes the chiller model to internally vary the flow rate so that the temperature leaving the chiller matches a setpoint at the evaporator outlet. For this absorption chiller, this mode also affects the flow rate on the generator connection. In all cases the operation of the external plant system can also impact the flow through the chiller – for example if the relative sizes and operation are such that flow is restricted and the requests cannot be met. The default, if not specified, is NotModulated. This flow mode does not impact the condenser loop connection.

Field: Generator Fluid Type[LINK]

This choice field specifies the type of fluid used to heat the generator solution. The valid choices are HotWater or Steam. This field should be specified as Steam or left blank if the generator inlet/outlet nodes are not specified.

Field: Design Generator Fluid Flow Rate[LINK]

This numeric field contains the absorption chiller’s design condenser fluid flow rate in cubic meters per second.

Field: Degree of Subcooling in Steam Generator[LINK]

Ideally, the steam trap located at the outlet of the generator should remove all the condensate immediately, however, there is a delay in this process in actual systems which causes the condensate to SubCool by a certain amount before leaving the generator. This amount of subcooling is included in the heat transferred to the solution in the generator. The minimum value is 0º Celsius and default is 5º Celsius. This field is not used when the generator inlet/outlet node are not specified or the generator is connected to a hot water loop.

Field: Sizing Factor[LINK]

This optional numeric field allows the user to specify a sizing factor for this component. The sizing factor is used when the component design inputs are autosized: the autosizing calculations are performed as usual and the results are multiplied by the sizing factor. For this component the inputs that would be altered by the sizing factor are: Nominal Capacity, Nominal Pumping Power, Design Chilled Water Flow Rate, Design Condenser Water Flow Rate and Design Generator Fluid Flow Rate. Sizing factor allows the user to size a component to meet part of the design load while continuing to use the autosizing feature.

Following is an example input for an Absorption Chiller.

Chiller:Absorption,
      Big Chiller,             !- Chiller Name
      50000,                   !- Nominal Capacity {W}
      250,                     !- Nominal Pumping Power {W}
      Big Chiller Inlet Node,  !- Plant_Side_Inlet_Node
      Big Chiller Outlet Node, !- Plant_Side_Outlet_Node
      Big Chiller Condenser Inlet Node,  !- Condenser_Side_Inlet_Node
      Big Chiller Condenser Outlet Node,  !- Condenser_Side_Outlet_Node
      0.15,                    !- Minimum Part Load Ratio
      1.0,                     !- Maximum Part Load Ratio
      0.65,                    !- Opt Part Load Ratio
      35.0,                    !- Temp Design Condenser Inlet {C}
      0.0011,                  !- Design Chilled Water Flow Rate {m3/s}
      0.0011,                  !- Design Condenser Water Flow Rate {m3/s}
      0.03303,                 !- Coefficient1 of the steam use part load ratio curve
      0.6852,                  !- Coefficient2 of the steam use part load ratio curve
      0.2818,                  !- Coefficient3 of the steam use part load ratio curve
      1.0,                     !- Coefficient1 of the pump electric use part load ratio curve
      0,                       !- Coefficient2 of the pump electric part load ratio curve
      0,                       !- Coefficient3 of the pump electric use part load ratio curve
      5,                       !- Chilled Water Outlet Temperature Lower Limit {C}
      AbsorberSteamInletNode,  !- Generator Inlet Node Name
      AbsorberSteamOutletNode, !- Generator Outlet Node Name
      VariableFlow,            !- Chiller Flow Mode
      Steam,                   !- Generator Fluid Type
      autosize,                !- Design Generator Volumetric Fluid Flow Rate {m3/s}
      2.0;                     !- Degree of Subcooling in Steam Generator {C}

Outputs[LINK]

  • HVAC,Average,Chiller Electric Power [W]

  • HVAC,Sum,Chiller Electric Energy [J]

  • Zone,Meter,Electricity:Plant [J]

  • Zone,Meter,Cooling:Electricity [J]

  • HVAC,Average,Chiller Evaporator Cooling Rate [W]

  • HVAC,Sum,Chiller Evaporator Cooling Energy [J]

  • Zone,Meter,EnergyTransfer:Plant [J]

  • Zone,Meter,Chillers:EnergyTransfer [J]

  • HVAC,Average,Chiller Evaporator Inlet Temperature [C]

  • HVAC,Average,Chiller Evaporator Outlet Temperature [C]

  • HVAC,Average,Chiller Evaporator Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller Condenser Heat Transfer Rate [W]

  • HVAC,Sum,Chiller Condenser Heat Transfer Energy [J]

  • Zone,Meter,HeatRejection:EnergyTransfer [J]

  • HVAC,Average,Chiller Condenser Inlet Temperature [C]

  • HVAC,Average,Chiller Condenser Outlet Temperature [C]

  • HVAC,Average,Chiller Condenser Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller COP [W/W]

For Chillers with Steam Generators:

  • HVAC,Average, Chiller Source Steam Rate [W]

  • HVAC,Sum, Chiller Source Steam Energy [J]

  • HVAC,Average,Chiller Steam Mass Flow Rate [kg/s]

For Chillers with Hot Water Generators:

  • HVAC,Average,Chiller Source Hot Water Rate [W]

  • HVAC,Sum,Chiller Source Hot Water Energy [J]

  • HVAC,Average,Chiller Hot Water Mass Flow Rate [kg/s]

These chiller output variables are defined above under “Generic Chiller Outputs.”

Chiller:Absorption:Indirect[LINK]

The Chiller:Absorption:Indirect object is an enhanced version of the absorption chiller model found in the Building Loads and System Thermodynamics (BLAST) program. This enhanced model is nearly identical to the existing absorption chiller model (Ref. Chiller:Absorption) with the exceptions that: 1) the enhanced indirect absorption chiller model provides more flexible performance curves and 2) chiller performance now includes the impact of varying evaporator, condenser, and generator temperatures. Since these absorption chiller models are nearly identical (i.e., the performance curves of the enhanced model can be manipulated to produce similar results to the previous model), it is quite probable that the Chiller:Absorption model will be deprecated in a future release of EnergyPlus.

Inputs[LINK]

Field: Name[LINK]

This required alpha field contains the identifying name for the indirect absorption chiller.

Field: Nominal Capacity[LINK]

This required numeric field contains the nominal cooling capability of the chiller in Watts. This field must be greater than 0 and is autosizable.

Field: Nominal Pumping Power[LINK]

This required numeric field contains the nominal pumping power of the chiller in Watts. The minimum value for this field is 0 and is autosizable.

Field: Chilled Water Inlet Node Name[LINK]

This required alpha field contains the identifying name for the chiller chilled water inlet node.

Field: Chilled Water Outlet Node Name[LINK]

This required alpha field contains the identifying name for the chiller chilled water outlet node.

Field: Condenser Inlet Node Name[LINK]

This required alpha field contains the identifying name for the chiller condenser inlet node.

Field: Condenser Outlet Node Name[LINK]

This required alpha field contains the identifying name given to the chiller outlet node.

Field: Minimum Part Load Ratio[LINK]

This numeric field contains the chiller’s minimum part-load ratio. The expected range is between 0 and 1. The minimum part load is not the load where the machine shuts off, but where the amount of power remains constant to produce smaller loads than this fraction.

Field: Maximum Part Load Ratio[LINK]

This numeric field contains the chiller’s maximum part-load ratio. This value may exceed 1, but the normal range is between 0 and 1.1.

Field: Optimum Part Load Ratio[LINK]

This numeric field contains the chiller’s optimum part-load ratio. This is the part-load ratio at which the chiller performs at its maximum COP.

Field: Design Condenser Inlet Temperature[LINK]

This numeric field contains the chiller’s condenser inlet design temperature in Celsius. The default value for this field is 30º C and is only used when the Design Chilled Water Flow Rate is autosized.

Field: Condenser Inlet Temperature Lower Limit[LINK]

This numeric field contains the chiller’s lower limit for the condenser entering water temperature in Celsius. The default value for this field is 15º C. If this limit is exceeded, a warning message will report the incident. No correction to chiller capacity is made for low condenser entering water temperatures.

Field: Chilled Water Outlet Temperature Lower Limit[LINK]

This numeric field contains the chiller’s lower limit for the evaporator leaving water temperature in Celsius. The default value for this field is 5º C. If this limit is exceeded, a warning message will report the incident. No correction to chiller capacity is made for low evaporator leaving water temperatures.

Field: Design Chilled Water Flow Rate[LINK]

This numeric input specifies the design evaporator volumetric flow rate in cubic meters per second. The value specified must be greater than 0 or this field is autosizable. For variable volume chiller this is the maximum flow and for constant flow chiller this is the design flow rate.

Field: Design Condenser Water Flow Rate[LINK]

This numeric field specifies the chiller’s design condenser water flow rate in cubic meters per second. The value specified must be greater than 0 or this field is autosizable.

Field: Chiller Flow Mode[LINK]

This choice field determines how the chiller operates with respect to the intended fluid flow through the device’s evaporator. There are three different choices for specifying operating modes for the intended flow behavior: “NotModulated,” “ConstantFlow,” and “LeavingSetpointModulated.” NotModulated is useful for either variable or constant speed pumping arrangements where the chiller is passive in the sense that although it makes a nominal request for its design flow rate it can operate at varying flow rates. ConstantFlow is useful for constant speed pumping arrangements where the chiller’s request for flow is stricter and can increase the overall loop flow. LeavingSetpointModulated changes the chiller model to internally vary the flow rate so that the temperature leaving the chiller matches a setpoint at the evaporator outlet. For this absorption chiller, this mode also affects the flow rate on the generator connection. In all cases the operation of the external plant system can also impact the flow through the chiller – for example if the relative sizes and operation are such that flow is restricted and the requests cannot be met. The default, if not specified, is NotModulated. This flow mode does not impact the condenser loop connection.

Field: Generator Heat Input Function of Part Load Ratio Curve Name[LINK]

This required alpha field specifies the name of the curve used to determine the heat input to the chiller. The curve is a quadratic or cubic curve which characterizes the heat input as a function of chiller part-load ratio. The curve output is multiplied by the chiller’s nominal capacity and operating part-load ratio or minimum part-load ratio, whichever is greater, to determine the amount of heat input required for the given operating conditons.

Field: Pump Electric Input Function of Part Load Ratio Curve Name[LINK]

This alpha field specifies the name of the curve used to determine the pump electrical input to the chiller. The curve is a quadratic or cubic curve which characterizes the pump electrical power as a function of chiller part-load ratio. The curve output is multiplied by the chiller’s nominal pumping power and operating part-load ratio or minimum part-load ratio, whichever is greater, to determine the amount of pumping power required for the given operating conditons.

Field: Generator Inlet Node Name[LINK]

This alpha field contains the identifying name given to the Generator Inlet Node. A steam or hot water loop is not required to simulate an indirect absorption chiller. If a steam/hot water loop is used, enter the name of the generator inlet node.

Field: Generator Outlet Node Name[LINK]

This alpha field contains the identifying name given to the Generator Outlet Node. A steam or hot water loop is not required to simulate an indirect absorption chiller. If a steam/hot water loop is used, enter the name of the generator outlet node.

Field: Capacity Correction Function of Condenser Temperature Curve Name[LINK]

This alpha field specifies the name of a quadratic or cubic curve which correlates the chiller’s evaporator capacity as a function of condenser entering water temperature. This curve is used to correct nominal capacity at off-design condensing temperatures.

Field: Capacity Correction Function of Chilled Water Temperature Curve Name[LINK]

This alpha field specifies the name of a quadratic or cubic curve which correlates the chiller’s evaporator capacity as a function of evaporator leaving water temperature. This curve is used to correct nominal capacity at off-design evaporator temperatures.

Field: Capacity Correction Function of Generator Temperature Curve Name[LINK]

This alpha field specifies the name of a quadratic or cubic curve which correlates the chiller’s evaporator capacity as a function of generator entering water temperature. This curve is used to correct nominal capacity at off-design evaporator temperatures and is only used when the Generator Fluid Type is specified as Hot Water.

Field: Generator Heat Input Correction Function of Condenser Temperature Curve Name[LINK]

This alpha field specifies the name of a quadratic or cubic curve which correlates the chiller’s heat input as a function of condenser entering water temperature. This curve is used to correct generator heat input at off-design condensing temperatures.

Field: Generator Heat Input Correction Function of Chilled Water Temperature Curve Name[LINK]

This alpha field specifies the name of a quadratic or cubic curve which correlates the chiller’s heat input as a function of evaporator leaving water temperature. This curve is used to correct generator heat input at off-design evaporator temperatures.

Field: Generator Heat Source Type[LINK]

This choice field specifies the type of fluid used to heat the generator solution. The valid choices are HotWater or Steam. This input is used to identify the method used to calculate the generator mass flow rate. This field is not used if the generator inlet/outlet nodes are not specified. The default value is Steam.

Field: Design Generator Fluid Flow Rate[LINK]

This numeric field specifies the chiller’s design generator fluid flow rate in cubic meters per second. The value specified must be greater than 0 or this field is autosizable. For variable flow chillers this is the maximum generator flow rate, for constant flow chillers this is the flow rate.

Field: Temperature Lower Limit Generator Inlet[LINK]

This numeric field specifies the lower limit of the generator’s entering water temperature. This field is not used iif the Generator Fluid Type is specified as steam.

Field: Degree of Subcooling in Steam Generator[LINK]

Ideally the steam trap located at the outlet of generator should remove all the condensate immediately, however there is a delay in this process in actual systems which causes the condensate to SubCool by a certain degree before leaving the generator. This amount of subcooling is included in the heat transferred to the solution in the generator. The minimum value is 0º Celsius, the maximum value is 20º Celsius, and the default is 1º Celsius.

Field: Degree of Subcooling in Steam Condensate Loop[LINK]

This essentially represents the heat loss to the atmosphere due to uninsulated condensate return piping to the boiler. Condensate return piping operates at atmospheric pressure and is not insulated. The condensate sub cools to certain degree before it is pumped back to the boiler. The minimum value is 0º Celsius and the default is 0º Celsius.

Field: Sizing Factor[LINK]

This optional numeric field allows the user to specify a sizing factor for this component. The sizing factor is used when the component design inputs are autosized: the autosizing calculations are performed as usual and the results are multiplied by the sizing factor. For this component the inputs that would be altered by the sizing factor are: Nominal Capacity, Nominal Pumping Power, Design Chilled Water Flow Rate, Design Condenser Water Flow Rate and Design Generator Fluid Flow Rate. Sizing factor allows the user to size a component to meet part of the design load while continuing to use the autosizing feature.

Following is an example input for an Absorption Chiller.

Chiller:Absorption:Indirect,
      Big Chiller,             !- Chiller Name
      100000,                  !- Nominal Capacity {W}
      250,                     !- Nominal Pumping Power {W}
      Big Chiller Inlet Node,  !- Evaporator Inlet Node Name
      Big Chiller Outlet Node, !- Evaporator Outlet Node Name
      Big Chiller Condenser Inlet Node,  !- Condenser Inlet Node Name
      Big Chiller Condenser Outlet Node,  !- Condenser Outlet Node Name
      0.15,                    !- Minimum Part Load Ratio
      1.0,                     !- Maximum Part Load Ratio
      0.65,                    !- Opt Part Load Ratio
      35.0,                    !- Temp Design Condenser Inlet {C}
      10.0,                    !- Temp Lower Limit Condenser Inlet {C}
      5.0,                     !- Chilled Water Outlet Temperature Lower Limit {C}
      0.0011,                  !- Design Chilled Water Flow Rate {m3/s}
      0.0011,                  !- Design Condenser Water Flow Rate {m3/s}
      VariableFlow,            !- Chiller Flow Mode
      SteamUseFPLR,            !- Generator Heat Input function of part-load ratio curve name
      PumpUseFPLR,             !- Pump Electric Input function of part-load ratio curve name
      AbsorberSteamInletNode,  !- Generator Inlet Node Name
      AbsorberSteamOutletNode, !- Generator Outlet Node Name
      CAPfCOND,                !- Capacity Correction function of condenser temperature curve name
      CAPfEVAP,                !- Capacity Correction function of evaporator temperature curve name
      ,                        !- Capacity Correction function of generator temperature curve name
      SteamFCondTemp,       !- Generator Heat Input Correction function of condenser temperature curve name
      SteamFEvapTemp,       !- Generator Heat Input Correction function of evaporator temperature curve name
      Steam,                   !- Generator Heat Source Type
      autosize,                !- Design Generator Volumetric Fluid Flow Rate {m3/s}
      30.0,                    !- Temp Lower Limit Generator Inlet {C}
      2.0,                     !- Degree of Subcooling in Steam Generator {C}
      12.0;                    !- Degree of Subcooling in Steam Condensate Loop {C}

Outputs[LINK]

  • HVAC,Average,Chiller Electric Power [W]

  • HVAC,Sum,Chiller Electric Energy [J]

  • Zone,Meter,Electricity:Plant [J]

  • Zone,Meter,Cooling:Electricity [J]

  • HVAC,Average,Chiller Evaporator Cooling Rate [W]

  • HVAC,Sum,Chiller Evaporator Cooling Energy [J]

  • Zone,Meter,EnergyTransfer:Plant [J]

  • Zone,Meter,Chillers:EnergyTransfer [J]

  • HVAC,Average,Chiller Evaporator Inlet Temperature [C]

  • HVAC,Average,Chiller Evaporator Outlet Temperature [C]

  • HVAC,Average,Chiller Evaporator Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller Condenser Heat Transfer Rate [W]

  • HVAC,Sum,Chiller Condenser Heat Transfer Energy [J]

  • Zone,Meter,HeatRejection:EnergyTransfer [J]

  • HVAC,Average,Chiller Condenser Inlet Temperature [C]

  • HVAC,Average,Chiller Condenser Outlet Temperature [C]

  • HVAC,Average,Chiller Condenser Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller COP [W/W]

  • HVAC,Average,Chiller Part-Load Ratio

  • HVAC,Average,Chiller Cycling Ratio

For Chillers with Steam Generators:

  • HVAC,Average, Chiller Source Steam Rate [W]

  • HVAC,Sum, Chiller Source Steam Energy [J]

  • Zone,Meter,Steam:Plant [J]

  • Zone,Meter,Cooling:Steam [J]

  • HVAC,Average, Chiller Steam Mass Flow Rate [kg/s]

  • HVAC,Average, Chiller Steam Heat Loss Rate [W]

For Chillers with Hot Water Generators:

  • HVAC,Average, Chiller Source Hot Water Rate [W]

  • HVAC,Sum, Chiller Source Hot Water Energy [J]

  • Zone,Meter,EnergyTransfer:Plant [J]

  • Zone,Meter,Cooling:EnergyTransfer [J]

  • HVAC,Average, Chiller Hot Water Mass Flow Rate [kg/s]

These chiller output variables are defined above under “Generic Chiller Outputs.”

Chiller:ConstantCOP[LINK]

This chiller model is based on a simple, constant COP simulation of the chiller. In this case, performance does not vary with chilled water temperature or condenser conditions.

Such a model is useful when the user does not have access to detailed performance data.

Inputs[LINK]

Field: Name[LINK]

This alpha field contains the identifying name for the constant COP chiller.

Field: Nominal Capacity[LINK]

This numeric field contains the nominal cooling capability of the chiller in Watts.

Field: Nominal COP[LINK]

This numeric field contains the Chiller’s coefficient of performance.

Field: Design Chilled Water Flow Rate[LINK]

For variable volume chiller this is the maximum flow and for constant flow chiller this is the design flow rate. The units are in cubic meters per second.

Field: Design Condenser Water Flow Rate[LINK]

This numeric field contains the electric chiller’s design condenser water flow rate in cubic meters per second. This field is autosizable. This field is not used for Condenser Type = AirCooled or EvaporativelyCooled.

Field: Chilled Water Inlet Node Name[LINK]

This required alpha field contains the identifying name for the constant COP chiller plant side inlet node.

Field: Chilled Water Outlet Node Name[LINK]

This required alpha field contains the identifying name for the constant COP chiller plant side outlet node.

Field: Condenser Inlet Node Name[LINK]

This alpha field contains the identifying name for the constant COP chiller condenser side inlet node. This node name is required if the chiller is WaterCooled, and optional if the chiller is AirCooled or EvaporativelyCooled. If the chiller is AirCooled or EvaporativelyCooled and a condenser inlet node name is specified here, the node name specified must also be specified in an OutdoorAir:Node object where the height of the node is taken into consideration when calculating outdoor air temperature from the weather data. Alternately, the node name may be specified in an OutdoorAir:NodeList object where the outdoor air temperature is taken directly from the weather data. If the chiller is AirCooled or EvaporativelyCooled and this field is left blank, the program automatically creates an outdoor air node and the air temperature information on this node is taken directly from the weather file (no node height adjustment).

Field: Condenser Outlet Node Name[LINK]

This alpha field contains the identifying name for the constant COP chiller condenser side outlet node. This node name is required if the chiller is WaterCooled, and optional if the chiller is AirCooled or EvaporativelyCooled. If the chiller is AirCooled or EvaporativelyCooled and this field is left blank, the program automatically creates a condenser side outlet air node.

Field: Condenser Type[LINK]

This alpha field determines what type of condenser will be modeled with this chiller. The 3 type of condensers are AirCooled, WaterCooled, and EvaporativelyCooled with the default being AirCooled if not specified. AirCooled and EvaporativelyCooled do not require a CondenserLoop to be specified, whereas the WaterCooled option requires the full specification of the CondenserLoop and its associated equipment.

Field: Chiller Flow Mode[LINK]

This choice field determines how the chiller operates with respect to the intended fluid flow through the device’s evaporator. There are three different choices for specifying operating modes for the intended flow behavior: “NotModulated,” “ConstantFlow,” and “LeavingSetpointModulated.” NotModulated is useful for either variable or constant speed pumping arrangements where the chiller is passive in the sense that although it makes a nominal request for its design flow rate it can operate at varying flow rates. ConstantFlow is useful for constant speed pumping arrangements where the chiller’s request for flow is stricter and can increase the overall loop flow. LeavingSetpointModulated changes the chiller model to internally vary the flow rate so that the temperature leaving the chiller matches a setpoint. In all cases the operation of the external plant system can also impact the flow through the chiller – for example if the relative sizes and operation are such that flow is restricted and the requests cannot be met. The default, if not specified, is NotModulated.

Field: Sizing Factor[LINK]

This optional numeric field allows the user to specify a sizing factor for this component. The sizing factor is used when the component design inputs are autosized: the autosizing calculations are performed as usual and the results are multiplied by the sizing factor. For this component the inputs that would be altered by the sizing factor are: Nominal Capacity, Design Chilled Water Flow Rate and Design Condenser Water Flow Rate. Sizing Factor allows the user to size a component to meet part of the design load while continuing to use the autosizing feature.

Field: Basin Heater Capacity[LINK]

This numeric field contains the capacity of the chiller’s electric basin heater in watts per degree Kelvin. This field only applies for Condenser Type = EvaporativelyCooled. This field is used in conjunction with the Basin Heater Setpoint Temperature described in the following field. The basin heater electric power is equal to this field multiplied by the difference between the basin heater set point temperature and the outdoor dry-bulb temperature. The basin heater only operates when the chiller is off, regardless of the basin heater schedule described below. The basin heater capacity must be greater than or equal to zero, with a default value of zero if this field is left blank.

Field: Basin Heater Setpoint Temperature[LINK]

This numeric field contains the set point temperature (˚C) for the basin heater described in the previous field. This field only applies for Condenser Type = EvaporativelyCooled. The basin heater is active when the outdoor air dry-bulb temperature falls below this setpoint temperature, as long as the chiller is off. This set point temperature must be greater than or equal to 2˚C, and the default value is 2˚C if this field is left blank.

Field: Basin Heater Operating Schedule Name[LINK]

This alpha field contains the name of the basin heater operating schedule. This field only applies for Condenser Type = EvaporativelyCooled. The basin heater operating schedule is assumed to be an on/off schedule and the heater is available to operate any time the schedule value is greater than 0. The basin heater operates when scheduled on and the outdoor air dry-bulb temperature is below the set point temperature described in the previous field. If this field is left blank, the basin heater is available to operate throughout the simulation. Regardless of this schedule, the basin heater may only operate when the chiller is off.

An example of this statement in an IDF is:

Chiller:ConstantCOP, Little Chiller,
          25000,             ! Nominal Capacity [W]
          2.5,               ! COP
          0.0011,            ! Design Chilled Water Flow Rate [m3/s]
          0.0011,            ! Design Condenser Water Flow Rate [m3/s]
          Little Chiller Inlet Node, Little Chiller Outlet Node,
          Little Chiller Condenser Inlet Node, Little Chiller Condenser Outlet Node,
          WaterCooled,
          VariableFlow;


  Chiller:ConstantCOP,
      Little Chiller,          !- Name
      25000,                   !- Nominal Capacity {W}
      2.5,                     !- Nominal COP {W/W}
      0.0011,                  !- Design Chilled Water Flow Rate {m3/s}
      0.0011,                  !- Design Condenser Water Flow Rate {m3/s}
      Little Chiller Inlet Node,   !- Chilled Water Inlet Node Name
      Little Chiller Outlet Node,  !- Chilled Water Outlet Node Name
      Little Chiller Condenser Inlet Node,   !- Condenser Inlet Node Name
      Little Chiller Condenser Outlet Node,  !- Condenser Outlet Node Name
      EvaporativelyCooled,                   !- Condenser Type
      VariableFlow,            !- Chiller Flow Mode
      ,                        !- Sizing Factor
      450;                     !- Basin Heater Capacity {W/K}

Outputs[LINK]

  • HVAC,Average,Chiller Electric Power [W]

  • HVAC,Sum,Chiller Electric Energy [J]

  • Zone,Meter,Electricity:Plant [J]

  • Zone,Meter,Cooling:Electricity [J]

  • HVAC,Average,Chiller Evaporator Cooling Rate [W]

  • HVAC,Sum,Chiller Evaporator Cooling Energy [J]

  • Zone,Meter,EnergyTransfer:Plant [J]

  • Zone,Meter,Chillers:EnergyTransfer [J]

  • HVAC,Average,Chiller Evaporator Inlet Temperature [C]

  • HVAC,Average,Chiller Evaporator Outlet Temperature [C]

  • HVAC,Average,Chiller Evaporator Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller Condenser Heat Transfer Rate [W]

  • HVAC,Sum,Chiller Condenser Heat Transfer Energy [J]

  • Zone,Meter,HeatRejection:EnergyTransfer [J]

Air-cooled or Evap-cooled:

  • HVAC,Average,Chiller Condenser Inlet Temperature [C]

Evap-cooled:

  • HVAC,Average,Chiller Basin Heater Electric Power [W]

  • HVAC,Average,Chiller Basin Heater Electric Energy [J]

Water-cooled:

  • HVAC,Average,Chiller Condenser Inlet Temperature [C]

  • HVAC,Average,Chiller Condenser Outlet Temperature [C]

  • HVAC,Average,Chiller Condenser Mass Flow Rate [kg/s]

These chiller output variables are defined above under “Generic Chiller Outputs.”

Chiller:Electric[LINK]

This chiller model is the empirical model from the Building Loads and System Thermodynamics (BLAST) program. Capacity, power, and full load are each defined by a set of performance curves (quadratics). Chiller performance curves are generated by fitting catalog data to third order polynomial equations. The nominal inputs and curves described below are combined as follows to calculate the chiller power:

Power=FracFullLoadPowerFullLoadPowerRatAvailToNominalCapacityRatioNominalCapacityCOP

where:

NominalCapacity = Nominal Capacity field

COP = COP field

AvailToNominalCapacityRatio = the result of the Capacity Ratio Curve

FullLoadPowerRat = the result of the Power Ratio Curve

FracFullLoadPower = the result of the Full Load Ratio Curve

Inputs[LINK]

Field: Name[LINK]

This alpha field contains the identifying name for the electric chiller.

Field: Condenser Type[LINK]

This alpha field determines what type of condenser will be modeled with this chiller. The 3 type of condensers are AirCooled, WaterCooled, and EvaporativelyCooled with the default being AirCooled if not specified. AirCooled and EvaporativelyCooled do not require a Condenser Loop to be specified, where the WaterCooled option requires the full specification of the Condenser Loop and its associated equipment.

Field: Nominal Capacity[LINK]

This numeric field contains the nominal cooling capability of the chiller in Watts.

Field: Nominal COP[LINK]

This numeric field contains the chiller’s coefficient of performance. For a water-cooled chiller, this number does not include energy use due to condenser pumps and/or fans. For an air-cooled or evap-cooled chiller, this number includes condenser fan power.

Field: Chilled Water Inlet Node Name[LINK]

This required alpha field contains the identifying name for the electric chiller plant side inlet node.

Field: Chilled Water Outlet Node Name[LINK]

This required alpha field contains the identifying name for the electric chiller plant side outlet node.

Field: Condenser Inlet Node Name[LINK]

This alpha field contains the identifying name for the electric chiller condenser side inlet node. This node name is required if the chiller is WaterCooled, and optional if the chiller is AirCooled or EvaporativelyCooled. If the chiller is AirCooled or EvaporativelyCooled and a condenser inlet node name is specified here, the node name specified must also be specified in an OutdoorAir:Node object where the height of the node is taken into consideration when calculating outdoor air temperature from the weather data. Alternately, the node name may be specified in an OutdoorAir:NodeList object where the outdoor air temperature is taken directly from the weather data. If the chiller is AirCooled or EvaporativelyCooled and this field is left blank, the program automatically creates an outdoor air node and the air temperature information on this node is taken directly from the weather file (no node height adjustment).

Field: Condenser Outlet Node Name[LINK]

This alpha field contains the identifying name for the electric chiller condenser side outlet node. This node name is required if the chiller is WaterCooled, and optional if the chiller is AirCooled or EvaporativelyCooled. If the chiller is AirCooled or EvaporativelyCooled and this field is left blank, the program automatically creates a condenser side outlet air node.

Field: Minimum Part Load Ratio[LINK]

This numeric field contains the electric chiller’s minimum part load ratio. The expected range is between 0 and 1. The minimum part load is not the load where the machine shuts off, but where the amount of power remains constant to produce smaller loads than this fraction.

Field: Maximum Part Load Ratio[LINK]

This numeric field contains the electric chiller’s maximum part load ratio. This value may exceed 1, but the normal range is between 0 and 1.1.

Field: Optimum Part Load Ratio[LINK]

This numeric field contains the electric chiller’s optimum part load ratio. This is the part load ratio at which the chiller performs at its maximum COP.

Field: Design Condenser Inlet Temperature[LINK]

This numeric field contains the electric chiller’s condenser inlet design temperature in Celsius.

Field: Temperature Rise Coefficient[LINK]

This numeric field contains the electric chiller’s temperature rise coefficient which is defined as the ratio of the required change in condenser water temperature to a given change in chilled water temperature, which maintains the capacity at the nominal value. This is calculated as the following ratio:

TCEntrequiredTCEntratedTELvrequiredTELvrated

where:

TCEntrequired = Required entering condenser air or water temperature to maintain rated capacity.

TCEntrated = Rated entering condenser air or water temperature at rated capacity.

TELvrequired = Required leaving evaporator water outlet temperature to maintain rated capacity.

TELvrated = Rated leaving evaporator water outlet temperature at rated capacity.

Field: Design Chilled Water Outlet Temperature[LINK]

This numeric field contains the electric chiller’s evaporator outlet design temperature in Celsius.

Field: Design Chilled Water Flow Rate[LINK]

For variable volume chiller this is the maximum flow and for constant flow chiller this is the design flow rate. The units are in cubic meters per second.

Field: Design Condenser Fluid Flow Rate[LINK]

This numeric field contains the electric chiller’s design condenser water flow rate in cubic meters per second. This field is autosizable. This field is also used to enter the air flow rate if the Condenser Type = AirCooled or EvaporativelyCooled and Heat Recovery is specified.

Capacity Ratio Curve[LINK]

The Capacity Ratio Curve is a quadratic equation that determines the Ratio of Available Capacity to Nominal Capacity. The defining equation is:

AvailToNominalCapacityRatio=C1+C2Δtemp+C3Δ2temp

Where the Delta Temperature is defined as:

ΔTemp=TempCondInTempCondInDesignTempRiseCoefficient(TempEvapOutTempEvapOutDesign)

TempCondIn = Temperature entering the condenser (water or air temperature depending on condenser type).

TempCondInDesign = Design Condenser Inlet Temperature from User input above.

TempEvapOut = Temperature leaving the evaporator.

TempEvapOutDesign = Design Chilled Water Outlet Temperature from User input above.

TempRiseCoefficient = User Input from above.

The following three fields contain the coefficients for the quadratic equation.

Field: Coefficient 1 of Capacity Ratio Curve[LINK]

This numeric field contains the first coefficient for the capacity ratio curve.

Field: Coefficient 2 of Capacity Ratio Curve[LINK]

This numeric field contains the second coefficient for the capacity ratio curve.

Field: Coefficient 3 of Capacity Ratio Curve[LINK]

This numeric field contains the third coefficient for the capacity ratio curve.

Power Ratio Curve[LINK]

The Power Ratio Curve is a quadratic equation that determines the Ratio of Full Load Power at Available Capacity to Full Load Power at Nominal Capacity. The defining equation is:

FullLoadPowerRatio=C1+C2AvailToNominalCapRatio+C3AvailToNominalCapRatio2 The following three fields contain the coefficients for the quadratic equation.

Field: Coefficient1 of the power ratio curve[LINK]

This numeric field contains the first coefficient for the power ratio curve.

Field: Coefficient 2 of Power Ratio Curve[LINK]

This numeric field contains the second coefficient for the power ratio curve.

Field: Coefficient 3 of Power Ratio Curve[LINK]

This numeric field contains the third coefficient for the power ratio curve.

Full Load Ratio Curve[LINK]

The Full Load Ratio Curve is a quadratic equation that determines the fraction of full load power. The defining equation is:

FracFullLoadPower=C1+C2PartLoadRatio+C3PartLoadRatio2

The following three fields contain the coefficients for the quadratic equation.

Field: Coefficient 1 of Full Load Ratio Curve[LINK]

This numeric field contains the first coefficient for the full load ratio curve.

Field: Coefficient 2 of Full Load Ratio Curve[LINK]

This numeric field contains the second coefficient for the full load ratio curve.

Field: Coefficient 3 of Full Load Ratio Curve[LINK]

This numeric field contains the third coefficient for the full load ratio curve.

Field: Chilled Water Outlet Temperature Lower Limit[LINK]

This numeric field contains the lower limit for the evaporator outlet temperature. This temperature acts as a cut off for heat transfer in the evaporator, so that the fluid doesn’t get too cold.

Field: Chiller Flow Mode[LINK]

This choice field determines how the chiller operates with respect to the intended fluid flow through the device’s evaporator. There are three different choices for specifying operating modes for the intended flow behavior: “NotModulated,” “ConstantFlow,” and “LeavingSetpointModulated.” NotModulated is useful for either variable or constant speed pumping arrangements where the chiller is passive in the sense that although it makes a nominal request for its design flow rate it can operate at varying flow rates. ConstantFlow is useful for constant speed pumping arrangements where the chiller’s request for flow is stricter and can increase the overall loop flow. LeavingSetpointModulated changes the chiller model to internally vary the flow rate so that the temperature leaving the chiller matches a setpoint. In all cases the operation of the external plant system can also impact the flow through the chiller – for example if the relative sizes and operation are such that flow is restricted and the requests cannot be met. The default, if not specified, is NotModulated.

Field: Design Heat Recovery Water Flow Rate[LINK]

This is the design flow rate used if the heat recovery option is being simulated. If this value is greater than 0.0 then a heat recovery loop must be specified and attached to the chiller using the next 2 node fields. To determine how the heat recovery algorithm works look at the Engineering Manual at the Chiller:Electric with Heat Recovery section. The units are in cubic meters per second. This field is autosizable. When autosizing, the flow rate is simply the product of the design condenser flow rate and the condenser heat recovery relative capacity fraction set in the field below. Note that heat recovery is only available with Condenser Type = WaterCooled.

Field: Heat Recovery Inlet Node Name[LINK]

This alpha field contains the identifying name for the electric chiller heat recovery side inlet node. A heat recovery loop must be specified.

Field: Heat Recovery Outlet Node Name[LINK]

This alpha field contains the identifying name for the electric chiller heat recovery side outlet node. A heat recovery loop must be specified.

Field: Sizing Factor[LINK]

This optional numeric field allows the user to specify a sizing factor for this component. The sizing factor is used when the component design inputs are autosized: the autosizing calculations are performed as usual and the results are multiplied by the sizing factor. For this component the inputs that would be altered by the sizing factor are: Nominal Capacity, Design Chilled Water Flow Rate and Design Condenser Water Flow Rate. Sizing Factor allows the user to size a component to meet part of the design load while continuing to use the autosizing feature.

Field: Basin Heater Capacity[LINK]

This numeric field contains the capacity of the chiller’s electric basin heater in watts per degree Kelvin. This field only applies for Condenser Type = EvaporativelyCooled. This field is used in conjunction with the Basin Heater Setpoint Temperature described in the following field. The basin heater electric power is equal to this field multiplied by the difference between the basin heater set point temperature and the outdoor dry-bulb temperature. The basin heater only operates when the chiller is off, regardless of the basin heater schedule described below. The basin heater capacity must be greater than or equal to zero, with a default value of zero if this field is left blank.

Field: Basin Heater Setpoint Temperature[LINK]

This numeric field contains the set point temperature (˚C) for the basin heater described in the previous field. This field only applies for Condenser Type = EvaporativelyCooled. The basin heater is active when the outdoor air dry-bulb temperature falls below this setpoint temperature, as long as the chiller is off. This set point temperature must be greater than or equal to 2˚C, and the default value is 2˚C if this field is left blank.

Field: Basin Heater Operating Schedule Name[LINK]

This alpha field contains the name of the basin heater operating schedule. This field only applies for Condenser Type = EvaporativelyCooled. The basin heater operating schedule is assumed to be an on/off schedule and the heater is available to operate any time the schedule value is greater than 0. The basin heater operates when scheduled on and the outdoor air dry-bulb temperature is below the set point temperature described in the previous field. If this field is left blank, the basin heater is available to operate throughout the simulation. Regardless of this schedule, the basin heater may only operate when the chiller is off.

Field: Condenser Heat Recovery Relative Capacity Fraction[LINK]

This field is optional. It can be used to describe the physical size of the heat recovery portion of a split bundle condenser section. This fraction describes the relative capacity of the heat recovery bundle of a split condenser compared to the nominal, full load heat rejection rate of the chiller. This fraction will be applied to the full heat rejection when operating at nominal capacity and nominal COP to model a capacity limit for the heat rejection. If this field is not entered then the capacity fraction is set to 1.0.

Field: Heat Recovery Inlet High Temperature Limit Schedule Name[LINK]

This field is optional. It can be used to control heat recovery operation of the chiller. The schedule named here should contain temperature values, in C, that describe an upper limit for the return fluid temperatures entering the chiller at the heat recovery inlet node. If the fluid temperature is too high, then the heat recovery will not operate. This is useful to restrict the chiller lift from becoming too high and to avoid overheating the hot water loop. This limit can be used with or without the alternate control using leaving setpoint that is set in the next field.

Field: Heat Recovery Leaving Temperature Setpoint Node Name[LINK]

This field is optional. It can be used to refine the model and controls for heat recovery operation of the chiller. The node named here should have a setpoint placed on it by a setpoint manager. If the plant loop’s demand calculation scheme is set to SingleSetpoint, then a single setpoint manager should be used. If the plant loop’s demand calculation is set to DualSetpointDeadband then a dual setpoint manager should be used and the upper setpoint is used for control. When this field is used, a different model is used for determining the distribution of rejected heat between the two bundles that is more appropriate for series bundle arrangements and for chiller’s that are able to produce relatively higher temperature heated fluids.

An example of this statement in an IDF is:

Chiller:Electric,
      Big Chiller,             !- Chiller Name
      WaterCooled,             !- Condenser Type
      100000,                  !- Nominal Capacity {W}
      2.75,                    !- COP
      Big Chiller Inlet Node,  !- Chilled Water Inlet Node Name
      Big Chiller Outlet Node, !- Chilled Water Outlet Node Name
      Big Chiller Condenser Inlet Node,  !- Condenser Inlet Node Name
      Big Chiller Condenser Outlet Node,  !- Condenser Outlet Node Name
      .15,                     !- Minimum Part Load Ratio
      1.0,                     !- Maximum Part Load Ratio
      .65,                     !- Optimum Part Load Ratio
      29.44,                   !- Design Condenser Inlet Temperature {C}
      2.682759,                !- Temperature Rise Coefficient
      6.667,                   !- Design Chilled Water Outlet Temperature {C}
      0.0011,                  !- Design Chilled Water Flow Rate {m3/s}
      0.0005,                  !- Design Condenser Water Flow Rate {m3/s}
      0.94483600,              !- Coefficient 1 of Capacity Ratio Curve
      -.05700880,              !- Coefficient 2 of Capacity Ratio Curve
      -.00185486,              !- Coefficient 3 of Capacity Ratio Curve
      1.907846,                !- Coefficient 1 of Power Ratio Curve
      -1.20498700,             !- Coefficient 2 of Power Ratio Curve
      0.26346230,              !- Coefficient 3 of Power Ratio Curve
      0.03303,                 !- Coefficient 1 of Full Load Ratio Curve
      0.6852,                  !- Coefficient 2 of Full Load Ratio Curve
      0.2818,                  !- Coefficient 3 of Full Load Ratio Curve
      5,                       !- Chilled Water Outlet Temperature Lower Limit {C}
      VariableFlow;            !- Chiller Flow Mode

An example of an Air-Cooled Chiller:

Chiller:Electric,
      Big Chiller,             !- Chiller Name
      AirCooled,              !- Condenser Type
      100000,                  !- Nominal Capacity {W}
      2.58,                    !- COP
      Big Chiller Inlet Node,  !- Chilled Water Inlet Node Name
      Big Chiller Outlet Node, !- Chilled Water Outlet Node Name
      Big Chiller Condenser Inlet Node,  !- Condenser Inlet Node Name
      Big Chiller Condenser Outlet Node,  !- Condenser Outlet Node Name
      .05,                     !- Minimum Part Load Ratio
      1.0,                     !- Maximum Part Load Ratio
      .65,                     !- Optimum Part Load Ratio
      35.0,                    !- Design Condenser Inlet Temperature {C}
      2.778,                   !- Temperature Rise Coefficient
      6.67,                    !- Design Chilled Water Outlet Temperature {C}
      0.0011,                  !- Design Chilled Water Flow Rate {m3/s}
      0.002,                   !- Design Condenser Water Flow Rate {m3/s}
      0.9949,                  !- Coefficient 1 of Capacity Ratio Curve
      -0.045954,               !- Coefficient 2 of Capacity Ratio Curve
      -0.0013543,              !- Coefficient 3 of Capacity Ratio Curve
      2.333,                   !- Coefficient 1 of Power Ratio Curve
      -1.975,                  !- Coefficient 2 of Power Ratio Curve
      0.6121,                  !- Coefficient 3 of Power Ratio Curve
      0.03303,                 !- Coefficient 1 of Full Load Ratio Curve
      0.6852,                  !- Coefficient 2 of Full Load Ratio Curve
      0.2818,                  !- Coefficient 3 of Full Load Ratio Curve
      5,                       !- Chilled Water Outlet Temperature Lower Limit {C}
      VariableFlow;            !- Chiller Flow Mode

  OutdoorAir:Node,
      Big Chiller Condenser Inlet Node,  !- Node Name
      -1.0;                    !- Height Above Ground {m}

An example of an Evaporatively-Cooled Chiller:

Chiller:Electric,
      Big Chiller,             !- Name
      EvaporativelyCooled,               !- Condenser Type
      100000,                  !- Nominal Capacity {W}
      2.58,                    !- Nominal COP
      Big Chiller Inlet Node,  !- Chilled Water Inlet Node Name
      Big Chiller Outlet Node, !- Chilled Water Outlet Node Name
      Big Chiller Condenser Inlet Node,  !- Condenser Inlet Node Name
      Big Chiller Condenser Outlet Node,  !- Condenser Outlet Node Name
      0.05,                    !- Minimum Part Load Ratio
      1.0,                     !- Maximum Part Load Ratio
      0.65,                    !- Optimum Part Load Ratio
      35.0,                    !- Design Condenser Inlet Temperature {C}
      2.778,                   !- Temperature Rise Coefficient
      6.67,                    !- Design Chilled Water Outlet Temperature {C}
      0.0011,                  !- Design Chilled Water Flow Rate {m3/s}
      0.002,                   !- Design Condenser Water Flow Rate {m3/s}
      0.9949,                  !- Coefficient 1 of Capacity Ratio Curve
      -0.045954,               !- Coefficient 2 of Capacity Ratio Curve
      -0.0013543,              !- Coefficient 3 of Capacity Ratio Curve
      2.333,                   !- Coefficient 1 of Power Ratio Curve
      -1.975,                  !- Coefficient 2 of Power Ratio Curve
      0.6121,                  !- Coefficient 3 of Power Ratio Curve
      0.03303,                 !- Coefficient 1 of Full Load Ratio Curve
      0.6852,                  !- Coefficient 2 of Full Load Ratio Curve
      0.2818,                  !- Coefficient 3 of Full Load Ratio Curve
      5,                       !- Chilled Water Outlet Temperature Lower Limit {C}
      VariableFlow,            !- Chiller Flow Mode
      ,                        !- Design Heat Recovery Water Flow Rate {m3/s}
      ,                        !- Heat Recovery Inlet Node Name
      ,                        !- Heat Recovery Outlet Node Name
      ,                        !- Sizing Factor
      450,                     !- Basin Heater Capacity {W/K}
      3,                       !- Basin Heater Setpoint Temperature {C}
      Basin heater sch;        !- Basin Heater Operating Schedule Name

    OutdoorAir:Node,
      Big Chiller Condenser Inlet Node,  !- Name
      -1.0;                    !- Height Above Ground {m}

An example of a Heat Recovery Chiller:

Chiller:Electric,
      Big Chiller,             !- Chiller Name
      WaterCooled,            !- Condenser Type
      25000,                   !- Nominal Capacity {W}
      2.75,                    !- COP
      Big Chiller Inlet Node,  !- Chilled Water Inlet Node Name
      Big Chiller Outlet Node, !- Chilled Water Outlet Node Name
      Big Chiller Condenser Inlet Node,  !- Condenser Inlet Node Name
      Big Chiller Condenser Outlet Node,  !- Condenser Outlet Node Name
      .15,                     !- Minimum Part Load Ratio
      1.0,                     !- Maximum Part Load Ratio
      .65,                     !- Optimum Part Load Ratio
      29.44,                   !- Design Condenser Inlet Temperature {C}
      2.682759,                !- Temperature Rise Coefficient
      6.667,                   !- Design Chilled Water Outlet Temperature {C}
      0.0011,                  !- Design Chilled Water Flow Rate {m3/s}
      0.0005,                  !- Design Condenser Water Flow Rate {m3/s}
      0.94483600,              !- Coefficient 1 of Capacity Ratio Curve
      -.05700880,              !- Coefficient 2 of Capacity Ratio Curve
      -.00185486,              !- Coefficient 3 of Capacity Ratio Curve
      1.907846,                !- Coefficient 1 of Power Ratio Curve
      -1.20498700,             !- Coefficient 2 of Power Ratio Curve
      0.26346230,              !- Coefficient 3 of Power Ratio Curve
      0.03303,                 !- Coefficient 1 of Full Load Ratio Curve
      0.6852,                  !- Coefficient 2 of Full Load Ratio Curve
      0.2818,                  !- Coefficient 3 of Full Load Ratio Curve
      5,                       !- Chilled Water Outlet Temperature Lower Limit {C}
      VariableFlow,            !- Chiller Flow Mode
      0.00055,                 !- Design heat recovery water flow rate {m3/s}
      Big Chiller Heat Rec Inlet Node,  !- Heat Recovery Inlet Node Name
      Big Chiller Heat Rec Outlet Node;  !- Heat Recovery Outlet Node Name

Outputs[LINK]

  • HVAC,Average,Chiller Electric Power [W]

  • HVAC,Sum,Chiller Electric Energy [J]

  • Zone,Meter,Electricity:Plant [J]

  • Zone,Meter,Cooling:Electricity [J]

  • HVAC,Average,Chiller Evaporator Cooling Rate [W]

  • HVAC,Sum,Chiller Evaporator Cooling Energy [J]

  • Zone,Meter,EnergyTransfer:Plant [J]

  • Zone,Meter,Chillers:EnergyTransfer [J]

  • HVAC,Average,Chiller Evaporator Inlet Temperature [C]

  • HVAC,Average,Chiller Evaporator Outlet Temperature [C]

  • HVAC,Average,Chiller Evaporator Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller COP [W/W]

  • HVAC,Average,Chiller Condenser Heat Transfer Rate [W]

  • HVAC,Sum,Chiller Condenser Heat Transfer Energy [J]

  • Zone,Meter,HeatRejection:EnergyTransfer [J]

Air-cooled or Evap-cooled:

  • HVAC,Average,Chiller Condenser Inlet Temperature [C]

Evap-cooled:

  • HVAC,Average,Chiller Basin Heater Electric Power [W]

  • HVAC,Average,Chiller Basin Heater Electric Energy [J]

Water-cooled:

  • HVAC,Average,Chiller Condenser Inlet Temperature [C]

  • HVAC,Average,Chiller Condenser Outlet Temperature [C]

  • HVAC,Average,Chiller Condenser Mass Flow Rate [kg/s]

HeatRecovery:

  • HVAC,Average,Chiller Total Recovered Heat Rate [W]

  • HVAC,Sum, Chiller Total Recovered Heat Energy [J]

  • HVAC,Average,Chiller Heat Recovery Inlet Temperature [C]

  • HVAC,Average,Chiller Heat Recovery Outlet Temperature [C]

  • HVAC,Average,Chiller Heat Recovery Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller Effective Heat Rejection Temperature [C]

These chiller output variables are defined above under “Generic Chiller Outputs.”

Chiller:Electric:EIR[LINK]

This chiller model is the empirical model used in the DOE-2.1 building energy simulation program. The model uses performance information at reference conditions along with three curve fits for cooling capacity and efficiency to determine chiller operation at off-reference conditions. Chiller performance curves can be generated by fitting manufacturer’s catalog data or measured data. Performance curves for more than 160 chillers, including the default DOE-2.1E reciprocating and centrifugal chillers, are provided in the EnergyPlus Reference DataSets (Chillers.idf and AllDataSets.idf).

Note: Chiller:Electric:EIR objects and their associated performance curve objects are developed using performance information for a specific chiller and should normally be used together for an EnergyPlus simulation. Changing the object input values, or swapping performance curves between chillers, should be done with caution.

Inputs[LINK]

Field: Name[LINK]

This alpha field contains the identifying name for the electric EIR chiller.

Field: Reference Capacity[LINK]

This numeric field contains the reference cooling capacity of the chiller in Watts. This should be the capacity of the chiller at the reference temperatures and water flow rates defined below. Alternately, this field can be autosized.

Field: Reference COP[LINK]

This numeric field contains the chiller’s coefficient of performance. This value should not include energy use due to pumps or cooling tower fans. This COP should be at the reference temperatures and water flow rates defined below. This value should include evap-cooled or air-cooled condenser fans except when the Condenser Fan Power Ratio input field defined below is used and that input value is greater than 0. For the case when condenser fan power is modeled separately, the calculated condenser fan energy is reported on the same electric meter as compressor power. Be careful to not duplicate this energy use.

Field: Reference Leaving Chilled Water Temperature[LINK]

This numeric field contains the chiller’s reference leaving chilled water temperature in Celsius. The default value is 6.67°C.

Field: Reference Entering Condenser Fluid Temperature[LINK]

This numeric field contains the chiller’s reference entering condenser fluid temperature in Celsius. The default value is 29.4°C. For water-cooled chillers this is the water temperature entering the condenser (e.g., leaving the cooling tower). For air- or evap-cooled condensers this is the entering outdoor air dry-bulb or wet-bulb temperature, respectively.

Field: Reference Chilled Water Flow Rate[LINK]

For a variable flow chiller this is the maximum water flow rate and for a constant flow chiller this is the operating water flow rate through the chiller’s evaporator. The units are in cubic meters per second. The minimum value for this numeric input field must be greater than zero, or this field can be autosized.

Field: Reference Condenser Fluid Flow Rate[LINK]

This numeric field contains the chiller’s operating condenser fluid flow rate in cubic meters per second. This field can be autosized. This field is also used to enter the air flow rate if Condenser Type = AirCooled or EvaporativelyCooled and Heat Recovery is specified. If AirCooled or EvaporativelyCooled and this field is autosized, the air flow rate is set to 0.000114 m3/s/W (850 cfm/ton) multiplied by the chiller Reference Capacity. For air- and evaporatively-cooled condensers, this flow rate is used to set condenser outlet air node conditions and used for evaporatively-cooled condensers to calculate water use rate.

Field: Cooling Capacity Function of Temperature Curve Name[LINK]

The name of a biquadratic performance curve (ref: Performance Curves) that parameterizes the variation of the cooling capacity as a function of the leaving chilled water temperature and the entering condenser fluid temperature. The output of this curve is multiplied by the reference capacity to give the cooling capacity at specific temperature operating conditions (i.e., at temperatures different from the reference temperatures). The curve should have a value of 1.0 at the reference temperatures and flow rates specified above. The biquadratic curve should be valid for the range of water temperatures anticipated for the simulation.

Field: Electric Input to Cooling Output Ratio Function of Temperature Curve Name[LINK]

The name of a biquadratic performance curve (ref: Performance Curves) that parameterizes the variation of the energy input to cooling output ratio (EIR) as a function of the leaving chilled water temperature and the entering condenser fluid temperature. The EIR is the inverse of the COP. The output of this curve is multiplied by the reference EIR (inverse of the reference COP) to give the EIR at specific temperature operating conditions (i.e., at temperatures different from the reference temperatures). The curve should have a value of 1.0 at the reference temperatures and flow rates specified above. The biquadratic curve should be valid for the range of water temperatures anticipated for the simulation.

Field: Electric Input to Cooling Output Ratio Function of Part Load Ratio Curve Name[LINK]

The name of a quadratic performance curve (ref: Performance Curves) that parameterizes the variation of the energy input ratio (EIR) as a function of the part-load ratio (EIRfTPLR). The EIR is the inverse of the COP, and the part-load ratio is the actual cooling load divided by the chiller’s available cooling capacity. This curve is generated by dividing the operating electric input power by the available full-load capacity (do not divide by load) at the specific operating temperatures. The curve output should decrease from 1 towards 0 as part-load ratio decreases from 1 to 0. The output of this curve is multiplied by the reference full-load EIR (inverse of the reference COP) and the Energy Input to Cooling Output Ratio Function of Temperature Curve to give the EIR at the specific temperatures and part-load ratio at which the chiller is operating. This curve should have a value of 1.0 when the part-load ratio equals 1.0. An ideal chiller with the same efficiency at all part-load ratio’s would use a performance curve that has a value of 0 when the part-load ratio equals 0 (i.;e., a line connecting 0,0 and 1,1 when plotted as EIRfTPLR versus PLR), however, actual systems can have part-load EIR’s slightly above or below this line (i.e., part-load efficiency often differs from rated efficiency). The quadratic curve should be valid for the range of part-load ratios anticipated for the simulation.

Field: Minimum Part Load Ratio[LINK]

This numeric field contains the chiller’s minimum part-load ratio. The expected range is between 0 and 1. Below this part-load ratio, the compressor cycles on and off to meet the cooling load. The Minimum Part Load Ratio must be less than or equal to the Maximum Part Load Ratio. The default value is 0.1.

Field: Maximum Part Load Ratio[LINK]

This numeric field contains the chiller’s maximum part-load ratio. This value may exceed 1, but the normal range is between 0 and 1.0. The Maximum Part Load Ratio must be greater than or equal to the Minimum Part Load Ratio. The default value is 1.0.

Field: Optimum Part Load Ratio[LINK]

This numeric field contains the chiller’s optimum part-load ratio. This is the part-load ratio at which the chiller performs at its maximum COP. The optimum part-load ratio must be greater than or equal to the Minimum Part Load Ratio, and less than or equal to the Maximum Part Load Ratio. The default value is 1.0.

Field: Minimum Unloading Ratio[LINK]

This numeric field contains the chiller’s minimum unloading ratio. The expected range is between 0 and 1. The minimum unloading ratio is where the chiller capacity can no longer be reduced by unloading and must be false loaded to meet smaller cooling loads. A typical false loading strategy is hot-gas bypass. The minimum unloading ratio must be greater than or equal to the Minimum Part Load Ratio, and less than or equal to the Maximum Part Load Ratio. The default value is 0.2.

Field: Chilled Water Inlet Node Name[LINK]

This required alpha field contains the identifying name for the chiller plant side (chilled water) inlet node.

Field: Chilled Water Outlet Node Name[LINK]

This required alpha field contains the identifying name for the chiller plant side (chilled water) outlet node.

Field: Condenser Inlet Node Name[LINK]

This alpha field contains the identifying name for the chiller condenser side inlet node. This node name is required if the chiller is WaterCooled, and optional if the chiller is AirCooled or EvaporativelyCooled. If the chiller is AirCooled or EvaporativelyCooled and a condenser inlet node name is specified here, the node name specified must also be specified in an OutdoorAir:Node object where the height of the node is taken into consideration when calculating outdoor air temperature from the weather data. Alternately, the node name may be specified in an OutdoorAir:NodeList object where the outdoor air temperature is taken directly from the weather data. If the chiller is AirCooled or EvaporativelyCooled and this field is left blank, the program automatically creates an outdoor air node and the air temperature information on this node is taken directly from the weather file (no node height adjustment).

Field: Condenser Outlet Node Name[LINK]

This alpha field contains the identifying name for the chiller condenser side outlet node. This node name is required if the chiller is WaterCooled, and optional if the chiller is AirCooled or EvaporativelyCooled. If the chiller is AirCooled or EvaporativelyCooled and this field is left blank, the program automatically creates a condenser side outlet air node.

Field: Condenser Type[LINK]

This alpha field determines what type of condenser will be modeled with this chiller. Valid condenser types are AirCooled, WaterCooled, and EvaporativelyCooled with the default being WaterCooled if not specified. AirCooled and EvaporativelyCooled do not require a Condenser Loop to be specified, whereas the WaterCooled option requires the full specification of the Condenser Loop and its associated equipment.

Field: Condenser Fan Power Ratio[LINK]

This field is used to model condenser fan power associated with air-cooled or evaporatively-cooled condensers (for cooling towers, refer to Group - Condenser Equipment). Enter the ratio of the condenser fan power to the reference chiller cooling capacity in W/W. If this input is greater than 0, the condenser fan power is modeled seperatly from compressor power. In addition, if condenser fan power is modeled using this input, the reference COP and “Electric Input to Cooling Output Ratio Function of” performance curves should not include condenser fan power.

Field: Fraction of Compressor Electric Power Rejected by Condenser[LINK]

This numeric input represents the fraction of compressor electrical energy consumption that must be rejected by the condenser. Enter a value of 1.0 when modeling hermetic chillers. For open chillers, enter the compressor motor efficiency. This value must be greater than 0.0 and less than or equal to 1.0, with a default value of 1.0.

Field: Leaving Chilled Water Lower Temperature Limit[LINK]

This numeric field contains the lower limit for the leaving chilled water temperature in Celsius. This temperature acts as a cut off for heat transfer in the evaporator, so that the fluid doesn’t get too cold. This input field is currently unused. The default value is 2°C.

Field: Chiller Flow Mode[LINK]

This choice field determines how the chiller operates with respect to the intended fluid flow through the device’s evaporator. There are three different choices for specifying operating modes for the intended flow behavior: “NotModulated,” “ConstantFlow,” and “LeavingSetpointModulated.” NotModulated is useful for either variable or constant speed pumping arrangements where the chiller is passive in the sense that although it makes a nominal request for its design flow rate it can operate at varying flow rates. ConstantFlow is useful for constant speed pumping arrangements where the chiller’s request for flow is stricter and can increase the overall loop flow. LeavingSetpointModulated changes the chiller model to internally vary the flow rate so that the temperature leaving the chiller matches a setpoint. In all cases the operation of the external plant system can also impact the flow through the chiller – for example if the relative sizes and operation are such that flow is restricted and the requests cannot be met. The default, if not specified, is NotModulated.

Field: Design Heat Recovery Water Flow Rate[LINK]

This is the design heat recovery water flow rate if the heat recovery option is being simulated. If this value is greater than 0.0 (or Autosize), a heat recovery loop must be specified and attached to the chiller using the next two node fields. The units are in cubic meters per second. This field is autosizable. When autosizing, the flow rate is simply the product of the design condenser flow rate and the condenser heat recovery relative capacity fraction set in the field below. Note that heat recovery is only available with Condenser Type = WaterCooled.

Field: Heat Recovery Inlet Node Name[LINK]

This alpha field contains the identifying name for the chiller heat recovery side inlet node. If the user wants to model chiller heat recovery, a heat recovery loop must be specified.

Field: Heat Recovery Outlet Node Name[LINK]

This alpha field contains the identifying name for the chiller heat recovery side outlet node. If the user wants to model chiller heat recovery, a heat recovery loop must be specified.

Field: Sizing Factor[LINK]

This optional numeric field allows the user to specify a sizing factor for this component. The sizing factor is used when the component design inputs are autosized: the autosizing calculations are performed as usual and the results are multiplied by the sizing factor. For this component the inputs that would be altered by the sizing factor are: Reference Capacity, Reference Chilled Water Flow Rate and Reference Condenser Water Flow Rate. Sizing Factor allows the user to size a component to meet part of the design load while continuing to use the autosizing feature.

Field: Basin Heater Capacity[LINK]

This numeric field contains the capacity of the chiller’s electric basin heater in watts per degree Kelvin. This field only applies for Condenser Type = EvaporativelyCooled. This field is used in conjunction with the Basin Heater Setpoint Temperature described in the following field. The basin heater electric power is equal to this field multiplied by the difference between the basin heater set point temperature and the outdoor dry-bulb temperature. The basin heater only operates when the chiller is off, regardless of the basin heater schedule described below. The basin heater capacity must be greater than or equal to zero, with a default value of zero if this field is left blank.

Field: Basin Heater Setpoint Temperature[LINK]

This numeric field contains the set point temperature (˚C) for the basin heater described in the previous field. This field only applies for Condenser Type = EvaporativelyCooled. The basin heater is active when the outdoor air dry-bulb temperature falls below this setpoint temperature, as long as the chiller is off. This set point temperature must be greater than or equal to 2˚C, and the default value is 2˚C if this field is left blank.

Field: Basin Heater Operating Schedule Name[LINK]

This alpha field contains the name of the basin heater operating schedule. This field only applies for Condenser Type = EvaporativelyCooled. The basin heater operating schedule is assumed to be an on/off schedule and the heater is available to operate any time the schedule value is greater than 0. The basin heater operates when scheduled on and the outdoor air dry-bulb temperature is below the set point temperature described in the previous field. If this field is left blank, the basin heater is available to operate throughout the simulation. Regardless of this schedule, the basin heater may only operate when the chiller is off.

Field: Condenser Heat Recovery Relative Capacity Fraction[LINK]

This field is optional. It can be used to describe the physical size of the heat recovery portion of a split bundle condenser section. This fraction describes the relative capacity of the heat recovery bundle of a split condenser compared to the nominal, full load heat rejection rate of the chiller. This fraction will be applied to the full heat rejection when operating at nominal capacity and nominal COP to model a capacity limit for the heat rejection. If this field is not entered then the capacity fraction is set to 1.0.

Field: Heat Recovery Inlet High Temperature Limit Schedule Name[LINK]

This field is optional. It can be used to control heat recovery operation of the chiller. The schedule named here should contain temperature values, in C, that describe an upper limit for the return fluid temperatures entering the chiller at the heat recovery inlet node. If the fluid temperature is too high, then the heat recovery will not operate. This is useful to restrict the chiller lift from becoming too high and to avoid overheating the hot water loop. This limit can be used with or without the alternate control using leaving setpoint that is set in the next field.

Field: Heat Recovery Leaving Temperature Setpoint Node Name[LINK]

This field is optional. It can be used to refine the model and controls for heat recovery operation of the chiller. The node named here should have a setpoint placed on it by a setpoint manager. If the plant loop’s demand calculation scheme is set to SingleSetpoint, then a single setpoint manager should be used. If the plant loop’s demand calculation is set to DualSetpointDeadband then a dual setpoint manager should be used and the upper setpoint is used for control. When this field is used, a different model is used for determining the distribution of rejected heat between the two bundles that is more appropriate for series bundle arrangements and for chiller’s that are able to produce relatively higher temperature heated fluilds.

An example of this statement in an IDF is:

! ElectricEIRChiller DOE-2 Centrifugal/5.50COP
  ! A generic centrifugal chiller from DOE-2.1E
  !
  Chiller:Electric:EIR,
   DOE-2 Centrifugal/5.50COP,  !- Chiller Name
   Autosize,                   !- Reference Capacity {W}
   5.5,                        !- Reference COP {W/W}
   6.67,                       !- Reference Leaving Chilled Water Temperature {C}
   29.4,                       !- Reference Entering Condenser Fluid Temperature {C}
   Autosize,                   !- Reference Chilled Water Flow Rate {m3/s}
   Autosize,                   !- Reference Condenser Water Flow Rate {m3/s}
   DOE-2 Centrifugal/5.50COP CAPFT,  !- Cooling Capacity Function of Temperature Curve
   DOE-2 Centrifugal/5.50COP EIRFT,  !- Electric Input to Cooling Output Ratio Function of
                                        Temperature Curve
   DOE-2 Centrifugal/5.50COP EIRFPLR,!- Electric Input to Cooling Output Ratio Function of Part Load
                                        Ratio Curve
   0.1,                        !- Minimum Part Load Ratio
   1.0,                        !- Maximum Part Load Ratio
   1.0,                        !- Optimum Part Load Ratio
   0.2,                        !- Minimum Unloading Ratio
   Chilled Water Side Inlet Node,        !- Chilled Water Side Inlet Node
   Chilled Water Side Outlet Node,       !- Chilled Water Side Outlet Node
   Condenser Side Inlet Node,  !- Condenser Side Inlet Node
   Condenser Side Outlet Node, !- Condenser Side Outlet Node
   WaterCooled,               !- Condenser Type
   ,                           !- Condenser Fan Power Ratio {W/W}
   1.0,                        !- Fraction of Compressor Electric Power Rejected by Condenser
   2.0,                        !- Leaving Chilled Water Lower Temperature Limit {C}
   ConstantFlow;               !- Chiller Evaporator Flow Mode


  !
  ! Curve set (3 Curves):
  !
  ! Cooling Capacity Function of Temperature Curve for open or hermetic water-cooled centrifugal
    chillers
  ! x = Leaving Chilled Water Temperature and y = Entering Condenser Water Temperature
  ! Same as DOE-2.1E HERM-CENT-CAP-FT (CCAPT3) and OPEN-CENT-CAP-FT (CCAPT1)
   Curve:Biquadratic,
   DOE-2 Centrifugal/5.50COP CAPFT,  !- Name
   0.257896E+00,               !- Coefficient1 Constant
   0.389016E-01,               !- Coefficient2 x
   -0.217080E-03,              !- Coefficient3 x**2
   0.468684E-01,               !- Coefficient4 y
   -0.942840E-03,              !- Coefficient5 y**2
   -0.343440E-03,              !- Coefficient6 x*y
   5.0,                        !- Minimum Value of x
   10.0,                       !- Maximum Value of x
   24.0,                       !- Minimum Value of y
   35.0;                       !- Maximum Value of y
  !
  ! Energy Input to Cooling Output Ratio Function of Temperature Curve for open or hermetic water-
    cooled centrifugal chillers
  ! x = Leaving Chilled Water Temperature and y = Entering Condenser Water Temperature
  ! Same as DOE-2.1E HERM-CENT-EIR-FT (EIRT3) and OPEN-CENT-EIR-FT (EIRT1)
   Curve:Biquadratic,
   DOE-2 Centrifugal/5.50COP EIRFT,  !- Name
   0.933884E+00,               !- Coefficient1 Constant
   -0.582120E-01,              !- Coefficient2 x
   0.450036E-02,               !- Coefficient3 x**2
   0.243000E-02,               !- Coefficient4 y
   0.486000E-03,               !- Coefficient5 y**2
   -0.121500E-02,              !- Coefficient6x*y
   5.0,                        !- Minimum Value of x
   10.0,                       !- Maximum Value of x
   24.0,                       !- Minimum Value of y
   35.0;                       !- Maximum Value of y
  !
  ! Energy Input to Cooling Output Ratio Function of Part Load Ratio Curve for open or hermetic
    water-cooled centrifugal chillers
  ! x = Part Load Ratio (load/capacity)
  ! Same as DOE-2.1E HERM-CENT-EIR-FPLR (EIRPLR3) and OPEN-CENT-EIR-FPLR (EIRPLR1)
   Curve:Quadratic,
   DOE-2 Centrifugal/5.50COP EIRFPLR, !- Name
   0.222903,                   !- Coefficient1 Constant
   0.313387,                   !- Coefficient2 x
   0.463710,                   !- Coefficient3 x**2
   0.0,                        !- Minimum Value of x
   1.0;                        !- Maximum Value of x

Outputs[LINK]

  • HVAC,Average,Chiller Electric Power [W]

  • HVAC,Sum,Chiller Electric Energy [J]

  • Zone,Meter,Electricity:Plant [J]

  • Zone,Meter,Cooling:Electricity [J]

  • HVAC,Average,Chiller Evaporator Cooling Rate [W]

  • HVAC,Sum,Chiller Evaporator Cooling Energy [J]

  • Zone,Meter,EnergyTransfer:Plant [J]

  • Zone,Meter,Chillers:EnergyTransfer [J]

  • HVAC,Average,Chiller Evaporator Inlet Temperature [C]

  • HVAC,Average,Chiller Evaporator Outlet Temperature [C]

  • HVAC,Average,Chiller Evaporator Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller COP [W/W]

  • HVAC,Average,Chiller Condenser Heat Transfer Rate [W]

  • HVAC,Sum,Chiller Condenser Heat Transfer Energy [J]

  • Zone,Meter,HeatRejection:EnergyTransfer [J]

  • HVAC,Average,Chiller Part Load Ratio []

  • HVAC,Average,Chiller Cycling Ratio []

  • HVAC,Average,Chiller False Load Heat Transfer Rate [W]

  • HVAC,Sum,Chiller False Load Heat Transfer Energy [J]

Curve object outputs:

  • HVAC,Average,Chiller Capacity Temperature Modifier Multiplier []

  • HVAC,Average,Chiller EIR Temperature Modifier Multiplier []

  • HVAC,Average,Chiller EIR Part Load Modifier Multiplier []

Air-cooled or Evap-cooled:

  • HVAC,Average,Chiller Condenser Inlet Temperature [C]

Air-cooled or Evap-cooled reported only when the condenser fan power ratio input field is greater than 0:

  • HVAC,Average,Chiller Condenser Fan Electric Power [W]

  • HVAC,Average,Chiller Condenser Fan Electric Consumption [J]

Evap-cooled:

  • HVAC,Average,Chiller Basin Heater Electric Power [W]

  • HVAC,Average,Chiller Basin Heater Electric Energy [J]

  • HVAC,Sum,Chiller Evaporative Condenser Water Volume [m3]

  • HVAC,Sum,Chiller Evaporative Condenser Mains Supply Water Volume [m3]

Water-cooled:

  • HVAC,Average,Chiller Condenser Inlet Temperature [C]

  • HVAC,Average,Chiller Condenser Outlet Temperature [C]

  • HVAC,Average,Chiller Condenser Mass Flow Rate [kg/s]

HeatRecovery:

  • HVAC,Average,Chiller Total Recovered Heat Rate [W]

  • Zone,Meter,HeatRecovery:EnergyTransfer [J]

  • HVAC,Sum,Chiller Heat Recovery [J]

  • HVAC,Average,Chiller Heat Recovery Inlet Temperature [C]

  • HVAC,Average,Chiller Heat Recovery Outlet Temperature [C]

  • HVAC,Average,Chiller Heat Recovery Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller Effective Heat Rejection Temperature [C]

Most of these chiller output variables are defined above under “Generic Chiller Outputs.” Output variables not described above are discussed here.

Chiller Condenser Fan Electric Power [W] [LINK]

Chiller Condenser Fan Electric Energy [J] [LINK]

These outputs are for the electric power consumption of the chiller condenser fan and are applicable to air- or evaporatively-cooled chillers. These reports are available only for the Chiller:Electric:EIR and only when the Condenser Fan Power Ratio input field is greater than 0. This output is also added to a meter object with Resource Type = Electricity, End Use Key = Chillers, Group Key = Plant (Ref. Output:Meter objects).

Chiller Capacity Temperature Modifier Multiplier [] [LINK]

This is the output of the curve object Cooling Capacity Function of Temperature Curve.

Chiller EIR Temperature Modifier Multiplier [] [LINK]

This is the output of the curve object Electric Input to Cooling Output Ratio Function of Temperature Curve.

Chiller EIR Part Load Modifier Multiplier [] [LINK]

This is the output of the curve object Electric Input to Cooling Output Ratio Function of Part Load Curve.

Chiller Part Load Ratio [] [LINK]

This output is the ratio of the evaporator heat transfer rate plus the false load heat transfer rate (if applicable) to the available chiller capacity. This value is used to determine Chiller EIR Part Load Modifier Multiplier.

Chiller Cycling Ratio [] [LINK]

The cycling ratio is the amount of time the chiller operates during each simulation timestep. If the chiller part-load ratio falls below the minimum part-load ratio, the chiller cycles on and off to meet the cooling load.

Chiller False Load Heat Transfer Rate [W] [LINK]

Chiller False Load Heat Transfer Energy [J] [LINK]

These outputs are the heat transfer rate and total heat transfer due to false loading of the chiller. When the chiller part-load ratio is below the minimum unloading ratio, the chiller false loads (e.g. hot-gas bypass) to further reduce capacity. The false load heat transfer output variable is not metered.

Chiller Evaporative Condenser Water Volume [m3] [LINK]

Chiller Evaporative Condenser Mains Supply Water Volume [m3] [LINK]

These outputs are the water use for evaporatively-cooled condensers. When the chiller operates, the water consumed by the evaporatively-cooled condenser is proportional to the chiller condenser heat transfer. The evaporative condenser is assumed to be 100% effective where the condenser inlet air dry-bulb temperature is equal to the outdoor wet-bulb temperature.

Chiller:Electric:ReformulatedEIR[LINK]

This chiller model, developed through the CoolTools™ project sponsored by Pacific Gas and Electric Company (PG&E), is an empirical model similar to EnergyPlus’ Chiller:Electric:EIR model. The model uses performance information at reference conditions along with three curve fits for cooling capacity and efficiency to determine chiller operation at off-reference conditions. The model has the same capabilities as the Chiller:Electric:EIR model, but can potentially provide significant accuracy improvement over the Chiller:Electric:EIR model for variable-speed compressor drive and variable condenser water flow applications. Chiller performance curves can be generated by fitting manufacturer’s catalog data or measured data. Performance curves developed from manufacturer’s performance data are provided in the EnergyPlus Reference DataSets (Chillers.idf and AllDataSets.idf). This chiller model can be used to predict the performance of various chiller types (e.g., reciprocating, screw, scroll, and centrifugal) with water-cooled condensers.

The main difference between this model and the Chiller:Electric:EIR model is the condenser fluid temperature used in the associated performance curves: the Chiller:Electric:ReformulatedEIR model uses the LEAVING condenser water temperature while the Chiller:Electric:EIR model uses the ENTERING condenser water temperature.

Note: Chiller:Electric:Reformulated EIR objects and their associated performance curve objects are developed using performance information for a specific chiller and should almost always be used together for an EnergyPlus simulation. Changing the object input values, or swapping performance curves between chillers, should be done with extreme caution. For example, if the user wishes to model a chiller size that is different from the reference capacity, it is highly recommended that the reference flow rates be scaled proportionately to the change in reference capacity. Although this model can provide more accurate prediction than the Chiller:Electric:EIR model, it requires more performance data to develop the associated performance curves (at least 12 points from full-load performance and 7 points from part-load performance).

Inputs[LINK]

Field: Chiller Name[LINK]

This alpha field contains the identifying name for this chiller.

Field: Reference Capacity[LINK]

This numeric field contains the reference cooling capacity of the chiller in Watts. This should be the capacity of the chiller at the reference temperatures and water flow rates defined below. Alternately, this field can be autosized.

Field: Reference COP[LINK]

This numeric field contains the chiller’s coefficient of performance. This value should not include energy use due to pumps or cooling tower fans. This COP should be at the reference temperatures and water flow rates defined below.

Field: Reference Leaving Chilled Water Temperature[LINK]

This numeric field contains the chiller’s reference leaving chilled water temperature in Celsius. The default value is 6.67°C.

Field: Reference Leaving Condenser Water Temperature[LINK]

This numeric field contains the chiller’s reference leaving condenser water temperature in Celsius. The default value is 35°C.

Field: Reference Chilled Water Flow Rate[LINK]

For a variable flow chiller this is the maximum water flow rate and for a constant flow chiller this is the operating water flow rate through the chiller’s evaporator. The units are in cubic meters per second. The minimum value for this numeric input field must be greater than zero, or this field can be autosized.

Field: Reference Condenser Water Flow Rate[LINK]

This numeric field contains the chiller’s operating condenser water flow rate in cubic meters per second. The units are in cubic meters per second. The minimum value for this numeric input field must be greater than zero, or this field can be autosized.

Field: Cooling Capacity Function of Temperature Curve Name[LINK]

The name of a biquadratic performance curve (ref: Performance Curves) that parameterizes the variation of the cooling capacity as a function of the leaving chilled water temperature and the leaving condenser water temperature. The output of this curve is multiplied by the reference capacity to give the cooling capacity at specific temperature operating conditions (i.e., at temperatures different from the reference temperatures). The curve should have a value of 1.0 at the reference temperatures and flow rates specified above. The biquadratic curve should be valid for the range of water temperatures anticipated for the simulation (otherwise the program issues warning messages).

Field: Electric Input to Cooling Output Ratio Function of Part Load Ratio Curve Type[LINK]

This choice field determines which type of the Electric Input to Cooling Output Ratio Function of Part Load Ratio Curve is used in the chiller modeling. Two curve types are available: (1) Type LeavingCondenserWaterTemperature is based on the leaving condenser water temperature. (2) Type Lift is based on the normalized lift, which is the temperature difference between the leaving condenser water temperature and the leaving evaporator water temperature.

Field: Electric Input to Cooling Output Ratio Function of Temperature Curve Name[LINK]

The name of the Electric Input to Cooling Output Ratio Function of Part Load Ratio Curve. The form of this curve is based on the input for Electric Input to Cooling Output RatioFunction of Part Load Ratio Curve Type. For the type of LeavingCondenserWaterTemperature, the curve object type should be Curve:Bicubic or Table:TwoIndependentVariables that parameterizes the variation of the energy input to cooling output ratio (EIR) as a function of the leaving chilled water temperature and the leaving condenser water temperature. For the type of Lift, the curve object type should be Curve:ChillerPartLoadWithLiftCurves or Table:MultiVariableLookup that parameterizes the variation of EIR as a function of the normalized fractional Lift, normalized Tdev and the PLR. Tdev is the difference between Leaving Chilled Water Temperature and Reference Chilled Water Temperature. Lift is the Leaving Condenser Water Temperature and Leaving Chilled Water Temperature. The EIR is the inverse of the COP. The output of this curve is multiplied by the reference EIR (inverse of the reference COP) to give the EIR at specific temperature operating conditions (i.e., at temperatures different from the reference temperatures). The curve should have a value of 1.0 at the reference temperatures and flow rates specified above. The biquadratic curve should be valid for the range of water temperatures anticipated for the simulation (otherwise the program issues warning messages).

Field: Electric Input to Cooling Output Ratio Function of Part Load Ratio Curve Name[LINK]

The name of a bicubic performance curve (ref: Performance Curves) that parameterizes the variation of the energy input ratio (EIR) as a function of the leaving condenser water temperature and the part-load ratio (EIRfTPLR). The EIR is the inverse of the COP, and the part-load ratio is the actual cooling load divided by the chiller’s available cooling capacity. This curve is generated by dividing the operating electric input power by the available full-load capacity (do not divide by load) at the specific operating temperatures. The curve output should decrease from 1 towards 0 as part-load ratio decreases from 1 to 0. The output of this curve is multiplied by the reference full-load EIR (inverse of the reference COP) and the Energy Input to Cooling Output Ratio Function of Temperature Curve to give the EIR at the specific temperatures and part-load ratio at which the chiller is operating. This curve should have a value of 1.0 at the reference leaving condenser water temperature with the part-load ratio equal to 1.0. An ideal chiller with the same efficiency at all part-load ratio’s would use a performance curve that has a value of 0 when the part-load ratio equals 0 (i.;e., a line connecting 0,0 and 1,1 when plotted as EIRfTPLR versus PLR), however, actual systems can have part-load EIR’s slightly above or below this line (i.e., part-load efficiency often differs from rated efficiency). The bicubic curve should be valid for the range of condenser water temperatures and part-load ratios anticipated for the simulation (otherwise the program issues warning messages).

Note: Although a bicubic curve requires 10 coefficients (ref. Curve:Bicubic), coefficients 7, 9 and 10 are typically not used in the performance curve described here and should be entered as 0 unless sufficient performance data and regression accuracy exist to justify the use of these coefficients. Additionally, coefficients 2, 3, and 6 should not be used unless sufficient temperature data is available to accurately define the performance curve (i.e., negative values may result from insufficient data).

Field: Minimum Part Load Ratio[LINK]

This numeric field contains the chiller’s minimum part-load ratio. The expected range is between 0 and 1. Below this part-load ratio, the compressor cycles on and off to meet the cooling load. The Minimum Part Load Ratio must be less than or equal to the Maximum Part Load Ratio. The default value is 0.1.

Field: Maximum Part Load Ratio[LINK]

This numeric field contains the chiller’s maximum part-load ratio. This value may exceed 1, but the normal range is between 0 and 1.0. The Maximum Part Load Ratio must be greater than or equal to the Minimum Part Load Ratio. The default value is 1.0.

Field: Optimum Part Load Ratio[LINK]

This numeric field contains the chiller’s optimum part-load ratio. This is the part-load ratio at which the chiller performs at its maximum COP. The optimum part-load ratio must be greater than or equal to the Minimum Part Load Ratio, and less than or equal to the Maximum Part Load Ratio. The default value is 1.0.

Field: Minimum Unloading Ratio[LINK]

This numeric field contains the chiller’s minimum unloading ratio. The expected range is between 0 and 1. The minimum unloading ratio is where the chiller capacity can no longer be reduced by unloading and must be false loaded to meet smaller cooling loads. A typical false loading strategy is hot-gas bypass. The minimum unloading ratio must be greater than or equal to the Minimum Part Load Ratio, and less than or equal to the Maximum Part Load Ratio. The default value is 0.2.

Field: Chilled Water Side Inlet Node[LINK]

This required alpha field contains the identifying name for the chiller plant side (chilled water) inlet node.

Field: Chilled Water Side Outlet Node[LINK]

This required alpha field contains the identifying name for the chiller plant side (chilled water) outlet node.

Field: Condenser Side Inlet Node[LINK]

This required alpha field contains the identifying name for the chiller condenser side inlet node.

Field: Condenser Side Outlet Node[LINK]

This required alpha field contains the identifying name for the chiller condenser side outlet node.

Field: Fraction of Compressor Electric Power Rejected by Condenser[LINK]

This numeric input represents the fraction of compressor electrical energy consumption that must be rejected by the condenser. Enter a value of 1.0 when modeling hermetic chillers. For open chillers, enter the compressor motor efficiency. This value must be greater than 0.0 and less than or equal to 1.0, with a default value of 1.0.

Field: Leaving Chilled Water Lower Temperature Limit[LINK]

This numeric field contains the lower limit for the leaving chilled water temperature in Celsius. This temperature acts as a cut off for heat transfer in the evaporator, so that the water doesn’t get too cold. This input field is currently unused. The default value is 2°C.

Field: Chiller Flow Mode Type[LINK]

This choice field determines how the chiller operates with respect to the intended fluid flow through the device’s evaporator. There are three different choices for specifying operating modes for the intended flow behavior: “NotModulated,” “ConstantFlow,” and “LeavingSetpointModulated.” NotModulated is useful for either variable or constant speed pumping arrangements where the chiller is passive in the sense that although it makes a nominal request for its design flow rate it can operate at varying flow rates. ConstantFlow is useful for constant speed pumping arrangements where the chiller’s request for flow is stricter and can increase the overall loop flow. LeavingSetpointModulated changes the chiller model to internally vary the flow rate so that the temperature leaving the chiller matches a setpoint. In all cases the operation of the external plant system can also impact the flow through the chiller – for example if the relative sizes and operation are such that flow is restricted and the requests cannot be met. The default, if not specified, is NotModulated.

Field: Design Heat Recovery Water Flow Rate[LINK]

This is the design heat recovery water flow rate if the heat recovery option is being simulated. If this value is greater than 0.0 (or autosize), a heat recovery loop must be specified and attached to the chiller using the next two node fields. The units are in cubic meters per second. This field is autosizable. When autosizing, the flow rate is simply the product of the design condenser flow rate and the condenser heat recovery relative capacity fraction set in the field below.

Field: Heat Recovery Inlet Node Name[LINK]

This alpha field contains the identifying name for the chiller heat recovery side inlet node. If the user wants to model chiller heat recovery, a heat recovery loop must be specified and it can only be used with a water-cooled condenser.

Field: Heat Recovery Outlet Node Name[LINK]

This alpha field contains the identifying name for the chiller heat recovery side outlet node. If the user wants to model chiller heat recovery, a heat recovery loop must be specified and it can only be used with a water-cooled condenser.

Field: Sizing Factor[LINK]

This optional numeric field allows the user to specify a sizing factor for this component. The sizing factor is used when the component design inputs are autosized: the autosizing calculations are performed as usual and the results are multiplied by the sizing factor. For this component the inputs that would be altered by the sizing factor are: Reference Capacity, Reference Chilled Water Flow Rate and Reference Condenser Water Flow Rate. Sizing Factor allows the user to size a component to meet part of the design load while continuing to use the autosizing feature.

Field: Condenser Heat Recovery Relative Capacity Fraction[LINK]

This field is optional. It can be used to describe the physical size of the heat recovery portion of a split bundle condenser section. This fraction describes the relative capacity of the heat recovery bundle of a split condenser compared to the nominal, full load heat rejection rate of the chiller. This fraction will be applied to the full heat rejection when operating at nominal capacity and nominal COP to model a capacity limit for the heat rejection. If this field is not entered then the capacity fraction is set to 1.0.

Field: Heat Recovery Inlet High Temperature Limit Schedule Name[LINK]

This field is optional. It can be used to control heat recovery operation of the chiller. The schedule named here should contain temperature values, in C, that describe an upper limit for the return fluid temperatures entering the chiller at the heat recovery inlet node. If the fluid temperature is too high, then the heat recovery will not operate. This is useful to restrict the chiller lift from becoming too high and to avoid overheating the hot water loop. This limit can be used with or without the alternate control using leaving setpoint that is set in the next field.

Field: Heat Recovery Leaving Temperature Setpoint Node Name[LINK]

This field is optional. It can be used to refine the model and controls for heat recovery operation of the chiller. The node named here should have a setpoint placed on it by a setpoint manager. If the plant loop’s demand calculation scheme is set to SingleSetpoint, then a single setpoint manager should be used. If the plant loop’s demand calculation is set to DualSetpointDeadband then a dual setpoint manager should be used and the upper setpoint is used for control. When this field is used, a different model is used for determining the distribution of rejected heat between the two bundles that is more appropriate for series bundle arrangements and for chiller’s that are able to produce relatively higher temperature heated fluilds.

An example of this statement in an IDF is:

Chiller:Electric:ReformulatedEIR,
    Main Chiller,                        !- Chiller Name
    50000,                               !- Reference Capacity {W}
    3.99,                                !- Reference COP
    6.67,                                !- Reference Leaving Chilled Water Temperature {C}
    35.0,                                !- Reference Leaving Condenser Water Temperature {C}
    0.00898,                             !- Reference Chilled Water Flow Rate {m3/s}
    0.01122,                             !- Reference Condenser Water Flow Rate {m3/s}
    Main Chiller RecipCapFT,             !- Cooling Capacity Function of Temperature Curve
    Main Chiller RecipEIRFT,             !- Electric Input to Cooling Output Ratio Function of Temperature Curve
  LeavingCondenserWaterTemperature     !- Electric Input to Cooling Output Ratio Function of Part Load Ratio Curve Type
    Main Chiller RecipEIRFPLR,           !- Electric Input to Cooling Output Ratio Function of Part Load Ratio Curve Name
    0.01,                                !- Minimum Part Load Ratio
    1,                                   !- Maximum Part Load Ratio
    1,                                   !- Optimum Part Load Ratio
    0.07,                                !- Minimum Unloading Ratio
    Main Chiller ChW Inlet,              !- Chilled Water Side Inlet Node
    Main Chiller ChW Outlet,             !- Chilled Water Side Outlet Node
    Main Chiller Cnd Inlet,              !- Condenser Side Inlet Node
    Main Chiller Cnd Outlet,             !- Condenser Side Outlet Node
    1,                                   !- Fraction of Compressor Electric Power Rejected by Condenser
    2,                                   !- Leaving Chilled Water Lower Temperature Limit {C}
    ConstantFlow;                        !- Chiller Flow Mode

  ! Cooling capacity to rated capacity function of Temperature Curve
  ! x = Leaving Chilled Water Temperature and y = Leaving Condenser Water Temperature

    Curve:Biquadratic,
      Main Chiller RecipCapFT,  !- Name
      0.958546443,       !- Coefficient1 Constant
      0.035168695,       !- Coefficient2 x
      0.000124662,       !- Coefficient3 x\*\*2
      -0.00274551,       !-Coefficient4y
      -0.00005000,       !-Coefficient5y\*\*2
      -0.00017234,       !-Coefficient6x\*y
      5.00,              !- Minimum Value of x
      10.0,              !- Maximum Value of x
      20.00,             !- Minimum Value of y
      40.94;             !- Maximum Value of y

  ! Energy Input to Cooling Output Ratio Function of Temperature Curve
  ! x = Leaving Chilled Water Temperature and y = Leaving Condenser Water Temperature

    Curve:Biquadratic,
      Main Chiller RecipEIRFT,  !- Name
      0.732700123,       !- Coefficient1 Constant
      -0.00834360,       !- Coefficient2 x
      0.000638530,       !- Coefficient3 x\*\*2
      -0.00303753,       !-Coefficient4y
      0.000484952,       !-Coefficient5y\*\*2
      -0.00083584,       !-Coefficient6x\*y
      5.00,              !- Minimum Value of x
      10.0,              !- Maximum Value of x
      20.00,             !- Minimum Value of y
      40.94;             !- Maximum Value of y

  ! Energy Input to Cooling Output Ratio Function of Part Load Ratio Curve
  ! x = Leaving Condenser water Temperature and y = Part Load Ratio

    Curve:Bicubic,
      Main Chiller RecipEIRFPLR, !- Name
      0.070862846,        !- Coefficient1 Constant
      0.002787560,        !- Coefficient2 x
      -0.00000891,        !- Coefficient3 x\*\*2
      0.230973399,        !-Coefficient4y
      1.250442176,        !-Coefficient5y\*\*2
      -0.00216102,        !-Coefficient6x\*y
      0.000000,           !-Coefficient7x\*\*3
      -0.56300936,        !-Coefficient8y\*\*3
      0.000000,           !-Coefficient9x\*\*2\*y
      0.000000,           !-Coefficient10x\*y\*\*2
      20.00,              !- Minimum Value of x
      40.94,              !- Maximum Value of x
      0.01,               !- Minimum Value of y
      1.0;               !- Maximum Value of y

Outputs[LINK]

The output variables for Chiller:Electric:ReformulatedEIR are the same as the output variables for Chiller:Electric:EIR (ref. Electric EIR Chiller Outputs). except for the Chiller Condenser Fan Electric Power and Energy reports

Chiller:EngineDriven[LINK]

Inputs[LINK]

Field: Name[LINK]

This alpha field contains the identifying name for the engine driven chiller.

Field: Condenser Type[LINK]

This alpha field determines what type of condenser will be modeled with this chiller. The 3 type of condensers are AirCooled, WaterCooled, and EvaporativelyCooled with the default being AirCooled if not specified. AirCooled and EvaporativelyCooled do not require a Condenser Loop to be specified, where the WaterCooled option requires the full specification of the Condenser Loop and its associated equipment.

Field: Nominal Capacity[LINK]

This numeric field contains the nominal cooling capability of the chiller in Watts.

Field: Nominal COP[LINK]

This numeric field contains the chiller’s coefficient of performance (COP).

Field: Chilled Water Inlet Node Name[LINK]

This required alpha field contains the identifying name for the chiller plant side inlet node.

Field: Chilled Water Outlet Node Name[LINK]

This required alpha field contains the identifying name for the chiller plant side outlet node.

Field: Condenser Inlet Node Name[LINK]

This alpha field contains the identifying name for the chiller condenser side inlet node. This node name is required if the chiller is WaterCooled, and optional if the chiller is AirCooled or EvaporativelyCooled. If the chiller is AirCooled or EvaporativelyCooled and a condenser inlet node name is specified here, the node name specified must also be specified in an OutdoorAir:Node object where the height of the node is taken into consideration when calculating outdoor air temperature from the weather data. Alternately, the node name may be specified in an OutdoorAir:NodeList object where the outdoor air temperature is taken directly from the weather data. If the chiller is AirCooled or EvaporativelyCooled and this field is left blank, the program automatically creates an outdoor air node and the air temperature information on this node is taken directly from the weather file (no node height adjustment).

Field: Condenser Outlet Node Name[LINK]

This alpha field contains the identifying name for the chiller condenser side outlet node. This node name is required if the chiller is WaterCooled, and optional if the chiller is AirCooled or EvaporativelyCooled. If the chiller is AirCooled or EvaporativelyCooled and this field is left blank, the program automatically creates a condenser side outlet air node.

Field: Minimum Part Load Ratio[LINK]

This numeric field contains the chiller’s minimum part load ratio. The expected range is between 0 and 1. The minimum part load is not the load where the machine shuts off, but where the amount of power remains constant to produce smaller loads than this fraction.

Field: Maximum Part Load Ratio[LINK]

This numeric field contains the chiller’s maximum part load ratio. This value may exceed 1, but the normal range is between 0 and 1.1.

Field: Optimum Part Load Ratio[LINK]

This numeric field contains the chiller’s optimum part load ratio. This is the part load ratio at which the chiller performs at its maximum COP.

Field: Design Condenser Inlet Temperature[LINK]

This numeric field contains the chiller’s condenser inlet design temperature in Celsius.

Field: Temperature Rise Coefficient[LINK]

This numeric field contains the electric chiller’s temperature rise coefficient which is defined as the ratio of the required change in condenser water temperature to a given change in chilled water temperature, which maintains the capacity at the nominal value. This is calculated as the following ratio:

TCEntrequiredTCEntratedTELvrequiredTELvrated

where:

TCEntrequired = Required entering condenser air or water temperature to maintain rated capacity.

TCEntrated = Rated entering condenser air or water temperature at rated capacity.

TELvrequired = Required leaving evaporator water outlet temperature to maintain rated capacity.

TELvrated = Rated leaving evaporator water outlet temperature at rated capacity.

Field: Design Chilled Water Outlet Temperature[LINK]

This numeric field contains the chiller’s evaporator outlet design temperature in Celsius.

Field: Design Chilled Water Flow Rate[LINK]

For variable volume chiller this is the maximum flow and for constant flow chiller this is the design flow rate. The units are in cubic meters per second.

Field: Design Condenser Water Flow Rate[LINK]

This numeric field contains the chiller’s design condenser water flow rate in cubic meters per second. This field can be autosized. This field is not user for Condenser Type = AirCooled or EvaporativelyCooled.

Capacity Ratio Curve[LINK]

The Capacity Ratio Curve is a quadratic equation that determines the Ratio of Available Capacity to Nominal Capacity. The defining equation is:

AvailToNominalCapacityRatio=C1+C2Δtemp+C3Δ2temp

Where the Delta Temperature is defined as:

FullLoadtoPowerRatio=C1+C2AvailToNominalCapRatio+C3AvailToNominalCapRatio2

TempCondIn = Temperature entering the condenser (water or air temperature depending on condenser type).

TempCondInDesign = Design Condenser Inlet Temperature from User input above.

TempEvapOut = Temperature leaving the evaporator.

TempEvapOutDesign = Design Chilled Water Outlet Temperature from User input above.

TempRiseCoefficient = User Input from above.

The following three fields contain the coefficients for the quadratic equation.

Field: Coefficient 1 of Capacity Ratio Curve[LINK]

This numeric field contains the first coefficient for the capacity ratio curve.

Field: Coefficient 2 of Capacity Ratio Curve[LINK]

This numeric field contains the second coefficient for the capacity ratio curve.

Field: Coefficient 3 of Capacity Ratio Curve[LINK]

This numeric field contains the third coefficient for the capacity ratio curve.

Power Ratio Curve[LINK]

The Power Ratio Curve is a quadratic equation that determines the Ratio of Full Load to Power. The defining equation is:

FracFullLoadPower=C1+C2PartLoadRatio+C3PartLoadRatio2 The following three fields contain the coefficients for the quadratic equation.

Field: Coefficient 1 of Power Ratio Curve[LINK]

This numeric field contains the first coefficient for the power ratio curve.

Field: Coefficient 2 of Power Ratio Curve[LINK]

This numeric field contains the second coefficient for the power ratio curve.

Field: Coefficient 3 of Power Ratio Curve[LINK]

This numeric field contains the third coefficient for the power ratio curve.

Full Load Ratio Curve[LINK]

The Full Load Ratio Curve is a quadratic equation that determines the fraction of full load power. The defining equation is:

CoolingLoadtoFuelCurve=C1+C2PLR+C3PLR2

The following three fields contain the coefficients for the quadratic equation.

Field: Coefficient 1 of Full Load Ratio Curve[LINK]

This numeric field contains the first coefficient for the full load ratio curve.

Field: Coefficient 2 of Full Load Ratio Curve[LINK]

This numeric field contains the second coefficient for the full load ratio curve.

Field: Coefficient 3 of Full Load Ratio Curve[LINK]

This numeric field contains the third coefficient for the full load ratio curve.

Field Chilled Water Outlet Temperature Lower Limit[LINK]

This numeric field contains the lower limit for the evaporator outlet temperature. This temperature acts as a cut off for heat transfer in the evaporator, so that the fluid doesn’t get too cold.

Field: Fuel Use Curve Name[LINK]

This alpha field contains the name of the Cooling Load to Fuel Use curve. The curve itself is specified separately using the EnergyPlus Curve Manager. The Fuel Use Curve is a quadratic equation that determines the ratio of Cooling Load to Fuel Energy. The defining equation is:

RecoveryJacketHeatToFuelRatio=C1+C2RL+C3RL2

where PLR is the Part Load Ratio from the Chiller. The Part Load Based Fuel Input Curve determines the ratio of fuel energy per unit time (J/s) / cooling load (W). This is illustrated by the logic block in the Engine Driven Chiller algorithm.

IF (PartLoadRat = = 0)THEN
   EngineDrivenFuelEnergy = 0
ELSE
   ClngLoadFuelRat = CurveValue(EngineDrivenChiller(ChillerNum)%ClngLoadtoFuelCurve, PartLoadRat )
   EngineDrivenFuelEnergy = QEvaporator / ClngLoadFuelRat
END IF

Field: Jacket Heat Recovery Curve Name[LINK]

This alpha field contains the name of the Recovery Jacket Heat curve. The curve itself is specified separately using the EnergyPlus Curve Manager. The Recovery Jacket Heat Curve is a quadratic equation that determines the ratio of recovery jacket heat to fuel energy. The defining equation is:

RecoveryLubeHeatToFuelRatio=C1+C2RL+C3RL2

where RL is the Ratio of Load to Diesel Engine Capacity

Field: Lube Heat Recovery Curve Name[LINK]

This alpha field contains the name of the Recovery Lube Heat curve. The curve itself is specified separately using the EnergyPlus Curve Manager. The Recovery Lubricant Heat Curve is a quadratic equation that determines the ratio of recovery lube heat to fuel energy. The defining equation is:

TotalExhaustToFuelRatio=C1+C2RL+C3RL2

where RL is the Ratio of Load to Diesel Engine Capacity

Field: Total Exhaust Energy Curve Name[LINK]

This alpha field contains the name of the Total Exhaust Energy curve. The curve itself is specified separately using the EnergyPlus Curve Manager. The Total Exhaust Energy Curve is a quadratic equation that determines the ratio of total exhaust energy to fuel energy. The defining equation is:

AbsoluteExhaustTemperature=C1+C2RL+C3RL2

where RL is the Ratio of Load to Diesel Engine Capacity

Field: Exhaust Temperature Curve Name[LINK]

This alpha field contains the name of the Exhaust Temperature curve. The curve itself is specified separately using the EnergyPlus Curve Manager. The Exhaust Temperature Curve is a quadratic equation that determines the absolute exhaust temperature. The defining equation is:

UAToCapacityRatio=C1EngineCapacityC2

where RL is the Ratio of Load to Diesel Engine Capacity

U-Factor Times Area Curve[LINK]

The U-Factor Times Area (UA) is an equation that determines the overall heat transfer coefficient for the exhaust gasses with the stack. The heat transfer coefficient ultimately helps determine the exhaust stack temperature. The defining equation is:

TCEntrequiredTCEntratedTELvrequiredTELvrated

The following two fields contain the coefficients for the equation.

Field: Coefficient 1 of U-Factor Times Area Curve[LINK]

This numeric field contains the first coefficient for the overall heat transfer coefficient curve.

Field: Coefficient 2 of U-Factor Times Area Curve[LINK]

This numeric field contains the second (exponential) coefficient for the overall heat transfer coefficient curve.

Field: Maximum Exhaust Flow per Unit of Power Output[LINK]

This numeric field contains the maximum exhaust gas mass flow rate per watt of cooling provided by the engine driven chiller

Field: Design Minimum Exhaust Temperature[LINK]

This numeric field contains the steam saturation temperature in Celsius that would be used to determine the energy recovered from a water jacket heat exchanger on the engine.

Field: Fuel Type[LINK]

This alpha value specifies the type of fuel used in the engine. The fuel type can be NaturalGas, PropaneGas, Diesel, Gasoline, FuelOil#1, FuelOil#2, OtherFuel1 or OtherFuel2. This field is required.

Field: Fuel Higher Heating Value[LINK]

This numeric field contains the higher heating value of the fuel used in kJ/kg.

Field: Design Heat Recovery Water Flow Rate[LINK]

This optional numeric field is the design heat recovery plant fluid flow rate, if the heat recovery option is being simulated. If this value is greater than 0.0, or autosize, then a heat recovery loop must be specified and attached to the chiller using the next two node input fields. The units are in cubic meters per second. This field is autosizable. When autosizing, the flow rate is simply the product of the design condenser flow rate and the Condenser Heat Recovery Relative Capacity Fraction set in the field below.

Field: Heat Recovery Inlet Node Name[LINK]

This alpha field contains the identifying name for the heat recovery side inlet node. If a loop is connected, then the jacket and lubricant heat will be recovered. There is no need for an effectiveness term, since the jacket and lubricant recovered heat energies are the actual recovered energies.

Field: Heat Recovery Outlet Node Name[LINK]

This alpha field contains the identifying name for the heat recovery side outlet node.

Field: Chiller Flow Mode[LINK]

This choice field determines how the chiller operates with respect to the intended fluid flow through the device’s evaporator. There are three different choices for specifying operating modes for the intended flow behavior: “NotModulated,” “ConstantFlow,” and “LeavingSetpointModulated.” NotModulated is useful for either variable or constant speed pumping arrangements where the chiller is passive in the sense that although it makes a nominal request for its design flow rate it can operate at varying flow rates. ConstantFlow is useful for constant speed pumping arrangements where the chiller’s request for flow is stricter and can increase the overall loop flow. LeavingSetpointModulated changes the chiller model to internally vary the flow rate so that the temperature leaving the chiller matches a setpoint. In all cases the operation of the external plant system can also impact the flow through the chiller – for example if the relative sizes and operation are such that flow is restricted and the requests cannot be met. The default, if not specified, is NotModulated.

Field: Maximum Temperature for Heat Recovery at Heat Recovery Outlet Node[LINK]

This field sets the maximum temperature that this piece of equipment can produce for heat recovery. The idea behind this field is that the current models do not take temperatures into account for availability and they just pass Q’s around the loop without a temperature limit. This temperature limit puts an upper bound on the recovered heat and limits the max temperatures leaving the component.

As temperatures in the loop approach the maximum temperature, the temperature difference between the entering water and the surfaces in the piece of equipment becomes smaller. For the given heat recovery flow rate and that temperature difference the amount of heat recovered will be reduced, and eventually there will be no heat recovered when the entering water temperature is equal to the maximum temperature specified by the user in this field. The reduced amount of heat recovered will diminish if the temperature of the loop approach is the maximum temperature, and this will show up in the reporting. This allows the user to set the availability or the quality of the heat recovered for usage in other parts of the system or to heat domestic hot water supply. The temperature is specified in degrees C.

Field: Sizing Factor[LINK]

This optional numeric field allows the user to specify a sizing factor for this component. The sizing factor is used when the component design inputs are autosized: the autosizing calculations are performed as usual and the results are multiplied by the sizing factor. For this component the inputs that would be altered by the sizing factor are: Nominal Capacity, Design Chilled Water Flow Rate and Design Condenser Water Flow Rate. Sizing Factor allows the user to size a component to meet part of the design load while continuing to use the autosizing feature.

Field: Basin Heater Capacity[LINK]

This numeric field contains the capacity of the chiller’s electric basin heater in watts per degree Kelvin. This field only applies for Condenser Type = EvaporativelyCooled. This field is used in conjunction with the Basin Heater Setpoint Temperature described in the following field. The basin heater electric power is equal to this field multiplied by the difference between the basin heater set point temperature and the outdoor dry-bulb temperature. The basin heater only operates when the chiller is off, regardless of the basin heater schedule described below. The basin heater capacity must be greater than or equal to zero, with a default value of zero if this field is left blank.

Field: Basin Heater Setpoint Temperature[LINK]

This numeric field contains the set point temperature (˚C) for the basin heater described in the previous field. This field only applies for Condenser Type = EvaporativelyCooled. The basin heater is active when the outdoor air dry-bulb temperature falls below this setpoint temperature, as long as the chiller is off. This set point temperature must be greater than or equal to 2˚C, and the default value is 2˚C if this field is left blank.

Field: Basin Heater Operating Schedule Name[LINK]

This alpha field contains the name of the basin heater operating schedule. This field only applies for Condenser Type = EvaporativelyCooled. The basin heater operating schedule is assumed to be an on/off schedule and the heater is available to operate any time the schedule value is greater than 0. The basin heater operates when scheduled on and the outdoor air dry-bulb temperature is below the set point temperature described in the previous field. If this field is left blank, the basin heater is available to operate throughout the simulation. Regardless of this schedule, the basin heater may only operate when the chiller is off.

Field: Condenser Heat Recovery Relative Capacity Fraction[LINK]

This field is optional. It can be used to describe the physical size of the heat recovery portion of a split bundle condenser section. This fraction describes the relative capacity of the heat recovery bundle of a split condenser compared to the nominal, full load heat rejection rate of the chiller. This fraction will be applied to the full heat rejection when operating at nominal capacity and nominal COP to model a capacity limit for the heat rejection. If this field is not entered then the capacity fraction is set to 1.0.

An example of this statement in an IDF is:

Chiller:EngineDriven,
      Central Chiller,         !- Chiller Name
      WaterCooled,            !- Condenser Type
      autosize,                !- Nominal Capacity {W}
      2.75,                    !- COP
      Central Chiller Inlet Node,  !- Chilled Water Inlet Node Name
      Central Chiller Outlet Node,  !- Chilled Water Outlet Node Name
      Central Chiller Condenser Inlet Node,  !- Condenser Inlet Node Name
      Central Chiller Condenser Outlet Node,  !- Condenser Outlet Node Name
      0.0,                     !- Minimum Part Load Ratio
      1.0,                     !- Maximum Part Load Ratio
      .65,                     !- Optimum Part Load Ratio
      35.0,                    !- Design Condenser Inlet Temperature {C}
      2.778,                   !- Temperature Rise Coefficient
      6.67,                    !- Design Chilled Water Outlet Temperature {C}
      autosize,                !- Design Chilled Water Flow Rate {m3/s}
      autosize,                !- Design Condenser Water Flow Rate {m3/s}
      0.9949,                  !- Coefficient 1 of Capacity Ratio Curve
      -0.045954,               !- Coefficient 2 of Capacity Ratio Curve
      -0.0013543,              !- Coefficient 3 of Capacity Ratio Curve
      2.333,                   !- Coefficient 1 of Power Ratio Curve
      -1.975,                  !- Coefficient 2 of Power Ratio Curve
      0.6121,                  !- Coefficient 3 of Power Ratio Curve
      0.03303,                 !- Coefficient 1 of Full Load Ratio Curve
      0.6852,                  !- Coefficient 2 of Full Load Ratio Curve
      0.2818,                  !- Coefficient 3 of Full Load Ratio Curve
      5,                       !- Chilled Water Outlet Temperature Lower Limit {C}
      Fuel Use Curve,          !- the Fuel Use Curve
      Jacket Heat Recovery Curve,  !- the Recovery Jacket Heat curve
      Lube Heat Recovery Curve,!- the Recovery Lube Heat curve
      Total Exhaust Energy Curve,  !- the Total Exhaust Energy curve
      Exhaust Temperature Curve,  !- the Exhaust Temperature curve
      0.01516,                 !- Coefficient1 of UA curve
      0.9,                     !- Coefficient2 of UA curve
      0.00063,                 !- Maximum Exhaust Flow per W of Power Output {(kg/s)/W}
      150,                     !- Design Minimum Exhaust temp. (Steam Saturation Temperature) {C}
      DIESEL,                  !- Fuel Type
      45500,                   !- Fuel Heating Value {kJ/kg}
      0.0,                     !- Design heat recovery water flow rate {m3/s}
      ,                        !- Heat Recovery Inlet Node Name
      ,                        !- Heat Recovery Outlet Node Name
      VariableFlow,            !- Chiller Flow Mode
      60.0;                    !- Maximum Temp for Heat Recovery. This sets max availability {C}

Outputs[LINK]

HVAC,Average,Chiller Electric Power [W]
  HVAC,Sum,Chiller Electric Energy [J]
  Zone,Meter,Electricity:Plant [J]
  Zone,Meter,Cooling:Electricity [J]
  HVAC,Average,Chiller Evaporator Cooling Rate [W]
  HVAC,Sum,Chiller Evaporator Cooling Energy [J]
  Zone,Meter,EnergyTransfer:Plant [J]
  Zone,Meter,Chillers:EnergyTransfer [J]
  HVAC,Average,Chiller Evaporator Inlet Temperature [C]
  HVAC,Average,Chiller Evaporator Outlet Temperature [C]
  HVAC,Average,Chiller Evaporator Mass Flow Rate [kg/s]
  HVAC,Average,Chiller COP [W/W]
  HVAC,Average,Chiller Condenser Heat Transfer Energy Rate [W]
  HVAC,Sum,Chiller Condenser Heat Transfer Energy [J]
  Zone,Meter,HeatRejection:EnergyTransfer [J]

Air-cooled or Evap-cooled:

  • HVAC,Average,Chiller Condenser Inlet Temperature [C]

Evap-cooled:

  • HVAC,Average,Chiller Basin Heater Electric Power [W]

  • HVAC,Average,Chiller Basin Heater Electric Energy [J]

Water-cooled:

  • HVAC,Average,Chiller Condenser Inlet Temperature [C]

  • HVAC,Average,Chiller Condenser Outlet Temperature [C]

  • HVAC,Average,Chiller Condenser Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller Drive Shaft Power [W]

  • HVAC,Sum,Chiller Drive Shaft Energy [J]

  • HVAC,Average,Chiller Jacket Recovered Heat Rate [W]

  • HVAC,Sum,Chiller Jacket Recovered Heat Energy [J]

  • Zone,Meter,HeatRecovery:EnergyTransfer [J]

  • HVAC,Average,Chiller Lube Recovered Heat Rate [W]

  • HVAC,Sum,Chiller Lube Recovered Heat Energy [J]

  • HVAC,Average,Chiller Exhaust Heat Recovery Rate [W]

  • HVAC,Sum,Chiller Exhaust Heat Recovery Energy [J]

  • HVAC,Average,Chiller Total Recovered Heat Rate [W]

  • HVAC,Sum,Chiller Total Recovered Heat Energy [J]

  • HVAC,Average,Chiller Heat Recovery Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller Heat Recovery Inlet Temperature [C]

  • HVAC,Average,Chiller Heat Recovery Outlet Temperature [C]

  • HVAC,Average,Chiller Exhaust Temperature [C]

One of the following blocks will be applicable based on fuel type:

  • HVAC,Average,Chiller Gas Rate [W]

  • HVAC,Sum,Chiller Gas Energy [J]

  • HVAC,Average,Chiller Gas Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller Propane Rate [W]

  • HVAC,Sum,Chiller Propane Energy [J]

  • HVAC,Average,Chiller Propane Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller Diesel Rate [W]

  • HVAC,Sum,Chiller Diesel Energy [J]

  • HVAC,Average,Chiller Diesel Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller Gasoline Rate [W]

  • HVAC,Sum,Chiller Gasoline Energy [J]

  • HVAC,Average,Chiller Gasoline Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller FuelOil#1 Rate [W]

  • HVAC,Sum,Chiller FuelOil#1 Energy [J]

  • HVAC,Average,Chiller FuelOil#1 Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller FuelOil#2 Rate [W]

  • HVAC,Sum,Chiller FuelOil#2 Energy [J]

  • HVAC,Average,Chiller FuelOil#2 Mass Flow Rate [kg/s

  • HVAC,Average,Chiller OtherFuel1 Rate [W]

  • HVAC,Sum,Chiller OtherFuel1 Energy [J]

  • HVAC,Average,Chiller OtherFuel1 Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller OtherFuel2 Rate [W]

  • HVAC,Sum,Chiller OtherFuel2 Energy [J]

  • HVAC,Average,Chiller OtherFuel2 Mass Flow Rate [kg/s]

These chiller output variables are defined above under “Generic Chiller Outputs.”

Chiller:CombustionTurbine[LINK]

This chiller model is the empirical model from the Building Loads and System Thermodynamics (BLAST) program. Chiller performance curves are generated by fitting catalog data to third order polynomial equations. Three sets of coefficients are required.

Inputs[LINK]

Field: Name[LINK]

This alpha field contains the identifying name for the combustion turbine chiller.

Field: Condenser Type[LINK]

This alpha field determines what type of condenser will be modeled with this chiller. The 3 type of condensers are AirCooled, WaterCooled, and EvaporativelyCooled with the default being AirCooled if not specified. AirCooled and EvaporativelyCooled do not require a Condenser Loop to be specified, where the WaterCooled option requires the full specification of the Condenser Loop and its associated equipment.

Field: Nominal Capacity[LINK]

This numeric field contains the nominal cooling capability of the chiller in Watts.

Field: Nominal COP[LINK]

This numeric field contains the chiller’s coefficient of performance (COP).

Field: Chilled Water Inlet Node Name[LINK]

This alpha field contains the identifying name for the combustion turbine chiller plant side inlet node.

Field: Chilled Water Outlet Node Name[LINK]

This required alpha field contains the identifying name for the combustion turbine chiller plant side inlet node.

Field: Chilled Water Outlet Node Name[LINK]

This required alpha field contains the identifying name for the combustion turbine chiller plant side outlet node.

Field: Condenser Inlet Node Name[LINK]

This alpha field contains the identifying name for the combustion turbine chiller condenser side inlet node. This node name is required if the chiller is WaterCooled, and optional if the chiller is AirCooled or EvaporativelyCooled. If the chiller is AirCooled or EvaporativelyCooled and a condenser inlet node name is specified here, the node name specified must also be specified in an OutdoorAir:Node object where the height of the node is taken into consideration when calculating outdoor air temperature from the weather data. Alternately, the node name may be specified in an OutdoorAir:NodeList object where the outdoor air temperature is taken directly from the weather data. If the chiller is AirCooled or EvaporativelyCooled and this field is left blank, the program automatically creates an outdoor air node and the air temperature information on this node is taken directly from the weather file (no node height adjustment).

Field: Condenser Outlet Node Name[LINK]

This alpha field contains the identifying name for the combustion turbine chiller condenser side outlet node. This node name is required if the chiller is WaterCooled, and optional if the chiller is AirCooled or EvaporativelyCooled. If the chiller is AirCooled or EvaporativelyCooled and this field is left blank, the program automatically creates a condenser side outlet air node.

Field: Minimum Part Load Ratio[LINK]

This numeric field contains the combustion turbine chiller’s minimum part load ratio. The expected range is between 0 and 1. The minimum part load is not the load where the machine shuts off, but where the amount of power remains constant to produce smaller loads than this fraction.

Field: Maximum Part Load Ratio[LINK]

This numeric field contains the combustion turbine chiller’s maximum part load ratio. This value may exceed 1, but the normal range is between 0 and 1.1.

Field: Optimum Part Load Ratio[LINK]

This numeric field contains the combustion turbine chiller’s optimum part load ratio. This is the part load ratio at which the chiller performs at its maximum COP.

Field: Design Condenser Inlet Temperature[LINK]

This numeric field contains the combustion turbine chiller’s condenser inlet design temperature in Celsius.

Field: Temperature Rise Coefficient[LINK]

This numeric field contains the electric chiller’s temperature rise coefficient which is defined as the ratio of the required change in condenser water temperature to a given change in chilled water temperature, which maintains the capacity at the nominal value. This is calculated as the following ratio:

TCEntrequiredTCEntratedTELvrequiredTELvrated

where:

TCEntrequired = Required entering condenser air or water temperature to maintain rated capacity.

TCEntrated = Rated entering condenser air or water temperature at rated capacity.

TELvrequired = Required leaving evaporator water outlet temperature to maintain rated capacity.

TELvrated = Rated leaving evaporator water outlet temperature at rated capacity.

Field: Design Chilled Water Outlet Temperature[LINK]

This numeric field contains the combustion turbine chiller’s evaporator outlet design temperature in Celsius.

Field: Design Chilled Water Flow Rate[LINK]

For variable volume chiller this is the maximum flow and for constant flow chiller this is the design flow rate. The units are in cubic meters per second.

Field: Design Condenser Water Flow Rate[LINK]

This numeric field contains the combustion turbine chiller’s design condenser water flow rate in cubic meters per second. This field can be autosized. This field is not used for Condenser Type = AirCooled or EvaporativelyCooled.

Capacity Ratio Curve[LINK]

The Capacity Ratio Curve is a quadratic equation that determines the Ratio of Available Capacity to Nominal Capacity. The defining equation is:

AvailToNominalCapacityRatio=C1+C2Δtemp+C3Δ2temp

Where the Delta Temperature is defined as:

FullLoadtoPowerRatio=C1+C2AvailToNominalCapRatio+C3AvailToNominalCapRatio2

TempCondIn = Temperature entering the condenser (water or air temperature depending on condenser type).

TempCondInDesign = Design Condenser Inlet Temperature from User input above.

TempEvapOut = Temperature leaving the evaporator.

TempEvapOutDesign = Design Chilled Water Outlet Temperature from User input above.

TempRiseCoefficient = User Input from above.

The following three fields contain the coefficients for the quadratic equation.

Field: Coefficient 1 of Capacity Ratio Curve[LINK]

This numeric field contains the first coefficient for the capacity ratio curve.

Field: Coefficient 2 of Capacity Ratio Curve[LINK]

This numeric field contains the second coefficient for the capacity ratio curve.

Field: Coefficient 3 of Capacity Ratio Curve[LINK]

This numeric field contains the third coefficient for the capacity ratio curve.

Power Ratio Curve[LINK]

The Power Ratio Curve is a quadratic equation that determines the Ratio of Full Load to Power. The defining equation is:

FracFullLoadPower=C1+C2PartLoadRatio+C3PartLoadRatio2 The following three fields contain the coefficients for the quadratic equation.

Field: Coefficient 1 of Power Ratio Curve[LINK]

This numeric field contains the first coefficient for the power ratio curve.

Field: Coefficient 2 of Power Ratio Curve[LINK]

This numeric field contains the second coefficient for the power ratio curve.

Field: Coefficient 3 of Power Ratio Curve[LINK]

This numeric field contains the third coefficient for the power ratio curve.

Full Load Ratio Curve[LINK]

The Full Load Ratio Curve is a quadratic equation that determines the fraction of full load power. The defining equation is:

FuelEnergyInput=PLoad(FIC1+FIC2RLoad+FIC3RLoad2)(TBFIC1+TBFIC2ATair+TBFIC3AT2air)

The following three fields contain the coefficients for the quadratic equation.

Field: Coefficient 1 of Full Load Ratio Curve[LINK]

This numeric field contains the first coefficient for the full load ratio curve.

Field: Coefficient 2 of Full Load Ratio Curve[LINK]

This numeric field contains the second coefficient for the full load ratio curve.

Field: Coefficient 3 of Full Load Ratio Curve[LINK]

This numeric field contains the third coefficient for the full load ratio curve.

Field: Chilled Water Outlet Temperature Lower Limit[LINK]

This numeric field contains the lower limit for the evaporator outlet temperature. This temperature acts as a cut off for heat transfer in the evaporator, so that the fluid doesn’t get too cold.

Fuel Input Curve[LINK]

The Fuel Input Curve is a polynomial equation that determines the Ratio of Fuel Input to Energy Output. The equation combines both the Fuel Input Curve Coefficients and the Temperature Based Fuel Input Curve Coefficients. The defining equation is:

ExhaustFlowRate=GTCapacity(C1+C2ATair+C3AT2air)

where FIC represents the Fuel Input Curve Coefficients, TBFIC represents the Temperature Based Fuel Input Curve Coefficients, Rload is the Ratio of Load to Combustion Turbine Engine Capacity, and ATair is the difference between the current ambient and design ambient temperatures.

The following three fields contain the coefficients for the fuel input curve.

Field: Coefficient 1 of Fuel Input Curve[LINK]

This numeric field contains the first coefficient for the Fuel Input Curve.

Field: Coefficient 2 of Fuel Input Curve[LINK]

This numeric field contains the second coefficient for the Fuel Input Curve.

Field: Coefficient 3 of Fuel Input Curve[LINK]

This numeric field contains the third coefficient for the Fuel Input Curve.

The following three fields contain the coefficients for the temperature based fuel input curve.

Field: Coefficient 1 of Temperature Based Fuel Input Curve[LINK]

This numeric field contains the first coefficient for the Temperature Based Fuel Input Curve.

Field: Coefficient 2 of Temperature Based Fuel Input Curve[LINK]

This numeric field contains the second coefficient for the Temperature Based Fuel Input Curve.

Field: Coefficient 3 of Temperature Based Fuel Input Curve[LINK]

This numeric field contains the third coefficient for the Temperature Based Fuel Input Curve.

Exhaust Flow Curve[LINK]

The Exhaust Flow Curve is a quadratic equation that determines the Ratio of Exhaust Gas Flow Rate to Engine Capacity. The defining equation is:

ExhaustTemperature=(C1+C2RLoad+C3RLoad2)(TBC1+TBC2ATair+TBC3AT2air)273.15

where GTCapacity is the Combustion Turbine Engine Capacity, and ATair is the difference between the current ambient and design ambient temperatures.

Field: Coefficient 1 of Exhaust Flow Curve[LINK]

This numeric field contains the first coefficient for the Exhaust Flow Curve.

Field: Coefficient 2 of Exhaust Flow Curve[LINK]

This numeric field contains the second coefficient for the Exhaust Flow Curve.

Field: Coefficient 3 of Exhaust Flow Curve[LINK]

This numeric field contains the third coefficient for the Exhaust Flow Curve.

Exhaust Gas Temperature Curve[LINK]

The Exhaust Gas Temperature Curve is a polynomial equation that determines the Exhaust Gas Temperature. The equation combines both the Exhaust Gas Temperature Curve Coefficients (Based on the Part Load Ratio) and the (Ambient) Temperature Based Exhaust Gas Temperature Curve Coefficients. The defining equation is:

RecoveryLubeEnergy=PLoad(C1+C2RL+C3RL2)

where C represents the Exhaust Gas Temperature Curve Coefficients, TBC are the Temperature Based Exhaust Gas Temperature Curve Coefficients, RLoad is the Ratio of Load to Combustion Turbine Engine Capacity, and ATair is the difference between the actual ambient and design ambient temperatures.

Field: Coefficient 1 of Exhaust Gas Temperature Curve[LINK]

This numeric field contains the first coefficient for the Exhaust Gas Temperature Curve.

Field: Coefficient 2 of Exhaust Gas Temperature Curve[LINK]

This numeric field contains the second coefficient for the Exhaust Gas Temperature Curve.

Field: Coefficient 3 of Exhaust Gas Temperature Curve[LINK]

This numeric field contains the third coefficient for the Exhaust Gas Temperature Curve.

Field: Coefficient 1 of Temperature Based Exhaust Gas Temperature Curve[LINK]

This numeric field contains the first coefficient for the Temperature Based Exhaust Gas Temperature Curve.

Field: Coefficient 2 of Temperature Based Exhaust Gas Temperature Curve[LINK]

This numeric field contains the second coefficient for the Temperature Based Exhaust Gas Temperature Curve.

Field: Coefficient 3 of Temperature Based Exhaust Gas Temperature Curve[LINK]

This numeric field contains the third coefficient for the Temperature Based Exhaust Gas Temperature Curve.

Recovery Lubricant Heat Curve[LINK]

The Recovery Lubricant Heat Curve is a quadratic equation that determines the recovery lube energy. The defining equation is:

UAToCapacityRatio=C1GasTurbineEngineCapacityC2

where Pload is the engine load and RL is the Ratio of Load to Combustion Turbine Engine Capacity

The following three fields contain the coefficients for the quadratic equation.

Field: Coefficient 1 of Recovery Lube Heat Curve[LINK]

This numeric field contains the first coefficient for the Recovery Lube Heat curve.

Field: Coefficient 2 of Recovery Lube Heat Curve[LINK]

This numeric field contains the second coefficient for the Recovery Lube Heat curve.

Field: Coefficient 3 of Recovery Lube Heat Curve[LINK]

This numeric field contains the third coefficient for the Recovery Lube Heat curve.

U-Factor Times Area Curve Curve[LINK]

The U-Factor Times Area Curve (UA) is an equation that determines the overall heat transfer coefficient for the exhaust gasses with the stack. The heat transfer coefficient ultimately helps determine the exhaust stack temperature. The defining equation is:

AvailableCoolingCapacity=NominalCoolingCapacityCoolCapfT(Tcw,l,Tcond)

The following two fields contain the coefficients for the equation.

Field: Coefficient 1 of U-Factor Times Area Curve[LINK]

This numeric field contains the first coefficient for the overall heat transfer coefficient curve.

Field: Coefficient 2 of U-Factor Times Area Curve[LINK]

This numeric field contains the second (exponential) coefficient for the overall heat transfer coefficient curve.

Field: Gas Turbine Engine Capacity[LINK]

This numeric field contains the capacity of the gas turbine engine in watts. This field is autosizable. When autosized the field below called Turbine Engine Effciency can be used to scale the resulting size.

Field: Maximum Exhaust Flow per Unit of Power Output[LINK]

This numeric field contains the maximum exhaust gas mass flow rate per kilowatt of power out.

Field: Design Steam Saturation Temperature[LINK]

This numeric field contains the design steam saturation temperature in Celsius.

Field: Fuel Higher Heating Value[LINK]

This numeric field contains the higher heating value of the fuel used in kJ/kg.

Field: Design Heat Recovery Water Flow Rate[LINK]

This optional numeric field is the design heat recovery plant fluid flow rate, if the heat recovery option is being simulated. If this value is greater than 0.0, or autosize, then a heat recovery loop must be specified and attached to the chiller using the next two node input fields. The units are in cubic meters per second. This field is autosizable. When autosizing, the flow rate is simply the product of the design condenser flow rate and the Condenser Heat Recovery Relative Capacity Fraction set in the field below.

Field: Heat Recovery Inlet Node Name[LINK]

This alpha field contains the identifying name for the heat recovery side inlet. If a loop is connected, then the jacket and lubricant heat will be recovered. There is no need for an effectiveness term, since the jacket and lubricant recovered heat energies are the actual recovered energies.

Field: Heat Recovery Outlet Node Name[LINK]

This alpha field contains the identifying name for the heat recovery side outlet.

Field: Chiller Flow Mode[LINK]

This choice field determines how the chiller operates with respect to the intended fluid flow through the device’s evaporator. There are three different choices for specifying operating modes for the intended flow behavior: “NotModulated,” “ConstantFlow,” and “LeavingSetpointModulated.” NotModulated is useful for either variable or constant speed pumping arrangements where the chiller is passive in the sense that although it makes a nominal request for its design flow rate it can operate at varying flow rates. ConstantFlow is useful for constant speed pumping arrangements where the chiller’s request for flow is stricter and can increase the overall loop flow. LeavingSetpointModulated changes the chiller model to internally vary the flow rate so that the temperature leaving the chiller matches a setpoint. In all cases the operation of the external plant system can also impact the flow through the chiller – for example if the relative sizes and operation are such that flow is restricted and the requests cannot be met. The default, if not specified, is NotModulated.

Field: Fuel Type[LINK]

This alpha field determines the type of fuel that the chiller uses. Valid choices are: NaturalGas, PropaneGas, Diesel, Gasoline, FuelOil#1, FuelOil#2, OtherFuel1 or OtherFuel2. The default is NaturalGas.

Field: Heat Recovery Maximum Temperature[LINK]

This field sets the maximum temperature that this piece of equipment can produce for heat recovery. The idea behind this field is that the current models do not take temperatures into account for availability and they just pass Q’s around the loop without a temperature limit. This temperature limit puts an upper bound on the recovered heat and limits the max temperatures leaving the component.

As temperatures in the loop approach the maximum temperature, the temperature difference between the entering water and the surfaces in the piece of equipment becomes smaller. For the given heat recovery flow rate and that temperature difference the amount of heat recovered will be reduced, and eventually there will be no heat recovered when the entering water temperature is equal to the maximum temperature specified by the user in this field. The reduced amount of heat recovered will diminish if the temperature of the loop approach is the maximum temperature, and this will show up in the reporting. This allows the user to set the availability or the quality of the heat recovered for usage in other parts of the system or to heat domestic hot water supply.

The temperature is specified in degrees C.

Field: Sizing Factor[LINK]

This optional numeric field allows the user to specify a sizing factor for this component. The sizing factor is used when the component design inputs are autosized: the autosizing calculations are performed as usual and the results are multiplied by the sizing factor. For this component the inputs that would be altered by the sizing factor are: Nominal Capacity, Design Chilled Water Flow Rate and Design Condenser Water Flow Rate. Sizing Factor allows the user to size a component to meet part of the design load while continuing to use the autosizing feature.

Field: Basin Heater Capacity[LINK]

This numeric field contains the capacity of the chiller’s electric basin heater in watts per degree Kelvin. This field only applies for Condenser Type = EvaporativelyCooled. This field is used in conjunction with the Basin Heater Setpoint Temperature described in the following field. The basin heater electric power is equal to this field multiplied by the difference between the basin heater set point temperature and the outdoor dry-bulb temperature. The basin heater only operates when the chiller is off, regardless of the basin heater schedule described below. The basin heater capacity must be greater than or equal to zero, with a default value of zero if this field is left blank.

Field: Basin Heater Setpoint Temperature[LINK]

This numeric field contains the set point temperature (˚C) for the basin heater described in the previous field. This field only applies for Condenser Type = EvaporativelyCooled. The basin heater is active when the outdoor air dry-bulb temperature falls below this setpoint temperature, as long as the chiller is off. This set point temperature must be greater than or equal to 2˚C, and the default value is 2˚C if this field is left blank.

Field: Basin Heater Operating Schedule Name[LINK]

This alpha field contains the name of the basin heater operating schedule. This field only applies for Condenser Type = EvaporativelyCooled. The basin heater operating schedule is assumed to be an on/off schedule and the heater is available to operate any time the schedule value is greater than 0. The basin heater operates when scheduled on and the outdoor air dry-bulb temperature is below the set point temperature described in the previous field. If this field is left blank, the basin heater is available to operate throughout the simulation. Regardless of this schedule, the basin heater may only operate when the chiller is off.

Field: Condenser Heat Recovery Relative Capacity Fraction[LINK]

This field is optional. It can be used to describe the physical size of the heat recovery portion of a split bundle condenser section. This fraction describes the relative capacity of the heat recovery bundle of a split condenser compared to the nominal, full load heat rejection rate of the chiller. This fraction will be applied to the full heat rejection when operating at nominal capacity and nominal COP to model a capacity limit for the heat rejection. If this field is not entered then the capacity fraction is set to 1.0.

Field: Turbine Engine Efficiency[LINK]

This field is optional. It can be used to scale the size of Gas Turbine Engine Capacity. the default is 0.35.

An example of this statement in an IDF is:

Chiller:CombustionTurbine,
      Big Chiller,             !- Chiller Name
      WaterCooled,            !- Condenser Type
      30000,                   !- Nominal Capacity {W}
      2.75,                    !- COP
      Big Chiller Inlet Node,  !- Chilled Water Inlet Node Name
      Big Chiller Outlet Node, !- Chilled Water Outlet Node Name
      Big Chiller Condenser Inlet Node,  !- Condenser Inlet Node Name
      Big Chiller Condenser Outlet Node,  !- Condenser Outlet Node Name
      .15,                     !- Minimum Part Load Ratio
      1.0,                     !- Maximum Part Load Ratio
      .65,                     !- Optimum Part Load Ratio
      35.0,                    !- Design Condenser Inlet Temperature {C}
      2.778,                   !- Temperature Rise Coefficient
      6.67,                    !- Design Chilled Water Outlet Temperature {C}
      0.0011,                  !- Design Chilled Water Flow Rate {m3/s}
      0.0011,                  !- Design Condenser Water Flow Rate {m3/s}
      0.9949,                  !- Coefficient 1 of Capacity Ratio Curve
      -0.045954,               !- Coefficient 2 of Capacity Ratio Curve
      -0.0013543,              !- Coefficient 3 of Capacity Ratio Curve
      2.333,                   !- Coefficient 1 of Power Ratio Curve
      -1.975,                  !- Coefficient 2 of Power Ratio Curve
      0.6121,                  !- Coefficient 3 of Power Ratio Curve
      0.03303,                 !- Coefficient 1 of Full Load Ratio Curve
      0.6852,                  !- Coefficient 2 of Full Load Ratio Curve
      0.2818,                  !- Coefficient 3 of Full Load Ratio Curve
      5,                       !- Chilled Water Outlet Temperature Lower Limit {C}
      9.41,                    !- Coefficient 1 of Fuel Input curve
      -9.48,                   !- Coefficient 2 of Fuel Input curve
      4.32,                    !- Coefficient 3 of Fuel Input curve
      1.0044,                  !- Coefficient 1 of Temperature Based Fuel Input curve
      -0.0008,                 !- Coefficient 2 of Temperature Based Fuel Input curve
      0,                       !- Coefficient 3 of Temperature Based Fuel Input curve
      15.63518363,             !- Coefficient 1 of Exhaust Flow curve
      -0.03059999,             !- Coefficient 2 of Exhaust Flow curve
      -0.0002,                 !- Coefficient 3 of Exhaust Flow curve
      916.992,                 !- Coefficient 1 of Exhaust Gas Temperature curve
      307.998,                 !- Coefficient 2 of Exhaust Gas Temperature curve
      79.992,                  !- Coefficient 3 of Exhaust Gas Temperature curve
      1.005,                   !- Coefficient 1 of Temperature Based Exhaust Gas Temperature c
      0.0018,                  !- Coefficient 2 of Temperature Based Exhaust Gas Temperature c
      0,                       !- Coefficient 3 of Temperature Based Exhaust Gas Temperature c
      0.223,                   !- Coefficient 1 of Recovery Lube Heat curve
      -0.4,                    !- Coefficient 2 of Recovery Lube Heat curve
      0.2286,                  !- Coefficient 3 of Recovery Lube Heat curve
      0.01907045,              !- Coefficient 1 of UA curve
      0.9,                     !- Coefficient 2 of UA curve
      50000,                   !- Gas Turbine Engine Capacity {W}
      0.00000504,              !- Maximum Exhaust Flow per Unit of Power Output {(kg/s)/W}
      150,                     !- Design Steam Saturation Temperature {C}
      43500,                   !- Fuel Higher Heating Value {kJ/kg}
      0.0,                     !- Design Heat Recovery Water Flow Rate {m3/s}
      ,                        !- Heat Recovery Inlet Node Name
      ,                        !- Heat Recovery Outlet Node Name
      VariableFlow,            !- Chiller Flow Mode
      NaturalGas,              !- Fuel Type
      80.0;                    !- Heat Recovery Maximum Temperature {C}

Outputs[LINK]

  • HVAC,Average,Chiller Electric Power [W]

  • HVAC,Sum,Chiller Electric Energy [J]

  • Zone,Meter,Electricity:Plant [J]

  • Zone,Meter,Cooling:Electricity [J]

  • HVAC,Average,Chiller Evaporator Cooling Rate [W]

  • HVAC,Sum,Chiller Evaporator Cooling Energy [J]

  • Zone,Meter,EnergyTransfer:Plant [J]

  • Zone,Meter,Chillers:EnergyTransfer [J]

  • HVAC,Average,Chiller Evaporator Inlet Temperature [C]

  • HVAC,Average,Chiller Evaporator Outlet Temperature [C]

  • HVAC,Average,Chiller Evaporator Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller Condenser Heat Transfer Energy Rate [W]

  • HVAC,Sum,Chiller Condenser Heat Transfer Energy [J]

  • Zone,Meter,HeatRejection:EnergyTransfer [J]

  • HVAC,Average,Chiller COP [W/W]

Air-cooled or Evap-cooled:

  • HVAC,Average,Chiller Condenser Inlet Temperature [C]

Evap-cooled:

  • HVAC,Average,Chiller Basin Heater Electric Power [W]

  • HVAC,Average,Chiller Basin Heater Electric Energy [J]

Water-cooled:

  • HVAC,Average,Chiller Condenser Inlet Temperature [C]

  • HVAC,Average,Chiller Condenser Outlet Temperature [C]

  • HVAC,Average,Chiller Condenser Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller Drive Shaft Power [W]

  • HVAC,Sum,Chiller Drive Shaft Energy [J]

  • HVAC,Sum,Chiller Lube Recovered Heat Energy [J]

  • Zone,Meter,HeatRecovery:EnergyTransfer [J]

  • HVAC,Average,Chiller Exhaust Temperature [C]

  • HVAC,Average,Chiller Heat Recovery Inlet Temperature [C]

  • HVAC,Average,Chiller Heat Recovery Outlet Temperature [C]

  • HVAC,Average,Chiller Heat Recovery Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller <Fuel Type> Rate [W]

  • HVAC,Sum,Chiller <Fuel Type> Energy [J]

  • HVAC,Average,Chiller <Fuel Type> Mass Flow Rate [kg/s]

  • HVAC,Sum,Chiller <Fuel Type> Mass [kg]

  • HVAC,Average,Chiller COP [W/W]

These chiller output variables are defined above under “Generic Chiller Outputs.” The Fuel Type input will determine which fuel type is displayed in the output. In this example with the user choice of NaturalGas, you will have Gas Consumption.

ChillerHeater:Absorption:DirectFired[LINK]

This chiller is a direct fired absorption chiller-heater which is modeled using performance curves similar to the equivalent chiller in DOE-2.1E. This type of chiller is unusual for EnergyPlus, because it may be used in the same plant on both a chilled water supply branch and a hot water supply branch. The chiller has six node connections for chilled water, condenser water, and hot water, and can provide simultaneous heating and cooling. During simultaneous operation, the heating capacity is reduced as the cooling load increases (for more details see below). Some equations are provided below to help explain the function of the various performance curves. For a detailed description of the algorithm and how the curves are used in the calculations, please see the Engineering Reference.

Inputs[LINK]

Field: Name[LINK]

This alpha field contains the identifying name for the chiller.

Field: Nominal Cooling Capacity[LINK]

This numeric field contains the nominal cooling capability of the chiller in Watts.

Field: Heating to Cooling Capacity Ratio[LINK]

A positive fraction that represents the ratio of the heating capacity divided by the cooling capacity at rated conditions. The default is 0.8.

Field: Fuel Input to Cooling Output Ratio[LINK]

A positive fraction that represents the ratio of the instantaneous cooling fuel used divided by the cooling capacity at rated conditions. The default is 0.97.

Field: Fuel Input to Heating Output Ratio[LINK]

A positive fraction that represents the ratio of the instantaneous heating fuel used divided by the nominal heating capacity. The default is 1.25.

Field: Electric Input to Cooling Output Ratio[LINK]

A positive fraction that represents the ratio of the instantaneous electricity used divided by the cooling capacity at rated conditions. If the chiller is both heating and cooling only the greater of the computed cooling and heating electricity is used. The default is 0.01.

Field: Electric Input to Heating Output Ratio[LINK]

A positive fraction that represents the ratio of the instantaneous electricity used divided by the nominal heating capacity. If the chiller is both heating and cooling, the greater of the cooling electricity and heating eletricity is used. The default is 0.0.

Field: Chilled Water Inlet Node Name[LINK]

This required alpha field contains the identifying name for the chiller chilled water side inlet node. This node name must be the same as the inlet node name for the chilled water supply branch on which this chiller is placed.

Field: Chilled Water Outlet Node Name[LINK]

This required alpha field contains the identifying name for the chiller chilled water side outlet node.

Field: Condenser Inlet Node Name[LINK]

This required alpha field contains the identifying name for the chiller condenser side inlet node. If the Chiller is AirCooled, the node name specified must also be specified in an OutdoorAir:Node object where the height of the node is taken into consideration when calculating outdoor air dry-bulb temperature from the weather data. Alternately, the node name may be specified in an OutdoorAir:NodeList object where the outdoor air dry-bulb temperature is taken directly from the weather data.

Field: Condenser Outlet Node Name[LINK]

This alpha field contains the identifying name for the chiller condenser side outlet node. It is required for WaterCooled chillers but not for AirCooled.

Field: Hot Water Inlet Node Name[LINK]

This required alpha field contains the identifying name for the chiller-heater hot water side inlet node. This node name must be the same as the inlet node name for the hot water supply branch on which this chiller-heater is placed.

Field: Hot Water Outlet Node Name[LINK]

This required alpha field contains the identifying name for the chiller-heater hot water side outlet node.

Field: Minimum Part Load Ratio[LINK]

A positive fraction that represents the minimum cooling or heating output possible when operated continually at rated temperature conditions divided by the available cooling or heating capacity at those same conditions. If the load on the chiller is below this fraction, the chiller will cycle. If the chiller is simultaneously heating and cooling, the greater part load ratio will be used. The default is 0.1.

Field: Maximum Part Load Ratio[LINK]

A positive fraction that represents the maximum cooling or heating output possible when operated continually at rated temperature conditions divided by the available cooling or heating capacity at those same conditions. If greater than 1.0, the chiller is typically thought of as capable of being overloaded. The default is 1.0.

Field: Optimum Part Load Ratio[LINK]

A positive fraction that represents the optimum cooling or heating output possible when operated continually at rated temperature conditions divided by the available cooling or heating capacity at those same conditions. It represents the most desirable operating point for the chiller. The default is 1.0.

Field: Design Entering Condenser Water Temperature[LINK]

The temperature in degrees C of the water entering the condenser of the chiller when operating at design conditions. This is usually based on the temperature delivered by the cooling tower in a water cooled application. The default is 29C.

Field: Design Leaving Chilled Water Temperature[LINK]

The temperature in degrees C of the water leaving the evaporator of the chiller when operating at design conditions; also called the chilled water supply temperature or leaving chilled water temperature. The default is 7C.

Field: Design Chilled Water Flow Rate[LINK]

For variable volume this is the max flow and for constant flow this is the chilled water flow rate in m3/s.

Field: Design Condenser Water Flow Rate[LINK]

The water flow rate at design conditions through the condenser in m3/s. This field can be autosized. This field can be autosized. This field is not used for Condenser Type = AirCooled.

Field: Design Hot Water Flow Rate[LINK]

The water flow rate at design conditions through the heater side in m3/s.

Field: Cooling Capacity Function of Temperature Curve Name[LINK]

The CoolCapfT curve represents the fraction of the cooling capacity of the chiller as it varies by temperature. The curve is normalized so that at design conditions the value of the curve should be 1.0. The curve is usually a biquadratic or bilinear curve with the input variables being the leaving chilled water temperature and either the entering or leaving condenser water temperature (see Temperature Curve Input Variable below). If the chiller is AirCooled, the temperature of the condenser inlet node (outdoor air node) is used for the condenser temperature. The available cooling capacity is computed as follows:

CoolFuelInput=AvailCoolCapRunFracCFIRCFIRfT(Tcw,l,Tcond)CFIRfPLR(CPLR)

Field: Fuel Input to Cooling Output Ratio Function of Temperature Curve Name[LINK]

The CFIRfT curve represents the fraction of the fuel input to the chiller at full load as it varies by temperature. The curve is normalized so that at design conditions the value of the curve should be 1.0. The curve is usually a biquadratic or bilinear curve with the input variables being the leaving chilled water temperature and either the entering or leaving condenser water temperature (see Temperature Curve Input Variable below). If the chiller is AirCooled, the temperature of the condenser inlet node (outdoor air node) is used for the condenser temperature.

Field: Fuel Input to Cooling Output Ratio Function of Part Load Ratio Curve Name[LINK]

The CFIRfPLR curve represents the fraction of the fuel input to the chiller as the load the chiller varies but the operating temperatures remain at the design values. The curve is normalized so that at full load the value of the curve should be 1.0. The curve is usually linear or quadratic. The cooling fuel input to the chiller is computed as follows:

CoolElectricPower=NomCoolCapRunFracCEIRCEIRfT(Tcw,l,Tcond)CEIRfPLR(CPLR)

Field: Electric Input to Cooling Output Ratio Function of Temperature Curve Name[LINK]

The ElecCoolFT curve represents the fraction of the electricity to the chiller at full load as it varies by temperature. The curve is normalized so that at design conditions the of the curve should be 1.0. The curve is usually a biquadratic or bilinear curve with the input variables being the leaving chilled water temperature and either the entering or leaving condenser water temperature (see Temperature Curve Input Variable below). If the chiller is AirCooled, the temperature of the condenser inlet node (outdoor air node) is used for the condenser temperature.

Field: Electric Input to Cooling Output Ratio Function of Part Load Ratio Curve Name[LINK]

The ElecCoolFPLR curve represents the fraction of the electricity to the chiller as the load on the chiller varies but This operating temperatures remain at the design values. The curve is normalized so that at full load the value of the curve should be 1.0. The curve is usually linear or quadratic. The cooling electric input to the chiller is computed as follows:

AvailHeatCap=NomCoolCapHeatCoolCapRatioHeatCapfCPLR(CPLRh)

Field: Heating Capacity Function of Cooling Capacity Curve Name[LINK]

The HeatCapFCool curve represents how the heating capacity of the chiller varies with cooling capacity when the chiller is simultaeous heating and cooling. The curve is normalized so an input of 1.0 represents the nominal cooling capacity and an output of 1.0 represents the full heating capacity (see the Heating to Cooling Capacity Ratio input) The curve is usually linear or quadratic. The available heating capacity is computed as follows:

HeatFuelInput=AvailHeatCapHFIRHFIRfHPLR(HPLR)

Field: Fuel Input to Heat Output Ratio During Heating Only Operation Curve Name[LINK]

When the chiller is operating as only a heater, the curve is used to represent the fraction of fuel used as the heating load varies. It is normalized so that a value of 1.0 is the full available heating capacity. The curve is usually linear or quadratic and will probably be similar to a boiler curve for most chillers.

AvailCoolCap=NomCoolCapCoolCapfT(Tcw,l,Tcond)

Field: Temperature Curve Input Variable[LINK]

This field sets the second independent variable in the three temperature dependent performance curves to either the leaving or entering condenser water temperature. Manufacturers express the performance of their chillers using either the leaving condenser water temperature (to the tower) or the entering condenser water temperature (from the tower). Valid choices for this field are: LeavingCondenser or EnteringCondenser. It is important that the performance curves and this field are consistent with each other. The default is EnteringCondenser.

Field: Condenser Type[LINK]

The condenser can either be air cooled or connected to a cooling tower. This alpha field contains the keyword for the type of condenser, either AirCooled, or WaterCooled. The default is WaterCooled.

Field: Chilled Water Temperature Lower Limit[LINK]

The chilled water supply temperature in degrees C below which the chiller will shut off. The default is 2C.

Field: Fuel Higher Heating Value[LINK]

The fuel higher heating value in kJ/kg. This field is not currently used.

Field: Fuel Type[LINK]

This alpha field determines the type of fuel that the chiller uses. The default is NaturalGas. Valid values are NaturalGas, PropaneGas, Diesel, Gasoline, FuelOil#1, FuelOil#2, OtherFuel1, OtherFuel2.

Field: Sizing Factor[LINK]

This optional numeric field allows the user to specify a sizing factor for this component. The sizing factor is used when the component design inputs are autosized: the autosizing calculations are performed as usual and the results are multiplied by the sizing factor. For this component the inputs that would be altered by the sizing factor are: Nominal Cooling Capacity, Design Chilled Water Flow Rate, Design Condenser Water Flow Rate and Design Hot Water Flow Rate. Sizing Factor allows the user to size a component to meet part of the design load while continuing to use the autosizing feature.

An example of this statement in an IDF is:

ChillerHeater:Absorption:DirectFired,
      Big Chiller,             !- Chiller Name
      100000,                  !- Nominal Cooling Capacity {W}
      0.8,                     !- Heating to Cooling capacity ratio
      0.97,                    !- Fuel Input to Cooling Output Ratio
      1.25,                    !- Fuel Input to Heating Output Ratio
      0.01,                    !- Electric Input to Cooling Output Ratio
      0.005,                   !- Electric Input to Heating Output Ratio
      Big Chiller Inlet Node,  !- Chilled Water Side Inlet Node Name
      Big Chiller Outlet Node, !- Chilled Water Side Outlet Node Name
      Big Chiller Condenser Inlet Node,  !- Condenser Side Inlet Node Name
      Big Chiller Condenser Outlet Node,  !- Condenser Side Outlet Node Name
      Purchased Heat Inlet Node,  !- Hot Water Side Inlet Node Name
      Purchased Heat Outlet Node,  !- Hot Water Side Outlet Node Name
      0.000001,                !- Minimum Part Load Ratio
      1.0,                     !- Maximum Part Load Ratio
      0.6,                     !- Optimum Part Load Ratio
      29,                      !- Design Entering Condenser Water Temperature {C}
      7,                       !- Design Leaving Chilled Water Temperature {C}
      0.0011,                  !- Design Chilled Water Flow Rate {m3/s}
      0.0011,                  !- Design Condenser Water Flow Rate {m3/s}
      0.0043,                  !- Design Hot Water Flow Rate {m3/s}
      GasAbsFlatBiQuad,        !- Cooling Capacity Function of Temperature Curve Name
      GasAbsFlatBiQuad,        !- Fuel Input to Cooling Output Ratio Function of Temperature Curve Name
      GasAbsLinearQuad,        !- Fuel Input to Cooling Output Ratio Function of Part Load Ratio Curve Name
      GasAbsFlatBiQuad,        !- Electric Input to Cooling Output Ratio Function of Temperature Curve Name
      GasAbsFlatQuad,          !- Electric Input to Cooling Output Ratio Function of Part Load Ratio Curve Name
      GasAbsInvLinearQuad,     !- Heating Capacity Function of Cooling Capacity Curve Name
      GasAbsLinearQuad,        !- Fuel Input to Heat Output Ratio During Heating Only Operation Curve Name
      EnteringCondenser,       !- Temperature Curve Input Variable
      WaterCooled,             !- Condenser Type
      2,                       !- Chilled Water Temperature Lower Limit {C}
      0,                       !- Fuel Higher Heating Value {kJ/kg}
      NaturalGas,              !- Fuel Type
      1.0;                     !- Sizing Factor

Outputs[LINK]

  • HVAC,Average,Chiller Heater Electric Power [W]

  • HVAC,Sum,Chiller Heater Electric Energy [J]

  • Zone,Meter,Electricity:Plant [J]

  • Zone,Meter,Cooling:Electricity [J]

  • HVAC,Average,Chiller <Fuel Type> Consumption Rate [W]

  • HVAC,Sum,Chiller <Fuel Type> Consumption [J]

  • Zone,Meter,<Fuel Type>:Plant [J]

  • Zone,Meter,Cooling:<Fuel Type> [J]

  • HVAC,Average,Chiller Evaporator Cooling Rate [W]

  • HVAC,Sum,Chiller Heater Evaporator Cooling Energy [J]

  • Zone,Meter,EnergyTransfer:Plant [J]

  • Zone,Meter,Chillers:EnergyTransfer [J]

  • HVAC,Average,Chiller Heater Evaporator Inlet Temperature [C]

  • HVAC,Average,Chiller Heater Evaporator Outlet Temperature [C]

  • HVAC,Average,Chiller Heater Evaporator Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller Heater Condenser Heat Transfer Rate [W]

  • HVAC,Sum,Chiller Heater Condenser Heat Transfer Energy [J]

  • Zone,Meter,HeatRejection:EnergyTransfer [J]

The following output is applicable only for air-cooled chillers

  • HVAC,Average,Chiller Heater Condenser Inlet Temperature [C]

The following three outputs are only available for water-cooled chillers

  • HVAC,Average,Chiller Heater Condenser Inlet Temperature [C]

  • HVAC,Average,Chiller Heater Condenser Outlet Temperature [C]

  • HVAC,Average,Chiller Heater Condenser Mass Flow Rate [kg/s]

Outputs specific to Direct Fired Absorption Chiller

  • HVAC,Average,Chiller Heater Runtime Fraction []

Outputs specific to Direct Fired Absorption Chiller during cooling operation

  • HVAC,Average,Chiller Heater Cooling <Fuel Type> Rate [W]

  • HVAC,Sum,Chiller Heater Cooling <Fuel Type> Consumption [J]

  • HVAC,Average,Chiller Heater Cooling Electric Power [W]

  • HVAC,Sum,Chiller Heater Cooling Electric Energy [J]

  • HVAC,Average,Chiller Heater Cooling Part Load Ratio

  • HVAC,Average,Chiller Heater Cooling Rate [W]

  • HVAC,Average,Chiller Heater Cooling COP [W/W]

Outputs specific to Direct Fired Absorption Chiller during heating operation

  • HVAC,Average,Chiller Heater Heating Rate [W]

  • HVAC,Sum,Chiller Heater Heating Energy [J]

  • HVAC,Average,Chiller Heater Heating <Fuel Type> Rate [W]

  • HVAC,Sum,Chiller Heater Heating <Fuel Type> Energy [J]

  • HVAC,Average,Chiller Heater Heating Electric Power [W]

  • HVAC,Sum,Chiller Heater Heating Electric Energy [J]

  • HVAC,Average,Chiller Heater Heating Part Load Ratio []

  • HVAC,Average,Chiller Heater Heating Rate [W]

  • HVAC,Average,Chiller Heater Heating Inlet Temperature [C]

  • HVAC,Average,Chiller Heater Heating Outlet Temperature [C]

  • HVAC,Average,Chiller Heater Heating Mass Flow Rate [kg/s]

The “Chiller” output variables are defined above under “Generic Chiller Outputs.” The specific “Direct Fired Absorption Chiller” output variables and exceptions to the generic outputs are defined below.

Chiller Heater Electric Power [W] [LINK]

Chiller Heater Electric Energy [J] [LINK]

These outputs are the electric power input to the chiller when operating in cooling mode, heating mode, or both. This value is not metered, but the separate cooling and heating electric consumption are metered (see below).

Chiller Heater <Fuel Type> Rate [W] [LINK]

Chiller Heater <Fuel Type> Energy [J] [LINK]

These outputs are the fuel input to the chiller when operating in cooling mode, heating mode, or both depending on the fuel type entered. This value is not metered, but the separate cooling and heating fuel consumption are metered (see below).

Chiller Heater Runtime Fraction [] [LINK]

This is the average fraction of the time period during which the direct fired absorption chiller-heater was operating in either cooling mode, heating mode, or both.

Chiller Heater Cooling <Fuel Type> Rate [W] [LINK]

Chiller Heater Cooling <Fuel Type> Energy [J] [LINK]

These outputs are the fuel input to the direct fired absorption chiller to serve cooling operation. Consumption is metered on Cooling:<Fuel Type>, <Fuel Type>:Plant, and <Fuel Type>:Facility.

Chiller Heater Cooling Electric Power [W] [LINK]

Chiller Heater Cooling Electric Energy [J] [LINK]

These outputs are the electricity input to the direct fired absorption chiller to serve cooling operation. Consumption is metered on Cooling:Electricity, Electricity:Plant, and Electricity:Facility.

Chiller Heater Cooling Rate [W] [LINK]

This is the average available cooling capacity for the reported time period.

Chiller Heater Cooling Part Load Ratio[LINK]

This is the average cooling load (Chiller Evaporator Cooling Rate [W]) divided by the average available cooling capacity (Chiller Heater Cooling Rate [W]) for the reported time period.

Chiller Heater Cooling COP[LINK]

This is the average coefficient of performance for the chiller in cooling operation, calculated as the average cooling load (Chiller Evaporator Cooling Rate [W]) divided by the average fuel consumption during cooling (Direct Fired Absorption Chiller Cooling <Fuel Type> Consumption Rate [W]) for the reported time period. If the chiller cooling fuel consumption rate (denominator) is zero, then this output variable is set to zero.

Chiller Heater Heating Rate [W] [LINK]

Chiller Heater Heating Energy [J] [LINK]

These outputs are the heating delivered by the direct fired absorption chiller-heater to serve heating operation. Energy is metered on Boilers:EnergyTransfer, EnergyTransfer:Plant, and EnergyTransfer:Facility.

Chiller Heater Heating <Fuel Type> Rate [W] [LINK]

Chiller Heater Heating <Fuel Type> Energy [J] [LINK]

These outputs are the fuel input to the direct fired absorption chiller-heater to serve heating operation. Consumption is metered on Heating:<Fuel Type>, <Fuel Type>:Plant, and <Fuel Type>:Facility.

Chiller Heater Heating Electric Power [W] [LINK]

Chiller Heating Heating Electric Energy [J] [LINK]

These outputs are the electric power input to the direct fired absorption chiller to serve heating operation. Consumption is metered on Heating:Electricity, Electricity:Plant, and Electricity:Facility.

Chiller Heater Heating Rate [W] [LINK]

This is the average available heating capacity for the reported time period.

Chiller Heater Heating Part Load Ratio[LINK]

This is the average heating load (Chiller Heater Heating Rate [W]) divided by the average available heating capacity (Chiller Heater Heating Rate [W]) for the reported time period.

Chiller Heater Heating Inlet Temperature [C] [LINK]

Chiller Heater Heating Outlet Temperature [C] [LINK]

Chiller Heater Heating Mass Flow Rate [kg/s] [LINK]

These outputs are the hot water inlet and outlet temperatures and flow rate for the direct fired absorption chiller-heater during heating mode operation.

ChillerHeater:Absorption:DoubleEffect[LINK]

This chiller is an exhaust fired absorption chiller-heater which is modeled using performance curves similar to the direct fired absorption chiller in DOE-2.1E. The model uses the exhaust gas output from MicroTurbine. This type of chiller is unusual for EnergyPlus, because it may be used in the same plant on both a chilled water supply branch and a hot water supply branch. The chiller has six node connections for chilled water, condenser water, and hot water, and can provide simultaneous heating and cooling. During simultaneous operation, the heating capacity is reduced as the cooling load increases (for more details see below). Some equations are provided below to help explain the function of the various performance curves. For a detailed description of the algorithm and how the curves are used in the calculations, please see the Engineering Reference.

Inputs[LINK]

Field: Name[LINK]

This alpha field contains the identifying name for the chiller.

Field: Nominal Cooling Capacity[LINK]

This numeric field contains the nominal cooling capability of the chiller in Watts. Autosize can be used for this field.

Field: Heating to Cooling Capacity Ratio[LINK]

A positive fraction that represents the ratio of the heating capacity divided by the cooling capacity at rated conditions. The default is 0.8.

Field: Thermal Energy Input to Cooling Output Ratio[LINK]

A positive fraction that represents the ratio of the instantaneous cooling Thermal Energy used divided by the cooling capacity at rated conditions. The default is 0.97.

Field: Thermal Energy Input to Heating Output Ratio[LINK]

A positive fraction that represents the ratio of the instantaneous heating Thermal Energy used divided by the nominal heating capacity. The default is 1.25.

Field: Electric Input to Cooling Output Ratio[LINK]

A positive fraction that represents the ratio of the instantaneous electricity used divided by the cooling capacity at rated conditions. If the chiller is both heating and cooling only the greater of the computed cooling and heating electricity is used. The default is 0.01.

Field: Electric Input to Heating Output Ratio[LINK]

A positive fraction that represents the ratio of the instantaneous electricity used divided by the nominal heating capacity. If the chiller is both heating and cooling, the greater of the cooling electricity and heating eletricity is used. The default is 0.0.

Field: Chilled Water Inlet Node Name[LINK]

This required alpha field contains the identifying name for the chiller chilled water side inlet node. This node name must be the same as the inlet node name for the chilled water supply branch on which this chiller is placed.

Field: Chilled Water Outlet Node Name[LINK]

This required alpha field contains the identifying name for the chiller chilled water side outlet node.

Field: Condenser Inlet Node Name[LINK]

This required alpha field contains the identifying name for the chiller condenser side inlet node. If the Chiller is AirCooled, the node name specified must also be specified in an OutdoorAir:Node object where the height of the node is taken into consideration when calculating outdoor air dry-bulb temperature from the weather data. Alternately, the node name may be specified in an OutdoorAir:NodeList object where the outdoor air dry-bulb temperature is taken directly from the weather data.

Field: Condenser Outlet Node Name[LINK]

This alpha field contains the identifying name for the chiller condenser side outlet node. It is required for WaterCooled chillers but not for AirCooled.

Field: Hot Water Inlet Node Name[LINK]

This required alpha field contains the identifying name for the chiller-heater hot water side inlet node. This node name must be the same as the inlet node name for the hot water supply branch on which this chiller-heater is placed.

Field: Hot Water Outlet Node Name[LINK]

This required alpha field contains the identifying name for the chiller-heater hot water side outlet node.

Field: Minimum Part Load Ratio[LINK]

A positive fraction that represents the minimum cooling or heating output possible when operated continually at rated temperature conditions divided by the available cooling or heating capacity at those same conditions. If the load on the chiller is below this fraction, the chiller will cycle. If the chiller is simultaneously heating and cooling, the greater part load ratio will be used. The default is 0.1.

Field: Maximum Part Load Ratio[LINK]

A positive fraction that represents the maximum cooling or heating output possible when operated continually at rated temperature conditions divided by the available cooling or heating capacity at those same conditions. If greater than 1.0, the chiller is typically thought of as capable of being overloaded. The default is 1.0.

Field: Optimum Part Load Ratio[LINK]

A positive fraction that represents the optimum cooling or heating output possible when operated continually at rated temperature conditions divided by the available cooling or heating capacity at those same conditions. It represents the most desirable operating point for the chiller. The default is 1.0.

Field: Design Entering Condenser Water Temperature[LINK]

The temperature in degrees C of the water entering the condenser of the chiller when operating at design conditions. This is usually based on the temperature delivered by the cooling tower in a water cooled application. The default is 29°C.

Field: Design Leaving Chilled Water Temperature[LINK]

The temperature in degrees C of the water leaving the evaporator of the chiller when operating at design conditions; also called the chilled water supply temperature or leaving chilled water temperature. The default is 7°C.

Field: Design Chilled Water Flow Rate[LINK]

For variable volume this is the max flow and for constant flow this is the chilled water flow rate in m3/s. This field can be autosized.

Field: Design Condenser Water Flow Rate[LINK]

The water flow rate at design conditions through the condenser in m3/s. This field can be autosized. This field is not used for Condenser Type = AirCooled.

Field: Design Hot Water Flow Rate[LINK]

The water flow rate at design conditions through the heater side in m3/s. This field can be autosized.

Field: Cooling Capacity Function of Temperature Curve Name[LINK]

The CoolCapfT curve represents the fraction of the cooling capacity of the chiller as it varies with temperature. The curve is normalized so that at design conditions the value of the curve should be 1.0. The curve is usually a biquadratic or bilinear curve with the input variables being the leaving chilled water temperature and the entering condenser water temperature (see Temperature Curve Input Variable below). If the chiller is AirCooled, the temperature of the condenser inlet node (outdoor air node) is used for the condenser temperature. The available cooling capacity is computed as follows:

CoolThermalEnergyInput=AvailCoolCapRunFracTeFIRTeFIRfT(Tcw,l,Tcond)TeFIRfPLR(CPLR)

Field: Thermal Energy Input to Cooling Output Ratio Function of Temperature Curve Name[LINK]

The TeFIRfT curve represents the fraction of the Thermal Energy Input to the chiller at full load as it varies with temperature. The curve is normalized so that at design conditions the value of the curve should be 1.0. The curve is usually a biquadratic or bilinear curve with the input variables being the leaving chilled water temperature and the entering condenser water temperature (see Temperature Curve Input Variable below). If the chiller is AirCooled, the temperature of the condenser inlet node (outdoor air node) is used for the condenser temperature.

Field: Thermal Energy Input to Cooling Output Ratio Function of Part Load Ratio Curve Name[LINK]

The TeFIRfPLR curve represents the fraction of the Thermal Energy Input to the chiller as the load on the chiller varies but the operating temperatures remain at the design values. The curve is normalized so that at full load the value of the curve should be 1.0. The curve is usually linear or quadratic.

The cooling Thermal Energy Input to the chiller is computed as follows:

CoolElectricPower=NomCoolCapRunFracCEIRCEIRfT(Tcw,l,Tcond)CEIRfPLR(CPLR)

Field: Electric Input to Cooling Output Ratio Function of Temperature Curve Name[LINK]

The CEIRfT curve represents the fraction of the electricity to the chiller at full load as it varies with temperature. The curve is normalized so that at design conditions the of the curve should be 1.0. The curve is usually a biquadratic or bilinear curve with the input variables being the leaving chilled water temperature and either the entering or leaving condenser water temperature (see Temperature Curve Input Variable below). If the chiller is AirCooled, the temperature of the condenser inlet node (outdoor air node) is used for the condenser temperature.

Field: Electric Input to Cooling Output Ratio Function of Part Load Ratio Curve Name[LINK]

The CEIRfPLR curve represents the fraction of the electricity to the chiller as the load on the chiller varies but This operating temperatures remain at the design values. The curve is normalized so that at full load the value of the curve should be 1.0. The curve is usually linear or quadratic.

The cooling electric input to the chiller is computed as follows:

AvailHeatCap=NomCoolCapHeatCoolCapRatioHeatCapfCPLR(CPLRh)

Field: Heating Capacity Function of Cooling Capacity Curve Name[LINK]

The HeatCapFCPLR curve represents how the heating capacity of the chiller varies with cooling capacity when the chiller is simultaneously heating and cooling. The curve is normalized so an input of 1.0 represents the nominal cooling capacity and an output of 1.0 represents the full heating capacity (see the Heating to Cooling Capacity Ratio input) The curve is usually linear or quadratic.

The available heating capacity is computed as follows:

HeatThermalEnergyInput=AvailHeatCapHFIRHFIRfHPLR(HPLR)

Field: Thermal Energy Input to Heat Output Ratio During Heating Only Operation Curve Name[LINK]

When the chiller is operating as only a heater, the curve is used to represent the fraction of Thermal Energy used as the heating load varies. It is normalized so that a value of 1.0 is the full available heating capacity. The curve is usually linear or quadratic and will probably be similar to a boiler curve for most chillers.

The heating Thermal Energy Input to the chiller is computed as follows:

TheoreticalFuelUse=BoilerLoadNominalThermalEfficiency

Field: Temperature Curve Input Variable[LINK]

This field sets the second independent variable in the three temperature dependent performance curves to the entering condenser water temperature. Manufacturers express the performance of their chillers typically using the entering condenser water temperature (from the tower). ). This alpha field contains the keyword for the type of temperature input variable, , either EnteringCondenserTemperature, or LeavingCondenserTemperature. The default is EnteringCondenserTemperature.

Field: Condenser Type[LINK]

The condenser can either be air cooled or water cooled (connected to a cooling tower). This alpha field contains the keyword for the type of condenser, either AirCooled, or WaterCooled. The default is WaterCooled.

Field: Chilled Water Temperature Lower Limit[LINK]

The chilled water supply temperature in degrees C below which the chiller will shut off. The default is 2°C.

Field: Exhaust Source[LINK]

This alpha field determines the type of exhaust source the chiller uses. The default is MicroTurbine. Key Generator:MicroTurbine

Field: Exhaust Source Object[LINK]

This alpha field shows the name of the Exhaust source object – a Generator:MicroTurbine in this case

Field: Sizing Factor[LINK]

This optional numeric field allows the user to specify a sizing factor for this component. Min value should not be less than 0 and here is no max. The default is 1. The sizing factor is used when the component design inputs are autosized: the autosizing calculations are performed as usual and the results are multiplied by the sizing factor. For this component the inputs that would be altered by the sizing factor are: Nominal Cooling Capacity, Design Chilled Water Flow Rate, Design Condenser Water Flow Rate and Design Hot Water Flow Rate. Sizing Factor allows the user to size a component to meet part of the design load while continuing to use the autosizing feature.

An example of this statement in an IDF is:

ChillerHeater:Absorption:DoubleEffect,
      Exh Chiller,             !- Chiller Name
      100000,                  !- Nominal Cooling Capacity {W}
      0.8,                     !- Heating to Cooling capacity ratio
      0.97,                    !- Thermal Energy Input to Cooling Output Ratio
      1.25,                    !- Thermal Energy Input to Heating Output Ratio
      0.01,                    !- Electric Input to Cooling Output Ratio
      0.005,                   !- Electric Input to Heating Output Ratio
      Exh Chiller Inlet Node,  !- Chilled Water Side Inlet Node Name
      Exh Chiller Outlet Node, !- Chilled Water Side Outlet Node Name
      Exh Chiller Condenser Inlet Node,  !- Condenser Side Inlet Node Name
      Exh Chiller Condenser Outlet Node,  !- Condenser Side Outlet Node Name
      Exh Chiller Heating Inlet Node,  !- Hot Water Side Inlet Node Name
      Exh Chiller Heating Outlet Node,  !- Hot Water Side Outlet Node Name
      0.000001,                !- Minimum Part Load Ratio
      1.0,                     !- Maximum Part Load Ratio
      0.6,                     !- Optimum Part Load Ratio
      29,                      !- Design Entering Condenser Water Temperature {C}
      7,                       !- Design Leaving Chilled Water Temperature {C}
      0.0011,                  !- Design Chilled Water Flow Rate {m3/s}
      0.0011,                  !- Design Condenser Water Flow Rate {m3/s}
      0.0043,                  !- Design Hot Water Flow Rate {m3/s}
       ExhAbsorb_CapFt,        !- Cooling Capacity Function of Temperature Curve Name
      ExhAbsorb_EIRFt,         !- Thermal Energy Input to Cooling Output Ratio Function of Temperature Curve Name
       ExhAbsorb_PLR,        !- Thermal Energy Input to Cooling Output Ratio Function of Part Load Ratio Curve Name
      ExhAbsFlatBiQuad,        !- Electric Input to Cooling Output Ratio Function of Temperature Curve Name
      ExhAbsFlatQuad,      !- Electric Input to Cooling Output Ratio Function of Part Load Ratio Curve Name
      ExhAbsInvLinearQuad,     !- Heating Capacity Function of Cooling Capacity Curve Name
      ExhAbsLinearQuad,        !- Thermal Energy Input to Heat Output Ratio During Heating Only Operation Curve Name
      EnteringCondenser,       !- Temperature Curve Input Variable
      WaterCooled,             !- Condenser Type
      2,                       !- Chilled Water Temperature Lower Limit {C}
      Generator:MicroTurbine ; ! Field Exhaust Source Object Type
  Capston500 ;                ! Field Exhaust Source name
  1.0;                       !- Sizing Factor

Outputs[LINK]

  • HVAC,Average,Chiller Heater Electric Power [W]

  • HVAC,Sum,Chiller Heater Electric Energy [J]

  • HVAC,Average,Chiller Heater Evaporator Cooling Rate [W]

  • HVAC,Sum,Chiller Heater Evaporator Cooling Energy [J]

  • HVAC,Average,Chiller Heater Evaporator Inlet Temperature [C]

  • HVAC,Average,Chiller Heater Evaporator Outlet Temperature [C]

  • HVAC,Average,Chiller Heater Evaporator Mass Flow Rate [kg/s]

  • HVAC,Average,Chiller Heater Condenser Heat Transfer Rate [W]

  • HVAC,Sum,Chiller Heater Condenser Heat Transfer Energy [J]

The following output is applicable only for air-cooled chillers

  • HVAC,Average,Chiller Heater Condenser Inlet Temperature [C]

The following three outputs are only available for water-cooled chillers

  • HVAC,Average,Chiller Heater Condenser Inlet Temperature [C]

  • HVAC,Average,Chiller Heater Condenser Outlet Temperature [C]

  • HVAC,Average,Chiller Heater Condenser Mass Flow Rate [kg/s]

Outputs specific to Exhaust Fired Absorption Chiller

  • HVAC,Average,Chiller Heater Runtime Fraction []

Outputs specific to Exhaust Fired Absorption Chiller during cooling operation

  • HVAC,Average,Chiller Heater Cooling Electric Power [W]

  • HVAC,Sum,Chiller Heater Cooling Electric Energy [J]

  • HVAC,Average,Chiller Heater Cooling Part Load Ratio

  • HVAC,Average,Chiller Heater Maximum Cooling Rate [W]HVAC,Average,Chiller Heater Cooling Source Heat Transfer Rate [W]

  • HVAC,Average, Chiller Heater Cooling Source Heat COP [W/W]

  • HVAC,Average, Chiller Heater Source Exhaust Inlet Mass Flow Rate [kg/s]

  • HVAC,Average, Chiller Heater Source Exhaust Inlet Temperature [C]

Outputs specific to Exhaust Fired Absorption Chiller during heating operation

  • HVAC,Average,Chiller Heater Heating Rate [W]

  • HVAC,Sum,Chiller Heater Heating Energy [J]

  • HVAC,Average,Chiller Heater Heating Electric Power [W]

  • HVAC,Sum,Chiller Heater Heating Electric Energy [J]

  • Zone,Meter,Heating:Electricity [J]

  • HVAC,Average,Chiller Heater Heating Part Load Ratio

  • HVAC,Average,Chiller Heater Maximum Heating Rate [W]

  • HVAC,Average,Chiller Heater Heating Source Heat Transfer Rate

  • HVAC,Average,Chiller Heater Heating Inlet Temperature [C]

  • HVAC,Average,Chiller Heater Heating Outlet Temperature [C]

  • HVAC,Average,Chiller Heater Heating Mass Flow Rate [kg/s]

The “Chiller” output variables are defined above under “Generic Chiller Outputs.” The specific “Exhaust Fired Absorption Chiller” output variables and exceptions to the generic outputs are defined below.

Chiller Heater Electric Power [W] [LINK]

Chiller Heater Electric Energy [J] [LINK]

These outputs are the electric power input to the chiller when operating in cooling mode, heating mode, or both. This value is not metered, but the separate cooling and heating electric consumption are metered (see below).

Chiller Heater Runtime Fraction [] [LINK]

This is the average fraction of the time period during which the Exhaust Fired absorption chiller-heater was operating in either cooling mode, heating mode, or both.

These outputs are the electricity input to the Exhaust Fired absorption chiller heater to serve cooling operation. Consumption is metered on Cooling:Electricity, Electricity:Plant, and Electricity:Facility.

Chiller Heater Maximum Cooling Rate [W] [LINK]

This is the average available cooling capacity for the reported time period.

Chiller Heater Cooling Part Load Ratio [] [LINK]

This is the average cooling load (Chiller Heater Evaporator Cooling Rate [W]) divided by the average available cooling capacity (Chiller Heater Maximum Cooling Rate [W]) for the reported time period.

Chiller Heater Cooling Source Heat COP [W/W] [LINK]

This is the average coefficient of performance for the chiller in cooling operation, calculated as the average cooling load (Chiller Heater Evaporator Cooling Rate [W]) divided by the average thermal energy use during cooling (Chiller Heater Cooling Source Heat Transfer Rate [W]) for the reported time period. If the chiller cooling thermal energy use rate (denominator) is zero, then this output variable is set to zero.

Chiller Heater Heating Rate [W] [LINK]

Chiller Heater Heating Energy [J] [LINK]

Chiller Heater Heating Electric Power [W] [LINK]

Chiller Heater Heating Electric Energy [J] [LINK]

These outputs are the electric power input to the Exhaust Fired absorption chiller to serve heating operation. Consumption is metered on Heating:Electricity, Electricity:Plant, and Electricity:Facility.

Chiller Heater Maximum Heating Rate [W] [LINK]

This is the average available heating capacity for the reported time period.

Chiller Heater Heating Part Load Ratio [] [LINK]

This is the average heating load (Chiller Heater Heating Rate [W]) divided by the average available heating capacity (Chiller Heater Maximum Heating Rate [W]) for the reported time period.

Chiller Heater Heating Inlet Temperature [C] [LINK]

Chiller Heater Heating Outlet Temperature [C] [LINK]

Chiller Heater Heating Mass Flow Rate [kg/s] [LINK]

These outputs are the hot water inlet and outlet temperatures and flow rate for the Exhaust Fired absorption chiller-heater during heating mode operation.

Chiller Heater Heating Heat Recovery Potential Rate (W)[LINK]

The heat recovery potential calculated based on Microturbine exhaust temperature and flow rate during heating mode

Chiller Heater Heating Source Heat Transfer Rate (W)[LINK]

The thermal energy consumption rate required for heating.

Chiller Heater Cooling Heat Recovery Potential Rate (W)[LINK]

The heat recovery potential calculated based on Microturbine exhaust temperature and flow rate during cooling mode.

Chiller Heater Cooling Source Heat Transfer Rate (W)[LINK]

The thermal energy consumption rate required for cooling.

Chiller Heater Condenser Inlet Temperature [C] [LINK]

The condenser (heat rejection) inlet temperature for air-cooled or water chiller heater. For an air-cooled chiller heater, this output would be the dry-bulb temperature of the air entering the condenser coil. For a water cooled chiller heater, this output would be the wet-bulb temperature of the air entering the condenser coil.

Chiller Heater Condenser Heat Transfer Energy [J] [LINK]

The condenser heat transfer energy is the heat rejected from the chiller heater to either a condenser water loop or through an air-cooled condenser. The values are calculated for each HVAC system time step being simulated, and the results are summed across the reporting period. Chiller Heater Condenser Heat Transfer Energy is metered on HeatRejection:EnergyTransfer, EnergyTransfer:Plant, and EnergyTransfer:Facility.

Chiller Heater Condenser Heat Transfer Rate [W] [LINK]

The condenser heat transfer is the rate of heat rejected from the chiller heater to either a condenser water loop or through an air-cooled condenser. This value is calculated for each HVAC system time step being simulated, and the results are averaged for the time step being reported.

Chiller Heater Condenser Mass Flow Rate [kg/s] [LINK]

This is the condenser coil outlet water mass flow rate in kilograms per second. This value is calculated for each HVAC system time step being simulated, and the results are averaged for the time step being reported.

Chiller Heater Condenser Outlet Temperature [C] [LINK]

This is the condenser coil outlet water temperature in degrees C. This value is calculated for each HVAC system time step being simulated, and the results are averaged for the time step being reported

Chiller Heater Evaporator Cooling Energy [J] [LINK]

The evaporator heat transfer is the cooling delivered by the chiller heater. The values are calculated for each HVAC system time step being simulated, and the results are summed across the reporting period. Chiller Heater Evaporator Cooling Energy is metered on Chillers:EnergyTransfer, EnergyTransfer:Plant, and EnergyTransfer:Facility.

Chiller Heater Evaporator Cooling Rate [W] [LINK]

The evaporator heat transfer rate of cooling delivered by the chiller heater. This value is calculated for each HVAC system time step being simulated, and the results are averaged for the time step being reported.

Chiller Heater Evaporator Inlet Temperature [C] [LINK]

The evaporator (chilled water) inlet temperature over the time step being reported.

Chiller Heater Evaporator Mass Flow Rate [kg/s] [LINK]

The evaporator (chilled water) average mass flow rate over the time step being reported

Chiller Heater Evaporator Outlet Temperature [C] [LINK]

The evaporator (chilled water) outlet temperature over the time step being reported

Chiller Heater Cooling Electric Energy [J] [LINK]

The electric power input to the exhaust fired absorption chiller to serve cooling operation. The values are calculated for each HVAC system time step being simulated, and the results are summed across the reporting period. Consumption is metered on Heating:Electricity, Electricity:Plant, and Electricity:Facility.

Chiller Heater Cooling Electric Power [W] [LINK]

The electric power input to the Exhaust Fired absorption chiller to serve cooling operation. This value is calculated for each HVAC system time step being simulated, and the results are averaged for the time step being reported.

Chiller Heater Source Exhaust Inlet Mass Flow Rate [kg/s] [LINK]

The exhaust flow rate from the Micro Turbine

Chiller Heater Source Exhaust Inlet Temperature [C] [LINK]

The exhaust temperature from the Micro Turbine

Boiler:HotWater[LINK]

The boiler model calculates the performance of fuel oil, gas and electric boilers. Boiler performance is based on nominal thermal efficiency. A normailized efficiency performance curve may be used to more accurately represent the performance of non-electric boilers but is not considered a required input. When using the normalized efficiency performance curve, if all coefficients are not required simply set the unused coefficients to 0. For example, an electric boiler could be modeled by setting the nominal thermal efficiency to a value in the range of 0.96 to 1.0. Coefficient A0 in the normalized efficiency performance curve would equal 1 and all other coefficients would be set to 0. Coefficients for other types of non-electric boilers would set a combination of the available coefficents to non-zero values.

Inputs[LINK]

Field: Name[LINK]

This required alpha field contains the identifying name for the boiler.

Field: Fuel Type[LINK]

This required choice field specifies the type of fuel used by the boiler. The fuel type can be Electricity, NaturalGas, PropaneGas, FuelOil#1, FuelOil#2, Coal, Diesel, Gasoline, OtherFuel1 or OtherFuel2.

Field: Nominal capacity[LINK]

This numeric field contains the nominal operating capacity (W) of the boiler. The boiler may be autosized and would require a heating plant sizing object.

Fuel Use Equation[LINK]

The model is based the following two equations:

FuelUsed=TheoreticalFuelUseNormalizedBoilerEfficiencyCurveOutput

LinearEff=A0+A1PLR

Field: Nominal Thermal Efficiency[LINK]

This required numeric field contains the heating efficiency (as a fraction between 0 and 1) of the boiler’s burner. This is the efficiency relative to the higher heating value (HHV) of fuel at a part load ratio of 1.0 and the temperature entered for the Design Boiler Water Outlet Temp. Manufacturers typically specify the efficiency of a boiler using the higher heating value of the fuel. For the rare occurences when a manufacturers (or particular data set) thermal efficiency is based on the lower heating value (LHV) of the fuel, multiply the thermal efficiency by the lower-to-higher heating value ratio. For example, assume a fuel’s lower and higher heating values are approximately 45,450 and 50,000 kJ/kg, respectively. For a manuracturers thermal effiency rating of 0.90 (based on the LHV), the nominal thermal efficiency entered here is 0.82 (i.e. 0.9 multiplied by 45,450/50,000).

Field: Efficiency Curve Temperature Evaluation Variable[LINK]

This field is used to control which value for hot water temperature is used when evaluating the efficiency curve specified in the next field (if applicable). There are two options, EnteringBoiler or LeavingBoiler. EnteringBoiler indicates that the efficiency curves will be evaluated using the temperature at boiler inlet node. LeavingBoiler indicates that the efficiency curves will be evaluated using the temperature at the boiler outlet. This field is only used if type of curve is one that uses temperature as a independent variable.

Field: Normalized Boiler Efficiency Curve Name[LINK]

This alpha field contains the curve name which describes the normalized heating efficiency (as a fraction of nominal thermal efficiency) of the boiler’s burner. If this field is left blank, the nominal thermal efficiency is assumed to be constant (i.e., Fuel Used is equal to the Theoretical Fuel Use in the equation above). When a boiler efficiency curve is used, the curve may be any valid curve object with 1 (PLR) or 2 (PLR and boiler outlet water temperature) independent variables. A tri-quadratic curve object is not allowed since it uses 3 independent variables. The linear, quadratic, and cubic curve types may be used when the boiler efficiency is solely a function of boiler part-load ratio (PLR). When this type of curve is used, the boiler should operate at (or very near) the design boiler water outlet temperature. Other curve types may be used when the boiler efficiency is a function of both PLR and boiler water temperature. Examples of valid single and dual independent variable equations are shown below. For all curve types PLR is always the x independent variable. When using 2 independent variables, the boiler outlet water temperature (Toutlet) is always the y independent variable.

QuadraticEff=A0+A1PLR+A2PLR2

CubicEff=A0+A1PLR+A2PLR2+A3PLR3

CubicEff=A0+A1PLR+A2PLR2+A3PLR3

BiQuadraticEff=A0+A1PLR+A2PLR2+A3Tw+A4Tw2+A5PLRTw

Quadrati