This coil input structure is meant to supplant the coil
objects from previous EnergyPlus versions
(Coil:Cooling:DX:SingleSpeed, Coil:Cooling:DX:TwoSpeed,Coil:Cooling:DX:MultiSpeed,
etc.). This coil input structure uses a combination of four
objects to fully define the performance of the coil under a
range of operating conditions.
Coil:Cooling:DX
- Defines where the coil’s evaporator and condenser sections
are connected to the HVAC system through node connections to
air loops or zones (if condenser section rejects heat to a
zone), as well as the coil’s availability.
Coil:Cooling:DX:CurveFit:OperatingMode
- Defines the rated coil characteristics (capacity, evaporator
section air flow rate, etc.) and capacity control method for a
given operating mode. Operating modes are generally used to
describe humidity control strategies for DX cooling coil
arrangements that enable enhanced dehumidification.
Coil:Cooling:DX:CurveFit:Speed
- Defines DX cooling coil performance for a specific speed
within a single operating mode.
Note: The Coil:Cooling:DX:CurveFit:Performance
object also allows users to input 3 operating modes: Base
Operating Mode, Alternative Operating Mode 1, and Alternative
Operating Mode 2. When the Base Operating Mode is an only mode
input, the coil performs like a regular cooling DX coil and no
specific dehumidication capability. The alternative operating
mode 1 is used for enhanced dehumidification. When all 3 modes
are inputs, the coil performs as a subcool rehat coil. When
load sensible heat ratio (SHR), defined as sensible cooling
load / (sensible cooling load + latent cooling load), is
greater than the SHR in the Base Operating Mode at given inlet
air conditions, the coil performs in Base Operating Mode only.
When the load SHR is less than the SHR in the Base Operating
Mode and greater than the SHR in the Alternative Operating
Mode 1 at the same given inlet air conditions, the coil
performs combination of both Base Operating Mode, and
Alternative Operating Mode 1. Mode ratio determines a fraction
of time Alternative Operating Mode 1 operates and the rest (1
- Mode ratio) of time Base Operating Mode operates in a single
time step. When the load SHR is less than the SHR in the
Alternative Operating Mode 1 and greater than the SHR in the
Alternative Operating Mode 2 at the same given inlet air
conditions, the coil performs combination of both Base
Operating Mode, and Alternative Operating Mode 2. Mode ratio
determines a fraction of time Alternative Operating Mode 2
operates and (1 - Mode ratio) of time Base Operating Mode
operates in a single time step. When the load SHR is greater
than the SHR in the Alternative Operating Mode 2, the coil
performs as Alternative Operating Mode 2 alone.
The name of the schedule (ref: Schedule) that denotes
whether the DX cooling coil can run during a given time
period. A schedule value greater than 0 (usually 1 is used)
indicates that the unit can be on during a given time period.
A value less than or equal to 0 (usually 0 is used) denotes
that the unit must be off. If this field is blank, the
schedule has values of 1 for all time periods.
The name of a conditioned or unconditioned zone where the
secondary coil (condenser) of DX system or a heat pump is to
be placed. This is an optional input field specified only when
user desires to reject the condenser heat into a zone. The
heat rejected is modelled as internal sensible heat gain of
the zone.
The name of the HVAC system node from which the condenser
of the DX cooling coil draws its inlet air. If the condenser
draws air from the outdoors, an OutdoorAir:Node
object must be referenced.
Field:
Condensate Collection Water Storage Tank Name[LINK]
This field is optional. It is used to describe where
condensate from the coil is collected. If blank or omitted,
then any coil condensate is discarded. Enter the name of a WaterUse:Storage
object defined elsewhere and the condensate will then be
collected in that tank.
Field:
Evaporative Condenser Supply Water Storage Tank Name[LINK]
This field is optional. It is used to describe where the
coil obtains water used for evaporative cooling of its
condenser. If blank or omitted, then the unit will obtain
water directly from the mains. If the name of a WaterUse:Storage
object is used here, then the unit will obtain its water from
that tank. If a tank is specified, the unit will attempt to
obtain all the water it uses from the tank. However, if the
tank cannot provide all the water the condenser needs, then
the unit will still operate and obtain the rest of the water
it needs from the mains (referred to as StarvedWater).
A unique user-assigned name for an instance of a cooling
coil performance specification. Any reference to this cooling
coil performance specification by a cooling coil object will
use this name.
This numeric field defines the crankcase heater capacity in
Watts. When the outdoor air dry-bulb temperature is below the
value specified in the input field Maximum Outdoor Dry-bulb
Temperature for Crankcase Heater Operation (described below),
the crankcase heater is enabled during the time that the
compressor is not running. If this cooling coil is used as
part of an air-to-air heat pump (Ref. AirLoopHVAC:UnitaryHeatPump:AirToAir
or PackageTerminal: HeatPump:AirToAir), the crankcase heater
defined for this DX cooling coil is ignored and the crankcase
heater power defined for the DX heating coil (Ref.
Coil:Heating:DX:SingleSpeed) is enabled during the time that
the compressor is not running for either heating or cooling.
The value for this input field must be greater than or equal
to 0, and the default value is 0. To simulate a DX cooling
coil without a crankcase heater, enter a value of 0.
Field:
Minimum Outdoor Dry-Bulb Temperature for Compressor
Operation[LINK]
This numeric field defines the minimum outdoor air dry-bulb
temperature where the cooling coil compressor turns off. If
this input field is left blank, the default value is -25 °C
(-13 °F).
Field:
Maximum Outdoor Dry-Bulb Temperature for Crankcase Heater
Operation[LINK]
This numeric field defines the outdoor air dry-bulb
temperature above which the compressor’s crankcase heater is
disabled. The value for this input field must be greater than
or equal to 0.0 °C (32 °F), and the default value is 10 °C (50
°F).
If this coil is used with a Fan:VariableVolume
to model a packaged variable-air-volume unit, then ratings for
standard rated net capacity, EER, and IEER will be calculated
per ANSI/AHRI Standard 340/360-2007 with Addenda 1 and 2. This
field is to specify the internal static air pressure, in units
of Pascals, associated with the unit’s supply air flow for
rating purposes. This field does not affect the performance
during operation. This field is optional. If this field is
used, then the internal static air pressure is used with the
associated fan characteristics when calculating standard rated
net capacity, EER, and IEER. If this field is not used, then
the standard ratings are still performed but use a default for
specific fan power of 773.3 (W/(m\(^{3}\)/s)). The air pressure
drop/rise input here should be internal in the sense that it
is for the entire package of unitary equipment as it would be
tested in a laboratory (including other non-cooling sections
inside the package for filters, dampers, and/or heating coils)
but none of the external pressure drop for distributing supply
air throughout the building. This is different from the input
field called Pressure Rise in the fan object which includes
both the external static pressure and the internal static
pressure. The results of standard rating calculations are
reported to the EIO file and to predefined output tables
called DX Cooling Coils and VAV DX Cooling Standard Rating
Details.
This choice field defined the capacity control method.
Valid choices for this input field are
DiscreteContinuous. The
default for this field is Discrete.
Discrete control mode allow the coil to
operate at discrete speed levels. Continuous
control mode allows the coil performance to be operated at
continuously variable speeds.
This numeric field contains the capacity of the coil’s
electric evaporative cooler basin heater in Watts per degree
Kelvin. This field only applies for Condenser Type =
EvaporativelyCooled. This field is used in
conjunction with the Evaporative Condenser Basin Heater
Setpoint Temperature and Evaporative Condenser Basin Heater
Operating Schedule Name described in the following fields. 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 DX coil 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.
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 DX coil is off. This
set point temperature must be greater than or equal to 2 °C
(35.6), and the default value is 2 °C (35.6) if this field is
left blank.
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 DX coil is off.
This alpha field determines the type of fuel that this
cooling coil’s compressor uses. This field has nine choices:
Electricity, NaturalGas,
Propane, Diesel,
Gasoline, FuelOilNo1,
FuelOilNo2, OtherFuel1 and
OtherFuel2. The default is
Electricity.
The name corresponding to a Coil:Cooling:DX:CurveFit:OperatingMode
object. Operating Mode is always used as the base design
operating mode. This field is required.
The name corresponding to a Coil:Cooling:DX:CurveFit:OperatingMode
object. Operating Mode is used as the alternate operating mode
operating mode to be used for enhanced deumidification when
needed. If field is blank, the base operating mode will be
used. This field is optional.
The name corresponding to a Coil:Cooling:DX:CurveFit:OperatingMode
object. Operating Mode is used as to represent a reheat mode
as a subcool reheat coil. If field is blank, the base
operating mode will be used. This field is optional.
If there are 3 operating modes, it represents a
subcool-reheat mode coil. The Operating Mode 1 represents a
base operating mode coil. The Operating Mode 2 represents a
subcool mode coil with lower SHR than the Operating Mode 1.
The Operating Mode 3 represents a rehaet mode coil with lower
SHR than the Operating Mode 2. All 3 operation modes work
together to represent a subcool reheat coil model. The
operation procedure is described in 0.1
This object defines DX cooling coil performance for a
single operating mode at rated conditions. Each operating mode
may have one or more speeds, which are defined using the Coil:Cooling:DX:CurveFit:Speed
object. Each operation mode can reference a maximum of 10 Coil:Cooling:DX:CurveFit:Speed
objects.
A unique user-assigned name for an instance of a cooling
coil operating mode. Any reference to this cooling coil
operating mode by a cooling coil performance specification
will use this name.
The total, full load gross cooling capacity (sensible plus
latent) in Watts of the DX coil unit at rated conditions (air
entering the cooling coil at 26.7 °C drybulb/19.4 °C wetbulb
(80 °F drybulb/67 °F wetbulb), air entering the outdoor
condenser coil at 35 °C drybulb/23.9 °C wetbulb (95 °F
drybulb/75 °F wetbulb), and a cooling coil air flow rate
defined by field rated air flow rate below). Capacity should
be gross (i.e., the effect of supply air fan heat is NOT
accounted for). When used in a heat pump, the gross rated
total cooling capacity should be within 20% of the gross rated
heating capacity, otherwise a warning message is issued.
The air volume flow rate, in m\(^{3}\) per second, across the DX
cooling coil evaporator section at rated conditions. The rated
air volume flow rate should be between 0.00004027 m\(^{3}\)/s and 0.00006041 m\(^{3}\)/s per Watt of gross rated
total cooling capacity (300 to 450 cfm/ton). For DOAS
applications the rated air volume flow rate should be between
0.00001677 m\(^{3}\)/s and
0.00003355 m\(^{3}\)/s per
watt of gross rated total cooling capacity (125 to 250
cfm/ton). The gross rated total cooling capacity, gross rated
SHR and gross rated COP should be performance information for
the unit with air entering the cooling coil at 26.7 °C
drybulb/19.4 °C wetbulb (80 °F drybulb/67 °F wetbulb), air
entering the outdoor condenser coil at 35 °C drybulb/23.9 °C
wetbulb (95 °F drybulb/75 °F wetbulb), and the rated air
volume flow rate defined here.
The air volume flow rate, in m\(^{3}\) per second, entering the
evaporative condenser. This value is used to calculate the
amount of water used to evaporatively cool the condenser inlet
air. The minimum value for this field must be greater than
zero, and this input field is autosizable (equivalent to
0.000144 m\(^{3}\)/s per watt
of rated total cooling capacity [850 cfm/ton]). This field is
not used when Condenser Type = AirCooled.
The maximum on-off cycling rate for the compressor (cycles
per hour), which occurs at 50% run time fraction. Suggested
value is 3; zero value means latent degradation model is
disabled. The default value for this field is zero. The supply
air fan operating mode must be continuous (i.e., the supply
air fan operating mode may be specified in other parent
objects and is assumed continuous in some objects (e.g.,
CoilSystem:Cooling:DX) or can be scheduled in other objects
(e.g., AirloopHVAC:UnitaryHeatCool); and this field, the
previous two fields and the next field must have positive
values in order to model latent capacity degradation.
Field:
Ratio of Initial Moisture Evaporation Rate and Steady State
Latent Capacity[LINK]
Ratio of the initial moisture evaporation rate from the
cooling coil (when the compressor first turns off, in Watts)
and the coil’s steady-state latent capacity (Watts) at rated
airflow and temperature conditions. Suggested value is 1.5;
zero value means the latent degradation model is disabled. The
default value for this field is zero. The supply air fan
operating mode must be continuous (i.e., the supply air fan
operating mode may be specified in other parent objects and is
assumed continuous in some objects (e.g.,
CoilSystem:Cooling:DX) or can be scheduled in other objects
(e.g., AirloopHVAC:UnitaryHeatCool); and this field, the
previous field and the next two fields must have positive
values in order to model latent capacity degradation.
Time constant (in seconds) for the cooling coil’s latent
capacity to reach steady state after startup. Suggested value
is 45: supply air fan operating mode must be continuous. That
is, the supply air fan operating mode may be specified in
other parent objects and is assumed continuous in some objects
(e.g., CoilSystem:Cooling:DX) or can be scheduled in other
objects (e.g., AirloopHVAC:UnitaryHeatCool).
Field:
Nominal Time for Condensate Removal to Begin[LINK]
The nominal time (in seconds) after startup for condensate
to begin leaving the coil’s condensate drain line at the
coil’s rated airflow and temperature conditions, starting with
a dry coil. Nominal time is equal to the ratio of the energy
of the coil’s maximum condensate holding capacity (J) to the
coil’s steady-state latent capacity (W). Suggested value is
1000; zero value means the latent degradation model is
disabled. The default value for this field is zero. The supply
air fan operating mode must be continuous (i.e., the supply
air fan operating mode may be specified in other parent
objects and is assumed continuous in some objects (e.g.,
CoilSystem:Cooling:DX) or can be scheduled in other objects
(e.g., AirloopHVAC:UnitaryHeatCool), and this field as well as
the previous three input fields for this object must have
positive values in order to model latent capacity
degradation.
Field:
Apply Latent Degradation to Speeds Greater than 1[LINK]
This field determines whether latent capacity degradation
is applied when the coil is operating at speeds greater than
speed 1. The allowed choices are Yes or
No, with the default being
No if this field is left blank. Other input
fields in this object allow the user to specify latent
capacity degradation at each speed.
The latent capacity degradation model only applies when the
ContinuousFanWithCyclingCompressor supply air fan operating
mode is specified, to account for moisture evaporation from
the wet cooling coil when the compressor cycles off but the
supply air fan continues to operate. For the case of a single
multi-speed compressor, latent capacity degradation may only
be significant when the compressor cycles between speed 1 and
off, but the losses may be extremely small when the compressor
operates between speed 1 and speed 2 (or between speeds 2 and
3, etc.). In this case, the user may choose to specify
No for this input field to neglect latent
capacity degradation impacts at higher operating speeds. If
latent capacity degradation is thought to be significant
(e.g., intertwined or row-split cooling coil with multiple
compressors feeding individual refrigerant circuits), then the
user may choose to specify Yes and the latent
capacity degradation model will be applied for speeds 2
through 10 as appropriate. The selection for this input field
does not affect latent capacity degradation between speed 1
and off.
The type of condenser used by the DX cooling coil. Valid
choices for this input field are AirCooled or
EvaporativelyCooled. The default for this
field is AirCooled.
The rated power of the evaporative condenser water pump in
Watts. This value is used to calculate the power required to
pump the water used to evaporatively cool the condenser inlet
air. The default value for this input field is zero, but it is
autosizable (equivalent to 0.004266 W per watt [15 W/ton] of
rated total cooling capacity). This field is not used when
Condenser Type = AirCooled.
This numeric field specifies the speed number which
corresponds to the rated capacity and air flow rates specified
in this object. This value must be lower than or equal to the
highest speed number defined below. If blank, defaults to the
highest speed number used.
For speed <x>, the name of the corresponding Coil:Cooling:DX:CurveFit:Speed
object. Speed 1 is always used as the lowest speed. Speeds
should be listed in ascending order from lowest capacity to
highest capacity. Each coil operating mode may have up to 10
speeds defined.
This object defines DX cooling coil performance for a
specific speed within a single operating mode. A speed can be
used for a combination of air flow rates and capacities
different than the rated air flow rates and capacities defined
in Coil:Cooling:DX:CurveFit:OperatingMode.
Each operating mode can reference a maximum of 10 speeds.
A unique user-assigned name for an instance of a cooling
coil operating mode’s speed. Any reference to a specific speed
by a cooling coil operating mode will use this name.
Field:
Gross Total Cooling Capacity Fraction[LINK]
This is the ratio of capacity at a specific speed to the
operating mode’s Rated Gross Total Cooling Capacity.
This field should be 1.0 for the Nominal Speed Number
specified in the Coil:Cooling:DX:CurveFit:OperatingMode
object.
This is the ratio of evaporator air flow rate at a specific
speed to the operating mode’s Rated Evaporator Air Flow
Rate. This field should be 1.0 for the Nominal Speed
Number specified in the Coil:Cooling:DX:CurveFit:OperatingMode
object.
This is the ratio of condenser air flow at a specific speed
to the operating mode’s Rated Condenser Air Flow
Rate. This field should be 1.0 for the Nominal Speed
Number specified in the Coil:Cooling:DX:CurveFit:OperatingMode
object.
This numeric field defines the gross sensible heat ratio
(sensible capacity divided by total cooling capacity) of the
DX cooling coil at rated conditions for a specific speed. Both
the sensible and total cooling capacities used should be gross
(i.e., the effect of supply air fan heat is NOT accounted
for).
The coefficient of performance is the ratio of the gross
total cooling capacity in Watts to electrical power input in
Watts of the DX cooling coil unit at rated conditions (air
entering the cooling coil at 26.7 °C drybulb/19.4 °C wetbulb
(80 °F drybulb/67 °F wetbulb), air entering the outdoor
condenser coil at 35 °C drybulb/ 23.9 °C wetbulb (95 °F
drybulb/75 °F wetbulb), and a cooling coil air flow rate
defined by field rated air flow rate below). The input power
includes electric power for the compressor(s) and condenser
fan(s) but does not include the power consumption of the
supply air fan. The gross COP should NOT account for the
supply air fan. If this input field is left blank, the default
value is 3.0.
Defines the fraction of the cooling coil face which is
actively cooled at a specific speed. Value varies between 0.0
and 1.0. For non-split-face coils, this should be 1.0.
Field:
Rated Evaporator Fan Power Per Volume Flow Rate[LINK]
This field is the electric power for the evaporator
(cooling coil) fan per air volume flow rate through the coil
at the rated conditions in W/(m\(^{3}\)/s). The default value is
773.3 W/(m\(^{3}\)/s) (365
W/1000 cfm) if this field is left blank. If a value is
entered, it must be > = 0.0 and < = 1250 W/(m\(^{3}\)/s). This value is only
used to calculate Seasonal Energy Efficiency Ratio (SEER),
Energy Efficiency Ratio (EER), Integrated Energy Efficiency
Ratio (IEER) and the Standard Rating (Net) Cooling Capacity
which will be outputs in the EnergyPlus eio file (ref.
EnergyPlus Engineering Reference, Single Speed DX Cooling
Coil, Standard Ratings). This value is not used for modeling
the evaporator (cooling coil) fan during simulations; instead,
it is used for calculating SEER, EER, IEER and Standard Rating
Cooling Capacity to assist the user in verifying their inputs
for modeling this type of equipment.
Field:
Evaporative Condenser Pump Power Fraction[LINK]
The ratio of evaporative condenser pump power at a specific
speed to the operating mode’s Nominal Evaporative
Condenser Pump Power. This field is not used when
Condenser Type = AirCooled.
The effectiveness of the evaporative condenser at a
specific speed, which is used to determine the temperature of
the air entering the outdoor condenser coil as follows:
T\(_{cond,inlet}\) = the
temperature of the air entering the condenser coil (C)
T\(_{wb,o}\) =
the wet-bulb temperature of the outdoor air (C)
T\(_{db,o}\) =
the dry-bulb temperature of the outdoor air (C)
The resulting condenser inlet air temperature is used by
the Total Cooling Capacity Modifier Function of Temperature
Curve and the Energy Input Ratio Modifier Function of
Temperature Curve. The default value for this field is 0.9,
although valid entries can range from 0.0 to 1.0. This field
is not used when Condenser Type =
AirCooled.
If the user wants to model an air-cooled condenser, they
should simply specify AirCooled in the field
Condenser Type. In this case, the Total Cooling
Capacity Modifier Function of Temperature Curve and the Energy
Input Ratio Modifier Function of Temperature Curve input
fields for this object should reference performance curves
that are a function of outdoor dry-bulb temperature.
If the user wishes to model an evaporative-cooled condenser
AND they have performance curves that are a function of the
wet-bulb temperature of air entering the condenser coil, then
the user should specify Condenser Type =
EvaporativelyCooled and the evaporative
condenser effectiveness value should be entered as 1.0. In
this case, the Total Cooling Capacity Modifier Function of
Temperature Curve and the Energy Input Ratio Modifier Function
of Temperature Curve input fields for this object should
reference performance curves that are a function of the
wet-bulb temperature of air entering the condenser coil.
If the user wishes to model an air-cooled condenser that
has evaporative media placed in front of it to cool the air
entering the condenser coil, then the user should specify
Condenser Type = EvaporativelyCooled. The
user must also enter the appropriate evaporative effectiveness
for the media. In this case, the Total Cooling Capacity
Modifier Function of Temperature Curve and the Energy Input
Ratio Modifier Function of Temperature Curve input fields for
this object should reference performance curves that are a
function of outdoor dry-bulb temperature. Be aware that the
evaporative media will significantly reduce the dry-bulb
temperature of the air entering the condenser coil, so the
Total Cooling Capacity and EIR Modifier Function of Air Flow
Fraction Curves must be valid for the expected range of
dry-bulb temperatures that will be entering the condenser
coil.
Field:
Total Cooling Capacity Modifier Function of Temperature Curve
Name[LINK]
The name of a bivariate (e.g. biquadratic) or univariate
(e.g. quadratic) curve or table object (ref Curve:* and
Table:*) that parameterizes the variation of the gross total
cooling capacity for a specific speed as a function of the
wet-bulb temperature of the air entering the evaporator
section, and the dry-bulb temperature of the air entering the
condenser section (wet-bulb temperature if modeling an
evaporative-cooled condenser). If a univariate curve or table
is specified, then the independent variable is the entering
condenser temperature. The curve is normalized to 1 at 19.44
°C (67 °F) indoor wet-bulb temperature and 35 °C (95 °F)
outdoor dry-bulb temperature. The output of this curve is
multiplied by the operating mode’s Rated Gross Total
Cooling Capacity to give the gross total cooling capacity
at specific temperature operating conditions (i.e., at
temperatures different from the rating point temperatures).
The curve is normalized to have the value of 1.0 at the rating
point.
Field:
Total Cooling Capacity Modifier Function of Air Flow Fraction
Curve Name[LINK]
The name of a univariate (e.g. quadratic) curve or table
object (ref Curve:* and Table:*) that parameterizes the
variation of the gross total cooling capacity for a specific
speed as a function of the ratio of actual air flow rate
across the cooling coil to the rated air flow rate for a
specific speed (i.e., fraction of full load flow). The output
of this curve is multiplied by the operating mode’s Rated
Gross Total Cooling Capacity and the total cooling
capacity modifier curve (function of temperature) to give the
gross total cooling capacity for a specific speed at the
specific temperature and air flow conditions at which the coil
is operating. The curve is normalized to have the value of 1.0
when the actual air flow rate equals the rated air flow rate
for Speed <x>.
Field:
Energy Input Ratio Modifier Function of Temperature Curve
Name[LINK]
The name of a bivariate (e.g. biquadratic) curve or table
object (ref Curve:* and Table:*) that parameterizes the
variation of the energy input ratio (EIR) for a specific speed
as a function of the wetbulb temperature of the air entering
the evaporator section and the drybulb temperature of the air
entering the condenser section (wetbulb temperature if
modeling an evaporative-cooled condenser). The curve is
normalized to 1 at 19.44 °C (67 °F) indoor wet-bulb
temperature and 35 °C (95 °F) outdoor dry-bulb temperature.
The EIR is the inverse of the COP. The output of this curve is
multiplied by the rated EIR for a specific speed (inverse of
rated COP for a specific speed) to give the EIR for a specific
speed at specific temperature operating conditions (i.e., at
temperatures different from the rating point
temperatures).
Field:
Energy Input Ratio Modifier Function of Air Flow Fraction
Curve Name[LINK]
The name of a univariate (e.g. quadratic) curve or table
object (ref Curve:* and Table:*) that parameterizes the
variation of the energy input ratio (EIR) for a specific speed
as a function of the ratio of actual air flow rate across the
cooling coil to the rated air flow rate for a specific speed
(i.e., fraction of full load flow). The EIR is the inverse of
the COP. The output of this curve is multiplied by the rated
EIR and the EIR modifier curve (function of temperature) to
give the EIR for a specific speed at the specific temperature
and air flow conditions at which the cooling coil is
operating. This curve is normalized to a value of 1.0 when the
actual air flow rate equals the rated air flow rate for a
specific speed.
Field:
Part Load Fraction Correlation Curve Name[LINK]
The name of a univariate (e.g. quadratic) curve or table
object (ref Curve:* and Table:*) that parameterizes the
variation of electrical power input to the DX unit as a
function of the part load ratio (PLR, sensible cooling
load/steady-state sensible cooling capacity for a specific
speed). The product of the rated EIR and EIR modifier curves
is divided by the output of this curve to give the effective
EIR for a given simulation timestep for a specific speed. The
part load fraction (PLF) correlation accounts for efficiency
losses due to compressor cycling.
The part load fraction correlation should be normalized to
a value of 1.0 when the part load ratio equals 1.0 (i.e., no
efficiency losses when the compressor(s) run continuously for
the simulation timestep). For PLR values between 0 and 1 (0
< = PLR < 1), the following rules apply:
PLF > = 0.7 and PLF > = PLR
If PLF < 0.7 a warning message is issued, the program
resets the PLF value to 0.7, and the simulation proceeds. The
runtime fraction of the coil is defined as PLR/PLF. If PLF
< PLR, then a warning message is issued and the runtime
fraction of the coil is limited to 1.0.
A typical part load fraction correlation for a conventional
DX cooling coil (a specific speed) would be:
PLF = 0.85 + 0.15(PLR)
If the user wishes to model no efficiency degradation due
to compressor cycling, the part load fraction correlation
should be defined as follows:
PLF = 1.0 + 0.0(PLR)
Field:
Rated Waste Heat Fraction of Power Input[LINK]
The fraction of energy input to the cooling coil that is
available as recoverable waste heat at full load and rated
conditions for a specific speed.
Field:
Waste Heat Modifier Function of Temperature Curve Name[LINK]
The name of a bivariate (e.g. biquadratic) curve or table
object (ref Curve:* and Table:*) that parameterizes the
variation of the waste heat recovery as a function of outdoor
dry-bulb temperature and the entering coil dry-bulb
temperature at a specific speed. The output of this curve is
multiplied by the rated waste heat fraction at specific
temperature operating conditions (i.e., at temperatures
different from the rating point). The curve is normalized to a
value of 1.0 at the rating point. When the fuel type is
electricity, this field can remain blank since it is ignored
by the program in this instance. When the fuel type is not
electricity and the parent object AirLoopHVAC:UnitaryHeatPump:AirToAir:MultiSpeed
does not require waste heat calculations, this field is
ignored. If the field is blank, a warning will be issued and
simulation continues. When the fuel type is not electricity
and the parent object AirLoopHVAC:UnitaryHeatPump:AirToAir:MultiSpeed
requires waste heat calculations, if this field is left blank,
the program assumes a constant value of 1 to make simulation
continue and a warning will be issued.
Field:
Sensible Heat Ratio Modifier Function of Temperature Curve
Name[LINK]
The name of a bivariate (e.g. biquadratic) curve or table
object (ref Curve:* and Table:*) that parameterizes the
variation of the sensible heat ratio (SHR) as a function of DX
cooling coil entering air wet-bulb and dry-bulb temperatures.
The output of this curve is multiplied by the rated SHR and
the SHR modifier curve (function of flow fraction) to give the
SHR at the specific coil entering air temperature and air flow
conditions at which the cooling coil is operating. This curve
is normalized to a value of 1.0 at the rated condition. This
input field is optional. If this input is not blank then the
Sensible Heat Ratio Modifier Function of Flow Fraction
Curve Name must also be entered. If left blank, SHR is
calculated using the apparatus dew point method based on total
capacity and coil bypass factor.
Field:
Sensible Heat Ratio Modifier Function of Flow Fraction Curve
Name[LINK]
The name of a univariate (e.g. quadratic) curve or table
object (ref Curve:* and Table:*) that parameterizes the
variation of the sensible heat ratio (SHR) as a function of
the ratio of actual air flow rate across the cooling coil to
the rated air flow rate (i.e., fraction of full load flow).
The output of this curve is multiplied by the rated SHR and
the SHR modifier curve (function of temperature) to give the
SHR at the specific temperature and air flow conditions at
which the cooling coil is operating. This curve is normalized
to a value of 1.0 when the actual air flow rate equals the
rated air flow rate. This input field is optional. If this
input is not blank then the Sensible Heat Ratio Modifier
Function of Temperature Curve Name must also be entered.
If left blank, SHR is calculated using the apparatus dew point
method based on total capacity and coil bypass factor.
Following is an example input for a single-speed air-cooled
cooling DX coil.
Coil:Cooling:DX,
Single Speed Cooling Coil, !- Name
Cooling Coil Air Inlet Node, !- Evaporator Inlet Node Name
Cooling Coil Air Outlet Node, !- Evaporator Outlet Node Name
FanAndCoilAvailSched, !- Availability Schedule Name
, !- Condenser Zone Name
Outdoor Condenser Air Inlet Node, !- Condenser Inlet Node Name
Outdoor Condenser Air Outlet Node, !- Condenser Outlet Node Name
Single Speed Cooling Coil Performance, !- Performance Object Name
, !- Condensate Collection Water Storage Tank Name
; !- Evaporative Condenser Supply Water Storage Tank Name
Coil:Cooling:DX:CurveFit:Performance,
Single Speed Cooling Coil Performance, !- Name
0.0, !- Crankcase Heater Capacity {W}
-25.0, !- Minimum Outdoor Dry-Bulb Temperature for Compressor Operation {C}
10.0, !- Maximum Outdoor Dry-Bulb Temperature for Crankcase Heater Operation {C}
500.0, !- Unit Internal Static Air Pressure {Pa}
Discrete, !- Capacity Control Method
, !- Evaporative Condenser Basin Heater Capacity {W}
, !- Evaporative Condenser Basin Heater Setpoint Temperature {C}
, !- Evaporative Condenser Basin Heater Operating Schedule Name
Electricity, !- Compressor Fuel Type
Single Speed Cooling Coil Operating Mode; !- Operating Mode 1 Name
Coil:Cooling:DX:CurveFit:OperatingMode,
Single Speed Cooling Coil Operating Mode, !- Name
Autosize, !- Rated Gross Total Cooling Capacity {W}
Autosize, !- Rated Evaporator Air Flow Rate {m3/s}
, !- Rated Condenser Air Flow Rate {m3/s}
0.0, !- Maximum Cycling Rate {cycles/hr}
0.0, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity
0.0, !- Latent Capacity Time Constant {s}
0.0, !- Nominal Time for Condensate Removal to Begin {s}
No, !- Apply Latent Degradation to Speeds Greater than 1
AirCooled, !- Condenser Type
1, !- Nominal Speed Number
Single Speed Cooling Coil Speed 1; !- Speed 1 Name
Coil:Cooling:DX:CurveFit:Speed,
Single Speed Cooling Coil Speed 1, !- Name
1.0, !- Gross Total Cooling Capacity Fraction
1.0, !- Evaporator Air Flow Rate Fraction
1.0, !- Condenser Air Flow Rate Fraction
Autosize, !- Gross Sensible Heat Ratio
3.0, !- Gross Cooling COP
1.0, !- Active Fraction of Coil Face Area
773.3, !- Rated Evaporator Fan Power Per Volume Flow Rate {W/(m3/s)}
1.0, !- Evaporative Condenser Pump Power Fraction
0.9, !- Evaporative Condenser Effectiveness
Single Speed Cool Cap fTemp, !- Total Cooling Capacity Modifier Function of Temperature Curve Name
Single Speed Cool Cap fFlow, !- Total Cooling Capacity Modifier Function of Air Flow Fraction Curve Name
Single Speed Cool EIR fTemp, !- Energy Input Ratio Modifier Function of Temperature Curve Name
Single Speed Cool EIR fFlow, !- Energy Input Ratio Modifier Function of Air Flow Fraction Curve Name
Single Speed Cool fPLR, !- Part Load Fraction Correlation Curve Name
0.2, !- Rated Waste Heat Fraction of Power Input
Single Speed Waste Heat fTemp; !- Waste Heat Function of Temperature Curve Name
, !- Sensible Heat Ratio Modifier Function of Temperature Curve Name
; !- Sensible Heat Ratio Modifier Function of Flow Fraction Curve Name
Following is an example input for a three-speed
evaporatively-cooled cooling DX coil.
Coil:Cooling:DX,
Three Speed Cooling Coil, !- Name
Cooling Coil Air Inlet Node, !- Evaporator Inlet Node Name
Cooling Coil Air Outlet Node, !- Evaporator Outlet Node Name
FanAndCoilAvailSched, !- Availability Schedule Name
, !- Condenser Zone Name
Outdoor Condenser Air Inlet Node, !- Condenser Inlet Node Name
Outdoor Condenser Air Outlet Node, !- Condenser Outlet Node Name
Three Speed Cooling Coil Performance, !- Performance Object Name
, !- Condensate Collection Water Storage Tank Name
; !- Evaporative Condenser Supply Water Storage Tank Name
Coil:Cooling:DX:CurveFit:Performance,
Three Speed Cooling Coil Performance, !- Name
0.0, !- Crankcase Heater Capacity {W}
-25.0, !- Minimum Outdoor Dry-Bulb Temperature for Compressor Operation {C}
10.0, !- Maximum Outdoor Dry-Bulb Temperature for Crankcase Heater Operation {C}
500.0, !- Unit Internal Static Air Pressure {Pa}
Discrete, !- Capacity Control Method
0.0, !- Evaporative Condenser Basin Heater Capacity {W}
2.0, !- Evaporative Condenser Basin Heater Setpoint Temperature {C}
FanAndCoilAvailSched, !- Evaporative Condenser Basin Heater Operating Schedule Name
Electricity, !- Compressor Fuel Type
Three Speed Cooling Coil Operating Mode; !- Operating Mode 1 Name
Coil:Cooling:DX:CurveFit:OperatingMode,
Three Speed Cooling Coil Operating Mode, !- Name
Autosize, !- Rated Gross Total Cooling Capacity {W}
Autosize, !- Rated Evaporator Air Flow Rate {m3/s}
Autosize, !- Rated Condenser Air Flow Rate {m3/s}
0.0, !- Maximum Cycling Rate {cycles/hr}
0.0, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity
0.0, !- Latent Capacity Time Constant {s}
0.0, !- Nominal Time for Condensate Removal to Begin {s}
No, !- Apply Latent Degradation to Speeds Greater than 1
Aircooled, !- Condenser Type
, !- Nominal Evaporative Condenser Pump Power
Three Speed Cooling Coil Speed 1, !- Speed 1 Name
Three Speed Cooling Coil Speed 2, !- Speed 2 Name
Three Speed Cooling Coil Speed 3; !- Speed 3 Name
Coil:Cooling:DX:CurveFit:Speed,
Three Speed Cooling Coil Speed 1, !- Name
0.4, !- Gross Total Cooling Capacity Fraction
0.4, !- Evaporator Air Flow Rate Fraction
0.4, !- Condenser Air Flow Rate Fraction
Autosize, !- Gross Sensible Heat Ratio
4.5, !- Gross Cooling COP
1.0, !- Active Fraction of Coil Face Area
453.3, !- Rated Evaporator Fan Power Per Volume Flow Rate {W/(m3/s)}
0.4, !- Evaporative Condenser Pump Power Fraction
0.9, !- Evaporative Condenser Effectiveness
Three Speed Cool Cap fTemp Spd 1, !- Total Cooling Capacity Modifier Function of Temperature Curve Name
Three Speed Cool Cap fFlow Spd 1, !- Total Cooling Capacity Modifier Function of Air Flow Fraction Curve Name
Three Speed Cool EIR fTemp Spd 1, !- Energy Input Ratio Modifier Function of Temperature Curve Name
Three Speed Cool EIR fFlow Spd 1, !- Energy Input Ratio Modifier Function of Air Flow Fraction Curve Name
Three Speed Cool fPLR Spd 1, !- Part Load Fraction Correlation Curve Name
0.2, !- Rated Waste Heat Fraction of Power Input
Three Speed Waste Heat fTemp Spd 1, !- Waste Heat Function of Temperature Curve Name
Three Speed SHR fTemp Spd 1, !- Sensible Heat Ratio Modifier Function of Temperature Curve Name
Three Speed SHR fFlow Spd 1; !- Sensible Heat Ratio Modifier Function of Flow Fraction Curve Name
Coil:Cooling:DX:CurveFit:Speed,
Three Speed Cooling Coil Speed 2, !- Name
0.7, !- Gross Total Cooling Capacity Fraction
0.7, !- Evaporator Air Flow Rate Fraction
0.7, !- Condenser Air Flow Rate Fraction
Autosize, !- Gross Sensible Heat Ratio
3.5, !- Gross Cooling COP
1.0, !- Active Fraction of Coil Face Area
613.3, !- Rated Evaporator Fan Power Per Volume Flow Rate {W/(m3/s)}
0.7, !- Evaporative Condenser Pump Power Fraction
0.9, !- Evaporative Condenser Effectiveness
Three Speed Cool Cap fTemp Spd 2, !- Total Cooling Capacity Modifier Function of Temperature Curve Name
Three Speed Cool Cap fFlow Spd 2, !- Total Cooling Capacity Modifier Function of Air Flow Fraction Curve Name
Three Speed Cool EIR fTemp Spd 2, !- Energy Input Ratio Modifier Function of Temperature Curve Name
Three Speed Cool EIR fFlow Spd 2, !- Energy Input Ratio Modifier Function of Air Flow Fraction Curve Name
Three Speed Cool fPLR Spd 2, !- Part Load Fraction Correlation Curve Name
0.2, !- Rated Waste Heat Fraction of Power Input
Three Speed Waste Heat fTemp Spd 2, !- Waste Heat Function of Temperature Curve Name
Three Speed SHR fTemp Spd 2, !- Sensible Heat Ratio Modifier Function of Temperature Curve Name
Three Speed SHR fFlow Spd 2; !- Sensible Heat Ratio Modifier Function of Flow Fraction Curve Name
Coil:Cooling:DX:CurveFit:Speed,
Three Speed Cooling Coil Speed 3, !- Name
1.0, !- Gross Total Cooling Capacity Fraction
1.0, !- Evaporator Air Flow Rate Fraction
1.0, !- Condenser Air Flow Rate Fraction
Autosize, !- Gross Sensible Heat Ratio
3.0, !- Gross Cooling COP
1.0, !- Active Fraction of Coil Face Area
773.3, !- Rated Evaporator Fan Power Per Volume Flow Rate {W/(m3/s)}
1.0, !- Evaporative Condenser Pump Power Fraction
0.9, !- Evaporative Condenser Effectiveness
Three Speed Cool Cap fTemp Spd 3, !- Total Cooling Capacity Modifier Function of Temperature Curve Name
Three Speed Cool Cap fFlow Spd 3, !- Total Cooling Capacity Modifier Function of Air Flow Fraction Curve Name
Three Speed Cool EIR fTemp Spd 3, !- Energy Input Ratio Modifier Function of Temperature Curve Name
Three Speed Cool EIR fFlow Spd 3, !- Energy Input Ratio Modifier Function of Air Flow Fraction Curve Name
Three Speed Cool fPLR Spd 3, !- Part Load Fraction Correlation Curve Name
0.2, !- Rated Waste Heat Fraction of Power Input
Three Speed Waste Heat fTemp Spd 3, !- Waste Heat Function of Temperature Curve Name
Three Speed SHR fTemp Spd 3, !- Sensible Heat Ratio Modifier Function of Temperature Curve Name
Following is an example input for a single cooling DX coil
with 3 operation modes as normal, subcool and reheat to
represent a subcool reheat coil model.
Coil:Cooling:DX,
Sys 1 Furnace DX Cool Cooling Coil, !- Name
Sys 1 Furnace DX Cool Supply Fan Outlet, !- Evaporator Inlet Node Name
Sys 1 Furnace DX Cool Cooling Coil Outlet, !- Evaporator Outlet Node Name
, !- Availability Schedule Name
, !- Condenser Zone Name
Sys 1 Furnace DX Cool Cooling Coil Condenser Inlet, !- Condenser Inlet Node Name
Sys 1 Furnace DX Cool Cooling Coil Condenser Outlet Node, !- Condenser Outlet Node Name
Sys 1 Furnace DX Cool Cooling Coil Performance, !- Performance Object Name
, !- Condensate Collection Water Storage Tank Name
; !- Evaporative Condenser Supply Water Storage Tank Name
Coil:Cooling:DX:CurveFit:Performance,
Sys 1 Furnace DX Cool Cooling Coil Performance, !- Name
0, !- Crankcase Heater Capacity {W}
, !- Minimum Outdoor Dry-Bulb Temperature for Compressor Operation {C}
10, !- Maximum Outdoor Dry-Bulb Temperature for Crankcase Heater Operation {C}
, !- Unit Internal Static Air Pressure {Pa}
, !- Capacity Control Method
, !- Evaporative Condenser Basin Heater Capacity {W/K}
, !- Evaporative Condenser Basin Heater Setpoint Temperature {C}
, !- Evaporative Condenser Basin Heater Operating Schedule Name
Electricity, !- Compressor Fuel Type
Sys 1 Furnace DX Cool Cooling Coil Operating Mode, !- Base Operating Mode
Sys 1 Furnace DX Cool Cooling Coil Alternative Mode 1, !- Alternative Operating Mode 1
Sys 1 Furnace DX Cool Cooling Coil Alternative Mode 2; !- Alternative Operating Mode 1
Coil:Cooling:DX:CurveFit:OperatingMode,
Sys 1 Furnace DX Cool Cooling Coil Operating Mode, !- Name
autosize, !- Rated Gross Total Cooling Capacity {W}
autosize, !- Rated Evaporator Air Flow Rate {m3/s}
, !- Rated Condenser Air Flow Rate {m3/s}
0, !- Maximum Cycling Rate {cycles/hr}
0, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
0, !- Latent Capacity Time Constant {s}
0, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Latent Degradation to Speeds Greater than 1
AirCooled, !- Condenser Type
0, !- Nominal Evaporative Condenser Pump Power {W}
1, !- Nominal Speed Number
Sys 1 Furnace DX Cool Cooling Coil Speed 1 Performance; !- Speed 1 Name
Coil:Cooling:DX:CurveFit:Speed,
Sys 1 Furnace DX Cool Cooling Coil Speed 1 Performance, !- Name
1.0, !- Gross Total Cooling Capacity Fraction
1.0, !- Evaporator Air Flow Rate Fraction
1.0, !- Condenser Air Flow Rate Fraction
0.77, !- Gross Sensible Heat Ratio
4.17, !- Gross Cooling COP {W/W}
1.0, !- Active Fraction of Coil Face Area
, !- Rated Evaporator Fan Power Per Volume Flow Rate {W/(m3/s)}
1.0, !- Evaporative Condenser Pump Power Fraction
0, !- Evaporative Condenser Effectiveness {dimensionless}
NormalTempCoolingCAPFTemp, !- Total Cooling Capacity Modifier Function of Temperature Curve Name
NormalFlowCoolingCAPFFF, !- Total Cooling Capacity Modifier Function of Air Flow Fraction Curve Name
NormalTempCoolingEIRFTemp, !- Energy Input Ratio Modifier Function of Temperature Curve Name
NormalFlowCoolingEIRFFF, !- Energy Input Ratio Modifier Function of Air Flow Fraction Curve Name
Sys 1 Furnace DX Cool Cool Coil PLF, !- Part Load Fraction Correlation Curve Name
, !- Rated Waste Heat Fraction of Power Input {dimensionless}
, !- Waste Heat Modifier Function of Temperature Curve Name
NormalSHRTempCoolingFFF, !- Sensible Heat Ratio Modifier Function of Temperature Curve Name
NormalSHRFlowCoolingFFF; !- Sensible Heat Ratio Modifier Function of Flow Fraction Curve Name
Coil:Cooling:DX:CurveFit:OperatingMode,
Sys 1 Furnace DX Cool Cooling Coil Alternative Mode 1, !- Name
autosize, !- Rated Gross Total Cooling Capacity {W}
autosize, !- Rated Evaporator Air Flow Rate {m3/s}
, !- Rated Condenser Air Flow Rate {m3/s}
0, !- Maximum Cycling Rate {cycles/hr}
0, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
0, !- Latent Capacity Time Constant {s}
0, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Latent Degradation to Speeds Greater than 1
AirCooled, !- Condenser Type
0, !- Nominal Evaporative Condenser Pump Power {W}
1, !- Nominal Speed Number
Sys 1 Furnace DX Cool Cooling Coil Alternative Mode 1 Performance; !- Speed 1 Name
Coil:Cooling:DX:CurveFit:Speed,
Sys 1 Furnace DX Cool Cooling Coil Alternative Mode 1 Performance, !- Name
1.0, !- Gross Total Cooling Capacity Fraction
1.0, !- Evaporator Air Flow Rate Fraction
1.0, !- Condenser Air Flow Rate Fraction
0.66, !- Gross Sensible Heat Ratio
4.10, !- Gross Cooling COP {W/W}
1.0, !- Active Fraction of Coil Face Area
, !- Rated Evaporator Fan Power Per Volume Flow Rate {W/(m3/s)}
1.0, !- Evaporative Condenser Pump Power Fraction
0, !- Evaporative Condenser Effectiveness {dimensionless}
SubcoolTempCoolingCAPFTemp, !- Total Cooling Capacity Modifier Function of Temperature Curve Name
SubcoolFlowCoolingCAPFFF, !- Total Cooling Capacity Modifier Function of Air Flow Fraction Curve Name
SubcoolTempCoolingEIRFTemp, !- Energy Input Ratio Modifier Function of Temperature Curve Name
SubcoolFlowCoolingEIRFFF, !- Energy Input Ratio Modifier Function of Air Flow Fraction Curve Name
Sys 1 Furnace DX Cool Cool Coil PLF, !- Part Load Fraction Correlation Curve Name
, !- Rated Waste Heat Fraction of Power Input {dimensionless}
, !- Waste Heat Modifier Function of Temperature Curve Name
SubcoolSHRTempCoolingCAPFTemp, !- Sensible Heat Ratio Modifier Function of Temperature Curve Name
SubcoolSHRFlowCoolingCAPFFF; !- Sensible Heat Ratio Modifier Function of Flow Fraction Curve Name
Coil:Cooling:DX:CurveFit:OperatingMode,
Sys 1 Furnace DX Cool Cooling Coil Alternative Mode 2, !- Name
autosize, !- Rated Gross Total Cooling Capacity {W}
autosize, !- Rated Evaporator Air Flow Rate {m3/s}
, !- Rated Condenser Air Flow Rate {m3/s}
0, !- Maximum Cycling Rate {cycles/hr}
0, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
0, !- Latent Capacity Time Constant {s}
0, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Latent Degradation to Speeds Greater than 1
AirCooled, !- Condenser Type
0, !- Nominal Evaporative Condenser Pump Power {W}
1, !- Nominal Speed Number
Sys 1 Furnace DX Cool Cooling Coil Alternative Mode 2 Performance; !- Speed 1 Name
Coil:Cooling:DX:CurveFit:Speed,
Sys 1 Furnace DX Cool Cooling Coil Alternative Mode 2 Performance, !- Name
1.0, !- Gross Total Cooling Capacity Fraction
1.0, !- Evaporator Air Flow Rate Fraction
1.0, !- Condenser Air Flow Rate Fraction
0.16, !- Gross Sensible Heat Ratio
1.41, !- Gross Cooling COP {W/W}
1.0, !- Active Fraction of Coil Face Area
, !- Rated Evaporator Fan Power Per Volume Flow Rate {W/(m3/s)}
1.0, !- Evaporative Condenser Pump Power Fraction
0, !- Evaporative Condenser Effectiveness {dimensionless}
ReheatTempCoolingCAPFTemp, !- Total Cooling Capacity Modifier Function of Temperature Curve Name
ReheatFlowCoolingCAPFFF, !- Total Cooling Capacity Modifier Function of Air Flow Fraction Curve Name
ReheatTempCoolingEIRFTemp, !- Energy Input Ratio Modifier Function of Temperature Curve Name
ReheatFlowCoolingEIRFFF, !- Energy Input Ratio Modifier Function of Air Flow Fraction Curve Name
Sys 1 Furnace DX Cool Cool Coil PLF, !- Part Load Fraction Correlation Curve Name
, !- Rated Waste Heat Fraction of Power Input {dimensionless}
, !- Waste Heat Modifier Function of Temperature Curve Name
ReheatSHRTempCoolingCAPFTemp, !- Sensible Heat Ratio Modifier Function of Temperature Curve Name
ReheatSHRFlowCoolingCAPFFF; !- Sensible Heat Ratio Modifier Function of Flow Fraction Curve Name
This field is the total (sensible and latent) cooling rate
output of the DX coil in Watts. This is determined by the coil
inlet and outlet air conditions and the air mass flow rate
through the coil.
This is the total (sensible plus latent) cooling output of
the DX coil in Joules over the timestep being reported. This
is determined by the coil inlet and outlet air conditions and
the air mass flow rate through the coil. This output is also
added to a meter with Resource Type = EnergyTransfer, End Use
Key = CoolingCoils, Group Key = System (Ref. Output:Meter
objects).
This output is the moist air sensible cooling rate output
of the DX coil in Watts. This is determined by the inlet and
outlet air conditions and the air mass flow rate through the
coil.
This is the moist air sensible cooling output of the DX
coil in Joules for the timestep being reported. This is
determined by the inlet and outlet air conditions and the air
mass flow rate through the coil.
This is the latent cooling rate output of the DX coil in
Watts. This is determined by the inlet and outlet air
conditions and the air mass flow rate through the coil.
This is the latent cooling output of the DX coil in Joules
for the timestep being reported. This is determined by the
inlet and outlet air conditions and the air mass flow rate
through the coil.
This output is the electricity consumption rate of the DX
coil compressor and condenser fan(s) in Watts. This value is
calculated for each HVAC system timestep, and the results are
averaged for the timestep being reported.
This is the electricity consumption of the DX coil
compressor and condenser fan(s) in Joules for the timestep
being reported. This output is also added to a meter with
Resource Type = Electricity, End Use Key = Cooling, Group Key
= System (Ref. Output:Meter
objects).
This output variable reports operating mode for a subcool
reheat coil. When the value is 1, the coil operates at normal
mode. When the value is 2, the coil operation is determined by
the mode ratio through linear interpolation between normal
mode and subcool mode. For example, when the mode ratio is
0.4, the coil operates at subcool mode for 40% of timestep and
at normal mode for 60% of timestep. When the value is 3, the
coil operation is determined by the mode ratio through linear
interpolation between normal mode and reheat mode.
SubcoolReheat
Cooling Coil Operation Mode Ratio [][LINK]
This output variable reports the ratio of time in a system
timestep between normal mode and subcool mode when the
operation mode = 2. The mode ratio represents how long the
subcool mode runs as a fraction of the system timestep, and
the normal mode runs in the rest of the system timestep. The
output variable also reports the ratio of time in a system
tiemstep between normal mode and reheat mode when the
operation mode = 3. The value is 0.0 when the operation mode =
1.
SubcoolReheat
Cooling Coil Recovered Heat Energy Rate [W][LINK]
This output is the recovered heat energy rate output of the
DX coil in Watts. This is determined by energy use difference
between normal mode and subcool or reheat mode, multiplied by
the mode ratio.
SubcoolReheat
Cooling Coil Recovered Heat Energy [J][LINK]
This output is the recovered heat energy rate output of the
DX coil in Jouals. This is determined by energy use difference
between normal mode and subcool or reheat mode, multiplied by
the mode ratio.
Coil:Cooling:DX[LINK]
This coil input structure is meant to supplant the coil objects from previous EnergyPlus versions (Coil:Cooling:DX:SingleSpeed, Coil:Cooling:DX:TwoSpeed, Coil:Cooling:DX:MultiSpeed, etc.). This coil input structure uses a combination of four objects to fully define the performance of the coil under a range of operating conditions.
Coil:Cooling:DX - Defines where the coil’s evaporator and condenser sections are connected to the HVAC system through node connections to air loops or zones (if condenser section rejects heat to a zone), as well as the coil’s availability.
Coil:Cooling:DX:CurveFit:Performance - Defines how the coil operates over a range of operating conditions.
Coil:Cooling:DX:CurveFit:OperatingMode - Defines the rated coil characteristics (capacity, evaporator section air flow rate, etc.) and capacity control method for a given operating mode. Operating modes are generally used to describe humidity control strategies for DX cooling coil arrangements that enable enhanced dehumidification.
Coil:Cooling:DX:CurveFit:Speed - Defines DX cooling coil performance for a specific speed within a single operating mode.
Note: The Coil:Cooling:DX:CurveFit:Performance object also allows users to input 3 operating modes: Base Operating Mode, Alternative Operating Mode 1, and Alternative Operating Mode 2. When the Base Operating Mode is an only mode input, the coil performs like a regular cooling DX coil and no specific dehumidication capability. The alternative operating mode 1 is used for enhanced dehumidification. When all 3 modes are inputs, the coil performs as a subcool rehat coil. When load sensible heat ratio (SHR), defined as sensible cooling load / (sensible cooling load + latent cooling load), is greater than the SHR in the Base Operating Mode at given inlet air conditions, the coil performs in Base Operating Mode only. When the load SHR is less than the SHR in the Base Operating Mode and greater than the SHR in the Alternative Operating Mode 1 at the same given inlet air conditions, the coil performs combination of both Base Operating Mode, and Alternative Operating Mode 1. Mode ratio determines a fraction of time Alternative Operating Mode 1 operates and the rest (1 - Mode ratio) of time Base Operating Mode operates in a single time step. When the load SHR is less than the SHR in the Alternative Operating Mode 1 and greater than the SHR in the Alternative Operating Mode 2 at the same given inlet air conditions, the coil performs combination of both Base Operating Mode, and Alternative Operating Mode 2. Mode ratio determines a fraction of time Alternative Operating Mode 2 operates and (1 - Mode ratio) of time Base Operating Mode operates in a single time step. When the load SHR is greater than the SHR in the Alternative Operating Mode 2, the coil performs as Alternative Operating Mode 2 alone.
Figure 1 below represents the hierarchy how these four input objects reference each other. Arrows pointing from one object to another represents where one object has an input field that references the name of a different object. For example, an input field of the Coil:Cooling:DX object references the name of a Coil:Cooling:DX:CurveFit:Performance object. For this coil input structure, one Coil:Cooling:DX object can only reference one Coil:Cooling:DX:CurveFit:Performance object. However, one Coil:Cooling:DX:CurveFit:Performance object can reference multiple Coil:Cooling:DX:CurveFit:OperatingMode objects, and each Coil:Cooling:DX:CurveFit:OperatingMode object can reference multiple Coil:Cooling:DX:CurveFit:Speed objects. In the image below, the cooling coil has one single-speed operating mode and a second two-speed operating mode.
Inputs[LINK]
Field: Name[LINK]
A unique user-assigned name for an instance of a cooling coil. Any reference to this cooling coil by another object will use this name.
Field: Evaporator Inlet Node Name[LINK]
The name of the HVAC system node from which the evaporator of the DX cooling coil draws its inlet air.
Field: Evaporator Outlet Node Name[LINK]
The name of the HVAC system node to which the evaporator of the DX cooling coil sends its outlet air.
Field: Availability Schedule Name[LINK]
The name of the schedule (ref: Schedule) that denotes whether the DX cooling coil can run during a given time period. A schedule value greater than 0 (usually 1 is used) indicates that the unit can be on during a given time period. A value less than or equal to 0 (usually 0 is used) denotes that the unit must be off. If this field is blank, the schedule has values of 1 for all time periods.
Field: Condenser Zone Name[LINK]
The name of a conditioned or unconditioned zone where the secondary coil (condenser) of DX system or a heat pump is to be placed. This is an optional input field specified only when user desires to reject the condenser heat into a zone. The heat rejected is modelled as internal sensible heat gain of the zone.
Field: Condenser Inlet Node Name[LINK]
The name of the HVAC system node from which the condenser of the DX cooling coil draws its inlet air. If the condenser draws air from the outdoors, an
OutdoorAir:Nodeobject must be referenced.Field: Condenser Outlet Node Name[LINK]
The name of the HVAC system node to which the condenser of the DX cooling coil sends its outlet air.
Field: Performance Object Name[LINK]
The name of the Coil:Cooling:DX:CurveFit:Performance object that defines this coil’s performance specifications.
Field: Condensate Collection Water Storage Tank Name[LINK]
This field is optional. It is used to describe where condensate from the coil is collected. If blank or omitted, then any coil condensate is discarded. Enter the name of a WaterUse:Storage object defined elsewhere and the condensate will then be collected in that tank.
Field: Evaporative Condenser Supply Water Storage Tank Name[LINK]
This field is optional. It is used to describe where the coil obtains water used for evaporative cooling of its condenser. If blank or omitted, then the unit will obtain water directly from the mains. If the name of a WaterUse:Storage object is used here, then the unit will obtain its water from that tank. If a tank is specified, the unit will attempt to obtain all the water it uses from the tank. However, if the tank cannot provide all the water the condenser needs, then the unit will still operate and obtain the rest of the water it needs from the mains (referred to as StarvedWater).
Coil:Cooling:DX:CurveFit:Performance[LINK]
This object defines basic unit control and other characteristics for one Coil:Cooling:DX object. For that Coil:Cooling:DX object, it also references one or more operating modes, which are defined using the Coil:Cooling:DX:CurveFit:OperatingMode object.
Inputs[LINK]
Field: Name[LINK]
A unique user-assigned name for an instance of a cooling coil performance specification. Any reference to this cooling coil performance specification by a cooling coil object will use this name.
Field: Crankcase Heater Capacity[LINK]
This numeric field defines the crankcase heater capacity in Watts. When the outdoor air dry-bulb temperature is below the value specified in the input field Maximum Outdoor Dry-bulb Temperature for Crankcase Heater Operation (described below), the crankcase heater is enabled during the time that the compressor is not running. If this cooling coil is used as part of an air-to-air heat pump (Ref. AirLoopHVAC:UnitaryHeatPump:AirToAir or PackageTerminal: HeatPump:AirToAir), the crankcase heater defined for this DX cooling coil is ignored and the crankcase heater power defined for the DX heating coil (Ref. Coil:Heating:DX:SingleSpeed) is enabled during the time that the compressor is not running for either heating or cooling. The value for this input field must be greater than or equal to 0, and the default value is 0. To simulate a DX cooling coil without a crankcase heater, enter a value of 0.
Field: Minimum Outdoor Dry-Bulb Temperature for Compressor Operation[LINK]
This numeric field defines the minimum outdoor air dry-bulb temperature where the cooling coil compressor turns off. If this input field is left blank, the default value is -25 °C (-13 °F).
Field: Maximum Outdoor Dry-Bulb Temperature for Crankcase Heater Operation[LINK]
This numeric field defines the outdoor air dry-bulb temperature above which the compressor’s crankcase heater is disabled. The value for this input field must be greater than or equal to 0.0 °C (32 °F), and the default value is 10 °C (50 °F).
Field: Unit Internal Static Air Pressure[LINK]
If this coil is used with a Fan:VariableVolume to model a packaged variable-air-volume unit, then ratings for standard rated net capacity, EER, and IEER will be calculated per ANSI/AHRI Standard 340/360-2007 with Addenda 1 and 2. This field is to specify the internal static air pressure, in units of Pascals, associated with the unit’s supply air flow for rating purposes. This field does not affect the performance during operation. This field is optional. If this field is used, then the internal static air pressure is used with the associated fan characteristics when calculating standard rated net capacity, EER, and IEER. If this field is not used, then the standard ratings are still performed but use a default for specific fan power of 773.3 (W/(m\(^{3}\)/s)). The air pressure drop/rise input here should be internal in the sense that it is for the entire package of unitary equipment as it would be tested in a laboratory (including other non-cooling sections inside the package for filters, dampers, and/or heating coils) but none of the external pressure drop for distributing supply air throughout the building. This is different from the input field called Pressure Rise in the fan object which includes both the external static pressure and the internal static pressure. The results of standard rating calculations are reported to the EIO file and to predefined output tables called DX Cooling Coils and VAV DX Cooling Standard Rating Details.
Field: Capacity Control Method[LINK]
This choice field defined the capacity control method. Valid choices for this input field are Discrete Continuous. The default for this field is Discrete. Discrete control mode allow the coil to operate at discrete speed levels. Continuous control mode allows the coil performance to be operated at continuously variable speeds.
Field: Evaporative Condenser Basin Heater Capacity[LINK]
This numeric field contains the capacity of the coil’s electric evaporative cooler basin heater in Watts per degree Kelvin. This field only applies for Condenser Type = EvaporativelyCooled. This field is used in conjunction with the Evaporative Condenser Basin Heater Setpoint Temperature and Evaporative Condenser Basin Heater Operating Schedule Name described in the following fields. 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 DX coil 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: Evaporative Condenser 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 DX coil is off. This set point temperature must be greater than or equal to 2 °C (35.6), and the default value is 2 °C (35.6) if this field is left blank.
Field: Evaporative Condenser 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 DX coil is off.
Field: Compressor Fuel Type[LINK]
This alpha field determines the type of fuel that this cooling coil’s compressor uses. This field has nine choices: Electricity, NaturalGas, Propane, Diesel, Gasoline, FuelOilNo1, FuelOilNo2, OtherFuel1 and OtherFuel2. The default is Electricity.
Field: Base Operating Mode[LINK]
The name corresponding to a Coil:Cooling:DX:CurveFit:OperatingMode object. Operating Mode is always used as the base design operating mode. This field is required.
Field: Alternate Operating Mode 1[LINK]
The name corresponding to a Coil:Cooling:DX:CurveFit:OperatingMode object. Operating Mode is used as the alternate operating mode operating mode to be used for enhanced deumidification when needed. If field is blank, the base operating mode will be used. This field is optional.
Field: Alternate Operating Mode 1[LINK]
The name corresponding to a Coil:Cooling:DX:CurveFit:OperatingMode object. Operating Mode is used as to represent a reheat mode as a subcool reheat coil. If field is blank, the base operating mode will be used. This field is optional.
If there are 3 operating modes, it represents a subcool-reheat mode coil. The Operating Mode 1 represents a base operating mode coil. The Operating Mode 2 represents a subcool mode coil with lower SHR than the Operating Mode 1. The Operating Mode 3 represents a rehaet mode coil with lower SHR than the Operating Mode 2. All 3 operation modes work together to represent a subcool reheat coil model. The operation procedure is described in 0.1
Coil:Cooling:DX:CurveFit:OperatingMode[LINK]
This object defines DX cooling coil performance for a single operating mode at rated conditions. Each operating mode may have one or more speeds, which are defined using the Coil:Cooling:DX:CurveFit:Speed object. Each operation mode can reference a maximum of 10 Coil:Cooling:DX:CurveFit:Speed objects.
Inputs[LINK]
Field: Name[LINK]
A unique user-assigned name for an instance of a cooling coil operating mode. Any reference to this cooling coil operating mode by a cooling coil performance specification will use this name.
Field: Rated Gross Total Cooling Capacity[LINK]
The total, full load gross cooling capacity (sensible plus latent) in Watts of the DX coil unit at rated conditions (air entering the cooling coil at 26.7 °C drybulb/19.4 °C wetbulb (80 °F drybulb/67 °F wetbulb), air entering the outdoor condenser coil at 35 °C drybulb/23.9 °C wetbulb (95 °F drybulb/75 °F wetbulb), and a cooling coil air flow rate defined by field rated air flow rate below). Capacity should be gross (i.e., the effect of supply air fan heat is NOT accounted for). When used in a heat pump, the gross rated total cooling capacity should be within 20% of the gross rated heating capacity, otherwise a warning message is issued.
Field: Rated Evaporator Air Flow Rate[LINK]
The air volume flow rate, in m\(^{3}\) per second, across the DX cooling coil evaporator section at rated conditions. The rated air volume flow rate should be between 0.00004027 m\(^{3}\)/s and 0.00006041 m\(^{3}\)/s per Watt of gross rated total cooling capacity (300 to 450 cfm/ton). For DOAS applications the rated air volume flow rate should be between 0.00001677 m\(^{3}\)/s and 0.00003355 m\(^{3}\)/s per watt of gross rated total cooling capacity (125 to 250 cfm/ton). The gross rated total cooling capacity, gross rated SHR and gross rated COP should be performance information for the unit with air entering the cooling coil at 26.7 °C drybulb/19.4 °C wetbulb (80 °F drybulb/67 °F wetbulb), air entering the outdoor condenser coil at 35 °C drybulb/23.9 °C wetbulb (95 °F drybulb/75 °F wetbulb), and the rated air volume flow rate defined here.
Field: Rated Condenser Air Flow Rate[LINK]
The air volume flow rate, in m\(^{3}\) per second, entering the evaporative condenser. This value is used to calculate the amount of water used to evaporatively cool the condenser inlet air. The minimum value for this field must be greater than zero, and this input field is autosizable (equivalent to 0.000144 m\(^{3}\)/s per watt of rated total cooling capacity [850 cfm/ton]). This field is not used when Condenser Type = AirCooled.
Field: Maximum Cycling Rate[LINK]
The maximum on-off cycling rate for the compressor (cycles per hour), which occurs at 50% run time fraction. Suggested value is 3; zero value means latent degradation model is disabled. The default value for this field is zero. The supply air fan operating mode must be continuous (i.e., the supply air fan operating mode may be specified in other parent objects and is assumed continuous in some objects (e.g., CoilSystem:Cooling:DX) or can be scheduled in other objects (e.g., AirloopHVAC:UnitaryHeatCool); and this field, the previous two fields and the next field must have positive values in order to model latent capacity degradation.
Field: Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity[LINK]
Ratio of the initial moisture evaporation rate from the cooling coil (when the compressor first turns off, in Watts) and the coil’s steady-state latent capacity (Watts) at rated airflow and temperature conditions. Suggested value is 1.5; zero value means the latent degradation model is disabled. The default value for this field is zero. The supply air fan operating mode must be continuous (i.e., the supply air fan operating mode may be specified in other parent objects and is assumed continuous in some objects (e.g., CoilSystem:Cooling:DX) or can be scheduled in other objects (e.g., AirloopHVAC:UnitaryHeatCool); and this field, the previous field and the next two fields must have positive values in order to model latent capacity degradation.
Field: Latent Capacity Time Constant[LINK]
Time constant (in seconds) for the cooling coil’s latent capacity to reach steady state after startup. Suggested value is 45: supply air fan operating mode must be continuous. That is, the supply air fan operating mode may be specified in other parent objects and is assumed continuous in some objects (e.g., CoilSystem:Cooling:DX) or can be scheduled in other objects (e.g., AirloopHVAC:UnitaryHeatCool).
Field: Nominal Time for Condensate Removal to Begin[LINK]
The nominal time (in seconds) after startup for condensate to begin leaving the coil’s condensate drain line at the coil’s rated airflow and temperature conditions, starting with a dry coil. Nominal time is equal to the ratio of the energy of the coil’s maximum condensate holding capacity (J) to the coil’s steady-state latent capacity (W). Suggested value is 1000; zero value means the latent degradation model is disabled. The default value for this field is zero. The supply air fan operating mode must be continuous (i.e., the supply air fan operating mode may be specified in other parent objects and is assumed continuous in some objects (e.g., CoilSystem:Cooling:DX) or can be scheduled in other objects (e.g., AirloopHVAC:UnitaryHeatCool), and this field as well as the previous three input fields for this object must have positive values in order to model latent capacity degradation.
Field: Apply Latent Degradation to Speeds Greater than 1[LINK]
This field determines whether latent capacity degradation is applied when the coil is operating at speeds greater than speed 1. The allowed choices are Yes or No, with the default being No if this field is left blank. Other input fields in this object allow the user to specify latent capacity degradation at each speed.
The latent capacity degradation model only applies when the ContinuousFanWithCyclingCompressor supply air fan operating mode is specified, to account for moisture evaporation from the wet cooling coil when the compressor cycles off but the supply air fan continues to operate. For the case of a single multi-speed compressor, latent capacity degradation may only be significant when the compressor cycles between speed 1 and off, but the losses may be extremely small when the compressor operates between speed 1 and speed 2 (or between speeds 2 and 3, etc.). In this case, the user may choose to specify No for this input field to neglect latent capacity degradation impacts at higher operating speeds. If latent capacity degradation is thought to be significant (e.g., intertwined or row-split cooling coil with multiple compressors feeding individual refrigerant circuits), then the user may choose to specify Yes and the latent capacity degradation model will be applied for speeds 2 through 10 as appropriate. The selection for this input field does not affect latent capacity degradation between speed 1 and off.
Field: Condenser Type[LINK]
The type of condenser used by the DX cooling coil. Valid choices for this input field are AirCooled or EvaporativelyCooled. The default for this field is AirCooled.
Field: Nominal Evaporative Condenser Pump Power[LINK]
The rated power of the evaporative condenser water pump in Watts. This value is used to calculate the power required to pump the water used to evaporatively cool the condenser inlet air. The default value for this input field is zero, but it is autosizable (equivalent to 0.004266 W per watt [15 W/ton] of rated total cooling capacity). This field is not used when Condenser Type = AirCooled.
Field: Nominal Speed Number[LINK]
This numeric field specifies the speed number which corresponds to the rated capacity and air flow rates specified in this object. This value must be lower than or equal to the highest speed number defined below. If blank, defaults to the highest speed number used.
Field: Speed <x> Name[LINK]
For speed <x>, the name of the corresponding Coil:Cooling:DX:CurveFit:Speed object. Speed 1 is always used as the lowest speed. Speeds should be listed in ascending order from lowest capacity to highest capacity. Each coil operating mode may have up to 10 speeds defined.
Coil:Cooling:DX:CurveFit:Speed[LINK]
This object defines DX cooling coil performance for a specific speed within a single operating mode. A speed can be used for a combination of air flow rates and capacities different than the rated air flow rates and capacities defined in Coil:Cooling:DX:CurveFit:OperatingMode. Each operating mode can reference a maximum of 10 speeds.
Inputs[LINK]
Field: Name[LINK]
A unique user-assigned name for an instance of a cooling coil operating mode’s speed. Any reference to a specific speed by a cooling coil operating mode will use this name.
Field: Gross Total Cooling Capacity Fraction[LINK]
This is the ratio of capacity at a specific speed to the operating mode’s Rated Gross Total Cooling Capacity. This field should be 1.0 for the Nominal Speed Number specified in the Coil:Cooling:DX:CurveFit:OperatingMode object.
Field: Evaporator Air Flow Rate Fraction[LINK]
This is the ratio of evaporator air flow rate at a specific speed to the operating mode’s Rated Evaporator Air Flow Rate. This field should be 1.0 for the Nominal Speed Number specified in the Coil:Cooling:DX:CurveFit:OperatingMode object.
Field: Condenser Air Flow Rate Fraction[LINK]
This is the ratio of condenser air flow at a specific speed to the operating mode’s Rated Condenser Air Flow Rate. This field should be 1.0 for the Nominal Speed Number specified in the Coil:Cooling:DX:CurveFit:OperatingMode object.
Field: Gross Sensible Heat Ratio[LINK]
This numeric field defines the gross sensible heat ratio (sensible capacity divided by total cooling capacity) of the DX cooling coil at rated conditions for a specific speed. Both the sensible and total cooling capacities used should be gross (i.e., the effect of supply air fan heat is NOT accounted for).
Field: Gross Cooling COP[LINK]
The coefficient of performance is the ratio of the gross total cooling capacity in Watts to electrical power input in Watts of the DX cooling coil unit at rated conditions (air entering the cooling coil at 26.7 °C drybulb/19.4 °C wetbulb (80 °F drybulb/67 °F wetbulb), air entering the outdoor condenser coil at 35 °C drybulb/ 23.9 °C wetbulb (95 °F drybulb/75 °F wetbulb), and a cooling coil air flow rate defined by field rated air flow rate below). The input power includes electric power for the compressor(s) and condenser fan(s) but does not include the power consumption of the supply air fan. The gross COP should NOT account for the supply air fan. If this input field is left blank, the default value is 3.0.
Field: Active Fraction of Coil Face Area[LINK]
Defines the fraction of the cooling coil face which is actively cooled at a specific speed. Value varies between 0.0 and 1.0. For non-split-face coils, this should be 1.0.
Field: Rated Evaporator Fan Power Per Volume Flow Rate[LINK]
This field is the electric power for the evaporator (cooling coil) fan per air volume flow rate through the coil at the rated conditions in W/(m\(^{3}\)/s). The default value is 773.3 W/(m\(^{3}\)/s) (365 W/1000 cfm) if this field is left blank. If a value is entered, it must be > = 0.0 and < = 1250 W/(m\(^{3}\)/s). This value is only used to calculate Seasonal Energy Efficiency Ratio (SEER), Energy Efficiency Ratio (EER), Integrated Energy Efficiency Ratio (IEER) and the Standard Rating (Net) Cooling Capacity which will be outputs in the EnergyPlus eio file (ref. EnergyPlus Engineering Reference, Single Speed DX Cooling Coil, Standard Ratings). This value is not used for modeling the evaporator (cooling coil) fan during simulations; instead, it is used for calculating SEER, EER, IEER and Standard Rating Cooling Capacity to assist the user in verifying their inputs for modeling this type of equipment.
Field: Evaporative Condenser Pump Power Fraction[LINK]
The ratio of evaporative condenser pump power at a specific speed to the operating mode’s Nominal Evaporative Condenser Pump Power. This field is not used when Condenser Type = AirCooled.
Field: Evaporative Condenser Effectiveness[LINK]
The effectiveness of the evaporative condenser at a specific speed, which is used to determine the temperature of the air entering the outdoor condenser coil as follows:
\[Tcond,inlet = \,\left( {Twb,o} \right)\,\, + \,\,\left( {1 - EvapCondEffectivenes} \right)\left( {Tdb,o\,\, - Twb,o} \right)\]
where
T\(_{cond,inlet}\) = the temperature of the air entering the condenser coil (C)
T\(_{wb,o}\) = the wet-bulb temperature of the outdoor air (C)
T\(_{db,o}\) = the dry-bulb temperature of the outdoor air (C)
The resulting condenser inlet air temperature is used by the Total Cooling Capacity Modifier Function of Temperature Curve and the Energy Input Ratio Modifier Function of Temperature Curve. The default value for this field is 0.9, although valid entries can range from 0.0 to 1.0. This field is not used when Condenser Type = AirCooled.
If the user wants to model an air-cooled condenser, they should simply specify AirCooled in the field Condenser Type. In this case, the Total Cooling Capacity Modifier Function of Temperature Curve and the Energy Input Ratio Modifier Function of Temperature Curve input fields for this object should reference performance curves that are a function of outdoor dry-bulb temperature.
If the user wishes to model an evaporative-cooled condenser AND they have performance curves that are a function of the wet-bulb temperature of air entering the condenser coil, then the user should specify Condenser Type = EvaporativelyCooled and the evaporative condenser effectiveness value should be entered as 1.0. In this case, the Total Cooling Capacity Modifier Function of Temperature Curve and the Energy Input Ratio Modifier Function of Temperature Curve input fields for this object should reference performance curves that are a function of the wet-bulb temperature of air entering the condenser coil.
If the user wishes to model an air-cooled condenser that has evaporative media placed in front of it to cool the air entering the condenser coil, then the user should specify Condenser Type = EvaporativelyCooled. The user must also enter the appropriate evaporative effectiveness for the media. In this case, the Total Cooling Capacity Modifier Function of Temperature Curve and the Energy Input Ratio Modifier Function of Temperature Curve input fields for this object should reference performance curves that are a function of outdoor dry-bulb temperature. Be aware that the evaporative media will significantly reduce the dry-bulb temperature of the air entering the condenser coil, so the Total Cooling Capacity and EIR Modifier Function of Air Flow Fraction Curves must be valid for the expected range of dry-bulb temperatures that will be entering the condenser coil.
Field: Total Cooling Capacity Modifier Function of Temperature Curve Name[LINK]
The name of a bivariate (e.g. biquadratic) or univariate (e.g. quadratic) curve or table object (ref Curve:* and Table:*) that parameterizes the variation of the gross total cooling capacity for a specific speed as a function of the wet-bulb temperature of the air entering the evaporator section, and the dry-bulb temperature of the air entering the condenser section (wet-bulb temperature if modeling an evaporative-cooled condenser). If a univariate curve or table is specified, then the independent variable is the entering condenser temperature. The curve is normalized to 1 at 19.44 °C (67 °F) indoor wet-bulb temperature and 35 °C (95 °F) outdoor dry-bulb temperature. The output of this curve is multiplied by the operating mode’s Rated Gross Total Cooling Capacity to give the gross total cooling capacity at specific temperature operating conditions (i.e., at temperatures different from the rating point temperatures). The curve is normalized to have the value of 1.0 at the rating point.
Field: Total Cooling Capacity Modifier Function of Air Flow Fraction Curve Name[LINK]
The name of a univariate (e.g. quadratic) curve or table object (ref Curve:* and Table:*) that parameterizes the variation of the gross total cooling capacity for a specific speed as a function of the ratio of actual air flow rate across the cooling coil to the rated air flow rate for a specific speed (i.e., fraction of full load flow). The output of this curve is multiplied by the operating mode’s Rated Gross Total Cooling Capacity and the total cooling capacity modifier curve (function of temperature) to give the gross total cooling capacity for a specific speed at the specific temperature and air flow conditions at which the coil is operating. The curve is normalized to have the value of 1.0 when the actual air flow rate equals the rated air flow rate for Speed <x>.
Field: Energy Input Ratio Modifier Function of Temperature Curve Name[LINK]
The name of a bivariate (e.g. biquadratic) curve or table object (ref Curve:* and Table:*) that parameterizes the variation of the energy input ratio (EIR) for a specific speed as a function of the wetbulb temperature of the air entering the evaporator section and the drybulb temperature of the air entering the condenser section (wetbulb temperature if modeling an evaporative-cooled condenser). The curve is normalized to 1 at 19.44 °C (67 °F) indoor wet-bulb temperature and 35 °C (95 °F) outdoor dry-bulb temperature. The EIR is the inverse of the COP. The output of this curve is multiplied by the rated EIR for a specific speed (inverse of rated COP for a specific speed) to give the EIR for a specific speed at specific temperature operating conditions (i.e., at temperatures different from the rating point temperatures).
Field: Energy Input Ratio Modifier Function of Air Flow Fraction Curve Name[LINK]
The name of a univariate (e.g. quadratic) curve or table object (ref Curve:* and Table:*) that parameterizes the variation of the energy input ratio (EIR) for a specific speed as a function of the ratio of actual air flow rate across the cooling coil to the rated air flow rate for a specific speed (i.e., fraction of full load flow). The EIR is the inverse of the COP. The output of this curve is multiplied by the rated EIR and the EIR modifier curve (function of temperature) to give the EIR for a specific speed at the specific temperature and air flow conditions at which the cooling coil is operating. This curve is normalized to a value of 1.0 when the actual air flow rate equals the rated air flow rate for a specific speed.
Field: Part Load Fraction Correlation Curve Name[LINK]
The name of a univariate (e.g. quadratic) curve or table object (ref Curve:* and Table:*) that parameterizes the variation of electrical power input to the DX unit as a function of the part load ratio (PLR, sensible cooling load/steady-state sensible cooling capacity for a specific speed). The product of the rated EIR and EIR modifier curves is divided by the output of this curve to give the effective EIR for a given simulation timestep for a specific speed. The part load fraction (PLF) correlation accounts for efficiency losses due to compressor cycling.
The part load fraction correlation should be normalized to a value of 1.0 when the part load ratio equals 1.0 (i.e., no efficiency losses when the compressor(s) run continuously for the simulation timestep). For PLR values between 0 and 1 (0 < = PLR < 1), the following rules apply:
If PLF < 0.7 a warning message is issued, the program resets the PLF value to 0.7, and the simulation proceeds. The runtime fraction of the coil is defined as PLR/PLF. If PLF < PLR, then a warning message is issued and the runtime fraction of the coil is limited to 1.0.
A typical part load fraction correlation for a conventional DX cooling coil (a specific speed) would be:
If the user wishes to model no efficiency degradation due to compressor cycling, the part load fraction correlation should be defined as follows:
Field: Rated Waste Heat Fraction of Power Input[LINK]
The fraction of energy input to the cooling coil that is available as recoverable waste heat at full load and rated conditions for a specific speed.
Field: Waste Heat Modifier Function of Temperature Curve Name[LINK]
The name of a bivariate (e.g. biquadratic) curve or table object (ref Curve:* and Table:*) that parameterizes the variation of the waste heat recovery as a function of outdoor dry-bulb temperature and the entering coil dry-bulb temperature at a specific speed. The output of this curve is multiplied by the rated waste heat fraction at specific temperature operating conditions (i.e., at temperatures different from the rating point). The curve is normalized to a value of 1.0 at the rating point. When the fuel type is electricity, this field can remain blank since it is ignored by the program in this instance. When the fuel type is not electricity and the parent object AirLoopHVAC:UnitaryHeatPump:AirToAir:MultiSpeed does not require waste heat calculations, this field is ignored. If the field is blank, a warning will be issued and simulation continues. When the fuel type is not electricity and the parent object AirLoopHVAC:UnitaryHeatPump:AirToAir:MultiSpeed requires waste heat calculations, if this field is left blank, the program assumes a constant value of 1 to make simulation continue and a warning will be issued.
Field: Sensible Heat Ratio Modifier Function of Temperature Curve Name[LINK]
The name of a bivariate (e.g. biquadratic) curve or table object (ref Curve:* and Table:*) that parameterizes the variation of the sensible heat ratio (SHR) as a function of DX cooling coil entering air wet-bulb and dry-bulb temperatures. The output of this curve is multiplied by the rated SHR and the SHR modifier curve (function of flow fraction) to give the SHR at the specific coil entering air temperature and air flow conditions at which the cooling coil is operating. This curve is normalized to a value of 1.0 at the rated condition. This input field is optional. If this input is not blank then the Sensible Heat Ratio Modifier Function of Flow Fraction Curve Name must also be entered. If left blank, SHR is calculated using the apparatus dew point method based on total capacity and coil bypass factor.
Field: Sensible Heat Ratio Modifier Function of Flow Fraction Curve Name[LINK]
The name of a univariate (e.g. quadratic) curve or table object (ref Curve:* and Table:*) that parameterizes the variation of the sensible heat ratio (SHR) as a function of the ratio of actual air flow rate across the cooling coil to the rated air flow rate (i.e., fraction of full load flow). The output of this curve is multiplied by the rated SHR and the SHR modifier curve (function of temperature) to give the SHR at the specific temperature and air flow conditions at which the cooling coil is operating. This curve is normalized to a value of 1.0 when the actual air flow rate equals the rated air flow rate. This input field is optional. If this input is not blank then the Sensible Heat Ratio Modifier Function of Temperature Curve Name must also be entered. If left blank, SHR is calculated using the apparatus dew point method based on total capacity and coil bypass factor.
Following is an example input for a single-speed air-cooled cooling DX coil.
Following is an example input for a three-speed evaporatively-cooled cooling DX coil.
Following is an example input for a single cooling DX coil with 3 operation modes as normal, subcool and reheat to represent a subcool reheat coil model.
Outputs[LINK]
Following are the list of possible output variables from this coil model:
HVAC,Average,Cooling Coil Total Cooling Rate [W]
HVAC,Sum,Cooling Coil Total Cooling Energy [J]
HVAC,Average,Cooling Coil Sensible Cooling Rate [W]
HVAC,Sum,Cooling Coil Sensible Cooling Energy [J]
HVAC,Average,Cooling Coil Latent Cooling Rate [W]
HVAC,Sum,Cooling Coil Latent Cooling Energy [J]
HVAC,Average,Cooling Coil Electricity Rate [W]
HVAC,Sum,Cooling Coil Electricity Energy [J]
HVAC,Average,Cooling Coil Runtime Fraction []
HVAC,Average,SubcoolReheat Cooling Coil Operation Mode []
HVAC,Average,SubcoolReheat Cooling Coil Operation Mode Ratio []
HVAC,Average,SubcoolReheat Cooling Coil Recovered Heat Energy Rate [W]
HVAC,Average,SubcoolReheat Cooling Coil Recovered Heat Energy [J]
Cooling Coil Total Cooling Rate [W][LINK]
This field is the total (sensible and latent) cooling rate output of the DX coil in Watts. This is determined by the coil inlet and outlet air conditions and the air mass flow rate through the coil.
Cooling Coil Total Cooling Energy [J][LINK]
This is the total (sensible plus latent) cooling output of the DX coil in Joules over the timestep being reported. This is determined by the coil inlet and outlet air conditions and the air mass flow rate through the coil. This output is also added to a meter with Resource Type = EnergyTransfer, End Use Key = CoolingCoils, Group Key = System (Ref. Output:Meter objects).
Cooling Coil Sensible Cooling Rate [W][LINK]
This output is the moist air sensible cooling rate output of the DX coil in Watts. This is determined by the inlet and outlet air conditions and the air mass flow rate through the coil.
Cooling Coil Sensible Cooling Energy [J][LINK]
This is the moist air sensible cooling output of the DX coil in Joules for the timestep being reported. This is determined by the inlet and outlet air conditions and the air mass flow rate through the coil.
Cooling Coil Latent Cooling Rate [W][LINK]
This is the latent cooling rate output of the DX coil in Watts. This is determined by the inlet and outlet air conditions and the air mass flow rate through the coil.
Cooling Coil Latent Cooling Energy [J][LINK]
This is the latent cooling output of the DX coil in Joules for the timestep being reported. This is determined by the inlet and outlet air conditions and the air mass flow rate through the coil.
Cooling Coil Electricity Rate [W][LINK]
This output is the electricity consumption rate of the DX coil compressor and condenser fan(s) in Watts. This value is calculated for each HVAC system timestep, and the results are averaged for the timestep being reported.
Cooling Coil Electricity Energy [J][LINK]
This is the electricity consumption of the DX coil compressor and condenser fan(s) in Joules for the timestep being reported. This output is also added to a meter with Resource Type = Electricity, End Use Key = Cooling, Group Key = System (Ref. Output:Meter objects).
Cooling Coil Runtime Fraction [][LINK]
This is the runtime fraction of the DX coil compressor and condenser fan(s) for the timestep being reported.
SubcoolReheat Cooling Coil Operation Mode [][LINK]
This output variable reports operating mode for a subcool reheat coil. When the value is 1, the coil operates at normal mode. When the value is 2, the coil operation is determined by the mode ratio through linear interpolation between normal mode and subcool mode. For example, when the mode ratio is 0.4, the coil operates at subcool mode for 40% of timestep and at normal mode for 60% of timestep. When the value is 3, the coil operation is determined by the mode ratio through linear interpolation between normal mode and reheat mode.
SubcoolReheat Cooling Coil Operation Mode Ratio [][LINK]
This output variable reports the ratio of time in a system timestep between normal mode and subcool mode when the operation mode = 2. The mode ratio represents how long the subcool mode runs as a fraction of the system timestep, and the normal mode runs in the rest of the system timestep. The output variable also reports the ratio of time in a system tiemstep between normal mode and reheat mode when the operation mode = 3. The value is 0.0 when the operation mode = 1.
SubcoolReheat Cooling Coil Recovered Heat Energy Rate [W][LINK]
This output is the recovered heat energy rate output of the DX coil in Watts. This is determined by energy use difference between normal mode and subcool or reheat mode, multiplied by the mode ratio.
SubcoolReheat Cooling Coil Recovered Heat Energy [J][LINK]
This output is the recovered heat energy rate output of the DX coil in Jouals. This is determined by energy use difference between normal mode and subcool or reheat mode, multiplied by the mode ratio.
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