This group of objects primarily consists of polynomial
curves that are used to characterize the performance of HVAC
equipment. Several other non-polynomial curves are also
included to characterize the performance of pumps and fans.
All of the curves are input, stored, and evaluated entirely
within the Curve module. The curves are usually derived from
fits or regressions to data covering a limited range. Results
for independent variable values outside this range are likely
to be invalid, so curve input always contains a range of
validity (maximum and minimum permitted values) for each
independent variable and can optionally have limits on the
curve output. No error or warning message is issued if an
independent variable is outside the range. Instead, the curve
manager uses the minimum value if an independent variable is
less than the minimum, and the maximum if a variable exceeds
the maximum. Similarly, no error or warning message is issued
if the curve output is outside the range of the optional
minimum and maximum curve output limits. Instead, the curve
manager uses the minimum and maximum curve limits to cap the
output of the performance curve.
Curve names must be unique across all curve types.
Input for the linear curve consists of a curve name, the
two coefficients, and the maximum and minimum valid
independent variable values. Optional inputs for curve minimum
and maximum may be used to limit the output of the performance
curve (e.g., limit extrapolation). The equation represented by
the linear curve is:
\[y = {C_1} +
{C_2}*x\]
A user assigned unique name for an instance of a linear
curve. When a curve is used, it is referenced by this
name.
Field: Coefficient1
Constant[LINK]
The constant coefficient (C\(_{1}\)) in the equation.
Field: Coefficient2 x[LINK]
The linear coefficient (C\(_{2}\)) in the equation.
Field: Minimum Value of
x[LINK]
The minimum allowable value of x. Values of x less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
x[LINK]
The maximum allowable value of x. Values of x greater than
the maximum will be replaced by the maximum.
Field: Minimum Curve
Output[LINK]
The minimum allowable value of the evaluated curve. Values
less than the minimum will be replaced by the minimum.
Field: Maximum Curve
Output[LINK]
The maximum allowable value of the evaluated curve. Values
greater than the maximum will be replaced by the maximum.
This field is used to indicate the kind of units that may
be associated with the x values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of X and Maximum Value of x. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Distance
Power
Field: Output Unit Type[LINK]
This field is used to indicate the kind of units that may
be associated with the output values. It is used by IDF Editor
to display the appropriate SI and IP units for the Minimum
Curve Output and Maximum Curve Output. The unit conversion is
not applied to the coefficients. The available options are
shown below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Capacity
Power
Following is an example input:
Curve:Linear,
Curve-Linear, ! name
-1, ! Coefficient1 Constant
2, ! Coefficient2 x
0.0, ! min curve output
1.0; ! max curve output
The following is another example, as might be applied in
the Fan:ComponentModel
to characterize duct static pressure reset (using a constant
duct static pressure set point of 248.84 Pa in this case):
Curve:Linear,
DiagnosticSPR, ! Curve Name f = C1 + C2\*x
248.84, ! Coefficient1 Constant [Pa]
0., ! Coefficient 2 Press/Flow [Pa-s/m3]
0., ! Minimum Value of x (Qfan) [m3/s]
100., ! Maximum Value of x (Qfan) [m3/s]
62.5, ! Minimum Curve Output [Pa]
248.84; ! Maximum Curve Output [Pa]
Curve:QuadLinear[LINK]
Input consists of the curve name, the five coefficients,
and maximum and minimum values for each of the independent
variables. Optional inputs for curve minimum and maximum may
be used to limit the output of the performance curve (e.g.,
limit extrapolation). The equation is represented by this
curve:
y = C1 + C2 * w + C3 * x +
C4 * y + C5 * z[LINK]
A user assigned unique name for an instance of this curve.
When a curve of this type is used, it is referenced by this
name.
Field: Coefficient1
Constant[LINK]
The constant coefficient (C1) in the equation.
Field: Coefficient2 w[LINK]
The coefficient (C2) in the equation.
Field: Coefficient3 x[LINK]
The coefficient (C3) in the equation.
Field: Coefficient4 y[LINK]
The coefficient (C4) in the equation.
Field: Coefficient5 z[LINK]
The coefficient (C5) in the equation.
Field: Minimum Value of
w[LINK]
The minimum allowable value of w. Values of w less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
w[LINK]
The maximum allowable value of w. Values of w greater than
the maximum will be replaced by the maximum.
Field: Minimum Value of
x[LINK]
The minimum allowable value of x. Values of x less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
x[LINK]
The maximum allowable value of x. Values of x greater than
the maximum will be replaced by the maximum.
Field: Minimum Value of
y[LINK]
The minimum allowable value of y. Values of y less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
y[LINK]
The maximum allowable value of y. Values of y greater than
the maximum will be replaced by the maximum.
Field: Minimum Value of
z[LINK]
The minimum allowable value of z. Values of z less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
z[LINK]
The maximum allowable value of z. Values of z greater than
the maximum will be replaced by the maximum.
This field is used to indicate the kind of units that may
be associated with the w values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of w and Maximum Value of w. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
VolumetricFlowPerPower
This field is used to indicate the kind of units that may
be associated with the x values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of x and Maximum Value of x. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
VolumetricFlowPerPower
This field is used to indicate the kind of units that may
be associated with the y values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of y and Maximum Value of y. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
VolumetricFlowPerPower
This field is used to indicate the kind of units that may
be associated with the z values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of z and Maximum Value of z. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
VolumetricFlowPerPower
Below are an example inputs for QuadLinear Curves.
CURVE:QUADLINEAR,
MinDsnWBCurveName, ! Curve Name
-3.3333, ! CoefficientC1
0.0, ! CoefficientC2
38.9, ! CoefficientC3
0., ! CoefficientC4
0., ! CoefficientC5
-30., ! Minimum Value of w
40., ! Maximum Value of w
0., ! Minimum Value of x
1., ! Maximum Value of x
10., ! Minimum Value of y
8., ! Maximum Value of y
1. E-8, ! Minimum Value of z
8. E-8, ! Maximum Value of z
0., ! Minimum Curve Output
38.; ! Maximum Curve Output
Curve:QuadLinear,
MinActWBCurveName, ! Curve Name
-8.3333, ! CoefficientC1
2.0, ! CoefficientC2
5.5556., ! CoefficientC3
-1.0, ! CoefficientC4
0., ! CoefficientC5
0., ! Minimum Value of w
38., ! Maximum Value of w
0., ! Minimum Value of x
1., ! Maximum Value of x
10., ! Minimum Value of y
38., ! Maximum Value of y
1. E-8, ! Minimum Value of z
8. E-8, ! Maximum Value of z
0., ! Minimum Curve Output
43.; ! Maximum Curve Output
Curve:QuadLinear,
OptCondEntCurveName, ! Curve Name
12.2711, ! CoefficientC1
0.80, ! CoefficientC2
6.6667, ! CoefficientC3
-0.266, ! CoefficientC4
-6193484., ! CoefficientC5
0., ! Minimum Value of w
38., ! Maximum Value of w
0., ! Minimum Value of x
1., ! Maximum Value of x
10., ! Minimum Value of y
38., ! Maximum Value of y
1. E-8, ! Minimum Value of z
8. E-8, ! Maximum Value of z
0., ! Minimum Curve Output
32.; ! Maximum Curve Output
Curve:QuintLinear[LINK]
Input consists of the curve name, the six coefficients, and
maximum and minimum values for each of the independent
variables. Optional inputs for curve minimum and maximum may
be used to limit the output of the performance curve (e.g.,
limit extrapolation). The equation is represented by this
curve:
y = C1 + C2 * v + C3 *
w + C4 * x + C5 * y + C6 * z[LINK]
A user assigned unique name for an instance of this curve.
When a curve of this type is used, it is referenced by this
name.
Field: Coefficient1
Constant[LINK]
The constant coefficient (C1) in the equation.
Field: Coefficient2 v[LINK]
The coefficient (C2) in the equation.
Field: Coefficient3 w[LINK]
The coefficient (C3) in the equation.
Field: Coefficient4 x[LINK]
The coefficient (C4) in the equation.
Field: Coefficient5 y[LINK]
The coefficient (C5) in the equation.
Field: Coefficient6 z[LINK]
The coefficient (C6) in the equation.
Field: Minimum Value of
v[LINK]
The minimum allowable value of v. Values of v less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
v[LINK]
The maximum allowable value of v. Values of v greater than
the maximum will be replaced by the maximum.
Field: Minimum Value of
w[LINK]
The minimum allowable value of w. Values of w less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
w[LINK]
The maximum allowable value of w. Values of w greater than
the maximum will be replaced by the maximum.
Field: Minimum Value of
x[LINK]
The minimum allowable value of x. Values of x less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
x[LINK]
The maximum allowable value of x. Values of x greater than
the maximum will be replaced by the maximum.
Field: Minimum Value of
y[LINK]
The minimum allowable value of y. Values of y less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
y[LINK]
The maximum allowable value of y. Values of y greater than
the maximum will be replaced by the maximum.
Field: Minimum Value of
z[LINK]
The minimum allowable value of z. Values of z less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
z[LINK]
The maximum allowable value of z. Values of z greater than
the maximum will be replaced by the maximum.
This field is used to indicate the kind of units that may
be associated with the v values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of v and Maximum Value of v. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
VolumetricFlowPerPower
This field is used to indicate the kind of units that may
be associated with the w values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of w and Maximum Value of w. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
VolumetricFlowPerPower
This field is used to indicate the kind of units that may
be associated with the x values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of x and Maximum Value of x. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
VolumetricFlowPerPower
This field is used to indicate the kind of units that may
be associated with the y values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of y and Maximum Value of y. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
VolumetricFlowPerPower
This field is used to indicate the kind of units that may
be associated with the z values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of z and Maximum Value of z. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
VolumetricFlowPerPower
Below are an example inputs for QuintLinear Curves.
CURVE:QUINTLINEAR,
CoolSensCapCurve, ! Curve Name
-5.462690012, ! CoefficientC1
17.95968138, ! CoefficientC2
-11.87818402, ! CoefficientC3
-0.980163419, ! CoefficientC4
0.767285761, ! CoefficientC5
0.0, ! CoefficientC6
-100, ! Minimum Value of v
100, ! Maximum Value of v
-100, ! Minimum Value of w
100, ! Maximum Value of w
-100, ! Minimum Value of x
100, ! Maximum Value of x
0, ! Minimum Value of y
100, ! Maximum Value of y
0, ! Minimum Value of z
100, ! Maximum Value of z
0, ! Minimum Curve Output
38; ! Maximum Curve Output
Curve:Quadratic[LINK]
Input for a quadratic curve consists of the curve name, the
three coefficients, and the maximum and minimum valid
independent variable values. Optional inputs for curve minimum
and maximum may be used to limit the output of the performance
curve (e.g., limit extrapolation). The equation represented by
the quadratic curve is:
\[y = {C_1} + {C_2}*x +
{C_3}*{x^2}\]
A user assigned unique name for an instance of a quadratic
curve. When a curve is used, it is referenced by this
name.
Field: Coefficient1
Constant[LINK]
The constant coefficient (C\(_{1}\)) in the equation.
Field: Coefficient2 x[LINK]
The linear coefficient (C\(_{2}\)) in the equation.
Field: Coefficient3 x**2[LINK]
The quadratic coefficient (C\(_{3}\)) in the equation.
Field: Minimum Value of
x[LINK]
The minimum allowable value of x. Values of x less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
x[LINK]
The maximum allowable value of x. Values of x greater than
the maximum will be replaced by the maximum.
Field: Minimum Curve
Output[LINK]
The minimum allowable value of the evaluated curve. Values
less than the minimum will be replaced by the minimum.
Field: Maximum Curve
Output[LINK]
The maximum allowable value of the evaluated curve. Values
greater than the maximum will be replaced by the maximum.
This field is used to indicate the kind of units that may
be associated with the x values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of X and Maximum Value of x. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Distance
Power
Field: Output Unit Type[LINK]
This field is used to indicate the kind of units that may
be associated with the output values. It is used by IDF Editor
to display the appropriate SI and IP units for the Minimum
Curve Output and Maximum Curve Output. The unit conversion is
not applied to the coefficients. The available options are
shown below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Capacity
Power
Following is an example input.
Curve:Quadratic,
WindACCBFFFF, ! name
-2.277, ! Coefficient1 Constant
5.2114, ! Coefficient2 x
-1.9344, ! Coefficient3 x\*\*2
0.0, ! Minimum Value of x
1.0; ! Maximum Value of x
Input for a cubic curve consists of the curve name, the 4
coefficients, and the maximum and minimum valid independent
variable values. Optional inputs for curve minimum and maximum
may be used to limit the output of the performance curve
(e.g., limit extrapolation). The equation represented by the
cubic curve is:
\[y = {C_1} + {C_2}*x +
{C_3}*{x^2} + {C_4}*{x^3}\]
A user assigned unique name for an instance of a cubic
curve. When a curve is used, it is referenced by this
name.
Field: Coefficient1
Constant[LINK]
The constant coefficient (C\(_{1}\)) in the equation.
Field: Coefficient2 x[LINK]
The linear coefficient (C\(_{2}\)) in the equation.
Field: Coefficient3 x**2[LINK]
The quadratic coefficient (C\(_{3}\)) in the equation.
Field: Coefficient4 x**3[LINK]
The cubic coefficient (C\(_{4}\)) in the equation.
Field: Minimum Value of
x[LINK]
The minimum allowable value of x. Values of x less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
x[LINK]
The maximum allowable value of x. Values of x greater than
the maximum will be replaced by the maximum.
Field: Minimum Curve
Output[LINK]
The minimum allowable value of the evaluated curve. Values
less than the minimum will be replaced by the minimum.
Field: Maximum Curve
Output[LINK]
The maximum allowable value of the evaluated curve. Values
greater than the maximum will be replaced by the maximum.
This field is used to indicate the kind of units that may
be associated with the x values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of X and Maximum Value of x. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Distance
Power
Field: Output Unit Type[LINK]
This field is used to indicate the kind of units that may
be associated with the output values. It is used by IDF Editor
to display the appropriate SI and IP units for the Minimum
Curve Output and Maximum Curve Output. The unit conversion is
not applied to the coefficients. The available options are
shown below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Capacity
Power
Following is an input example.
Curve:Cubic,
WindACEIRFPLF, ! name
.00000273404, ! Coefficient1 Constant
1.05259, ! Coefficient2 x
-.0552087, ! Coefficient3 x**2
.00262236, ! Coefficient4
0.0, ! min
1.1; ! max
Curve:Quartic[LINK]
Input for a Quartic (fourth order polynomial) curve
consists of the curve name, the five coefficients, and the
maximum and minimum valid independent variable values.
Optional inputs for curve minimum and maximum may be used to
limit the output of the performance curve (e.g., limit
extrapolation). The equation represented by the quartic curve
is:
\[y = {C_1} + {C_2}x +
{C_3}{x^2} + {C_4}{x^3} + {C_5}{x^4}\]
A user assigned unique name for an instance of a Quartic
curve. When a curve is used, it is referenced by this
name.
Field: Coefficient1
Constant[LINK]
The constant coefficient (C\(_{1}\)) in the equation.
Field: Coefficient2 x[LINK]
The linear coefficient (C\(_{2}\)) in the equation.
Field: Coefficient3 x**2[LINK]
The quadratic coefficient (C\(_{3}\)) in the equation.
Field: Coefficient4 x**3[LINK]
The cubic coefficient (C\(_{4}\)) in the equation.
Field: Coefficient5 x**4[LINK]
The fourth-order coefficient (C\(_{5}\)) in the equation.
Field: Minimum Value of
x[LINK]
The minimum allowable value of x. Values of x less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
x[LINK]
The maximum allowable value of x. Values of x greater than
the maximum will be replaced by the maximum.
Field: Minimum Curve
Output[LINK]
The minimum allowable value of the evaluated curve. Values
less than the minimum will be replaced by the minimum.
Field: Maximum Value of
x[LINK]
The maximum allowable value of the evaluated curve. Values
greater than the maximum will be replaced by the maximum.
This field is used to indicate the kind of units that may
be associated with the x values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of X and Maximum Value of x. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Distance
Power
Field: Output Unit Type[LINK]
This field is used to indicate the kind of units that may
be associated with the output values. It is used by IDF Editor
to display the appropriate SI and IP units for the Minimum
Curve Output and Maximum Curve Output. The unit conversion is
not applied to the coefficients. The available options are
shown below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Capacity
Power
Following is an input example.
Curve:Quartic,
BGSeries60, !- y = -611.41x4 + 192.68x3 - 88.843x2 + 4.7634x + 5.5656
5.5656, !- Constant
4.7634, !- 1st coefficient
-88.843, !- 2nd coefficient
192.68, !- 3rd coefficient
-611.41, !- 4th coefficient
0.0, !- Min Phi Value
0.2412; !- Max Phi Value
The following is another example, as might be applied in
the Fan:ComponentModel
to characterize belt maximum efficiency (using a medium
efficiency belt in this case):
Curve:Quartic,
BeltMaxEffMedium, ! Curve Name
-0.09504, ! CoefficientC1
0.03415, ! CoefficientC2
-0.008897, ! CoefficientC3
0.001159, ! CoefficientC4
-0.00006132, ! CoefficientC5
-1.2, ! Minimum Value of x
6.2, ! Maximum Value of x
-4.6, ! Minimum Curve Output
0.; ! Maximum Curve Output
Curve:Exponent[LINK]
Input for a exponent curve consists of the curve name, the
3 coefficients, and the maximum and minimum valid independent
variable values. Optional inputs for curve minimum and maximum
may be used to limit the output of the performance curve
(e.g., limit extrapolation). The equation represented by the
exponent curve is:
\[y = C1 +
C2*{x^{C3}}\]
A user assigned unique name for an instance of an exponent
curve. When a curve is used, it is referenced by this
name.
Field: Coefficient1
Constant[LINK]
The constant coefficient (C\(_{1}\)) in the equation.
Field: Coefficient2
Constant[LINK]
The linear coefficient (C\(_{2}\)) in the equation.
Field: Coefficient3
Constant[LINK]
The exponent coefficient (C\(_{3}\)) in the equation.
Field: Minimum Value of
x[LINK]
The minimum allowable value of x. Values of x less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
x[LINK]
The maximum allowable value of x. Values of x greater than
the maximum will be replaced by the maximum.
Field: Minimum Curve
Output[LINK]
The minimum allowable value of the evaluated curve. Values
less than the minimum will be replaced by the minimum.
Field: Maximum Curve
Output[LINK]
The maximum allowable value of the evaluated curve. Values
greater than the maximum will be replaced by the maximum.
This field is used to indicate the kind of units that may
be associated with the x values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of X and Maximum Value of x. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Distance
Power
Field: Output Unit Type[LINK]
This field is used to indicate the kind of units that may
be associated with the output values. It is used by IDF Editor
to display the appropriate SI and IP units for the Minimum
Curve Output and Maximum Curve Output. The unit conversion is
not applied to the coefficients. The available options are
shown below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Capacity
Power
Following is an input example.
Curve:Exponent,
! Curve = C1 + C2\*x\*\*C3, x = fan speed ratio
FanPowerExponentCurve, !- Name
0.0, !- Coefficient1 Constant
1.0, !- Coefficient2 Constant
3.0, !- Coefficient3 Constant
0.0, !- Minimum Value of x
1.5, !- Maximum Value of x
0.1, !- Minimum Curve Output
1.5; !- Maximum Curve Output
Curve:Bicubic[LINK]
This curve type is a function of two independent variables.
Input consists of the curve name, the ten coefficients, and
the minimum and maximum values for each of the independent
variables. Optional inputs for curve minimum and maximum may
be used to limit the output of the performance curve (e.g.,
limit extrapolation). The equation represented by the bicubic
curve is:
\[z = {C_1} + {C_2}*x +
{C_3}*{x^2} + {C_4}*y + {C_5}*{y^2} + {C_6}*xy + {C_7}*{x^3} +
{C_8}*{y^3} + {C_9}*{x^2}y + {C_{10}}*x{y^2}\]
A user assigned unique name for an instance of a bicubic
curve. When a curve is used by another object, it is
referenced by this name.
Field: Coefficient1
Constant[LINK]
The constant coefficient (C\(_{1}\)) in the equation.
Field: Coefficient2 x[LINK]
The coefficient C\(_{2}\)
in the equation.
Field: Coefficient3 x**2[LINK]
The coefficient C\(_{3}\)
in the equation.
Field: Coefficient4 y[LINK]
The coefficient C\(_{4}\)
in the equation.
Field: Coefficient5 y**2[LINK]
The coefficient C\(_{5}\)
in the equation.
Field: Coefficient6 x*y[LINK]
The coefficient C\(_{6}\)
in the equation.
Field: Coefficient7 x**3[LINK]
The coefficient C\(_{7}\)
in the equation.
Field: Coefficient8 y**3[LINK]
The coefficient C\(_{8}\)
in the equation.
Field: Coefficient9
x**2*y[LINK]
The coefficient C\(_{9}\)
in the equation.
Field: Coefficient10
x*y**2[LINK]
The coefficient C\(_{10}\)
in the equation.
Field: Minimum Value of
x[LINK]
The minimum allowable value of x. Values of x less than
this minimum will be replaced by the minimum.
Field: Maximum Value of
x[LINK]
The maximum allowable value of x. Values of x greater than
this maximum will be replaced by the maximum.
Field: Minimum Value of
y[LINK]
The minimum allowable value of y. Values of y less than
this minimum will be replaced by the minimum.
Field: Maximum Value of
y[LINK]
The maximum allowable value of y. Values of y greater than
this maximum will be replaced by the maximum.
Field: Minimum Curve
Output[LINK]
The minimum allowable value of the evaluated curve. Values
less than the minimum will be replaced by the minimum.
Field: Maximum Curve
Output[LINK]
The maximum allowable value of the evaluated curve. Values
greater than the maximum will be replaced by the maximum.
This field is used to indicate the kind of units that may
be associated with the x values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of X and Maximum Value of x. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
This field is used to indicate the kind of units that may
be associated with the y values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of Y and Maximum Value of Y. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
Field: Output Unit Type[LINK]
This field is used to indicate the kind of units that may
be associated with the output values. It is used by IDF Editor
to display the appropriate SI and IP units for the Minimum
Curve Output and Maximum Curve Output. The unit conversion is
not applied to the coefficients. The available options are
shown below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Capacity
Power
Below is an example input.
Curve:Bicubic,
Main Chiller EIRFPLR, !- Name
7.086284E-02, !- Coefficient1 Constant
2.787561E-03, !- Coefficient2 x
-8.917038E-06, !- Coefficient3 x\*\*2
2.309734E-01, !- Coefficient4 y
1.250442E+00, !- Coefficient5 y\*\*2
-2.161029E-03, !- Coefficient6 x\*y
0.000000E+00, !- Coefficient7 x\*\*3
-5.630094E-01, !- Coefficient8 y\*\*3
0.000000E+00, !- Coefficient9 x\*\*2\*y
0.000000E+00, !- Coefficient10 x\*y\*\*2
20.33, !- Minimum Value of x
35.00, !- Maximum Value of x
0.25, !- Minimum Value of y
1.01; !- Maximum Value of y
Curve:Biquadratic[LINK]
This curve is a function of two independent variables.
Input consists of the curve name, the six coefficients, and
min and max values for each of the independent variables.
Optional inputs for curve minimum and maximum may be used to
limit the output of the performance curve (e.g., limit
extrapolation). The equation represented by the bicubic curve
is:
\[z = {C_1} + {C_2}*x +
{C_3}*{x^2} + {C_4}*y + {C_5}*{y^2} + {C_6}*xy\]
A user assigned unique name for an instance of a
biquadratic curve. When a curve is used, it is referenced by
this name.
Field: Coefficient1
Constant[LINK]
The constant coefficient (C\(_{1}\)) in the equation.
Field: Coefficient2 x[LINK]
The coefficient C\(_{2}\)
in the equation.
Field: Coefficient3 x**2[LINK]
The coefficient C\(_{3}\)
in the equation.
Field: Coefficient4 y[LINK]
The coefficient C\(_{4}\)
in the equation.
Field: Coefficient5 y**2[LINK]
The coefficient C\(_{5}\)
in the equation.
Field: Coefficient6 x*y[LINK]
The coefficient C\(_{6}\)
in the equation.
Field: Minimum Value of
x[LINK]
The minimum allowable value of x. Values of x less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
x[LINK]
The maximum allowable value of x. Values of x greater than
the maximum will be replaced by the maximum.
Field: Minimum Value of
y[LINK]
The minimum allowable value of y. Values of y less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
y[LINK]
The maximum allowable value of y. Values of y greater than
the maximum will be replaced by the maximum.
Field: Minimum Curve
Output[LINK]
The minimum allowable value of the evaluated curve. Values
less than the minimum will be replaced by the minimum.
Field: Maximum Curve
Output[LINK]
The maximum allowable value of the evaluated curve. Values
greater than the maximum will be replaced by the maximum.
This field is used to indicate the kind of units that may
be associated with the x values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of X and Maximum Value of x. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
This field is used to indicate the kind of units that may
be associated with the y values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of Y and Maximum Value of Y. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
Field: Output Unit Type[LINK]
This field is used to indicate the kind of units that may
be associated with the output values. It is used by IDF Editor
to display the appropriate SI and IP units for the Minimum
Curve Output and Maximum Curve Output. The unit conversion is
not applied to the coefficients. The available options are
shown below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Capacity
Power
Below is an example input.
Curve:Biquadratic,
WindACCoolCapFT, ! name
0.942587793, ! Coefficient1 Constant
0.009543347, ! Coefficient2 x
0.000683770, ! Coefficient3 x\*\*2
-0.011042676, ! Coefficient4 y
0.000005249, ! Coefficient5 y\*\*2
-0.000009720, ! Coefficient6 x\*y
15., 22., ! min and max of first independent variable
29., 47.; ! min and max of second independent variable
Curve:CubicLinear[LINK]
This curve is a function of two independent variables.
Input consists of the curve name, the six coefficients, and
min and max values for each of the independent variables.
Optional inputs for curve minimum and maximum may be used to
limit the output of the performance curve (e.g., limit
extrapolation). The equation represented by the cubic linear
curve:
\[y = \left( {{C_1} + {C_2}*x +
{C_3}*{x^2} + {C_4}*{x^3}} \right) + \left( {{C_5} + {C_6}*x}
\right)*y\]
A user assigned unique name for an instance of a
quadratic-linear curve. When a curve is used, it is referenced
by this name.
Field: Coefficient1
Constant[LINK]
The constant coefficient (\(C_1\) ) in the equation.
Field: Coefficient2 x[LINK]
The coefficient \(C_2\) in
the equation.
Field:
Coefficient3 x**2 The coefficient \(C_3\) in the equation.[LINK]
Field:
Coefficient4 x**3 The coefficient \(C_4\) in the equation.[LINK]
Field: Coefficient5 y[LINK]
The coefficient \(C_5\) in
the equation.
Field:
Coefficient6 x*y The coefficient \(C_6\) in the equation.[LINK]
Field: Minimum Value of
x[LINK]
The minimum allowable value of x. Values of x less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
x[LINK]
The maximum allowable value of x. Values of x greater than
the maximum will be replaced by the maximum.
Field: Minimum Value of
y[LINK]
The minimum allowable value of y. Values of y less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
y[LINK]
The maximum allowable value of y. Values of y greater than
the maximum will be replaced by the maximum.
Field: Minimum Curve
Output[LINK]
The minimum allowable value of the evaluated curve. Values
less than the minimum will be replaced by the minimum.
Field: Maximum Curve
Output[LINK]
The maximum allowable value of the evaluated curve. Values
greater than the maximum will be replaced by the maximum.
This field is used to indicate the kind of units that may
be associated with the x values. The only option at this time
is Dimensionless.
This field is used to indicate the kind of units that may
be associated with the x values. The only option at this time
is Dimensionless.
Field: Output Unit Type[LINK]
This field is used to indicate the kind of units that may
be associated with the output values. The only option at this
time is Dimensionless.
An example input for the CubicLinear equation form is shown
below.
Curve:CubicLinear,
InsideMeltIceDischarging, !- Name
0.108734675, !- Coefficient1 Constant
-0.989874286, !- Coefficient2 x
0.696303562, !- Coefficient3 x**2
-0.134945307, !- Coefficient4 x**3
1.724007415, !- Coefficient5 y
-1.094020457, !- Coefficient6 y*x
0.25, !- Minimum Value of x
1, !- Maximum Value of x
0.69, !- Minimum Value of y
1.26, !- Maximum Value of y
0.0926, !- Minimum Curve Output
0.4938, !- Maximum Curve Output
Dimensionless, !- Input Unit Type for X
Dimensionless, !- Input Unit Type for Y
Dimensionless, !- Output Unit Type
Curve:ChillerPartLoadWithLift[LINK]
A custom chiller part-load performance curve is a function
of three independent variables, i.e., x, y, and z. Input
consists of the curve name, the twelve coefficients, and min
and max values for each of the independent variables. Optional
inputs for curve minimum and maximum may be used to limit the
output of the performance curve.
The equation represented by the custom curve is:
\[C_1 + C_2 \cdot x + C_3 \cdot
x^2 + C_4 \cdot y + C_5 \cdot y^2 + C_6 \cdot x \cdot y + C_7
\cdot x^3 + C_8 \cdot y^3 + C_9 \cdot x^2 \cdot y + C_{10}
\cdot x \cdot y^2 + C_{11} \cdot x^2 \cdot y^2 + C_{12} \cdot
z \cdot y^3\]
where,
x represents the normalized fractional lift (the delta
of temperature across the leaving condenser water temperature
and leaving evaporator water temperature of a
chiller).
y represents the normalized deviation of leaving
chilled water temperature from the reference
condition.
z represents the part load ratio.
A user assigned unique name for an instance of a
biquadratic curve. When a curve is used, it is referenced by
this name.
Field: Coefficient1[LINK]
The constant coefficient (C1) in the equation.
Field: Coefficient2[LINK]
The coefficient C2 in the equation.
Field: Coefficient3[LINK]
The coefficient C3 in the equation.
Field: Coefficient4[LINK]
The coefficient C4 in the equation.
Field: Coefficient5[LINK]
The coefficient C5 in the equation.
Field: Coefficient6[LINK]
The coefficient C6 in the equation.
Field: Coefficient7[LINK]
The constant coefficient (C7) in the equation.
Field: Coefficient8[LINK]
The coefficient C8 in the equation.
Field: Coefficient9[LINK]
The coefficient C9 in the equation.
Field: Coefficient10[LINK]
The coefficient C10 in the equation.
Field: Coefficient11[LINK]
The coefficient C11 in the equation.
Field: Coefficient12[LINK]
The coefficient C12 in the equation.
Field: Minimum Value of
x[LINK]
The minimum allowable value of x. Values of x less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
x[LINK]
The maximum allowable value of x. Values of x greater than
the maximum will be replaced by the maximum.
Field: Minimum Value of
y[LINK]
The minimum allowable value of y. Values of y less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
y[LINK]
The maximum allowable value of y. Values of y greater than
the maximum will be replaced by the maximum.
Field: Minimum Value of
z[LINK]
The minimum allowable value of z. Values of y less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
z[LINK]
The maximum allowable value of z. Values of y greater than
the maximum will be replaced by the maximum.
Field: Minimum Curve
Output[LINK]
The minimum allowable value of the evaluated curve. Values
less than the minimum will be replaced by the minimum.
Field: Maximum Curve
Output[LINK]
The maximum allowable value of the evaluated curve. Values
greater than the maximum will be replaced by the maximum.
This field is used to indicate the kind of units that may
be associated with the x values. Select Dimensionless.
This field is used to indicate the kind of units that may
be associated with the y values. Select Dimensionless.
This field is used to indicate the kind of units that may
be associated with the y values. Select Dimensionless.
Field: Output Unit Type[LINK]
This field is used to indicate the kind of units that may
be associated with the output values. Select
Dimensionless.
Below is an example input:
Curve:ChillerPartLoadWithLift,
EIRFPLR, !- Name
0.093291598, !- Coefficient1 Constant
-0.234322952, !- Coefficient2 x
0.426950368, !- Coefficient3 x**2
0.188624721, !- Coefficient4 y
-0.608010978, !- Coefficient5 y**2
0.992031248, !- Coefficient6 x*y
0.000000E+00, !- Coefficient7 x**3
0.502338322, !- Coefficient8 y**3
0.000000E+00, !- Coefficient9 x**2*y
0.000000E+00, !- Coefficient 10 x*y**2
-0.360902326, !- Coefficient 11 x**2*y**2
-0.097978985, !- Coefficient 12 z*y**3
0.2562, !- Minimum Value of x
1.0365, !- Maximum Value of x
0.1, !- Minimum Value of y
1, !- Maximum Value of y
-0.035, !- Minimum Value of z
0.3144, !- Maximum Value of z
, !- Minimum Curve Output
, !- Maximum Curve Output
Dimensionless, !- Input Unit Type for x
Dimensionless, !- Input Unit Type for y
Dimensionless, !- Input Unit Type for z
Dimensionless; !- Output Unit Type
Curve:QuadraticLinear[LINK]
This curve is a function of two independent variables.
Input consists of the curve name, the six coefficients, and
min and max values for each of the independent variables.
Optional inputs for curve minimum and maximum may be used to
limit the output of the performance curve (e.g., limit
extrapolation). The equation represented by the quadratic
linear curve:
\[z = \left( {{C_1} + {C_2}*x +
{C_3}*{x^2}} \right) + \left( {{C_4} + {C_5}*x + {C_6}*{x^2}}
\right)*y\]
A user assigned unique name for an instance of a
quadratic-linear curve. When a curve is used, it is referenced
by this name.
Field: Coefficient1
Constant[LINK]
The constant coefficient (C\(_{1}\)) in the equation.
Field: Coefficient2 x[LINK]
The coefficient C\(_{2}\)
in the equation.
Field: Coefficient3 x**2[LINK]
The coefficient C\(_{3}\)
in the equation.
Field: Coefficient4 y[LINK]
The coefficient C\(_{4}\)
in the equation.
Field: Coefficient5 x*y[LINK]
The coefficient C\(_{5}\)
in the equation.
Field: Coefficient6
x**2*y[LINK]
The coefficient C\(_{6}\)
in the equation.
Field: Minimum Value of
x[LINK]
The minimum allowable value of x. Values of x less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
x[LINK]
The maximum allowable value of x. Values of x greater than
the maximum will be replaced by the maximum.
Field: Minimum Value of
y[LINK]
The minimum allowable value of y. Values of y less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
y[LINK]
The maximum allowable value of y. Values of y greater than
the maximum will be replaced by the maximum.
Field: Minimum Curve
Output[LINK]
The minimum allowable value of the evaluated curve. Values
less than the minimum will be replaced by the minimum.
Field: Maximum Curve
Output[LINK]
The maximum allowable value of the evaluated curve. Values
greater than the maximum will be replaced by the maximum.
This field is used to indicate the kind of units that may
be associated with the x values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of X and Maximum Value of x. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
This field is used to indicate the kind of units that may
be associated with the y values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of Y and Maximum Value of Y. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
Field: Output Unit Type[LINK]
This field is used to indicate the kind of units that may
be associated with the output values. It is used by IDF Editor
to display the appropriate SI and IP units for the Minimum
Curve Output and Maximum Curve Output. The unit conversion is
not applied to the coefficients. The available options are
shown below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Capacity
Power
Below is an example input.
Curve:QuadraticLinear,
DischargeCurve, !- Curve Name
0.0, !- Coefficient1 Constant
0.09, !- Coefficient2 x
-0.15, !- Coefficient3 x\*\*2
0.612, !- Coefficient4 y
-0.324, !- Coefficient5 x\*y
-0.216, !-Coefficient6 x\*\*2\*y
0.0, !- Minimum Value of x
1.0, !- Maximum Value of x
0.0, !- Minimum Value of y
9.9; !- Maximum Value of y
Curve:Triquadratic[LINK]
This curve is a 2\(^{nd}\)
order polynomial function of three variable polynomial
independent variables. Input consists of the curve name, the
twenty seven coefficients, and min and max values for each of
the independent variables. Optional inputs for curve minimum
and maximum may be used to limit the output of the performance
curve (e.g., limit extrapolation). The equation represented by
the triquadratic curve:
\[\begin{array}{l}
CurveValue = {A_0} + {A_1}*{x^2} + {A_2}*x + {A_3}*{y^2} +
{A_4}*y + {A_5}*{z^2} + {A_6}*z + {A_7}*{x^2}{y^2} + {A_8}*xy
+ \\
\quad \quad \quad \quad \quad {A_9}*x{y^2} +
{A_{10}}*{x^2}y + {A_{11}}*{x^2}{z^2} + {A_{12}}*xz +
{A_{13}}*x{z^2} + {A_{14}}*{x^2}z + {A_{15}}*{y^2}{z^2} + \\
\quad \quad \quad \quad \quad {A_{16}}*yz +
{A_{17}}*y{z^2} + {A_{18}}*{y^2}z + {A_{19}}*{x^2}{y^2}{z^2} +
{A_{20}}*{x^2}{y^2}z + {A_{21}}{x^2}y{z^2} +
{A_{22}}x{y^2}{z^2} + \\
\quad \quad \quad \quad \quad {A_{23}}{x^2}yz +
{A_{24}}x{y^2}z + {A_{25}}xy{z^2} + {A_{26}}xyz
\end{array}\]
Field: Coefficient1
Constant[LINK]
The constant coefficient (A\(_{0}\)) in the equation.
Field: Coefficient2 x**2[LINK]
The coefficient (A\(_{1}\)) in the equation.
Field: Coefficient3 x[LINK]
The coefficient (A\(_{2}\)) in the equation.
Field: Coefficient4 y**2[LINK]
The coefficient (A\(_{3}\)) in the equation.
Field: Coefficient5 y[LINK]
The coefficient (A\(_{4}\)) in the equation.
Field: Coefficient6 z**2[LINK]
The coefficient (A\(_{5}\)) in the equation.
Field: Coefficient7 z[LINK]
The coefficient (A\(_{6}\)) in the equation.
Field: Coefficient8
x**2*y**2[LINK]
The coefficient (A\(_{7}\)) in the equation.
Field: Coefficient9 x*y[LINK]
The coefficient (A\(_{8}\)) in the equation.
Field: Coefficient10
x*y**2[LINK]
The coefficient (A\(_{9}\)) in the equation.
Field: Coefficient11
x**2*y[LINK]
The coefficient (A\(_{10}\)) in the equation.
Field: Coefficient12
x**2*z**2[LINK]
The coefficient (A\(_{11}\)) in the equation.
Field: Coefficient13 x*z[LINK]
The coefficient (A\(_{12}\)) in the equation.
Field: Coefficient14
x*z**2[LINK]
The coefficient (A\(_{13}\)) in the equation.
Field: Coefficient15
x**2*z[LINK]
The coefficient (A\(_{14}\)) in the equation.
Field: Coefficient16
y**2*z**2[LINK]
The coefficient (A\(_{15}\)) in the equation.
Field: Coefficient17 y*z[LINK]
The coefficient (A\(_{16}\)) in the equation.
Field: Coefficient18
y*z**2[LINK]
The coefficient (A\(_{17}\)) in the equation.
Field: Coefficient19
y**2*z[LINK]
The coefficient (A\(_{18}\)) in the equation.
Field: Coefficient20
x**2*y**2*z**2[LINK]
The coefficient (A\(_{19}\)) in the equation.
Field: Coefficient21
x**2*y**2*z[LINK]
The coefficient (A\(_{20}\)) in the equation.
Field: Coefficient22
x**2*y*z**2[LINK]
The coefficient (A\(_{21}\)) in the equation.
Field: Coefficient23
x*y**2*z**2[LINK]
The coefficient (A\(_{22}\)) in the equation.
Field: Coefficient24
x**2*y*z[LINK]
The coefficient (A\(_{23}\)) in the equation.
Field: Coefficient25
x*y**2*z[LINK]
The coefficient (A\(_{24}\)) in the equation.
Field: Coefficient26
x*y*z**2[LINK]
The coefficient (A\(_{25}\)) in the equation.
Field: Coefficient27
x*y*z[LINK]
The coefficient (A\(_{26}\)) in the equation.
Field: Minimum Value of
x[LINK]
The minimum allowable value of x. Values of x less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
x[LINK]
The maximum allowable value of x. Values of x greater than
the maximum will be replaced by the maximum.
Field: Minimum Value of
y[LINK]
The minimum allowable value of y. Values of y less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
y[LINK]
The maximum allowable value of y. Values of y greater than
the maximum will be replaced by the maximum.
Field: Minimum Value of
z[LINK]
The minimum allowable value of z. Values of z less than the
minimum will be replaced by the minimum.
Field: Maximum Value of
z[LINK]
The maximum allowable value of z. Values of z greater than
the maximum will be replaced by the maximum.
Field: Minimum Curve
Output[LINK]
The minimum allowable value of the evaluated curve. Values
less than the minimum will be replaced by the minimum.
Field: Maximum Curve
Output[LINK]
The maximum allowable value of the evaluated curve. Values
greater than the maximum will be replaced by the maximum.
This field is used to indicate the kind of units that may
be associated with the x values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of X and Maximum Value of x. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
This field is used to indicate the kind of units that may
be associated with the y values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of Y and Maximum Value of Y. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
This field is used to indicate the kind of units that may
be associated with the z values. It is used by IDF Editor to
display the appropriate SI and IP units for the Minimum Value
of Z and Maximum Value of Z. The unit conversion is not
applied to the coefficients. The available options are shown
below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
Field: Output Unit
Type[LINK]
This field is used to indicate the kind of units that may
be associated with the output values. It is used by IDF Editor
to display the appropriate SI and IP units for the Minimum
Curve Output and Maximum Curve Output. The unit conversion is
not applied to the coefficients. The available options are
shown below. If none of these options are appropriate, select
Dimensionless which will have no unit
conversion.
Dimensionless
Capacity
Power
Curve:Functional:PressureDrop[LINK]
Input for a pressure drop curve consists of the curve name,
a varying number of parameters, and the maximum and minimum
valid independent variable values. The equation represented by
the pressure drop curve is:
\[\Delta P = \left( {K +
f\frac{L}{D}} \right)\frac{{\rho {V^2}}}{2}\]
A user assigned unique name for an instance of a pressure
drop curve. When a curve is used, it is referenced by this
name.
Field: Diameter[LINK]
This diameter represents an equivalent diameter for the
given branch. This is parameter (D) in the equation, and has
units of {m}. Since varying components may be found on the
same branch, this value must be selected along with the other
inputs in order to provide a proper value of pressure drop.
This is used to calculate the velocity in addition to being
used directly in the frictional pressure drop calculation.
Field: Minor Loss
Coefficient[LINK]
This is the pressure drop coefficient typically applied to
components such as fittings and occasionally heat pumps. This
is parameter (K) in the equation and is dimensionless. This
coefficient is used to describe the amount of dynamic pressure
lost during the process. This value may be left blank if the
user only wants to account for frictional losses in this
branch.
Field: Length[LINK]
This is the length of a pressure drop process in which
friction is applied. This is parameter (L) in the equation and
has units of {m}. In a pipe, this would be the length of the
pipe, however in many cases, pressure drop in other components
are applied as an equivalent length. This is only required if
the user is wanting to perform frictional pressure drop
calculations.
Field: Roughness[LINK]
This field represents the first method to simulate
frictional losses. This parameter does not appear directly in
the equation above, as it is only used to develop the friction
factor (f), but the roughness will have units of {m} if
entered. If the user enters this roughness value, the pressure
system will use it along with an approximation to the Moody
chart to estimate the friction factor given the current flow
conditions. This allows the friction calculate to be dynamic
throughout the simulation.
Field: Fixed Friction
Factor[LINK]
This field represents the second method to simulate
frictional losses. This is parameter (f) in the equation and
is dimensionless. This parameter is a fixed value of friction
factor which would override any calculations performed based
on roughness, etc. If the user has a known friction factor for
a given component, this is where it should be entered.
In the curve outputs for this object:
Following is an input example.
Curve:Functional:PressureDrop,
PressureMinorAndFriction,!- Name
0.05, !- Diameter
53.8, !- Minor Loss Coefficient
200, !- Length
, !- Roughness
0.008; !- Fixed Friction Factor
Curve:FanPressureRise[LINK]
Input for the fan total pressure rise curve consists of the
curve name, the four coefficients, and the maximum and minimum
valid independent variable values. Optional inputs for the
curve minimum and maximum may be used to limit the output of
the performance curve (e.g., limit extrapolation). The
equation is:
\[\Delta {P_{fan,tot}} =
{C_1}*Q_{fan}^2 + {C_2}*Q_{fan}^{} + {C_3}*Q_{fan}^{}*\sqrt
{{P_{sm}} - {P_o}} + {C_4}*\left( {{P_{sm}} - {P_o}}
\right)\]
where \(\Delta
P_{fan,tot}\) is the fan total pressure rise (Pa) as a
function of volumetric flow through the fan (\(Q_{fan}, m^3/s\) ), duct static
pressure set point (\(P_{sm}\) , Pa), and static
pressure surrounding the ducts (\(P_o\) , Pa). \(P_o\) is assumed to be zero.
The first term of the curve looks like the common system
curve in which the fan pressure rise is proportional to the
square of the fan flow, but here it also depends implicitly on
supply and return pressure losses, and in part on the fraction
of the fan flow that is outdoor air (essentially “leaks” into
and out of the return side of the system). Very often it is
the only term considered, but that would only be correct with
fixed-position dampers, no distribution system leakage, no
linear resistance components, and no duct static pressure
control.
The second term accounts for significant flow resistances
in the system where the pressure difference is linearly
proportional to the flow. Some filters and coils in the return
may need this term to be adequately described. This term could
be ignored if there are no linear components or if their
pressure drops are very small compared to the other terms.
The third term, which depends on the fan flow and square
root of the supply duct pressure P\(_{sm}\), accounts in part
for leakage from the supply system when damper positions are
fixed or are changed independently of static pressure or fan
flow. In this case, reducing or eliminating supply leakage
results in a different system curve. This, however, might be
only a minor correction to the simple system curves generally
used. The third term is zero when the VAV box dampers are
modulated to control flow. Consequently, with
variable-position supply dampers, reducing or eliminating
supply leakage does not change the system curve.
The last term also accounts in part for leakage from the
supply system when damper positions are fixed or are changed
independently of static pressure or fan flow. This term
indicates that the same fan pressure rise can be achieved by
raising the duct pressure and closing dampers. The only change
in the system in such a case is that the leakage flow may
increase. The coefficient for this term is one when the VAV
box dampers are modulated to control flow. In both cases, this
term may be the most important correction to the simple system
curves generally used, especially at low flows.
The required user-assigned unique alpha name for an
instance of this curve. When a curve of this type is used, it
is referenced by this name.
Field: Fan
Pressure Rise Coefficient1 C1[LINK]
The required numeric constant coefficient C\(_{1}\) (Pa s\(^{2}\)/m\(^{6}\)) in the curve. Must be
greater than zero.
Field: Fan
Pressure Rise Coefficient2 C2[LINK]
The required numeric constant coefficient C\(_{2}\) (Pa s/m\(^{3}\)) in the
curve.
Field: Fan
Pressure Rise Coefficient3 C3[LINK]
The required numeric constant coefficient C\(_{3}\) (Pa\(^{0.5}\) s/m\(^{3}\)) in the
curve.
Field: Fan
Pressure Rise Coefficient4 C4[LINK]
The required numeric constant coefficient C\(_{4}\) (dimensionless) in
the curve.
Field: Minimum Value of
Qfan[LINK]
The required numeric minimum allowable value of Q\(_{fan}\) (m\(^{3}\)/s). Values of Q\(_{fan}\) less than the
minimum will be replaced within this curve by the minimum.
Field: Maximum Value of
Qfan[LINK]
The required numeric maximum allowable value of Q\(_{fan}\) (m\(^{3}\)/s). Values of Q\(_{fan}\) greater than the
maximum will be replaced within this curve by the maximum.
Field: Minimum Value of
Psm[LINK]
The required numeric minimum allowable value of P\(_{sm}\) (Pa). Values of
P\(_{sm}\) less than
the minimum will be replaced within this curve by the
minimum.
Field: Maximum Value of
Psm[LINK]
The required numeric maximum allowable value of P\(_{sm}\) (Pa). Values of
P\(_{sm}\) greater
than the maximum will be replaced within this curve by the
maximum.
Field: Minimum Curve
Output[LINK]
The optional numeric minimum allowable value of the
evaluated curve (Pa). Values less than the minimum will be
replaced within this curve by the minimum.
Field: Maximum Curve
Output[LINK]
The optional numeric maximum allowable value of the
evaluated curve (Pa). Values greater than the maximum will be
replaced within this curve by the maximum.
The following is an input example describing the fan total
pressure rise for a VAV system with a constant non-zero duct
static pressure set point (the set point is described
separately; see the Curve:Linear
object for a related example):
Curve:FanPressureRise,
VSD Example, ! Curve Name f = C1*Qfan**2+C2*Qfan+C3*Qfan*(Psm-Po)**0.5+C4*(Psm-Po) with Po = 0
1446.75833497653, ! CoefficientC1 Alpha [Pa s2/m6]
0., ! CoefficientC2 Beta [Pa s/m3]
0., ! CoefficientC3 Gamma [Pa0.5 s/m3]
1., ! CoefficientC4 Delta [-]
0., ! Minimum Value of Qfan [m3/s]
100., ! Maximum Value of Qfan [m3/s]
62.5, ! Minimum Value of Psm [Pa]
300., ! Maximum Value of Psm [Pa]
0.; ! Minimum Curve Output [Pa]
5000.; ! Maximum Curve Output [Pa]
Curve:ExponentialSkewNormal[LINK]
Input for the exponential-modified skew normal curve
consists of the curve name, the four coefficients, and the
maximum and minimum valid independent variable values.
Optional inputs for the curve minimum and maximum may be used
to limit the output of the performance curve (e.g., limit
extrapolation). The equation is:
\[y = \frac{{{e^{( - 0.5 \cdot
{Z_1}^2)}}[1 + \frac{{{Z_2}}}{{\left| {{Z_2}} \right|}} \cdot
erf\left( {\frac{{\left| {{Z_2}} \right|}}{{\sqrt 2 }}}
\right)}}{{{e^{( - 0.5 \cdot {Z_3}^2)}}[1 +
\frac{{{Z_3}}}{{\left| {{Z_3}} \right|}} \cdot erf\left(
{\frac{{\left| {{Z_3}} \right|}}{{\sqrt 2 }}}
\right)}}\]
where:
\[\begin{aligned}
Z_1 &= \frac{x - C_1}{C_2} \\
Z_2 &= \frac{e^{C_3 \cdot x} \cdot C_4 \cdot x -
C_1}{C_2} \\
Z_3 &= -\frac{C_1}{C_2}\end{aligned}\]
The required user-assigned unique alpha name for an
instance of this curve. When a curve of this type is used, it
is referenced by this name.
Field: Coefficient1 C1[LINK]
The required numeric constant coefficient C\(_{1}\) in the curve.
Field: Coefficient2 C2[LINK]
The required numeric constant coefficient C\(_{2}\) in the curve. Must be
non-zero.
Field: Coefficient3 C3[LINK]
The required numeric constant coefficient C\(_{3}\) in the curve.
Field: Coefficient4 C4[LINK]
The required numeric constant coefficient C\(_{4}\) in the curve.
Field: Minimum Value of
x[LINK]
The required numeric minimum allowable value of x.
Values of x less than the minimum will be replaced by
the minimum.
Field: Maximum Value of
x[LINK]
The required numeric maximum allowable value of x.
Values of x greater than the maximum will be replaced
by the maximum.
Field: Minimum Curve
Output[LINK]
The optional numeric minimum allowable value of the
evaluated curve. Values less than the minimum will be replaced
by the minimum.
Field: Maximum Curve
Output[LINK]
The optional numeric maximum allowable value of the
evaluated curve. Values greater than the maximum will be
replaced by the maximum.
This optional field is provided for future purposes so that
the IDF Editor could display the appropriate SI or IP units
for the Minimum Value of x and Maximum Value of
x (currently dimensionless). At this time, only the
Dimensionless option is provided so that no
unit conversion is used for this curve.
Field: Output Unit
Type[LINK]
This optional field is provided for future purposes so that
the IDF Editor could display the appropriate SI or IP units
for the Minimum Curve Output and Maximum Curve Output
(currently dimensionless). At this time, only the
Dimensionless option is provided so that no
unit conversion is used for this curve.
The following are input examples describing the normalized
fan efficiency for the normal (non-stall) and stall operating
regions of a backward-curved airfoil centrifugal fan:
Curve:ExponentialSkewNormal,
FanEff120CPLANormal, ! Curve Name
0.072613, ! CoefficientC1 Afan
0.833213, ! CoefficientC2 Bfan
0., ! CoefficientC3 Cfan
0.013911, ! CoefficientC4 Dfan
-4., ! Minimum Value of x
5., ! Maximum Value of x
0.1, ! Minimum Curve Output
1.; ! Maximum Curve Output
Curve:ExponentialSkewNormal,
FanEff120CPLAStall, ! Curve Name
-1.674931, ! CoefficientC1 Afan
1.980182, ! CoefficientC2 Bfan
0., ! CoefficientC3 Cfan
1.844950, ! CoefficientC4 Dfan
-4., ! Minimum Value of x
5., ! Maximum Value of x
0.1, ! Minimum Curve Output
1.; ! Maximum Curve Output
Curve:Sigmoid[LINK]
Input for the sigmoid curve consists of the curve name, the
five coefficients, and the maximum and minimum valid
independent variable values. Optional inputs for the curve
minimum and maximum may be used to limit the output of the
performance curve (e.g., limit extrapolation). The equation
is:
\[y = {C_1} +
\frac{{{C_2}}}{{\left( {{{(1 + {e^{\left[ {\frac{{({C_3} -
x)}}{{{C_4}}}} \right]}})}^{{C_5}}}} \right)}}\]
The required user-assigned unique alpha name for an
instance of this curve. When a curve of this type is used, it
is referenced by this name.
Field: Coefficient1 C1[LINK]
The required numeric constant coefficient C\(_{1}\) in the equation.
Field: Coefficient2 C2[LINK]
The required numeric constant coefficient C\(_{2}\) in the equation.
Field: Coefficient3 C3[LINK]
The required numeric constant coefficient C\(_{3}\) in the equation.
Field: Coefficient4 C4[LINK]
The required numeric constant coefficient C\(_{4}\) in the equation.
Field: Coefficient5 C5[LINK]
The required numeric constant coefficient C\(_{5}\) in the equation.
Field: Minimum Value of
x[LINK]
The required numeric minimum allowable value of x.
Values of x less than the minimum will be replaced by
the minimum.
Field: Maximum Value of
x[LINK]
The required numeric maximum allowable value of x.
Values of x greater than the maximum will be replaced
by the maximum.
Field: Minimum Curve
Output[LINK]
The optional numeric minimum allowable value of the
evaluated curve. Values less than the minimum will be replaced
by the minimum.
Field: Maximum Curve
Output[LINK]
The optional numeric maximum allowable value of the
evaluated curve. Values greater than the maximum will be
replaced by the maximum.
This optional field is provided for future purposes so that
the IDF Editor could display the appropriate SI or IP units
for the Minimum Value of x and Maximum Value of
x (currently dimensionless). At this time, only the
Dimensionless option is provided so that no
unit conversion is used for this curve.
Field: Output Unit
Type[LINK]
This optional field is provided for future purposes so that
the IDF Editor could display the appropriate SI or IP units
for the Minimum Curve Output and Maximum Curve Output
(currently dimensionless). At this time, only the
Dimensionless option is provided so that no
unit conversion is used for this curve.
The following are input examples describing the normalized
dimensionless flow for normal (non-stall) and stall operating
regions of a backward-curved airfoil centrifugal fan:
Curve:Sigmoid,
FanDimFlowNormal, ! Curve Name
0., ! CoefficientC1 Aspd
1.001423, ! CoefficientC2 Bspd
0.123935, ! CoefficientC3 Cspd
-0.476026, ! CoefficientC4 Dspd
1., ! CoefficientC5 Espd
-4., ! Minimum Value of x
5., ! Maximum Value of x
0.05, ! Minimum Curve Output
1.; ! Maximum Curve Output
Curve:Sigmoid,
FanDimFlowStall, ! Curve Name
0., ! CoefficientC1 Aspd
5.924993, ! CoefficientC2 Bspd
-1.91636, ! CoefficientC3 Cspd
-0.851779, ! CoefficientC4 Dspd
1., ! CoefficientC5 Espd
-4., ! Minimum Value of x
5., ! Maximum Value of x
0.05, ! Minimum Curve Output
1.; ! Maximum Curve Output
Curve:RectangularHyperbola1[LINK]
Input for the single rectangular hyperbola type 1 curve
consists of the curve name, the three coefficients, and the
maximum and minimum valid independent variable values.
Optional inputs for the curve minimum and maximum may be used
to limit the output of the performance curve (e.g., limit
extrapolation). The equation is:
y =(C\(_{1}\)
* x) / (C\(_{2}\)+x) + C\(_{3}\)
The required user-assigned unique alpha name for an
instance of this curve. When a curve of this type is used, it
is referenced by this name.
Field: Coefficient1 C1[LINK]
The required numeric constant coefficient C\(_{1}\) in the equation.
Field: Coefficient2 C2[LINK]
The required numeric constant coefficient C\(_{2}\) in the equation.
Field: Coefficient3 C3[LINK]
The required numeric constant coefficient C\(_{3}\) in the equation.
Field: Minimum Value of
x[LINK]
The required numeric minimum allowable value of x.
Values of x less than the minimum will be replaced by
the minimum.
Field: Maximum Value of
x[LINK]
The required numeric maximum allowable value of x.
Values of x greater than the maximum will be replaced
by the maximum.
Field: Minimum Curve
Output[LINK]
The optional numeric minimum allowable value of the
evaluated curve. Values less than the minimum will be replaced
by the minimum.
Field: Maximum Curve
Output[LINK]
The optional numeric maximum allowable value of the
evaluated curve. Values greater than the maximum will be
replaced by the maximum.
This optional field is provided for future purposes so that
the IDF Editor could display the appropriate SI or IP units
for the Minimum Value of x and Maximum Value of
x (currently dimensionless). At this time, only the
Dimensionless option is provided so that no
unit conversion is used for this curve.
Field: Output Unit
Type[LINK]
This optional field is provided for future purposes so that
the IDF Editor could display the appropriate SI or IP units
for the Minimum Curve Output and Maximum Curve Output
(currently dimensionless). At this time, only the
Dimensionless option is provided so that no
unit conversion is used for this curve.
The following is an input example describing the maximum
efficiency variation for a mid- or average-efficiency type of
motor:
Curve:RectangularHyperbola1,
MotorMaxEffAvg, ! Curve Name
0.29228, ! CoefficientC1
3.368739, ! CoefficientC2
0.762471, ! CoefficientC3
0., ! Minimum Value of x
7.6, ! Maximum Value of x
0.01, ! Minimum Curve Output
1.; ! Maximum Curve Output
Curve:RectangularHyperbola2[LINK]
Input for the single rectangular hyperbola type 2 curve
consists of the curve name, the three coefficients, and the
maximum and minimum valid independent variable values.
Optional inputs for the curve minimum and maximum may be used
to limit the output of the performance curve (e.g., limit
extrapolation). The equation is:
y =(C\(_{1}\)
* x) / (C\(_{2}\)+x) + C\(_{3}\) * x
The required user-assigned unique alpha name for an
instance of this curve. When a curve of this type is used, it
is referenced by this name.
Field: Coefficient1 C1[LINK]
The required numeric constant coefficient C\(_{1}\) in the equation.
Field: Coefficient2 C2[LINK]
The required numeric constant coefficient C\(_{2}\) in the equation.
Field: Coefficient3 C3[LINK]
The required numeric constant coefficient C\(_{3}\) in the equation.
Field: Minimum Value of
x[LINK]
The required numeric minimum allowable value of x.
Values of x less than the minimum will be replaced by
the minimum.
Field: Maximum Value of
x[LINK]
The required numeric maximum allowable value of x.
Values of x greater than the maximum will be replaced
by the maximum.
Field: Minimum Curve
Output[LINK]
The optional numeric minimum allowable value of the
evaluated curve. Values less than the minimum will be replaced
by the minimum.
Field: Maximum Curve
Output[LINK]
The optional numeric maximum allowable value of the
evaluated curve. Values greater than the maximum will be
replaced by the maximum.
This optional field is provided for future purposes so that
the IDF Editor could display the appropriate SI or IP units
for the Minimum Value of x and Maximum Value of
x (currently dimensionless). At this time, only the
Dimensionless option is provided so that no
unit conversion is used for this curve.
Field: Output Unit
Type[LINK]
This optional field is provided for future purposes so that
the IDF Editor could display the appropriate SI or IP units
for the Minimum Curve Output and Maximum Curve Output
(currently dimensionless). At this time, only the
Dimensionless option is provided so that no
unit conversion is used for this curve.
The following are input examples describing part-load
efficiency variations for a medium efficiency type of V-belt
(Regions 1 and 3), for a mid- or average-efficiency nominal 25
hp 4-pole motor, and a nominal 30 hp VFD:
Curve:RectangularHyperbola2,
BeltPartLoadRegion1, ! Curve Name
0.920797, ! CoefficientC1
0.0262686, ! CoefficientC2
0.151594, ! CoefficientC3
0., ! Minimum Value of x
1., ! Maximum Value of x
0.01, ! Minimum Curve Output
1.; ! Maximum Curve Output
Curve:RectangularHyperbola2,
BeltPartLoadRegion3, ! Curve Name
1.037778, ! CoefficientC1
0.0103068, ! CoefficientC2
-0.0268146, ! CoefficientC3
0., ! Minimum Value of x
1., ! Maximum Value of x
0.01, ! Minimum Curve Output
1.; ! Maximum Curve Output
Curve:RectangularHyperbola2,
MotorPartLoad, ! Curve Name
1.137209, ! CoefficientC1
0.0502359, ! CoefficientC2
-0.0891503, ! CoefficientC3
0., ! Minimum Value of x
1., ! Maximum Value of x
0.01, ! Minimum Curve Output
1.; ! Maximum Curve Output
Curve:RectangularHyperbola2,
VFDPartLoad, ! Curve Name
0.987405, ! CoefficientC1
0.0155361, ! CoefficientC2
-0.0059365, ! CoefficientC3
0., ! Minimum Value of x
1., ! Maximum Value of x
0.01, ! Minimum Curve Output
1.; ! Maximum Curve Output
Curve:ExponentialDecay[LINK]
Input for the exponential decay curve consists of the curve
name, the three coefficients, and the maximum and minimum
valid independent variable values. Optional inputs for the
curve minimum and maximum may be used to limit the output of
the performance curve (e.g., limit extrapolation). The
equation is:
\[y = C_1 + C_2 \cdot e^{C_3
x}\]
The required user-assigned unique alpha name for an
instance of this curve. When a curve of this type is used, it
is referenced by this name.
Field: Coefficient1 C1[LINK]
The required numeric constant coefficient C\(_{1}\) in the equation.
Field: Coefficient2 C2[LINK]
The required numeric constant coefficient C\(_{2}\) in the equation.
Field: Coefficient3 C3[LINK]
The required numeric constant coefficient C\(_{3}\) in the equation.
Field: Minimum Value of
x[LINK]
The required numeric minimum allowable value of x.
Values of x less than the minimum will be replaced by
the minimum.
Field: Maximum Value of
x[LINK]
The required numeric maximum allowable value of x.
Values of x greater than the maximum will be replaced
by the maximum.
Field: Minimum Curve
Output[LINK]
The optional numeric minimum allowable value of the
evaluated curve. Values less than the minimum will be replaced
by the minimum.
Field: Maximum Curve
Output[LINK]
The optional numeric maximum allowable value of the
evaluated curve. Values greater than the maximum will be
replaced by the maximum.
This optional field is provided for future purposes so that
the IDF Editor could display the appropriate SI or IP units
for the Minimum Value of x and Maximum Value of
x (currently dimensionless). At this time, only the
Dimensionless option is provided so that no
unit conversion is used for this curve.
Field: Output Unit
Type[LINK]
This optional field is provided for future purposes so that
the IDF Editor could display the appropriate SI or IP units
for the Minimum Curve Output and Maximum Curve Output
(currently dimensionless). At this time, only the
Dimensionless option is provided so that no
unit conversion is used for this curve.
The following is an input example describing the part-load
efficiency variation for a medium efficiency type of V-belt
(Region 2):
Curve:ExponentialDecay,
BeltPartLoadRegion2, ! Curve Name
1.011965, ! CoefficientC1
-0.339038, ! CoefficientC2
-3.43626, ! CoefficientC3
0., ! Minimum Value of x
1., ! Maximum Value of x
0.01, ! Minimum Curve Output
1.; ! Maximum Curve Output
Curve:DoubleExponentialDecay[LINK]
Input for the double exponential decay curve consists of
the curve name, the five coefficients, and the maximum and
minimum valid independent variable values. Optional inputs for
the curve include the minimum and maximum output of the
performance curve. The equation is:
\[y = {C_1} + {C_2}{\exp
^{({C_3}x)}} + {C_4}{\exp ^{({C_5}x)}}\]
This field indicates the required user-assigned name for an
instance of this curve. When a curve of this type is used, it
is referenced by this name.
Field: Coefficient1 C1[LINK]
The required numeric constant coefficient C\(_{1}\) in the equation.
Field: Coefficient2 C2[LINK]
The required numeric constant coefficient C\(_{2}\) in the equation.
Field: Coefficient3 C3[LINK]
The required numeric constant coefficient C\(_{3}\) in the equation.
Field: Coefficient4 C4[LINK]
The required numeric constant coefficient C\(_{4}\) in the equation.
Field: Coefficient5 C5[LINK]
The required numeric constant coefficient C\(_{5}\) in the equation.
Field: Minimum Value of
x[LINK]
The required numeric minimum allowable value of x. Values
of x less than the minimum will be replaced by the minimum
Field: Maximum Value of
x[LINK]
The required numeric maximum allowable value of x. Values
of x greater than the maximum will be replaced by the
maximum
Field: Minimum Curve
Output[LINK]
The optional numeric minimum allowable value of the
evaluated curve. Values less than the minimum will be replaced
by the minimum
Field: Maximum Curve
Output[LINK]
The optional numeric maximum allowable value of the
evaluated curve. Values greater than the maximum will be
replaced by the maximum
The optional field is provided for future purposes so that
the IDF Editor could display the appropriate SI or IP units
for the Minimum and Maximum Value of x. Currently, only
Dimensionless option is provided so that no unit conversion is
used for this curve
Field: Output Unit
Type[LINK]
The optional field is provided for future purposes so that
the IDF Editor could display the appropriate SI or IP units
for the Minimum and Maximum Curve output. Currently, only
Dimensionless option is provided so that no unit conversion is
used for this curve.
An example input of the Curve:DoubleExponentialDecay
input is:
Curve:DoubleExponentialDecay,
BatteryCycleCurve, !- Name
1380, !- Coefficient1 C1
6834, !- Coefficient2 C2
-8.75, !- Coefficient3 C3
6747, !- Coefficient4 C4
-6.22, !- Coefficient5 C5
0, !- Minimum Value of x
1.0; !- Maximum Value of x
The current value of the performance curve. This value is
averaged over the time step being reported. Inactive or unused
performance curves will show a value of -999 (e.g., equipment
is off, a specific performance curve is not required for this
aspect of the equipment model at this time step, etc.). This
value means that the performance curve was not called during
the simulation and, therefore, not evaluated. This inactive
state value is only set at the beginning of each environment.
When averaging over long periods of time, this inactive state
value may skew results. In this case, use a detailed reporting
frequency (ref. Output:Variable
object) to view results at each HVAC time step.
The current value of the nth independent variable passed to
the performance curve. The order of the independent variables
is in the same order as the model equation represented by this
performance curve object. This value is averaged over the time
step being reported.
HVAC,Average,Performance Curve Output Value []
HVAC,Average,Performance Curve Input Variable 1 Value
[]
HVAC,Average,Performance Curve Input Variable 2 Value
[]
HVAC,Average,Performance Curve Input Variable 3 Value
[]
Group - Performance Curves[LINK]
This group of objects primarily consists of polynomial curves that are used to characterize the performance of HVAC equipment. Several other non-polynomial curves are also included to characterize the performance of pumps and fans. All of the curves are input, stored, and evaluated entirely within the Curve module. The curves are usually derived from fits or regressions to data covering a limited range. Results for independent variable values outside this range are likely to be invalid, so curve input always contains a range of validity (maximum and minimum permitted values) for each independent variable and can optionally have limits on the curve output. No error or warning message is issued if an independent variable is outside the range. Instead, the curve manager uses the minimum value if an independent variable is less than the minimum, and the maximum if a variable exceeds the maximum. Similarly, no error or warning message is issued if the curve output is outside the range of the optional minimum and maximum curve output limits. Instead, the curve manager uses the minimum and maximum curve limits to cap the output of the performance curve.
Curve names must be unique across all curve types.
Curve:Linear[LINK]
Input for the linear curve consists of a curve name, the two coefficients, and the maximum and minimum valid independent variable values. Optional inputs for curve minimum and maximum may be used to limit the output of the performance curve (e.g., limit extrapolation). The equation represented by the linear curve is:
\[y = {C_1} + {C_2}*x\]
Inputs[LINK]
Field: Name[LINK]
A user assigned unique name for an instance of a linear curve. When a curve is used, it is referenced by this name.
Field: Coefficient1 Constant[LINK]
The constant coefficient (C\(_{1}\)) in the equation.
Field: Coefficient2 x[LINK]
The linear coefficient (C\(_{2}\)) in the equation.
Field: Minimum Value of x[LINK]
The minimum allowable value of x. Values of x less than the minimum will be replaced by the minimum.
Field: Maximum Value of x[LINK]
The maximum allowable value of x. Values of x greater than the maximum will be replaced by the maximum.
Field: Minimum Curve Output[LINK]
The minimum allowable value of the evaluated curve. Values less than the minimum will be replaced by the minimum.
Field: Maximum Curve Output[LINK]
The maximum allowable value of the evaluated curve. Values greater than the maximum will be replaced by the maximum.
Field: Input Unit Type for X[LINK]
This field is used to indicate the kind of units that may be associated with the x values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of X and Maximum Value of x. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Distance
Power
Field: Output Unit Type[LINK]
This field is used to indicate the kind of units that may be associated with the output values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Curve Output and Maximum Curve Output. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Capacity
Power
Following is an example input:
The following is another example, as might be applied in the Fan:ComponentModel to characterize duct static pressure reset (using a constant duct static pressure set point of 248.84 Pa in this case):
Curve:QuadLinear[LINK]
Input consists of the curve name, the five coefficients, and maximum and minimum values for each of the independent variables. Optional inputs for curve minimum and maximum may be used to limit the output of the performance curve (e.g., limit extrapolation). The equation is represented by this curve:
Inputs[LINK]
y = C1 + C2 * w + C3 * x + C4 * y + C5 * z[LINK]
Field: Name[LINK]
A user assigned unique name for an instance of this curve. When a curve of this type is used, it is referenced by this name.
Field: Coefficient1 Constant[LINK]
The constant coefficient (C1) in the equation.
Field: Coefficient2 w[LINK]
The coefficient (C2) in the equation.
Field: Coefficient3 x[LINK]
The coefficient (C3) in the equation.
Field: Coefficient4 y[LINK]
The coefficient (C4) in the equation.
Field: Coefficient5 z[LINK]
The coefficient (C5) in the equation.
Field: Minimum Value of w[LINK]
The minimum allowable value of w. Values of w less than the minimum will be replaced by the minimum.
Field: Maximum Value of w[LINK]
The maximum allowable value of w. Values of w greater than the maximum will be replaced by the maximum.
Field: Minimum Value of x[LINK]
The minimum allowable value of x. Values of x less than the minimum will be replaced by the minimum.
Field: Maximum Value of x[LINK]
The maximum allowable value of x. Values of x greater than the maximum will be replaced by the maximum.
Field: Minimum Value of y[LINK]
The minimum allowable value of y. Values of y less than the minimum will be replaced by the minimum.
Field: Maximum Value of y[LINK]
The maximum allowable value of y. Values of y greater than the maximum will be replaced by the maximum.
Field: Minimum Value of z[LINK]
The minimum allowable value of z. Values of z less than the minimum will be replaced by the minimum.
Field: Maximum Value of z[LINK]
The maximum allowable value of z. Values of z greater than the maximum will be replaced by the maximum.
Field: Input Unit Type for w[LINK]
This field is used to indicate the kind of units that may be associated with the w values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of w and Maximum Value of w. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
VolumetricFlowPerPower
Field: Input Unit Type for x[LINK]
This field is used to indicate the kind of units that may be associated with the x values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of x and Maximum Value of x. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
VolumetricFlowPerPower
Field: Input Unit Type for y[LINK]
This field is used to indicate the kind of units that may be associated with the y values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of y and Maximum Value of y. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
VolumetricFlowPerPower
Field: Input Unit Type for z[LINK]
This field is used to indicate the kind of units that may be associated with the z values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of z and Maximum Value of z. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
VolumetricFlowPerPower
Below are an example inputs for QuadLinear Curves.
Curve:QuintLinear[LINK]
Input consists of the curve name, the six coefficients, and maximum and minimum values for each of the independent variables. Optional inputs for curve minimum and maximum may be used to limit the output of the performance curve (e.g., limit extrapolation). The equation is represented by this curve:
Inputs[LINK]
y = C1 + C2 * v + C3 * w + C4 * x + C5 * y + C6 * z[LINK]
Field: Name[LINK]
A user assigned unique name for an instance of this curve. When a curve of this type is used, it is referenced by this name.
Field: Coefficient1 Constant[LINK]
The constant coefficient (C1) in the equation.
Field: Coefficient2 v[LINK]
The coefficient (C2) in the equation.
Field: Coefficient3 w[LINK]
The coefficient (C3) in the equation.
Field: Coefficient4 x[LINK]
The coefficient (C4) in the equation.
Field: Coefficient5 y[LINK]
The coefficient (C5) in the equation.
Field: Coefficient6 z[LINK]
The coefficient (C6) in the equation.
Field: Minimum Value of v[LINK]
The minimum allowable value of v. Values of v less than the minimum will be replaced by the minimum.
Field: Maximum Value of v[LINK]
The maximum allowable value of v. Values of v greater than the maximum will be replaced by the maximum.
Field: Minimum Value of w[LINK]
The minimum allowable value of w. Values of w less than the minimum will be replaced by the minimum.
Field: Maximum Value of w[LINK]
The maximum allowable value of w. Values of w greater than the maximum will be replaced by the maximum.
Field: Minimum Value of x[LINK]
The minimum allowable value of x. Values of x less than the minimum will be replaced by the minimum.
Field: Maximum Value of x[LINK]
The maximum allowable value of x. Values of x greater than the maximum will be replaced by the maximum.
Field: Minimum Value of y[LINK]
The minimum allowable value of y. Values of y less than the minimum will be replaced by the minimum.
Field: Maximum Value of y[LINK]
The maximum allowable value of y. Values of y greater than the maximum will be replaced by the maximum.
Field: Minimum Value of z[LINK]
The minimum allowable value of z. Values of z less than the minimum will be replaced by the minimum.
Field: Maximum Value of z[LINK]
The maximum allowable value of z. Values of z greater than the maximum will be replaced by the maximum.
Field: Input Unit Type for v[LINK]
This field is used to indicate the kind of units that may be associated with the v values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of v and Maximum Value of v. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
VolumetricFlowPerPower
Field: Input Unit Type for w[LINK]
This field is used to indicate the kind of units that may be associated with the w values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of w and Maximum Value of w. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
VolumetricFlowPerPower
Field: Input Unit Type for x[LINK]
This field is used to indicate the kind of units that may be associated with the x values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of x and Maximum Value of x. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
VolumetricFlowPerPower
Field: Input Unit Type for y[LINK]
This field is used to indicate the kind of units that may be associated with the y values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of y and Maximum Value of y. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
VolumetricFlowPerPower
Field: Input Unit Type for z[LINK]
This field is used to indicate the kind of units that may be associated with the z values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of z and Maximum Value of z. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
VolumetricFlowPerPower
Below are an example inputs for QuintLinear Curves.
Curve:Quadratic[LINK]
Input for a quadratic curve consists of the curve name, the three coefficients, and the maximum and minimum valid independent variable values. Optional inputs for curve minimum and maximum may be used to limit the output of the performance curve (e.g., limit extrapolation). The equation represented by the quadratic curve is:
\[y = {C_1} + {C_2}*x + {C_3}*{x^2}\]
Inputs[LINK]
Field: Name[LINK]
A user assigned unique name for an instance of a quadratic curve. When a curve is used, it is referenced by this name.
Field: Coefficient1 Constant[LINK]
The constant coefficient (C\(_{1}\)) in the equation.
Field: Coefficient2 x[LINK]
The linear coefficient (C\(_{2}\)) in the equation.
Field: Coefficient3 x**2[LINK]
The quadratic coefficient (C\(_{3}\)) in the equation.
Field: Minimum Value of x[LINK]
The minimum allowable value of x. Values of x less than the minimum will be replaced by the minimum.
Field: Maximum Value of x[LINK]
The maximum allowable value of x. Values of x greater than the maximum will be replaced by the maximum.
Field: Minimum Curve Output[LINK]
The minimum allowable value of the evaluated curve. Values less than the minimum will be replaced by the minimum.
Field: Maximum Curve Output[LINK]
The maximum allowable value of the evaluated curve. Values greater than the maximum will be replaced by the maximum.
Field: Input Unit Type for X[LINK]
This field is used to indicate the kind of units that may be associated with the x values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of X and Maximum Value of x. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Distance
Power
Field: Output Unit Type[LINK]
This field is used to indicate the kind of units that may be associated with the output values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Curve Output and Maximum Curve Output. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Capacity
Power
Following is an example input.
Curve:Cubic[LINK]
Input for a cubic curve consists of the curve name, the 4 coefficients, and the maximum and minimum valid independent variable values. Optional inputs for curve minimum and maximum may be used to limit the output of the performance curve (e.g., limit extrapolation). The equation represented by the cubic curve is:
\[y = {C_1} + {C_2}*x + {C_3}*{x^2} + {C_4}*{x^3}\]
Inputs[LINK]
Field: Name[LINK]
A user assigned unique name for an instance of a cubic curve. When a curve is used, it is referenced by this name.
Field: Coefficient1 Constant[LINK]
The constant coefficient (C\(_{1}\)) in the equation.
Field: Coefficient2 x[LINK]
The linear coefficient (C\(_{2}\)) in the equation.
Field: Coefficient3 x**2[LINK]
The quadratic coefficient (C\(_{3}\)) in the equation.
Field: Coefficient4 x**3[LINK]
The cubic coefficient (C\(_{4}\)) in the equation.
Field: Minimum Value of x[LINK]
The minimum allowable value of x. Values of x less than the minimum will be replaced by the minimum.
Field: Maximum Value of x[LINK]
The maximum allowable value of x. Values of x greater than the maximum will be replaced by the maximum.
Field: Minimum Curve Output[LINK]
The minimum allowable value of the evaluated curve. Values less than the minimum will be replaced by the minimum.
Field: Maximum Curve Output[LINK]
The maximum allowable value of the evaluated curve. Values greater than the maximum will be replaced by the maximum.
Field: Input Unit Type for X[LINK]
This field is used to indicate the kind of units that may be associated with the x values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of X and Maximum Value of x. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Distance
Power
Field: Output Unit Type[LINK]
This field is used to indicate the kind of units that may be associated with the output values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Curve Output and Maximum Curve Output. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Capacity
Power
Following is an input example.
Curve:Quartic[LINK]
Input for a Quartic (fourth order polynomial) curve consists of the curve name, the five coefficients, and the maximum and minimum valid independent variable values. Optional inputs for curve minimum and maximum may be used to limit the output of the performance curve (e.g., limit extrapolation). The equation represented by the quartic curve is:
\[y = {C_1} + {C_2}x + {C_3}{x^2} + {C_4}{x^3} + {C_5}{x^4}\]
Inputs[LINK]
Field: Name[LINK]
A user assigned unique name for an instance of a Quartic curve. When a curve is used, it is referenced by this name.
Field: Coefficient1 Constant[LINK]
The constant coefficient (C\(_{1}\)) in the equation.
Field: Coefficient2 x[LINK]
The linear coefficient (C\(_{2}\)) in the equation.
Field: Coefficient3 x**2[LINK]
The quadratic coefficient (C\(_{3}\)) in the equation.
Field: Coefficient4 x**3[LINK]
The cubic coefficient (C\(_{4}\)) in the equation.
Field: Coefficient5 x**4[LINK]
The fourth-order coefficient (C\(_{5}\)) in the equation.
Field: Minimum Value of x[LINK]
The minimum allowable value of x. Values of x less than the minimum will be replaced by the minimum.
Field: Maximum Value of x[LINK]
The maximum allowable value of x. Values of x greater than the maximum will be replaced by the maximum.
Field: Minimum Curve Output[LINK]
The minimum allowable value of the evaluated curve. Values less than the minimum will be replaced by the minimum.
Field: Maximum Value of x[LINK]
The maximum allowable value of the evaluated curve. Values greater than the maximum will be replaced by the maximum.
Field: Input Unit Type for X[LINK]
This field is used to indicate the kind of units that may be associated with the x values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of X and Maximum Value of x. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Distance
Power
Field: Output Unit Type[LINK]
This field is used to indicate the kind of units that may be associated with the output values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Curve Output and Maximum Curve Output. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Capacity
Power
Following is an input example.
The following is another example, as might be applied in the Fan:ComponentModel to characterize belt maximum efficiency (using a medium efficiency belt in this case):
Curve:Exponent[LINK]
Input for a exponent curve consists of the curve name, the 3 coefficients, and the maximum and minimum valid independent variable values. Optional inputs for curve minimum and maximum may be used to limit the output of the performance curve (e.g., limit extrapolation). The equation represented by the exponent curve is:
\[y = C1 + C2*{x^{C3}}\]
Inputs[LINK]
Field: Name[LINK]
A user assigned unique name for an instance of an exponent curve. When a curve is used, it is referenced by this name.
Field: Coefficient1 Constant[LINK]
The constant coefficient (C\(_{1}\)) in the equation.
Field: Coefficient2 Constant[LINK]
The linear coefficient (C\(_{2}\)) in the equation.
Field: Coefficient3 Constant[LINK]
The exponent coefficient (C\(_{3}\)) in the equation.
Field: Minimum Value of x[LINK]
The minimum allowable value of x. Values of x less than the minimum will be replaced by the minimum.
Field: Maximum Value of x[LINK]
The maximum allowable value of x. Values of x greater than the maximum will be replaced by the maximum.
Field: Minimum Curve Output[LINK]
The minimum allowable value of the evaluated curve. Values less than the minimum will be replaced by the minimum.
Field: Maximum Curve Output[LINK]
The maximum allowable value of the evaluated curve. Values greater than the maximum will be replaced by the maximum.
Field: Input Unit Type for X[LINK]
This field is used to indicate the kind of units that may be associated with the x values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of X and Maximum Value of x. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Distance
Power
Field: Output Unit Type[LINK]
This field is used to indicate the kind of units that may be associated with the output values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Curve Output and Maximum Curve Output. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Capacity
Power
Following is an input example.
Curve:Bicubic[LINK]
This curve type is a function of two independent variables. Input consists of the curve name, the ten coefficients, and the minimum and maximum values for each of the independent variables. Optional inputs for curve minimum and maximum may be used to limit the output of the performance curve (e.g., limit extrapolation). The equation represented by the bicubic curve is:
\[z = {C_1} + {C_2}*x + {C_3}*{x^2} + {C_4}*y + {C_5}*{y^2} + {C_6}*xy + {C_7}*{x^3} + {C_8}*{y^3} + {C_9}*{x^2}y + {C_{10}}*x{y^2}\]
Inputs[LINK]
Field: Name[LINK]
A user assigned unique name for an instance of a bicubic curve. When a curve is used by another object, it is referenced by this name.
Field: Coefficient1 Constant[LINK]
The constant coefficient (C\(_{1}\)) in the equation.
Field: Coefficient2 x[LINK]
The coefficient C\(_{2}\) in the equation.
Field: Coefficient3 x**2[LINK]
The coefficient C\(_{3}\) in the equation.
Field: Coefficient4 y[LINK]
The coefficient C\(_{4}\) in the equation.
Field: Coefficient5 y**2[LINK]
The coefficient C\(_{5}\) in the equation.
Field: Coefficient6 x*y[LINK]
The coefficient C\(_{6}\) in the equation.
Field: Coefficient7 x**3[LINK]
The coefficient C\(_{7}\) in the equation.
Field: Coefficient8 y**3[LINK]
The coefficient C\(_{8}\) in the equation.
Field: Coefficient9 x**2*y[LINK]
The coefficient C\(_{9}\) in the equation.
Field: Coefficient10 x*y**2[LINK]
The coefficient C\(_{10}\) in the equation.
Field: Minimum Value of x[LINK]
The minimum allowable value of x. Values of x less than this minimum will be replaced by the minimum.
Field: Maximum Value of x[LINK]
The maximum allowable value of x. Values of x greater than this maximum will be replaced by the maximum.
Field: Minimum Value of y[LINK]
The minimum allowable value of y. Values of y less than this minimum will be replaced by the minimum.
Field: Maximum Value of y[LINK]
The maximum allowable value of y. Values of y greater than this maximum will be replaced by the maximum.
Field: Minimum Curve Output[LINK]
The minimum allowable value of the evaluated curve. Values less than the minimum will be replaced by the minimum.
Field: Maximum Curve Output[LINK]
The maximum allowable value of the evaluated curve. Values greater than the maximum will be replaced by the maximum.
Field: Input Unit Type for X[LINK]
This field is used to indicate the kind of units that may be associated with the x values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of X and Maximum Value of x. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
Field: Input Unit Type for Y[LINK]
This field is used to indicate the kind of units that may be associated with the y values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of Y and Maximum Value of Y. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
Field: Output Unit Type[LINK]
This field is used to indicate the kind of units that may be associated with the output values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Curve Output and Maximum Curve Output. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Capacity
Power
Below is an example input.
Curve:Biquadratic[LINK]
This curve is a function of two independent variables. Input consists of the curve name, the six coefficients, and min and max values for each of the independent variables. Optional inputs for curve minimum and maximum may be used to limit the output of the performance curve (e.g., limit extrapolation). The equation represented by the bicubic curve is:
\[z = {C_1} + {C_2}*x + {C_3}*{x^2} + {C_4}*y + {C_5}*{y^2} + {C_6}*xy\]
Inputs[LINK]
Field: Name[LINK]
A user assigned unique name for an instance of a biquadratic curve. When a curve is used, it is referenced by this name.
Field: Coefficient1 Constant[LINK]
The constant coefficient (C\(_{1}\)) in the equation.
Field: Coefficient2 x[LINK]
The coefficient C\(_{2}\) in the equation.
Field: Coefficient3 x**2[LINK]
The coefficient C\(_{3}\) in the equation.
Field: Coefficient4 y[LINK]
The coefficient C\(_{4}\) in the equation.
Field: Coefficient5 y**2[LINK]
The coefficient C\(_{5}\) in the equation.
Field: Coefficient6 x*y[LINK]
The coefficient C\(_{6}\) in the equation.
Field: Minimum Value of x[LINK]
The minimum allowable value of x. Values of x less than the minimum will be replaced by the minimum.
Field: Maximum Value of x[LINK]
The maximum allowable value of x. Values of x greater than the maximum will be replaced by the maximum.
Field: Minimum Value of y[LINK]
The minimum allowable value of y. Values of y less than the minimum will be replaced by the minimum.
Field: Maximum Value of y[LINK]
The maximum allowable value of y. Values of y greater than the maximum will be replaced by the maximum.
Field: Minimum Curve Output[LINK]
The minimum allowable value of the evaluated curve. Values less than the minimum will be replaced by the minimum.
Field: Maximum Curve Output[LINK]
The maximum allowable value of the evaluated curve. Values greater than the maximum will be replaced by the maximum.
Field: Input Unit Type for X[LINK]
This field is used to indicate the kind of units that may be associated with the x values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of X and Maximum Value of x. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
Field: Input Unit Type for Y[LINK]
This field is used to indicate the kind of units that may be associated with the y values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of Y and Maximum Value of Y. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
Field: Output Unit Type[LINK]
This field is used to indicate the kind of units that may be associated with the output values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Curve Output and Maximum Curve Output. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Capacity
Power
Below is an example input.
Curve:CubicLinear[LINK]
This curve is a function of two independent variables. Input consists of the curve name, the six coefficients, and min and max values for each of the independent variables. Optional inputs for curve minimum and maximum may be used to limit the output of the performance curve (e.g., limit extrapolation). The equation represented by the cubic linear curve:
\[y = \left( {{C_1} + {C_2}*x + {C_3}*{x^2} + {C_4}*{x^3}} \right) + \left( {{C_5} + {C_6}*x} \right)*y\]
Inputs[LINK]
Field: Name[LINK]
A user assigned unique name for an instance of a quadratic-linear curve. When a curve is used, it is referenced by this name.
Field: Coefficient1 Constant[LINK]
The constant coefficient (\(C_1\) ) in the equation.
Field: Coefficient2 x[LINK]
The coefficient \(C_2\) in the equation.
Field: Coefficient3 x**2 The coefficient \(C_3\) in the equation.[LINK]
Field: Coefficient4 x**3 The coefficient \(C_4\) in the equation.[LINK]
Field: Coefficient5 y[LINK]
The coefficient \(C_5\) in the equation.
Field: Coefficient6 x*y The coefficient \(C_6\) in the equation.[LINK]
Field: Minimum Value of x[LINK]
The minimum allowable value of x. Values of x less than the minimum will be replaced by the minimum.
Field: Maximum Value of x[LINK]
The maximum allowable value of x. Values of x greater than the maximum will be replaced by the maximum.
Field: Minimum Value of y[LINK]
The minimum allowable value of y. Values of y less than the minimum will be replaced by the minimum.
Field: Maximum Value of y[LINK]
The maximum allowable value of y. Values of y greater than the maximum will be replaced by the maximum.
Field: Minimum Curve Output[LINK]
The minimum allowable value of the evaluated curve. Values less than the minimum will be replaced by the minimum.
Field: Maximum Curve Output[LINK]
The maximum allowable value of the evaluated curve. Values greater than the maximum will be replaced by the maximum.
Field: Input Unit Type for X[LINK]
This field is used to indicate the kind of units that may be associated with the x values. The only option at this time is Dimensionless.
Field: Input Unit Type for Y[LINK]
This field is used to indicate the kind of units that may be associated with the x values. The only option at this time is Dimensionless.
Field: Output Unit Type[LINK]
This field is used to indicate the kind of units that may be associated with the output values. The only option at this time is Dimensionless.
An example input for the CubicLinear equation form is shown below.
Curve:ChillerPartLoadWithLift[LINK]
A custom chiller part-load performance curve is a function of three independent variables, i.e., x, y, and z. Input consists of the curve name, the twelve coefficients, and min and max values for each of the independent variables. Optional inputs for curve minimum and maximum may be used to limit the output of the performance curve.
The equation represented by the custom curve is:
\[C_1 + C_2 \cdot x + C_3 \cdot x^2 + C_4 \cdot y + C_5 \cdot y^2 + C_6 \cdot x \cdot y + C_7 \cdot x^3 + C_8 \cdot y^3 + C_9 \cdot x^2 \cdot y + C_{10} \cdot x \cdot y^2 + C_{11} \cdot x^2 \cdot y^2 + C_{12} \cdot z \cdot y^3\]
where,
x represents the normalized fractional lift (the delta of temperature across the leaving condenser water temperature and leaving evaporator water temperature of a chiller).
y represents the normalized deviation of leaving chilled water temperature from the reference condition.
z represents the part load ratio.
Field: Name[LINK]
A user assigned unique name for an instance of a biquadratic curve. When a curve is used, it is referenced by this name.
Field: Coefficient1[LINK]
The constant coefficient (C1) in the equation.
Field: Coefficient2[LINK]
The coefficient C2 in the equation.
Field: Coefficient3[LINK]
The coefficient C3 in the equation.
Field: Coefficient4[LINK]
The coefficient C4 in the equation.
Field: Coefficient5[LINK]
The coefficient C5 in the equation.
Field: Coefficient6[LINK]
The coefficient C6 in the equation.
Field: Coefficient7[LINK]
The constant coefficient (C7) in the equation.
Field: Coefficient8[LINK]
The coefficient C8 in the equation.
Field: Coefficient9[LINK]
The coefficient C9 in the equation.
Field: Coefficient10[LINK]
The coefficient C10 in the equation.
Field: Coefficient11[LINK]
The coefficient C11 in the equation.
Field: Coefficient12[LINK]
The coefficient C12 in the equation.
Field: Minimum Value of x[LINK]
The minimum allowable value of x. Values of x less than the minimum will be replaced by the minimum.
Field: Maximum Value of x[LINK]
The maximum allowable value of x. Values of x greater than the maximum will be replaced by the maximum.
Field: Minimum Value of y[LINK]
The minimum allowable value of y. Values of y less than the minimum will be replaced by the minimum.
Field: Maximum Value of y[LINK]
The maximum allowable value of y. Values of y greater than the maximum will be replaced by the maximum.
Field: Minimum Value of z[LINK]
The minimum allowable value of z. Values of y less than the minimum will be replaced by the minimum.
Field: Maximum Value of z[LINK]
The maximum allowable value of z. Values of y greater than the maximum will be replaced by the maximum.
Field: Minimum Curve Output[LINK]
The minimum allowable value of the evaluated curve. Values less than the minimum will be replaced by the minimum.
Field: Maximum Curve Output[LINK]
The maximum allowable value of the evaluated curve. Values greater than the maximum will be replaced by the maximum.
Field: Input Unit Type for x[LINK]
This field is used to indicate the kind of units that may be associated with the x values. Select Dimensionless.
Field: Input Unit Type for y[LINK]
This field is used to indicate the kind of units that may be associated with the y values. Select Dimensionless.
Field: Input Unit Type for z[LINK]
This field is used to indicate the kind of units that may be associated with the y values. Select Dimensionless.
Field: Output Unit Type[LINK]
This field is used to indicate the kind of units that may be associated with the output values. Select Dimensionless.
Below is an example input:
Curve:QuadraticLinear[LINK]
This curve is a function of two independent variables. Input consists of the curve name, the six coefficients, and min and max values for each of the independent variables. Optional inputs for curve minimum and maximum may be used to limit the output of the performance curve (e.g., limit extrapolation). The equation represented by the quadratic linear curve:
\[z = \left( {{C_1} + {C_2}*x + {C_3}*{x^2}} \right) + \left( {{C_4} + {C_5}*x + {C_6}*{x^2}} \right)*y\]
Inputs[LINK]
Field: Name[LINK]
A user assigned unique name for an instance of a quadratic-linear curve. When a curve is used, it is referenced by this name.
Field: Coefficient1 Constant[LINK]
The constant coefficient (C\(_{1}\)) in the equation.
Field: Coefficient2 x[LINK]
The coefficient C\(_{2}\) in the equation.
Field: Coefficient3 x**2[LINK]
The coefficient C\(_{3}\) in the equation.
Field: Coefficient4 y[LINK]
The coefficient C\(_{4}\) in the equation.
Field: Coefficient5 x*y[LINK]
The coefficient C\(_{5}\) in the equation.
Field: Coefficient6 x**2*y[LINK]
The coefficient C\(_{6}\) in the equation.
Field: Minimum Value of x[LINK]
The minimum allowable value of x. Values of x less than the minimum will be replaced by the minimum.
Field: Maximum Value of x[LINK]
The maximum allowable value of x. Values of x greater than the maximum will be replaced by the maximum.
Field: Minimum Value of y[LINK]
The minimum allowable value of y. Values of y less than the minimum will be replaced by the minimum.
Field: Maximum Value of y[LINK]
The maximum allowable value of y. Values of y greater than the maximum will be replaced by the maximum.
Field: Minimum Curve Output[LINK]
The minimum allowable value of the evaluated curve. Values less than the minimum will be replaced by the minimum.
Field: Maximum Curve Output[LINK]
The maximum allowable value of the evaluated curve. Values greater than the maximum will be replaced by the maximum.
Field: Input Unit Type for X[LINK]
This field is used to indicate the kind of units that may be associated with the x values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of X and Maximum Value of x. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
Field: Input Unit Type for Y[LINK]
This field is used to indicate the kind of units that may be associated with the y values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of Y and Maximum Value of Y. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
Field: Output Unit Type[LINK]
This field is used to indicate the kind of units that may be associated with the output values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Curve Output and Maximum Curve Output. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Capacity
Power
Below is an example input.
Curve:Triquadratic[LINK]
This curve is a 2\(^{nd}\) order polynomial function of three variable polynomial independent variables. Input consists of the curve name, the twenty seven coefficients, and min and max values for each of the independent variables. Optional inputs for curve minimum and maximum may be used to limit the output of the performance curve (e.g., limit extrapolation). The equation represented by the triquadratic curve:
\[\begin{array}{l} CurveValue = {A_0} + {A_1}*{x^2} + {A_2}*x + {A_3}*{y^2} + {A_4}*y + {A_5}*{z^2} + {A_6}*z + {A_7}*{x^2}{y^2} + {A_8}*xy + \\ \quad \quad \quad \quad \quad {A_9}*x{y^2} + {A_{10}}*{x^2}y + {A_{11}}*{x^2}{z^2} + {A_{12}}*xz + {A_{13}}*x{z^2} + {A_{14}}*{x^2}z + {A_{15}}*{y^2}{z^2} + \\ \quad \quad \quad \quad \quad {A_{16}}*yz + {A_{17}}*y{z^2} + {A_{18}}*{y^2}z + {A_{19}}*{x^2}{y^2}{z^2} + {A_{20}}*{x^2}{y^2}z + {A_{21}}{x^2}y{z^2} + {A_{22}}x{y^2}{z^2} + \\ \quad \quad \quad \quad \quad {A_{23}}{x^2}yz + {A_{24}}x{y^2}z + {A_{25}}xy{z^2} + {A_{26}}xyz \end{array}\]
Inputs[LINK]
Field: Coefficient1 Constant[LINK]
The constant coefficient (A\(_{0}\)) in the equation.
Field: Coefficient2 x**2[LINK]
The coefficient (A\(_{1}\)) in the equation.
Field: Coefficient3 x[LINK]
The coefficient (A\(_{2}\)) in the equation.
Field: Coefficient4 y**2[LINK]
The coefficient (A\(_{3}\)) in the equation.
Field: Coefficient5 y[LINK]
The coefficient (A\(_{4}\)) in the equation.
Field: Coefficient6 z**2[LINK]
The coefficient (A\(_{5}\)) in the equation.
Field: Coefficient7 z[LINK]
The coefficient (A\(_{6}\)) in the equation.
Field: Coefficient8 x**2*y**2[LINK]
The coefficient (A\(_{7}\)) in the equation.
Field: Coefficient9 x*y[LINK]
The coefficient (A\(_{8}\)) in the equation.
Field: Coefficient10 x*y**2[LINK]
The coefficient (A\(_{9}\)) in the equation.
Field: Coefficient11 x**2*y[LINK]
The coefficient (A\(_{10}\)) in the equation.
Field: Coefficient12 x**2*z**2[LINK]
The coefficient (A\(_{11}\)) in the equation.
Field: Coefficient13 x*z[LINK]
The coefficient (A\(_{12}\)) in the equation.
Field: Coefficient14 x*z**2[LINK]
The coefficient (A\(_{13}\)) in the equation.
Field: Coefficient15 x**2*z[LINK]
The coefficient (A\(_{14}\)) in the equation.
Field: Coefficient16 y**2*z**2[LINK]
The coefficient (A\(_{15}\)) in the equation.
Field: Coefficient17 y*z[LINK]
The coefficient (A\(_{16}\)) in the equation.
Field: Coefficient18 y*z**2[LINK]
The coefficient (A\(_{17}\)) in the equation.
Field: Coefficient19 y**2*z[LINK]
The coefficient (A\(_{18}\)) in the equation.
Field: Coefficient20 x**2*y**2*z**2[LINK]
The coefficient (A\(_{19}\)) in the equation.
Field: Coefficient21 x**2*y**2*z[LINK]
The coefficient (A\(_{20}\)) in the equation.
Field: Coefficient22 x**2*y*z**2[LINK]
The coefficient (A\(_{21}\)) in the equation.
Field: Coefficient23 x*y**2*z**2[LINK]
The coefficient (A\(_{22}\)) in the equation.
Field: Coefficient24 x**2*y*z[LINK]
The coefficient (A\(_{23}\)) in the equation.
Field: Coefficient25 x*y**2*z[LINK]
The coefficient (A\(_{24}\)) in the equation.
Field: Coefficient26 x*y*z**2[LINK]
The coefficient (A\(_{25}\)) in the equation.
Field: Coefficient27 x*y*z[LINK]
The coefficient (A\(_{26}\)) in the equation.
Field: Minimum Value of x[LINK]
The minimum allowable value of x. Values of x less than the minimum will be replaced by the minimum.
Field: Maximum Value of x[LINK]
The maximum allowable value of x. Values of x greater than the maximum will be replaced by the maximum.
Field: Minimum Value of y[LINK]
The minimum allowable value of y. Values of y less than the minimum will be replaced by the minimum.
Field: Maximum Value of y[LINK]
The maximum allowable value of y. Values of y greater than the maximum will be replaced by the maximum.
Field: Minimum Value of z[LINK]
The minimum allowable value of z. Values of z less than the minimum will be replaced by the minimum.
Field: Maximum Value of z[LINK]
The maximum allowable value of z. Values of z greater than the maximum will be replaced by the maximum.
Field: Minimum Curve Output[LINK]
The minimum allowable value of the evaluated curve. Values less than the minimum will be replaced by the minimum.
Field: Maximum Curve Output[LINK]
The maximum allowable value of the evaluated curve. Values greater than the maximum will be replaced by the maximum.
Field: Input Unit Type for X[LINK]
This field is used to indicate the kind of units that may be associated with the x values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of X and Maximum Value of x. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
Field: Input Unit Type for Y[LINK]
This field is used to indicate the kind of units that may be associated with the y values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of Y and Maximum Value of Y. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
Field: Input Unit Type for Z[LINK]
This field is used to indicate the kind of units that may be associated with the z values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Value of Z and Maximum Value of Z. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Temperature
VolumetricFlow
MassFlow
Power
Distance
Field: Output Unit Type[LINK]
This field is used to indicate the kind of units that may be associated with the output values. It is used by IDF Editor to display the appropriate SI and IP units for the Minimum Curve Output and Maximum Curve Output. The unit conversion is not applied to the coefficients. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.
Dimensionless
Capacity
Power
Curve:Functional:PressureDrop[LINK]
Input for a pressure drop curve consists of the curve name, a varying number of parameters, and the maximum and minimum valid independent variable values. The equation represented by the pressure drop curve is:
\[\Delta P = \left( {K + f\frac{L}{D}} \right)\frac{{\rho {V^2}}}{2}\]
Inputs[LINK]
Field: Name[LINK]
A user assigned unique name for an instance of a pressure drop curve. When a curve is used, it is referenced by this name.
Field: Diameter[LINK]
This diameter represents an equivalent diameter for the given branch. This is parameter (D) in the equation, and has units of {m}. Since varying components may be found on the same branch, this value must be selected along with the other inputs in order to provide a proper value of pressure drop. This is used to calculate the velocity in addition to being used directly in the frictional pressure drop calculation.
Field: Minor Loss Coefficient[LINK]
This is the pressure drop coefficient typically applied to components such as fittings and occasionally heat pumps. This is parameter (K) in the equation and is dimensionless. This coefficient is used to describe the amount of dynamic pressure lost during the process. This value may be left blank if the user only wants to account for frictional losses in this branch.
Field: Length[LINK]
This is the length of a pressure drop process in which friction is applied. This is parameter (L) in the equation and has units of {m}. In a pipe, this would be the length of the pipe, however in many cases, pressure drop in other components are applied as an equivalent length. This is only required if the user is wanting to perform frictional pressure drop calculations.
Field: Roughness[LINK]
This field represents the first method to simulate frictional losses. This parameter does not appear directly in the equation above, as it is only used to develop the friction factor (f), but the roughness will have units of {m} if entered. If the user enters this roughness value, the pressure system will use it along with an approximation to the Moody chart to estimate the friction factor given the current flow conditions. This allows the friction calculate to be dynamic throughout the simulation.
Field: Fixed Friction Factor[LINK]
This field represents the second method to simulate frictional losses. This is parameter (f) in the equation and is dimensionless. This parameter is a fixed value of friction factor which would override any calculations performed based on roughness, etc. If the user has a known friction factor for a given component, this is where it should be entered.
In the curve outputs for this object:
Curve Input 1: MassFlow
Curve Input 2: Density
Curve Input 3: Velocity
Curve Output: the resultant value
Following is an input example.
Curve:FanPressureRise[LINK]
Input for the fan total pressure rise curve consists of the curve name, the four coefficients, and the maximum and minimum valid independent variable values. Optional inputs for the curve minimum and maximum may be used to limit the output of the performance curve (e.g., limit extrapolation). The equation is:
\[\Delta {P_{fan,tot}} = {C_1}*Q_{fan}^2 + {C_2}*Q_{fan}^{} + {C_3}*Q_{fan}^{}*\sqrt {{P_{sm}} - {P_o}} + {C_4}*\left( {{P_{sm}} - {P_o}} \right)\]
where \(\Delta P_{fan,tot}\) is the fan total pressure rise (Pa) as a function of volumetric flow through the fan (\(Q_{fan}, m^3/s\) ), duct static pressure set point (\(P_{sm}\) , Pa), and static pressure surrounding the ducts (\(P_o\) , Pa). \(P_o\) is assumed to be zero.
The first term of the curve looks like the common system curve in which the fan pressure rise is proportional to the square of the fan flow, but here it also depends implicitly on supply and return pressure losses, and in part on the fraction of the fan flow that is outdoor air (essentially “leaks” into and out of the return side of the system). Very often it is the only term considered, but that would only be correct with fixed-position dampers, no distribution system leakage, no linear resistance components, and no duct static pressure control.
The second term accounts for significant flow resistances in the system where the pressure difference is linearly proportional to the flow. Some filters and coils in the return may need this term to be adequately described. This term could be ignored if there are no linear components or if their pressure drops are very small compared to the other terms.
The third term, which depends on the fan flow and square root of the supply duct pressure P\(_{sm}\), accounts in part for leakage from the supply system when damper positions are fixed or are changed independently of static pressure or fan flow. In this case, reducing or eliminating supply leakage results in a different system curve. This, however, might be only a minor correction to the simple system curves generally used. The third term is zero when the VAV box dampers are modulated to control flow. Consequently, with variable-position supply dampers, reducing or eliminating supply leakage does not change the system curve.
The last term also accounts in part for leakage from the supply system when damper positions are fixed or are changed independently of static pressure or fan flow. This term indicates that the same fan pressure rise can be achieved by raising the duct pressure and closing dampers. The only change in the system in such a case is that the leakage flow may increase. The coefficient for this term is one when the VAV box dampers are modulated to control flow. In both cases, this term may be the most important correction to the simple system curves generally used, especially at low flows.
Inputs[LINK]
Field: Name[LINK]
The required user-assigned unique alpha name for an instance of this curve. When a curve of this type is used, it is referenced by this name.
Field: Fan Pressure Rise Coefficient1 C1[LINK]
The required numeric constant coefficient C\(_{1}\) (Pa s\(^{2}\)/m\(^{6}\)) in the curve. Must be greater than zero.
Field: Fan Pressure Rise Coefficient2 C2[LINK]
The required numeric constant coefficient C\(_{2}\) (Pa s/m\(^{3}\)) in the curve.
Field: Fan Pressure Rise Coefficient3 C3[LINK]
The required numeric constant coefficient C\(_{3}\) (Pa\(^{0.5}\) s/m\(^{3}\)) in the curve.
Field: Fan Pressure Rise Coefficient4 C4[LINK]
The required numeric constant coefficient C\(_{4}\) (dimensionless) in the curve.
Field: Minimum Value of Qfan[LINK]
The required numeric minimum allowable value of Q\(_{fan}\) (m\(^{3}\)/s). Values of Q\(_{fan}\) less than the minimum will be replaced within this curve by the minimum.
Field: Maximum Value of Qfan[LINK]
The required numeric maximum allowable value of Q\(_{fan}\) (m\(^{3}\)/s). Values of Q\(_{fan}\) greater than the maximum will be replaced within this curve by the maximum.
Field: Minimum Value of Psm[LINK]
The required numeric minimum allowable value of P\(_{sm}\) (Pa). Values of P\(_{sm}\) less than the minimum will be replaced within this curve by the minimum.
Field: Maximum Value of Psm[LINK]
The required numeric maximum allowable value of P\(_{sm}\) (Pa). Values of P\(_{sm}\) greater than the maximum will be replaced within this curve by the maximum.
Field: Minimum Curve Output[LINK]
The optional numeric minimum allowable value of the evaluated curve (Pa). Values less than the minimum will be replaced within this curve by the minimum.
Field: Maximum Curve Output[LINK]
The optional numeric maximum allowable value of the evaluated curve (Pa). Values greater than the maximum will be replaced within this curve by the maximum.
The following is an input example describing the fan total pressure rise for a VAV system with a constant non-zero duct static pressure set point (the set point is described separately; see the Curve:Linear object for a related example):
Curve:ExponentialSkewNormal[LINK]
Input for the exponential-modified skew normal curve consists of the curve name, the four coefficients, and the maximum and minimum valid independent variable values. Optional inputs for the curve minimum and maximum may be used to limit the output of the performance curve (e.g., limit extrapolation). The equation is:
\[y = \frac{{{e^{( - 0.5 \cdot {Z_1}^2)}}[1 + \frac{{{Z_2}}}{{\left| {{Z_2}} \right|}} \cdot erf\left( {\frac{{\left| {{Z_2}} \right|}}{{\sqrt 2 }}} \right)}}{{{e^{( - 0.5 \cdot {Z_3}^2)}}[1 + \frac{{{Z_3}}}{{\left| {{Z_3}} \right|}} \cdot erf\left( {\frac{{\left| {{Z_3}} \right|}}{{\sqrt 2 }}} \right)}}\]
where:
\[\begin{aligned} Z_1 &= \frac{x - C_1}{C_2} \\ Z_2 &= \frac{e^{C_3 \cdot x} \cdot C_4 \cdot x - C_1}{C_2} \\ Z_3 &= -\frac{C_1}{C_2}\end{aligned}\]
Inputs[LINK]
Field: Name[LINK]
The required user-assigned unique alpha name for an instance of this curve. When a curve of this type is used, it is referenced by this name.
Field: Coefficient1 C1[LINK]
The required numeric constant coefficient C\(_{1}\) in the curve.
Field: Coefficient2 C2[LINK]
The required numeric constant coefficient C\(_{2}\) in the curve. Must be non-zero.
Field: Coefficient3 C3[LINK]
The required numeric constant coefficient C\(_{3}\) in the curve.
Field: Coefficient4 C4[LINK]
The required numeric constant coefficient C\(_{4}\) in the curve.
Field: Minimum Value of x[LINK]
The required numeric minimum allowable value of x. Values of x less than the minimum will be replaced by the minimum.
Field: Maximum Value of x[LINK]
The required numeric maximum allowable value of x. Values of x greater than the maximum will be replaced by the maximum.
Field: Minimum Curve Output[LINK]
The optional numeric minimum allowable value of the evaluated curve. Values less than the minimum will be replaced by the minimum.
Field: Maximum Curve Output[LINK]
The optional numeric maximum allowable value of the evaluated curve. Values greater than the maximum will be replaced by the maximum.
Field: Input Unit Type for x[LINK]
This optional field is provided for future purposes so that the IDF Editor could display the appropriate SI or IP units for the Minimum Value of x and Maximum Value of x (currently dimensionless). At this time, only the Dimensionless option is provided so that no unit conversion is used for this curve.
Field: Output Unit Type[LINK]
This optional field is provided for future purposes so that the IDF Editor could display the appropriate SI or IP units for the Minimum Curve Output and Maximum Curve Output (currently dimensionless). At this time, only the Dimensionless option is provided so that no unit conversion is used for this curve.
The following are input examples describing the normalized fan efficiency for the normal (non-stall) and stall operating regions of a backward-curved airfoil centrifugal fan:
Curve:Sigmoid[LINK]
Input for the sigmoid curve consists of the curve name, the five coefficients, and the maximum and minimum valid independent variable values. Optional inputs for the curve minimum and maximum may be used to limit the output of the performance curve (e.g., limit extrapolation). The equation is:
\[y = {C_1} + \frac{{{C_2}}}{{\left( {{{(1 + {e^{\left[ {\frac{{({C_3} - x)}}{{{C_4}}}} \right]}})}^{{C_5}}}} \right)}}\]
Inputs[LINK]
Field: Name[LINK]
The required user-assigned unique alpha name for an instance of this curve. When a curve of this type is used, it is referenced by this name.
Field: Coefficient1 C1[LINK]
The required numeric constant coefficient C\(_{1}\) in the equation.
Field: Coefficient2 C2[LINK]
The required numeric constant coefficient C\(_{2}\) in the equation.
Field: Coefficient3 C3[LINK]
The required numeric constant coefficient C\(_{3}\) in the equation.
Field: Coefficient4 C4[LINK]
The required numeric constant coefficient C\(_{4}\) in the equation.
Field: Coefficient5 C5[LINK]
The required numeric constant coefficient C\(_{5}\) in the equation.
Field: Minimum Value of x[LINK]
The required numeric minimum allowable value of x. Values of x less than the minimum will be replaced by the minimum.
Field: Maximum Value of x[LINK]
The required numeric maximum allowable value of x. Values of x greater than the maximum will be replaced by the maximum.
Field: Minimum Curve Output[LINK]
The optional numeric minimum allowable value of the evaluated curve. Values less than the minimum will be replaced by the minimum.
Field: Maximum Curve Output[LINK]
The optional numeric maximum allowable value of the evaluated curve. Values greater than the maximum will be replaced by the maximum.
Field: Input Unit Type for x[LINK]
This optional field is provided for future purposes so that the IDF Editor could display the appropriate SI or IP units for the Minimum Value of x and Maximum Value of x (currently dimensionless). At this time, only the Dimensionless option is provided so that no unit conversion is used for this curve.
Field: Output Unit Type[LINK]
This optional field is provided for future purposes so that the IDF Editor could display the appropriate SI or IP units for the Minimum Curve Output and Maximum Curve Output (currently dimensionless). At this time, only the Dimensionless option is provided so that no unit conversion is used for this curve.
The following are input examples describing the normalized dimensionless flow for normal (non-stall) and stall operating regions of a backward-curved airfoil centrifugal fan:
Curve:RectangularHyperbola1[LINK]
Input for the single rectangular hyperbola type 1 curve consists of the curve name, the three coefficients, and the maximum and minimum valid independent variable values. Optional inputs for the curve minimum and maximum may be used to limit the output of the performance curve (e.g., limit extrapolation). The equation is:
y =(C\(_{1}\) * x) / (C\(_{2}\)+x) + C\(_{3}\)
Inputs[LINK]
Field: Name[LINK]
The required user-assigned unique alpha name for an instance of this curve. When a curve of this type is used, it is referenced by this name.
Field: Coefficient1 C1[LINK]
The required numeric constant coefficient C\(_{1}\) in the equation.
Field: Coefficient2 C2[LINK]
The required numeric constant coefficient C\(_{2}\) in the equation.
Field: Coefficient3 C3[LINK]
The required numeric constant coefficient C\(_{3}\) in the equation.
Field: Minimum Value of x[LINK]
The required numeric minimum allowable value of x. Values of x less than the minimum will be replaced by the minimum.
Field: Maximum Value of x[LINK]
The required numeric maximum allowable value of x. Values of x greater than the maximum will be replaced by the maximum.
Field: Minimum Curve Output[LINK]
The optional numeric minimum allowable value of the evaluated curve. Values less than the minimum will be replaced by the minimum.
Field: Maximum Curve Output[LINK]
The optional numeric maximum allowable value of the evaluated curve. Values greater than the maximum will be replaced by the maximum.
Field: Input Unit Type for x[LINK]
This optional field is provided for future purposes so that the IDF Editor could display the appropriate SI or IP units for the Minimum Value of x and Maximum Value of x (currently dimensionless). At this time, only the Dimensionless option is provided so that no unit conversion is used for this curve.
Field: Output Unit Type[LINK]
This optional field is provided for future purposes so that the IDF Editor could display the appropriate SI or IP units for the Minimum Curve Output and Maximum Curve Output (currently dimensionless). At this time, only the Dimensionless option is provided so that no unit conversion is used for this curve.
The following is an input example describing the maximum efficiency variation for a mid- or average-efficiency type of motor:
Curve:RectangularHyperbola2[LINK]
Input for the single rectangular hyperbola type 2 curve consists of the curve name, the three coefficients, and the maximum and minimum valid independent variable values. Optional inputs for the curve minimum and maximum may be used to limit the output of the performance curve (e.g., limit extrapolation). The equation is:
y =(C\(_{1}\) * x) / (C\(_{2}\)+x) + C\(_{3}\) * x
Inputs[LINK]
Field: Name[LINK]
The required user-assigned unique alpha name for an instance of this curve. When a curve of this type is used, it is referenced by this name.
Field: Coefficient1 C1[LINK]
The required numeric constant coefficient C\(_{1}\) in the equation.
Field: Coefficient2 C2[LINK]
The required numeric constant coefficient C\(_{2}\) in the equation.
Field: Coefficient3 C3[LINK]
The required numeric constant coefficient C\(_{3}\) in the equation.
Field: Minimum Value of x[LINK]
The required numeric minimum allowable value of x. Values of x less than the minimum will be replaced by the minimum.
Field: Maximum Value of x[LINK]
The required numeric maximum allowable value of x. Values of x greater than the maximum will be replaced by the maximum.
Field: Minimum Curve Output[LINK]
The optional numeric minimum allowable value of the evaluated curve. Values less than the minimum will be replaced by the minimum.
Field: Maximum Curve Output[LINK]
The optional numeric maximum allowable value of the evaluated curve. Values greater than the maximum will be replaced by the maximum.
Field: Input Unit Type for x[LINK]
This optional field is provided for future purposes so that the IDF Editor could display the appropriate SI or IP units for the Minimum Value of x and Maximum Value of x (currently dimensionless). At this time, only the Dimensionless option is provided so that no unit conversion is used for this curve.
Field: Output Unit Type[LINK]
This optional field is provided for future purposes so that the IDF Editor could display the appropriate SI or IP units for the Minimum Curve Output and Maximum Curve Output (currently dimensionless). At this time, only the Dimensionless option is provided so that no unit conversion is used for this curve.
The following are input examples describing part-load efficiency variations for a medium efficiency type of V-belt (Regions 1 and 3), for a mid- or average-efficiency nominal 25 hp 4-pole motor, and a nominal 30 hp VFD:
Curve:ExponentialDecay[LINK]
Input for the exponential decay curve consists of the curve name, the three coefficients, and the maximum and minimum valid independent variable values. Optional inputs for the curve minimum and maximum may be used to limit the output of the performance curve (e.g., limit extrapolation). The equation is:
\[y = C_1 + C_2 \cdot e^{C_3 x}\]
Inputs[LINK]
Field: Name[LINK]
The required user-assigned unique alpha name for an instance of this curve. When a curve of this type is used, it is referenced by this name.
Field: Coefficient1 C1[LINK]
The required numeric constant coefficient C\(_{1}\) in the equation.
Field: Coefficient2 C2[LINK]
The required numeric constant coefficient C\(_{2}\) in the equation.
Field: Coefficient3 C3[LINK]
The required numeric constant coefficient C\(_{3}\) in the equation.
Field: Minimum Value of x[LINK]
The required numeric minimum allowable value of x. Values of x less than the minimum will be replaced by the minimum.
Field: Maximum Value of x[LINK]
The required numeric maximum allowable value of x. Values of x greater than the maximum will be replaced by the maximum.
Field: Minimum Curve Output[LINK]
The optional numeric minimum allowable value of the evaluated curve. Values less than the minimum will be replaced by the minimum.
Field: Maximum Curve Output[LINK]
The optional numeric maximum allowable value of the evaluated curve. Values greater than the maximum will be replaced by the maximum.
Field: Input Unit Type for x[LINK]
This optional field is provided for future purposes so that the IDF Editor could display the appropriate SI or IP units for the Minimum Value of x and Maximum Value of x (currently dimensionless). At this time, only the Dimensionless option is provided so that no unit conversion is used for this curve.
Field: Output Unit Type[LINK]
This optional field is provided for future purposes so that the IDF Editor could display the appropriate SI or IP units for the Minimum Curve Output and Maximum Curve Output (currently dimensionless). At this time, only the Dimensionless option is provided so that no unit conversion is used for this curve.
The following is an input example describing the part-load efficiency variation for a medium efficiency type of V-belt (Region 2):
Curve:DoubleExponentialDecay[LINK]
Input for the double exponential decay curve consists of the curve name, the five coefficients, and the maximum and minimum valid independent variable values. Optional inputs for the curve include the minimum and maximum output of the performance curve. The equation is:
\[y = {C_1} + {C_2}{\exp ^{({C_3}x)}} + {C_4}{\exp ^{({C_5}x)}}\]
Inputs[LINK]
Field: Name[LINK]
This field indicates the required user-assigned name for an instance of this curve. When a curve of this type is used, it is referenced by this name.
Field: Coefficient1 C1[LINK]
The required numeric constant coefficient C\(_{1}\) in the equation.
Field: Coefficient2 C2[LINK]
The required numeric constant coefficient C\(_{2}\) in the equation.
Field: Coefficient3 C3[LINK]
The required numeric constant coefficient C\(_{3}\) in the equation.
Field: Coefficient4 C4[LINK]
The required numeric constant coefficient C\(_{4}\) in the equation.
Field: Coefficient5 C5[LINK]
The required numeric constant coefficient C\(_{5}\) in the equation.
Field: Minimum Value of x[LINK]
The required numeric minimum allowable value of x. Values of x less than the minimum will be replaced by the minimum
Field: Maximum Value of x[LINK]
The required numeric maximum allowable value of x. Values of x greater than the maximum will be replaced by the maximum
Field: Minimum Curve Output[LINK]
The optional numeric minimum allowable value of the evaluated curve. Values less than the minimum will be replaced by the minimum
Field: Maximum Curve Output[LINK]
The optional numeric maximum allowable value of the evaluated curve. Values greater than the maximum will be replaced by the maximum
Field: Input Unit Type for x[LINK]
The optional field is provided for future purposes so that the IDF Editor could display the appropriate SI or IP units for the Minimum and Maximum Value of x. Currently, only Dimensionless option is provided so that no unit conversion is used for this curve
Field: Output Unit Type[LINK]
The optional field is provided for future purposes so that the IDF Editor could display the appropriate SI or IP units for the Minimum and Maximum Curve output. Currently, only Dimensionless option is provided so that no unit conversion is used for this curve.
An example input of the Curve:DoubleExponentialDecay input is:
Outputs[LINK]
Performance Curve Output Value[LINK]
The current value of the performance curve. This value is averaged over the time step being reported. Inactive or unused performance curves will show a value of -999 (e.g., equipment is off, a specific performance curve is not required for this aspect of the equipment model at this time step, etc.). This value means that the performance curve was not called during the simulation and, therefore, not evaluated. This inactive state value is only set at the beginning of each environment. When averaging over long periods of time, this inactive state value may skew results. In this case, use a detailed reporting frequency (ref. Output:Variable object) to view results at each HVAC time step.
Performance Curve Input Variable 1(-N) Value [][LINK]
The current value of the nth independent variable passed to the performance curve. The order of the independent variables is in the same order as the model equation represented by this performance curve object. This value is averaged over the time step being reported.
HVAC,Average,Performance Curve Output Value []
HVAC,Average,Performance Curve Input Variable 1 Value []
HVAC,Average,Performance Curve Input Variable 2 Value []
HVAC,Average,Performance Curve Input Variable 3 Value []
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This documentation is made available under the EnergyPlus Open Source License v1.0.