Water-Cooled Chillers
Water cooled chillers are devices used to make cold water with a water cooled condenser. In this library, you can create different types of water cooled chillers:
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Water Cooled (Simple and Detailed)
This chiller uses performance information at reference conditions along with three curve fits (capacity, ambient relief, and power consumed) for cooling capacity and efficiency to determine the chiller operation at off-reference conditions. Simple water cooled chillers use entering condenser water temperature in the curves where detailed water cooled chillers use leaving condenser water temperature. The other difference is the power consumed curve for calculating part load power; the simple water cooled chiller uses a quadratic equation where the detailed water cooled chiller uses a bicubic equation.
Product tab
Nominal Cooling Capacity
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Default: Auto Size
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Typical Range: 50 to 500 tons
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Min Max: 0 < X < 999,999
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Units: W; kW; Btuh; Mbh
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This field specifies the nominal cooling capacity of the chiller.
Full Load Energy Rate
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Default: 0
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Typical Range: 4.0 to 5.6 COP
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Min Max: 0 to 999,999
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Units: kW/ton, therms/ton-hr, Mbh/ton, kW/Mbh, kW/kW, COP, EER
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This numeric input field is the chiller’s coefficient of performance for compressor energy. It should not include energy use due to pumps.
Optimum Part Load Ratio
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Default: 100%
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Typical Range: 10 to 100%
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Min Max: 0 to 100%
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Units: %
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This numeric field contains the chiller’s optimum part-load ratio. This is the part-load ratio at which the chiller performs at its maximum COP.
Sizing Factor
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Default: 100%
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Typical Range: 10 to 100%
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Min Max: 0 to 999,999
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Units: %
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The sizing factor is used when the capacity is selected as auto sized. The autosizing calculations are performed as usual and the results are multiplied by the sizing factor.
Design Water Temperatures
Design Leaving Chilled Water Temperature
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Default: 44°F/6.67°C
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Typical Range: 44 to 45°F/6.67 to 7.2°C
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Min Max: 20°F/-7°C
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Units: °F/°C
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This field contains the chiller’s leaving chilled water temperature.
Design Entering Condenser Water Temperature
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Default: 85°F/29.4°C
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Typical Range: 85 to 95°F / 29.4 to 35°C
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Min Max: 75 to 120°F/23.8 to 48.8°C
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Units: °F/°C
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This field contains the chiller’s entering condenser fluid temperature.
Compressor
Compressor Type
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Default: N/A
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Typical Range: N/A
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Min Max: N/A
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Units: N/A
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This field defines the chiller’s type of compressor. The available options are: Centrifugal, Generic Screw, Helical Rotary, Reciprocating and Scroll.
Compressor Heat Rejection Fraction
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Default: 100
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Typical Range: 60 < x < 100
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Min Max: 0 < x < 100
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Units: %
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This input represents the fraction of compressor electrical energy consumption that must be rejected by the condenser loop. Enter a value of 100% when modeling hermetic chillers. For open chillers, enter the compressor motor efficiency.
Operational Limits
Leaving Chilled Water Temperature Low Limit
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Default: 44°F/6.67°C
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Typical Range: N/A
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Min Max: 10 to 60°F
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Units: °F / °C
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This field contains the lower limit for the leaving chilled water temperature. This temperature acts as a cut off for heat transfer in the evaporator, so that the fluid doesn’t get too cold.
Heat Recovery
Enable Heat Recovery
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Default: N/A
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Typical Range: N/A
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Min Max: N/A
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Units: Yes/No
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This field is prompting the user if heat recovery is enabled on this chiller. Heat recovery can be achieved with either a single condenser bundle or an auxiliary condenser.
Nominal Heat Recovery Capacity
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Default: 100%
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Typical Range: 50 to 100%
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Min Max: 0 to 100%
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Units: % of Cooling Capacity
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This field is represents the amount of thermal energy, as a percentage of the cooling capacity, which can be extracted for service-water heating / pre-heating. It is only displayed when Enable Heat Recovery is set to Yes.
Entering Condenser Water Temp. High Limit
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Default: 100°F/37.78°C
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Typical Range: 100°F to 105°F/37.78°C to 40.56°C
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Min Max: 100°F to 105°F/37.78°C to 40.56°C
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Units: °F/°C
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This field is represents the high limit for the condensing temperature of the water. It is only displayed when Enable Heat Recovery is set to Yes.
Heat Recovery Pump Type
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Default: Constant Speed Pump
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Typical Range: N/A
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Min Max: N/A
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Units: N/A
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This field is represents what pump type is used to circulate hot water to service-water destination. User can choose either constant speed or variable speed. It is only displayed when Enable Heat Recovery is set to Yes.
Heat Recovery Pump
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Default: 90.1 CV Chilled Water Pump
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Typical Range: N/A
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Min Max: N/A
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Units: N/A
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This field is represents the actual pump and its’ associated properties that will be used for heat recovery. It is only displayed when Enable Heat Recovery is set to Yes.
Curve tab
There are two sets of curves for Water Cooled Chillers depending on the operating mode of the chiller: Cooling Mode and Ice Storage. The description of the curves are below. The Water Cooled–Simple chiller uses Entering Condenser Temperature in the curves while the Water Cooled–Detailed chiller uses Leaving Condenser Temperature in the curves.
Cooling Mode
Capacity Curve
This biquadratic curve shows the percentage of full cooling capacity as a function of the condenser fluid temperature and the leaving chilled water temperature. Inputs consists of two independent variables, six coefficients, and min and max values for each of the independent variables. The equation for the capacity curve is:
Where:
Z = Cooling Capacity
C1 to C6 = coefficients
X = Condenser temperature
Y = Chilled Water Temperature
The curve has the following fields:
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X Axis:
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Condenser fluid temperature (°F, °C). Depending on the input for Condenser Temperature Type on the product’s tab, this axis will be either the Leaving or Entering Condenser Fluid temperature.
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Y Axis:
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Cooling Capacity (%).
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Tchw,l Min / Max :
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Minimum and maximum temperature values (°F, °C) for the Chilled water leaving temperature variable. These values determine the three chilled water temperatures plotted, one is the maximum, one is the minimum and the last one is the midpoint between them.
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Tcond,e Min / Max or Tcond,l Min / Max :
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Minimum and Maximum temperature values (°F, °C) for the Condenser Temperature variable on the X axis. E is for entering, l is for leaving condenser water temperature. The Water Cooled–Simple chiller uses Entering Condenser Temperature in the curves while the Water Cooled–Detailed chiller uses Leaving Condenser Temperature in the curves.
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Ambient Relief Curve
This biquadratic curve represents the chiller’s energy input to cooling output ratio as a function of the condenser fluid temperature and the leaving chilled water temperature.
Inputs consists of two independent variables, six coefficients, and min and max values for each of the independent variables. The equation for the capacity curve is:
Where:
Z = Chiller’s electric consumption (%)
C1 to C6 = coefficients
X = Condenser temperature
Y = Leaving Chilled Water Temperature
The curve has the following fields:
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X Axis:
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Condenser fluid temperature (°F, °C). Depending on the input for Condenser Temperature Type on the product’s tab, this axis will be either the Leaving or Entering Condenser Fluid temperature.
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Y Axis:
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Chiller's electric consumption (%).
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Tchw,l Min / Max :
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Minimum and maximum temperature values (°F, °C) for the Chilled water leaving temperature variable. These values determine the three chilled water temperatures plotted, one is the maximum, one is the minimum and the last one is the midpoint between them.
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Tcond,e Min/Max; Tcond, l Min / Max:
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Minimum and Maximum temperature values (°F, °C) for the Condenser Temperature variable on the X axis. E is for entering, L is for leaving condenser water temperature. The Water Cooled–Simple chiller uses Entering Condenser Temperature in the curves while the Water Cooled–Detailed chiller uses Leaving Condenser Temperature in the curves.
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Power Curve (simplified Chillers)
This quadratic curve represents the chiller’s electric consumption at part load with operating temperatures at design values. This curve is generated by plotting the percentage of full load power consumed by the compressor vs. the percentage of full load cooling capacity. The curve output should be 0% power when there is 0% load and should be 100% power when there is 100% load.
The equation for the Power Curve is:
Where:
y = Chiller’s electric consumption (%)
C1 to C3 = coefficients
X = Part Load
The curve has the following fields:
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X Axis:
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Full Load (%)
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Y Axis:
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Full Power (%).
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Capacity Min/Max:
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The curve can be selected as quadratic or cubic.
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Load Min/Max
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Minimum and Maximum Load Percentage
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Power Curve (detailed Chillers)
This bicubic curve represents the chiller’s electric consumption at part load with operating temperatures at design values. This curve is generated by plotting the percentage of full load power consumed by the compressor vs. the percentage of full load cooling capacity. The curve output should be 0% power when there is 0% load and should be 100% power when there is 100% load.
The equation for the Power Curve is:
Where:
z = Chiller’s electric consumption (%)
C1 to C6 = coefficients
x = Condenser Temperature
y = Part Load Ratio
The curve has the following fields:
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X Axis:
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Full Load (%)
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Y Axis:
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Full Power (%).
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Capacity Min/Max:
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The curve can be selected as quadratic or cubic.
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Load Min/Max
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Minimum and Maximum Load Percentage
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Ice Mode tab
The Water Cooled–Simple chiller uses Entering Condenser Temperature in the curves while the Water Cooled–Detailed chiller uses Leaving Condenser Temperature in the curves.
Capacity Curve
This biquadratic curve shows the percentage of full cooling capacity as a function of the condenser fluid temperature and the leaving chilled water temperature. Inputs consists of two independent variables, six coefficients, and min and max values for each of the independent variables. The equation for the capacity curve is:
Where:
Z = Ice Making Capacity
C1 to C6 = coefficients
X = Condenser temperature
Y = Full load capacity
The curve has the following fields:
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X Axis:
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Condenser fluid temperature (°F, °C)
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Y Axis:
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Cooling Capacity (%)
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Tchw,l Min / Max:
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Minimum and maximum temperature values (°F, °C) for the Chilled water leaving temperature variable. These values determine the three chilled water temperatures plotted, one is the maximum, one is the minimum and the last one is the midpoint between them
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Tcond,e Min/Max or Tcond,l Min/Max:
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Minimum and Maximum temperature values (°F, °C) for the Condenser Temperature variable on the X axis. E is for entering, L is for leaving condenser water temperature.
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See information previously discussed.
See information previously discussed.
Combustion Turbine Chiller
The Combustion Turbine Chiller uses a combustion turbine to generate electrical output to run the chiller. It can burn different types of fuels to generate steam to move the turbine.
Product tab
Nominal Cooling Capacity
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Default: Autosize
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Typical Range: 50 to 500 tons
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Min Max: 0 < x < 999,999
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Units: W, kW, Btuh, Mbh
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This field specifies the nominal cooling capacity of the chiller.
Full Load Energy Rate
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Default: 2.75 COP
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Typical Range: 2.5 to 3.5 COP
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Min Max: 0 to 999,999
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Units: kW/ton, therms/ton-hr, Mbh/ton, kW/Mbh, kW/kW, COP, EER
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This field is the chiller’s coefficient of performance.
Temperature Rise Coefficient
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Default: 2.778
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Typical Range: 2.778
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Min Max: 0 to 999,999
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Units: N/A
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This field contains the electric chiller’s temperature rise coefficient which is defined as the ratio of the required change in condenser water temperature to a given change in chilled water temperature, which maintains the capacity at the nominal value. This is calculated as the following ratio:
where:
TCEntrequired = required entering condenser air or water temperature to maintain rated capacity
TCEntrated = rated entering condenser air or water temperature at rated capacity
TELvrequired = required leaving evaporator water outlet temperature to maintain rated capacity
TELvrated = rated leaving evaporator water outlet temperature at rated capacity
Fuel Type
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Default: Natural gas
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Typical Range: N/A
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Min Max: N/A
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Units: N/A
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This field determines the type of fuel that the chiller uses. Fuel types are: NaturalGas, PropaneGas, Diesel, Gasoline, FuelOil#1, FuelOil#2, OtherFuel1 or OtherFuel2.
Optimum Part Load Ratio
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Default: 100%
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Typical Range: 0 to 100%
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Min Max: 0 to 100%
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Units: %
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This numeric field contains the chiller’s optimum part-load ratio. This is the part-load ratio at which the chiller performs at its maximum COP.
Sizing Factor
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Default: 100%
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Typical Range: 10 to 100%
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Min Max: 0 to 100%
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Units: %
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The sizing factor is used when the capacity is selected as auto sized. The autosizing calculations are performed as usual and the results are multiplied by the sizing factor.
Design Water Temperatures
Design Entering Condenser Water Temperature
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Default: 95°F/35°C
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Typical Range: 85 to 95°F / 29.4 to 35°C
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Min Max: 75 to 120°F / 23.8 to 48.8°C
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Units: °F / °C
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This field contains the combustion turbine chiller’s condenser inlet design temperature.
Design Leaving Chilled Water Temperature
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Default: 44°F/ 6.67°C
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Typical Range: 43 to 45°F/ 6.11 to 7.22°C
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Min Max: -130 to 158°F / -90 to 70°C
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Units: °F / °C
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This field contains the combustion turbine chiller’s evaporator outlet design temperature.
Operational Limits
Leaving Chilled Water Temperature Low Limit
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Default: 41°F/ 5°C
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Typical Range: 34 to 41°F/ 1.11 to 5°C
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Min Max: -130 to 158°F / -90 to 70°C
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Units: °F / °C
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This numeric field contains the lower limit for the evaporator outlet temperature. This temperature acts as a cut off for heat transfer in the evaporator, so that the fluid doesn’t get too cold.
Gas turbine
Nominal Engine Capacity
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Default: Autosize
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Typical Range: Autosize
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Min Max: 0 to 99,999,999 kW
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Units: W, kW, tons, Btuh, Mbh
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This field contains the capacity of the gas turbine engine in watts.
Exhaust Flow per Engine Capacity
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Default: 0.0000054 (kg/s)/W
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Typical Range: Depends on chiller performance
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Min Max: 0 to 99,999,999 kW
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Units: (lb/hr)/W, (kg/s)/W
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This field contains the maximum exhaust gas mass flow rate per kilowatt of power out.
Design Steam Saturation Temperature
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Default: 302°F
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Typical Range: Depends on chiller performance
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Min Max: 212 to 420°F/ 100 to 215°C
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Units: °F/°C
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This field contains the design steam saturation temperature.
Fuel Higher Heating Value
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Default: 43,500 kJ/kg for Natural Gas
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Typical Range: Depends on fuel type
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Min Max: 20267 to 22453 Btu/lb / 47,130 to 52,210 kJ/kg
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Units: Btu/lb, kJ/kg, J/kg
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Also known as the gross energy of a fuel or gross calorific value. This field contains the higher heating value of the fuel.
Heat Recovery
Enable Heat Recovery
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Default: N/A
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Typical Range: N/A
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Min Max: N/A
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Units: Yes/No
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This field is prompting the user if heat recovery is enabled on this chiller. Heat recovery can be achieved with either a single condenser bundle or an auxiliary condenser.
Nominal Heat Recovery Capacity
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Default: 100%
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Typical Range: 50 to 100%
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Min Max: 0 to 100%
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Units: % of cooling capacity
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This field is represents the amount of thermal energy, as a percentage of the cooling capacity, which can be extracted for service-water heating / pre-heating.
Entering Condenser Water Temp. High Limit
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Default: 100°F/37.78°C
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Typical Range: 100°F to 105°F/37.78°C to 40.56°C
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Min Max: 65°F to 105°F/18.33°C to 40.56°C
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Units: °F/°C
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This field is represents the high limit for the condensing temperature of the water.
Heat Recovery Pump Type
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Default: Constant speed pump
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Typical Range: N/A
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Min Max: N/A
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Units: N/A
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This field is represents what pump type is used to circulate hot water to service-water destination. User can choose either constant speed or variable speed.
Heat Recovery Pump
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Default: 90.1 CV Chilled Water Pump
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Typical Range: N/A
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Min Max: N/A
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Units: N/A
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This field is represents the actual pump and its’ associated properties that will be used for heat recovery.
Curve tab
There are two sets of curves for Water Cooled Chillers depending on the operating mode of the chiller: Cooling Mode and Ice Storage. The description of the curves are below.
The description of the performance curves for the Combustion Turbine Water cooled chillers is listed below.
Capacity Curve
This quadratic curve determines the ratio of available capacity to nominal capacity.
The equation for the Capacity Curve is:
Where:
Nominal Capacity Ratio = Chiller’s available capacity to nominal capacity ratio (%)
C1 to C3 = coefficients
TempCondIn = Temperature entering the condenser (water or air temperature depending on condenser type)
TempCondInDesign = Temp Design Condenser Inlet from User input above
TempEvapOut = Temperature leaving the evaporator
TempEvapOutDesign = Temp Design Evaporator Outlet from User input above
TempRiseCoefficient = User Input from above
The curve has the following fields:
X Axis: Δtemp (°F)
Y Axis: Full Capacity (%)
Curve Type: The curve is quadratic
Min / Max: Minimum and Maximum Delta T
Capacity—Power Curve (Power ratio curve)
This quadratic curve determines the Ratio of Full Load to Power. The equation for the Capacity-Power Curve is:
Where:
C1 to C3 = coefficients
The curve has the following fields:
X Axis: Full capacity (%)
Y Axis: Full Power (%)
Curve Type: The curve is quadratic
Capacity Min / Max: Minimum and Maximum percentage of the capacity
Power Curve (Full Load Ratio)
This quadratic curve determines the fraction of full load power. The equation for the Capacity-Power Curve is:
Where:
C1 to C3 = coefficients
The curve has the following fields:
X Axis: Full capacity (%)
Y Axis: Full Power (%)
Curve Type: The curve is quadratic
Capacity Min / Max: Minimum and Maximum percentage of the capacity
Fuel used Curve (Fuel Input curve)
This polynomial curve determines the Ratio of Fuel Input to Energy Output. The equation for the Fuel used Curve is:
Where:
FIC = Fuel Input Curve Coefficients
TBFIC = Temperature Based Fuel Input Curve Coefficients
RLoad = Ratio of Load to Combustion Turbine Engine Capacity
ATair = The difference between the current ambient temperature and the design ambient temperature
The curve has the following fields:
X Axis: Full load to Capacity (%)
Y Axis: Fuel Use (%)
Curve Type: The curve is quadratic
Load to Capacity Min / Max: Minimum and Maximum percentage of the load to capacity
Fuel used—Temperature Curve
This quadratic curve determines the Ratio of Fuel Input to the Temperature Difference between the current and design ambient temperatures. The equation for the Fuel used Curve is:
Where:
TBFIC = Temperature Based Fuel Input Curve Coefficients
ATair = The difference between the current ambient temperature and the design ambient temperature
The curve has the following fields:
X Axis: 
(°F)
(°F)Y Axis: Fuel Use (%)
Curve Type: The curve is quadratic
, Outdoor Min / Max: Minimum and Maximum Outdoor temperature differenceExhaust Flow Curve
This quadratic curve determines the Ratio of Fuel Input to the Temperature Difference between the current and design ambient temperatures. The equation for the Fuel used Curve is:
Where:
y = Exhaust Flow
(%)
(%)C1 to C3 = coefficients
GTCapacity = The Combustion Turbine Engine Capacity
ATair = The difference between the current ambient temperature and the design ambient temperature
The curve has the following fields:
X Axis: (°F)
(°F)Y Axis: Fuel Use (%)
Curve Type: The curve is quadratic
Outdoor Min / Max: Minimum and Maximum Outdoor temperature differenceExhaust Temperature – Load Curve
This quadratic curve determines the Ratio of Exhaust Gas Flow Rate to the Engine Capacity. The equation for the Fuel used Curve is:
Where:
C1 to C3 = coefficients
TBC = Temperature Based Exhaust Gas Curve Coefficients
RLoad = the Ratio of Load to Combustion turbine capacity
ATair = The difference between the current ambient temperature and the design ambient temperature
The curve has the following fields:
X Axis: Load to Capacity (%)
Y Axis: Exhaust Temperature (%)
Curve Type: The curve is quadratic
, Outdoor Min / Max: Minimum and Maximum Outdoor temperature differenceExhaust Temperature – Ambient Curve
This quadratic curve determines the Ratio of Fuel Input to the Temperature Difference between the current and design ambient temperatures. The equation for the Fuel used Curve is:
Where:
Exhaust Temperature = ()
)TBC = Temperature Based Exhaust Gas Curve Coefficients
RLoad = the Ratio of Load to Combustion turbine capacity
ATair = The difference between the current ambient temperature and the design ambient temperature
The curve has the following fields:
X Axis: ΔT (°F)
Y Axis: Exhaust Temperature ()
)Curve Type: The curve is quadratic
ΔT, Outdoor Min / Max: Minimum and Maximum Outdoor temperature difference
Lube Heat Recovery Curve
This quadratic curve determines the Ratio of Fuel Input to the Temperature Difference between the current and design ambient temperatures. The equation for the Fuel used Curve is:
Where:
PLoad = Engine load
C1 to C3 = coefficients
RL = Ratio of Load to Combustion Turbine Engine Capacity
The curve has the following fields:
X Axis: Load to Capacity (%)
Y Axis: Heat Recovery (%)
Curve Type: The curve is quadratic
ΔT, Outdoor Min / Max: Minimum and Maximum Outdoor temperature difference
UA Capacity Curve
This linear curve determines the overall heat transfer coefficient for the exhaust gasses in the stack. The heat transfer coefficient ultimately helps determine the exhaust stack temperature.
Where:
y = UA (%)
C1 = coefficient
GasTurbineEngineCapacity = Engine Capacity (W)
The curve has the following fields:
X Axis: Load to Capacity (%)
Y Axis: Heat Recovery (%)
Curve Type: The curve is quadratic
ΔT, Outdoor Min / Max: Minimum and Maximum Outdoor temperature difference
Engine Driven Chiller
The Engine Driven Chiller uses a fuel fired engine to drive the compressor. The fuel can be natural gas, propane gas, diesel or gasoline.
Nominal Cooling Capacity
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Default: Autosize
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Typical Range: 50 to 500 tons
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Min Max: 0 < X< 999,999
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Units: tons, W, kW, Btuh, Mbh
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This field specifies the nominal cooling capacity of the chiller.
Full Load Energy Rate
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Default: 1.28 COP
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Typical Range: 1 to 1.5 COP
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Min Max: 0 to 999,999
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Units: kW/ton, therms/ton-hr, Mbh/ton, kW/Mbh, kW/kW, COP, EER
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This numeric input field is the chiller’s coefficient of performance.
Temperature Rise Coefficient
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Default: 2.778
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Typical Range: 2.778
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Min Max: 0 to 999,999
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Units: N/A
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This field contains the electric chiller’s temperature rise coefficient which is defined as the ratio of the required change in condenser water temperature to a given change in chilled water temperature, which maintains the capacity at the nominal value. This is calculated as the following ratio:
where:
TCEntrequired = required entering condenser air or water temperature to maintain rated capacity
TCEntrated = rated entering condenser air or water temperature at rated capacity
TELvrequired = required leaving evaporator water outlet temperature to maintain rated capacity
TELvrated = rated leaving evaporator water outlet temperature at rated capacity
Fuel Type
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Default: Natural Gas
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Typical Range: N/A
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Min Max: N/A
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Units: N/A
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This field determines the type of fuel that the chiller uses. Fuel types are: NaturalGas, PropaneGas, Diesel, Gasoline, FuelOil#1, FuelOil#2, OtherFuel1 or OtherFuel2.
Optimum Part Load Ratio
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Default: 100%
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Typical Range: 10 to 100%
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Min Max: 0 to 100%
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Units: %
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This numeric field contains the chiller’s optimum part-load ratio. This is the part-load ratio at which the chiller performs at its maximum COP.
Sizing Factor
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Default: 100%
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Typical Range: 10 to 100%
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Min Max: 0 to 100%
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Units: %
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The sizing factor is used when the capacity is selected as auto sized. The autosizing calculations are performed as usual and the results are multiplied by the sizing factor.
Max Temp for Heat Recovery
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Default: 60°F/15.56°C
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Typical Range: 50 to 60°F / 10 to 15.56°C
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Min Max: 50 to 60°F / 10 to 15.56°C
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Units: °F / °C
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The max temp for heat recovery is the maximum condensing temperature that can be used.
Design Water Temperatures
Design Entering Condenser Water Temperature
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Default: 95°F/35°C
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Typical Range: 85 to 95°F / 29.4 to 35°C
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Min Max: 75 to 120°F / 23.8 to 35°C
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Units: °F / °C
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This field contains the combustion turbine chiller’s condenser inlet design temperature.
Design Leaving Chilled Water Temperature
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Default: 44°F/6.67°C
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Typical Range: 43 to 45°F/ 6.11 to 7.22°C
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Min Max: -130 to 158°F / -90 to 70°C
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Units: °F / °C
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This field contains the combustion turbine chiller’s evaporator outlet design temperature.
Operational Limits
Leaving Chilled Water Temperature Low Limit
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Default: 41°F/5°C
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Typical Range: 34 to 41°F/ 1.11 to 5°C
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Min Max: -130 to 158°F / -90 to 70°C
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Units: °F / °C
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This numeric field contains the lower limit for the evaporator outlet temperature. This temperature acts as a cut off for heat transfer in the evaporator, so that the fluid doesn’t get too cold.
Exhaust
Exhaust Flow per Engine Capacity
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Default: 0.00063 (kg/s)/W
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Typical Range: Depends on chiller performance
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Min Max: 0 to 99,999,999 kW
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Units: (lb/hr)/W, (kg/s)/W
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This field contains the maximum exhaust gas mass flow rate per kilowatt of cooling provided by the engine driven chiller.
Design Minimum Exhaust Temperature
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Default: 32°F
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Typical Range: Depends on chiller performance
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Min Max: 212 to 420°F/100 to 215°C
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Units: °F/°C
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This field contains the design steam saturation temperature that would be used to determine the energy recovered from a water jacket heat exchanger on the engine.
Fuel Higher Heating Value
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Default: 43,500 kJ/kg for Natural Gas
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Typical Range: Depends on fuel type
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Min Max: 20267 to 22453 Btu/lb / 47,130 to 52,210 kJ/kg
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Units: Btu/lb, kJ/kg, J/kg
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Also known as the gross energy of a fuel or gross calorific value. This field contains the higher heating value of the fuel used.
Heat Recovery
Enable Heat Recovery
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Default: N/A
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Typical Range: N/A
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Min Max: N/A
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Units: Yes/No
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This field is prompting the user if heat recovery is enabled on this chiller. Heat recovery can be achieved with either a single condenser bundle or an auxiliary condenser.
Heat Recovery Maximum Temperature
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Default: 140°F
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Typical Range: 100 to 140°F / 37.78 to 60 °C
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Min Max: 100 to 140°F / 37.78 to 60 °C
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Units: °F
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This field is represents the maximum service-water temperature that can be generated from heat recovery.
Nominal Heat Recovery Capacity
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Default: 100%
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Typical Range: 50 to 100%
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Min Max: 0 to 100%
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Units: % of cooling capacity
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This field is represents the amount of thermal energy, as a percentage of the cooling capacity, which can be extracted for service-water heating / pre-heating.
Heat Recovery Pump Type
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Default: constant speed pump
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Typical Range: N/A
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Min Max: N/A
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Units: N/A
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This field is represents what pump type is used to circulate hot water to service-water destination. User can choose either constant speed or variable speed.
Heat Recovery Pump
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Default: 90.1 CV chilled water pump
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Typical Range: N/A
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Min Max: N/A
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Units: N/A
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This field is represents the actual pump and its’ associated properties that will be used for heat recovery.
Curve tab
The description of the performance curves for the Engine Driven Air cooled chillers is listed below.
Capacity Ratio Curve
This quadratic curve determines the ratio of available capacity to nominal capacity.
The equation for the Capacity Curve is:
Where:
y = Chiller’s available capacity to nominal capacity ratio (%)
C1 to C3 = coefficients
TempCondIn = Temperature entering the condenser (water or air temperature depending on condenser type)
TempCondInDesign = Temp Design Condenser Inlet from User input above
TempEvapOut = Temperature leaving the evaporator
TempEvapOutDesign = Temp Design Evaporator Outlet from User input above
TempRiseCoefficient = User Input from above
The curve has the following fields:
X Axis: ΔT (°F)
Y Axis: Full Capacity (%)
Curve Type: The curve is quadratic
ΔT Min / Max: Minimum and Maximum Delta T
Capacity –Power Curve (Power ratio curve)
This quadratic curve shows the percentage of full power capacity as a function of the chiller’s capacity. The equation for the Capacity-Power Curve is:
Where:
C1 to C3 = coefficients
The curve has the following fields:
X Axis: Full capacity (%)
Y Axis: Full Power (%)
Curve Type: The curve is quadratic
Capacity Min / Max: Minimum and Maximum percentage of the capacity
Power Curve (Full Load Ratio )
This quadratic curve determines the fraction of full load power. The equation for the Capacity-Power Curve is:
Where:
C1 to C3 = coefficients
The curve has the following fields:
X Axis: Full capacity (%)
Y Axis: Full Power (%)
Curve Type: The curve is quadratic
Capacity Min / Max: Minimum and Maximum percentage of the capacity
Fuel used Curve (Fuel Input curve )
This quadratic curve determines the Ratio of Cooling Load to Fuel Energy. The equation for the Fuel used Curve is:
Where:
C1 to C3 = Coefficients
PLR = Part Load Ratio
The curve has the following fields:
X Axis: Full load (%)
Y Axis: Full Power (%)
Curve Type: The curve is quadratic
Capacity Min / Max: Minimum and Maximum percentage of the load
Jacket Heat Recovery Curve
This quadratic curve determines the ratio of heat recovery to fuel energy. The equation for the Jacket Heat Recovery Curve is:
Where:
y = Heat Recovery Ratio
C1 to C3 = coefficients
RL = Ratio of Load to Engine Capacity
The curve has the following fields:
X Axis: Ratio of Load to Diesel Energy Consumption
Y Axis: Heat Recovery Ratio (%)
Curve Type: The curve is quadratic
Full Load Min / Max: Minimum and Maximum percentage of the load to capacity
Lube Heat Recovery Curve
This quadratic curve determines the ratio of recovery lube heat to fuel energy. The equation for the Jacket Heat Recovery Curve is:
Where:
y = Heat Recovery Ratio
C1 to C3 = coefficients
RL = Ratio of Load to Engine Capacity
The curve has the following fields:
X Axis: Ratio of Load to Diesel Energy Capacity
Y Axis: Heat Recovery Ratio (%)
Curve Type: The curve is quadratic
Full Load Min / Max: Minimum and Maximum percentage of the load to capacity
Total Exhaust Energy Curve
This quadratic curve determines the ratio of total exhaust energy to fuel energy. The equation for the Total Exhaust Energy is:
Where:
y = Heat Recovery Ratio
C1 to C3 = coefficients
RL = Ratio of Load to Engine Capacity
The curve has the following fields:
X Axis: Ratio of Load to Diesel Energy Capacity
Y Axis: Exhaust Temperature (%)
Curve Type: The curve is quadratic
Outdoor Min / Max: Minimum and Maximum Outdoor temperature differenceExhaust Temperature Curve
This quadratic curve determines the Ratio of Fuel Input to the Temperature Difference between the current and design ambient temperatures. The equation for the Exhaust Temperature is:
Where:
y = Heat Recovery Ratio
C1 to C3 = coefficients
RL = Ratio of Load to Engine Capacity
The curve has the following fields:
X Axis: ΔT (°F)
Y Axis: Exhaust Temperature (%)
Curve Type: The curve is quadratic
, Outdoor Min / Max: Minimum and Maximum Outdoor temperature differenceUA Capacity Curve
The U-Factor times Area (UA) is an equation that determines the overall heat transfer coefficient for the exhaust gasses with the stack:
Where:
y = UA
C1 to C2 = coefficients
The curve has the following fields:
X Axis: Load to Capacity (%)
Y Axis: Heat Recovery (%)
Curve Type: The curve is quadratic
Water-to-Water Heat Pump
The heat pump has a reciprocating compressor that serves both the hot water and the chilled water loop.
Rated Cooling Capacity
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Default: Autosize
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Typical Range: 50 to 500 tons
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Min Max: 0 < x < 999,999
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Units: tons, W, kW, Btuh, Mbh
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This field specifies the rated cooling capacity of the heat pump.
Rated Cooling Power Consumption
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Default: 0.44 kW/ton
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Typical Range: 0.4 to 0.5 kW/ton
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Min Max: 0 to 999,999
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Units: kW/ton, therms/ton-hr, Mbh/ton, kW/Mbh, kW/kW, COP, EER
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This numeric input field is the heat pumps’ rated electric power consumption.
Sizing Factor
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Default: 100%
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Typical Range: 10 to 100%
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Min Max: 0 to 999,999
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Units: %
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The sizing factor is used when the capacity is selected as auto sized. The autosizing calculations are performed as usual and the results are multiplied by the sizing factor.
Heating Mode
Rated Heating Capacity
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Default: Autosize
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Typical Range: 5 to 150 tons
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Min Max: 0 < x < 999,999
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Units: tons, W, kW, Btuh, Mbh
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This field specifies the rated heating capacity of the chiller.
Rated Heating Power Consumption
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Default: 0.04 kW/MBH heating
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Typical Range: 0.03 to 0.05 kW/MBH
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Min Max: 0 to 999,999
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Units: kW/ton, therms/ton-hr, Mbh/ton, kW/Mbh, kW/kW, COP, EER
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This numeric input field is the heat pumps’ rater power consumption.
Curve tab
The description of the performance curves for the Engine Driven Air cooled chillers is listed below.
Cooling Mode
Capacity Curve
This equation uses a least square method with a set of performance coefficients to simulate heat pump performance
The equation for the Capacity Curve is:
Where:
Qc = Load Side Heat Transfer Rate
Qc,ref = Highest Cooling Capacity / Design Cooling Capacity
A1-A5 = Equation Fit Coefficients for Cooling Mode Capacity
TL,in = Entering Load Side Water Temperature, K
Tref = 283.15 K
TS,in = Entering Source Side Water Temperature, K
= Load Side Volumetric Flow Rate, m3/s= Supply Side Volumetric Flow Rate, m3/sThe curve has the following fields:
X Axis:Tload (°F)
Y Axis: Full Capacity (%)
Power Curve
This biquadratic curve shows the percentage of full load power as a function of the load. The equation for the Power Curve is:
Where:
Powerc = Power Consumption in Cooling Mode
Powerc,ref = Highest Power Consumption/ Design Power Consumption Capacity
B1-B5 = Equation Fit Coefficients for Cooling Mode Capacity
TL,in = Entering Load Side Water Temperature, K
Tref = 283.15 K
TS,in = Entering Source Side Water Temperature, K
= Load Side Volumetric Flow Rate, m3/s= Supply Side Volumetric Flow Rate, m3/sThe curve has the following fields:
X Axis:Tload (°F)
Y Axis: Full Capacity (%)
Heating Mode
Capacity Curve
This equation uses a least square method with a set of performance coefficients to simulate heat pump performance. The equation for the Capacity Curve is:
Where:
Qc = Load Side Heat Transfer Rate
Qc,ref = Highest Cooling Capacity / Design Cooling Capacity
C1-C5 = Equation Fit Coefficients for Cooling Mode Capacity
TL,in = Entering Load Side Water Temperature, K
Tref = 283.15 K
TS,in = Entering Source Side Water Temperature, K
= Load Side Volumetric Flow Rate, m3/s= Supply Side Volumetric Flow Rate, m3/sThe curve has the following fields:
X Axis:Tload (°F)
Y Axis: Full Capacity (%)
Power Curve
This biquadratic curve shows the percentage of full load power as a function of the load. The equation for the Power Curve is:
Where:
Powerh = Power Consumption in Heating Mode
Powerh,ref = Highest Power Consumption/ Design Power Consumption Capacity
D1-D5 = Equation Fit Coefficients for Cooling Mode Capacity
TL,in = Entering Load Side Water Temperature, K
Tref = 283.15 K
TS,in = Entering Source Side Water Temperature, K
= Load Side Volumetric Flow Rate, m3/s= Supply Side Volumetric Flow Rate, m3/sThe curve has the following fields:
X Axis:Tload (°F)
Y Axis: Full Capacity (%)