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