Evaporator water temperature control for a chiller system
First Claim
1. A method of controlling the capacity of a chiller system, the chiller system including a circularly linked compressor, condenser, expansion device, and evaporator, the method comprising the steps of:
- measuring a first chiller system parameter;
determining a first parameter error as a function of the difference between the first parameter and a first setpoint;
measuring a second chiller system parameter;
determining a second parameter error as a function of the difference between the second parameter and a second setpoint;
providing a first mode of capacity control where the compressor is modulated in response to the first parameter error and the expansion valve is modulated in response to the second parameter error; and
providing a second mode of capacity control where the compressor is maintained at a minimum capacity and the expansion valve is modulated in response to the first parameter error.
3 Assignments
0 Petitions
Accused Products
Abstract
A method of controlling the capacity of a chiller system, the chiller system including a circularly linked compressor, condenser, expansion device, and evaporator. The method comprises the steps of: measuring a first chiller system parameter; determining a first parameter error as a function of the difference between the first parameter and a first setpoint; measuring a second chiller system parameter; determining a second parameter error as a function of the difference between the second parameter and a second setpoint; providing a first mode of capacity control where the compressor is modulated in response to the first parameter error and the expansion valve is modulated in response to the second parameter error; and providing a second mode of capacity control where the compressor is maintained at a minimum capacity and the expansion valve is modulated in response to the first parameter error.
67 Citations
19 Claims
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1. A method of controlling the capacity of a chiller system, the chiller system including a circularly linked compressor, condenser, expansion device, and evaporator, the method comprising the steps of:
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measuring a first chiller system parameter; determining a first parameter error as a function of the difference between the first parameter and a first setpoint; measuring a second chiller system parameter; determining a second parameter error as a function of the difference between the second parameter and a second setpoint; providing a first mode of capacity control where the compressor is modulated in response to the first parameter error and the expansion valve is modulated in response to the second parameter error; and providing a second mode of capacity control where the compressor is maintained at a minimum capacity and the expansion valve is modulated in response to the first parameter error. - View Dependent Claims (2, 3, 4, 5)
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6. A method of controlling the capacity of a chiller system, the chiller system including a circularly linked compressor, condenser, expansion device, and evaporator, where the evaporator receives entering water having an entering water temperature and provides leaving water having a leaving water temperature and where the compressor compresses refrigerant having a measured superheat, the method comprising the steps of:
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measuring the leaving water temperature and the refrigerant superheat; determining a leaving water temperature error as a function of the difference between the leaving water temperature and a setpoint; providing a first mode of capacity control wherein the compressor is modulated in response to the leaving water temperature error and the expansion valve is modulated in response to the measured superheat; and providing a second mode of capacity control where the compressor is maintained at its minimum capacity and the expansion valve is modulated in response to the leaving water temperature error. - View Dependent Claims (7, 8, 9)
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10. A method of controlling the capacity of a chiller system comprising the steps of:
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determining a needed capacity for the chiller system; adjusting a compressor flow control means to meet the needed capacity; repositioning an expansion valve in response to the adjusting step; determining if the compressor flow control means is at an end of range capacity; and modulating the position of the expansion valve to control chiller system capacity whenever the flow control means has been determined to be at an end of capacity range. - View Dependent Claims (11)
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12. A method of controlling the capacity of a water chiller system having a variable capacity compressor, a variable capacity expansion device, and an evaporator having a leaving water temperature, the method comprising the steps of:
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measuring the leaving water temperature; comparing the leaving water temperature to a setpoint so as to determine an error; modulating the compressor capacity to minimize the error unless the compressor capacity is at a minimum capacity position; maintaining the compressor at the minimum capacity position; and modulating the expansion device to minimize the error.
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13. A method of selecting between first and second modes of capacity control for a water chiller system including an evaporator having an entering fluid temperature and a leaving fluid temperature, the method comprising the steps of:
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determining the leaving fluid temperature; determining the entering fluid temperature; determining a differential temperature as a function of the difference between the leaving fluid temperature and the entering fluid temperature; determining a temperature error as a function of the difference between the leaving fluid temperature and a setpoint; and selecting either the first or second mode of capacity control as a function of the temperature differential and the temperature error. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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Specification