Fuzzy logic liquid level control
AssigneeYork International Corporation
InventorsGregory K. Beaverson, Craig N. Shores, Russel P. Wueschinski
Life of this patent
Estimating the term…
Abstract
Chiller operating efficiency is optimized by controlling the system to maintain the condenser liquid refrigerant level at a value which will minimize or prevent gas bypass to the evaporator. This is accomplished by sensing the level of liquid refrigerant in the condensor and incorporating fuzzy logic to properly position a multi-position valve which can variably restrict the flow of this liquid into the evaporator, according to this sensed parameter. The fuzzy logic utilizes as inputs both the level error from a set point level and the rate of change of the sensed level. Each of these inputs are combined by fuzzy logic techniques to provide the required output signal to control the opening and closing of the valve.
Claims21
A refrigeration system comprising:
- an evaporator, a compressor, a condensor, and an expansion device, all connected in a closed refrigeration circuit through which refrigerant is cycled;
- refrigerant liquid within the condensor;
- a sensor for measuring the liquid refrigerant level in the condensor and providing a measurement signal;
- said expansion device being capable of selectively varying the degree of restriction it applies to the flow of refrigerant as it flows through the device in response to a control signal;
- and
- a microprocessor control which samples the measurement signal at selected intervals and applies the sampled measurement signals in a programmable predetermined manner designed to minimize or eliminate the flow of gas refrigerant to said evaporator.
A refrigeration system comprising:
- an evaporator, a compressor, a condensor and an expansion device, all connected in a closed refrigeration circuit, through which refrigerant is cycled,
- refrigerant liquid in the condensor;
- a sensor for measuring the refrigerant liquid level in the condensor and providing a measurement signal;
- said expansion device being positioned between the evaporator and the condensor and being capable of selectively varying the degree of restriction it applies to the flow of refrigerant between the condensor and the evaporator in response to a control signal;
- and
- a microprocessor control which receives the measurement signal from the sensor and develops the control signal to thereby control the flow of refrigerant from the condensor to the evaporator, wherein the control uses a fuzzy logic algorithm having programmable fuzzy logic membership functions to minimize or eliminate the flow of gas refrigerant to said evaporator.
Dependencies are inferred from the claim text.