Method and apparatus for optimizing refrigeration systems
First Claim
1. A method for controlling operation of a refrigeration system having an evaporator and a refrigerant accumulator within the refrigeration system, comprising:
- measuring evaporator performance during operation with respect to refrigerant level;
defining an inner control loop for controlling a rate of supply of liquid refrigerant to the evaporator; and
defining an outer control loop which controls a partitioning of refrigerant between the evaporator and the refrigerant accumulator, to selectively alter a refrigerant level in the evaporator, said refrigerant level being altered based on at least the measured evaporator performance during operation.
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Accused Products
Abstract
A refrigeration system comprising a compressor for compressing a refrigerant, a condenser for condensing refrigerant to a liquid, an evaporator for evaporating liquid refrigerant from the condenser to a gas, an inner control loop for optimizing a supply of liquid refrigerant to the evaporator, and an outer control loop for optimizing a level of refrigerant in the evaporator, said outer control loop defining a supply rate for said inner control loop based on an optimization including measurement of evaporator performance, and said inner control loop optimizing liquid refrigerant supply based on said defined supply rate. Independent variables, such as proportion of oil in refrigerant, amount of refrigerant, contaminants, non-condensibles, scale and other deposits on heat transfer surfaces, may be estimated or measured. A model of the system and/or a thermodynamic model approximating the system, for example derived from temperature and pressure gages, as well as power computations or measurements, is employed to determine or estimate the effect on efficiency of deviance from an optimal state. Various methods are provided for returning the system to an optimal state, and for calculating a cost-effectiveness of employing such processes.
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Citations
20 Claims
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1. A method for controlling operation of a refrigeration system having an evaporator and a refrigerant accumulator within the refrigeration system, comprising:
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measuring evaporator performance during operation with respect to refrigerant level; defining an inner control loop for controlling a rate of supply of liquid refrigerant to the evaporator; and defining an outer control loop which controls a partitioning of refrigerant between the evaporator and the refrigerant accumulator, to selectively alter a refrigerant level in the evaporator, said refrigerant level being altered based on at least the measured evaporator performance during operation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A refrigeration system comprising:
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a compressor configured to compress a refrigerant; a condenser configured to condense refrigerant to a liquid; an evaporator configured to evaporate liquid refrigerant from the condenser to a gas; and an adaptive controller which is configured to control both; a supply rate of liquid refrigerant to the evaporator, and a varying partitioning of liquid refrigerant between the evaporator and an accumulator, to vary a level of liquid refrigerant in the evaporator, based on at least system load and prior measurements of refrigeration system performance at respectively different system loads. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A control system adapted for controlling operation of a refrigeration system having an evaporator, comprising:
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an input configured to receive data representing at least one measurement of refrigeration system efficiency during operation with respect to at least a refrigerant level in the evaporator and a respective system load; an inner control loop configured to control a rate of supply of liquid refrigerant to the evaporator; and an outer control loop configured to influence the inner control loop, to modify the rate of supply of liquid refrigerant to the evaporator to alter a level of refrigerant in the evaporator and a partitioning of refrigerant between the evaporator and a refrigerant accumulator, said altered level being determined based on at least a prior measured refrigeration system efficiency during operation and a system load. - View Dependent Claims (18, 19, 20)
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Specification