Method and apparatus for measuring and improving efficiency in refrigeration systems
An apparatus for optimizing an efficiency of a refrigeration system, comprising means for measuring a refrigeration efficiency of an operating refrigeration system; means for altering a process variable of the refrigeration system during efficiency measurement; and a processor for calculating a process variable level which achieves an optimum efficiency. The process variables may include refrigerant charge and refrigerant oil concentration in evaporator.
1. A multivariate system for controlling a refrigeration system, comprising:
a plurality of inputs which together represent a plurality of independent variables representing a thermodynamic operational state of the refrigeration system;
a memory storing data describing a thermodynamic predictive mathematical model of the refrigeration system associated with the plurality of inputs, the model being adaptively defined based on prior operational states of the plurality of inputs and having at least one adaptively defined timeconstant;
at least one processor, configured to receive the plurality of inputs, to access the stored model, to perform an analysis of the model with respect to the plurality of inputs to determine a probable deviance from an optimal operating point, and to determine change in the operational state of the refrigeration system to achieve a predicted most-efficient operational state; and
an output port configured to present an output signal representing the determined change in the operational state.
2. The system according to claim 1 , wherein the at least one processor is further configured to generate a revised model when an actual performance of the refrigeration system does not correspond to the model stored in the memory.
3. The system according to claim 1 , wherein the output signal comprises at least two control signals adapted for independently controlling different physical elements of the refrigeration system.
4. The system according to claim 1 , wherein the predicted most-efficient operational state is a predicted most cost-efficient operational state of the refrigeration system.
5. The system according to claim 1 , wherein the predicted most-efficient operational state is a predicted most cost-efficient operational state of the refrigeration system and a process which produces heat removed by the refrigeration system.
6. The system according to claim 1 , wherein the at least one processor is configured to accounts for a plurality of time delays inherent in the refrigeration system and a process which produces heat removed by the refrigeration system.
7. The system according to claim 1 , wherein the model accounts for a time response of the refrigeration system, and the processor is configured to selectively define at least one dynamic control variable for the refrigeration system in a manner which damps an oscillation of the refrigeration system.
8. The system according to claim 1 , wherein the plurality of inputs comprise at least two different temperatures and at least two different temperatures of different portions of the refrigeration system which are concurrently presented.
9. The system according to claim 1 , wherein the at least one processor is configured to analyze the model to define a physical remediation representing an external change to the refrigeration system adapted to increase an efficiency of the refrigeration system over a range of operating conditions, based on at least a change in the refrigeration system inferred from the plurality of inputs since a prior remediation was completed.
10. A method for controlling a refrigeration system, comprising:
receiving a plurality of inputs which together represent a plurality of independent variables representing a thermodynamic operational state of the refrigeration system;
storing data describing a thermodynamic predictive mathematical model of the refrigeration system associated with the plurality of inputs in a memory, the model being adaptively defined based on prior operational states of the plurality of inputs and having at least one adaptively defined timeconstant;
performing an analysis of the model, using at least one automated processor, with respect to the plurality of inputs to:
determine a probable deviance from an optimal operating point, and
determine change in the operational state of the refrigeration system to achieve a predicted most-efficient operational state; and
presenting an output signal representing the determined change.
11. The method according to claim 10 , wherein the output signal represents a control signal for dynamically controlling the refrigeration system, further comprising controlling the refrigeration system selectively in dependence on the output signal to tend toward the predicted most-efficient operational state.
12. The method according to claim 10 , further comprising generating a revised model when an actual performance of the refrigeration system does not correspond to the model.
13. The method according to claim 10 , wherein the output signal comprises at least two control signals for independently controlling different physical elements of the refrigeration system.
14. The method according to claim 10 , wherein the predicted most-efficient state is a predicted most cost-efficient operational state of the refrigeration system and a process which produces heat removed by the refrigeration system.
15. The method according to claim 10 , further comprising accounting for a plurality of time delays in order to produce the output signal.
16. The method according to claim 10 , wherein the model accounts for a time response of the refrigeration system, further comprising selectively defining at least one dynamic control variable for the refrigeration system in a manner which damps an oscillation of the refrigeration system.
17. The method according to claim 10 , wherein the plurality of inputs comprise at least two different temperatures and at least two different temperatures of different portions of the refrigeration system which are concurrently presented.
18. The method according to claim 10 , further comprising analyzing the model to determine a physical remediation representing an external change to the refrigeration system adapted to increase an efficiency of the refrigeration system over a range of operating conditions, based on at least a change in the refrigeration system inferred from the plurality of inputs since a prior remediation was completed.
19. The method according to claim 18 , wherein the physical remediation comprises a physical removal of impurities from at least a refrigerant in an evaporator of the refrigeration system.
20. A method for controlling a thermodynamic system comprising a compressible gas, a compressor, and an expander, comprising:
receiving a plurality of inputs which represent a thermodynamic state of the compressor, and a thermodynamic state of the expander, and together having sufficient information to derive an efficiency of the thermodynamic system;
storing data describing a mathematical model of the thermodynamic system associated with the plurality of inputs in a memory, the model being adaptively defined and having at least one dynamically changing timeconstant;
performing an analysis of the model, using at least one automated processor, with respect to the plurality of inputs to:
determine a probable deviance from an optimal efficiency, and
determine change in an operational state of the thermodynamic system to achieve a state representing the optimal efficiency; and
presenting an output signal for controlling the thermodynamic system selectively defined in dependence on the determined change.