OIL CIRCULATION OBSERVER FOR HVAC SYSTEMS
First Claim
1. A method of monitoring a parameter related to lubricant in a first component of a vapor compression cycle system, comprising:
- estimating a first parameter which indicates a first amount of retained lubricant in a first other component of the vapor compression cycle system using a dynamic, non-linear observer model to generate an estimated first parameter;
estimating a second parameter which indicates a second amount of retained lubricant in a second other component of the vapor compression cycle system to generate an estimated second parameter;
summing the estimated first parameter and the estimated second parameter to generate a summed estimated parameter; and
subtracting the summed estimated parameter from a parameter related to a known total lubricant in the vapor compression cycle system to generate a difference parameter, the difference parameter indicating an amount of lubricant retained in the first component of the vapor compression cycle system.
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Abstract
An innovative oil observer for estimating oil concentration and oil amount in a refrigerant compressor in a vapor compression cycle is described. The invention ensures the safe operation of the compressor by ensuring that adequate lubricant is present in the compressor. This oil observer is based on oil models for components of air conditioning and refrigeration systems. Oil models for HVAC components estimate oil mass and refrigerant mass in each component. With all component oil models and heat exchanger observers which provide the estimation of inner geometric lengths of two-phase flow heat exchangers, a system-level oil observer is established by integrating all component models. Experimental testing has been conducted to verify the performance of this oil observer for steady state operation and dynamic processes. The invention has direct applications in residential and commercial air conditioning and refrigeration systems.
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Citations
22 Claims
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1. A method of monitoring a parameter related to lubricant in a first component of a vapor compression cycle system, comprising:
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estimating a first parameter which indicates a first amount of retained lubricant in a first other component of the vapor compression cycle system using a dynamic, non-linear observer model to generate an estimated first parameter; estimating a second parameter which indicates a second amount of retained lubricant in a second other component of the vapor compression cycle system to generate an estimated second parameter; summing the estimated first parameter and the estimated second parameter to generate a summed estimated parameter; and subtracting the summed estimated parameter from a parameter related to a known total lubricant in the vapor compression cycle system to generate a difference parameter, the difference parameter indicating an amount of lubricant retained in the first component of the vapor compression cycle system. - View Dependent Claims (2, 3, 4, 21)
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- 5. A refrigeration apparatus comprising a device for monitoring a parameter related to lubricant in a first component of the refrigeration apparatus, the device estimating a first parameter which indicates a first amount of retained lubricant in a first other component of the refrigeration apparatus using a dynamic, non-linear observer model to generate an estimated first parameter, estimating a second parameter which indicates a second amount of retained lubricant in a second other component of the refrigeration apparatus to generate an estimated second parameter, summing the estimated first parameter and the estimated second parameter to generate a summed estimated parameter, and subtracting the summed estimated parameter from a parameter related to a known total lubricant in the refrigeration apparatus to generate a difference parameter, the difference parameter indicating an amount of lubricant retained in the first component of the refrigeration apparatus.
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9. A method of monitoring a parameter related to lubricant in a component of a vapor compression cycle system, comprising:
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detecting a parameter related to a state of the component; and using the parameter related to the state of the component and a dynamic, non-linear observer model in which the state of the component is a function of time, estimating the parameter related to lubricant in the component. - View Dependent Claims (10, 11, 12)
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- 13. A refrigeration apparatus comprising a device for monitoring a parameter related to lubricant in a component of the refrigeration apparatus, the device detecting a parameter related to a state of the component and, using the parameter related to the state of the component and a dynamic, non-linear observer model in which the state of the component is a function of time, estimating the parameter related to lubricant in the component.
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17. A method of monitoring a parameter related to lubricant in a heat exchanger of a vapor compression cycle system, comprising:
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determining a length of a two-phase portion of the heat exchanger; and using the length of the two-phase portion of the heat exchanger and a dynamic, non-linear heat exchanger observer model in which the length of the two-phase portion is a function of time, estimating the parameter related to lubricant in the heat exchanger.
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18. A refrigeration apparatus for monitoring a parameter related to lubricant in a heat exchanger of a vapor compression cycle system, comprising a device for determining a length of a two-phase portion of the heat exchanger and, using the length of the two-phase portion of the heat exchanger and a dynamic, non-linear heat exchanger observer model in which the length of the two-phase portion is a function of time, estimating the parameter related to lubricant in the heat exchanger and producing an output signal indicative of a parameter related to lubricant in the heat exchanger.
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19. A method of monitoring a parameter related to lubricant in a heat exchanger of a vapor compression cycle system, comprising:
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determining a length of a single-phase portion of the heat exchanger; and using the length of the single-phase portion of the heat exchanger and a dynamic, non-linear heat exchanger observer model in which the length of the single-phase portion is a function of time, estimating the parameter related to lubricant in the heat exchanger.
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20. A refrigeration apparatus for monitoring a parameter related to lubricant in a heat exchanger of a vapor compression cycle system, comprising a device for determining a length of a single-phase portion of the heat exchanger and, using the length of the single-phase portion of the heat exchanger and a dynamic, non-linear heat exchanger observer model in which the length of the single-phase portion is a function of time, estimating the parameter related to lubricant in the heat exchanger and producing an output signal indicative of a parameter related to lubricant in the heat exchanger.
Specification