Refrigeration System and Method Enabling Demand Flexibility

Abstract

A refrigeration system includes one or multiple refrigeration compartments, one or multiple phase change evaporators, one or multiple fans, a compressor and a condenser. The phase change evaporators and fans are within the refrigeration compartments, and comprises an open cell heat conductive foam having a phase change material embedded within the cells of the open cell heat conductive foam. A refrigerant conduit is provided and is in thermal contact with the open cell heat conductive foam, and contains a refrigerant fluid and communicates with a refrigeration cycle conduit which circulates the refrigerant in a refrigeration cycle. The fans are provided to increase heat transfer between the phase change evaporators and the refrigeration compartments. A method of refrigerating a refrigeration compartment and a phase change evaporator are disclosed. A method for refrigerating a refrigeration compartment, and an evaporator for a refrigeration system are also disclosed.

We claim: 
     
         1 . A refrigeration system, comprising:
 a refrigeration compartment;   a phase change evaporator in thermal contact with the refrigeration compartment, the phase change evaporator comprising a housing containing an open cell heat conductive metal foam and a phase change material embedded within the cells of the open cell heat conductive metal foam, and a refrigerant conduit in thermal contact with the open cell heat conductive foam, the refrigerant conduit containing a refrigerant fluid;   a compressor and a condenser in refrigerant fluid communication with the refrigerant conduit of the phase change evaporator; and,   a fan designated for enforced heat transfer between the phase change evaporator and the refrigeration compartment air.   
     
     
         2 . The refrigeration system of  claim 1 , further comprising a target temperature for the refrigeration compartment, and wherein the phase change material has a phase change temperature within ±5° C. of the target temperature. 
     
     
         3 . The refrigeration system of  claim 1 , wherein the refrigeration system is a freezer/refrigerator comprising a freezer refrigeration compartment with a freezer phase change evaporator and a fresh food refrigeration compartment with a fresh food phase change evaporator, the freezer phase change evaporator in the freezer refrigeration compartment having a freezer phase change material in the open cell heat conductive metal foam of the freezer phase change evaporator, and the fresh food compartment having a fresh food phase change material in the open cell heat conductive metal foam of the fresh food phase change evaporator. 
     
     
         4 . The refrigeration system of  claim 3 , wherein the freezer refrigeration compartment comprises a fan designated for heat transfer between the freezer phase change evaporator and the freezer refrigeration compartment, and the fresh food compartment comprises a fan designated for heat transfer between the fresh food phase change evaporator and the fresh food compartment. 
     
     
         5 . The refrigeration system of  claim 3 , comprising a freezer target temperature for the freezer refrigeration compartment, and wherein the freezer phase change material has a phase change temperature within ±5° C. of the freezer target temperature, and comprising a fresh food target temperature for the fresh food refrigeration compartment, wherein the fresh food phase change material has a phase change temperature within ±5° C. of the fresh food target temperature. 
     
     
         6 . The refrigeration system of  claim 3 , wherein the freezer phase change evaporator comprises a freezer refrigerant conduit and the fresh food phase change evaporator comprises a fresh food refrigerant conduit, and wherein circulating refrigerant passes first through the freezer refrigerant conduit and then through the fresh food refrigerant conduit. 
     
     
         7 . The refrigeration system of  claim 3 , comprising a three-way control valve, the three-way valve configured to switch operation between possible two modes, wherein in the first mode of operation, refrigerant flows through the refrigerant conduit of the freezer phase change evaporator and the three-way valve into the refrigerant conduit of the fresh food phase change evaporator, and in the second mode of operation, refrigerant flows from the expansion device into the three-way valve, and then into the refrigerant conduit of the fresh food phase change evaporator, providing an individually controllable flow of refrigerant through either the refresh food phase change evaporator or both of the freezer phase change evaporator and the refresh food phase change evaporator. 
     
     
         8 . The refrigeration system of  claim 1 , further comprising a processor for monitoring the time of day for off-peak hours, and operating the compressor only during off-peak hours. 
     
     
         9 . The refrigeration system of  claim 8 , wherein the processor further connects to the compressor, the condenser, the expansion valve, a fan, and defrosting heaters array in the refrigeration system. 
     
     
         10 . The refrigeration system of  claim 1 , wherein the refrigerant conduit is provided within the evaporator unit housing. 
     
     
         11 . The refrigeration system of  claim 1 , wherein the refrigerant conduit is affixed to an exterior surface of the phase change evaporator housing. 
     
     
         12 . The refrigeration system of  claim 1 , further comprising a defrosting heater array in the refrigeration compartment. 
     
     
         13 . The refrigeration system of  claim 12 , wherein the defrosting heater array comprises polyimide heater arrays. 
     
     
         14 . The refrigeration system of  claim 12 , wherein the defrosting heater array is affixed to an exterior surface of the phase change evaporator housing. 
     
     
         15 . The refrigeration system of  claim 1 , wherein the refrigerant comprises at least one selected from the group consisting of HFO-1234ze and HFO-1234yf. 
     
     
         16 . A method for refrigerating a refrigeration compartment, comprising the steps of:
 providing in the refrigeration compartment a phase change evaporator comprising a housing containing an open cell heat conductive foam and a phase change material embedded within the cells of the open cell heat conductive foam, and a refrigerant conduit in thermal contact with the open cell heat conductive foam, the refrigerant conduit containing a refrigerant fluid;   flowing refrigerant through the refrigerant conduit sufficient to change the phase of the phase change material during an active cooling cycle; and,   allowing the phase change material to change phase and thereby absorb heat from the refrigeration compartment through the heat conductive open cell foam during a passive cooling cycle.   
     
     
         17 . The method of  claim 16 , wherein the active cooling cycle is performed only during off-peak hours. 
     
     
         18 . The method of  claim 17 , further comprising the step of using a processor for monitoring the time of day for off-peak hours, and operating the compressor and the active cooling cycle only during off-peak hours. 
     
     
         19 . The method of  claim 16 , further comprising the step of monitoring the temperature in the refrigeration compartment with a temperature sensor. 
     
     
         20 . The method of  claim 16 , the method further comprising the step of providing a freezer refrigeration compartment with a freezer phase change evaporator and a fresh food refrigeration compartment with a fresh food phase change evaporator, the freezer phase change evaporator in the freezer refrigeration compartment having a freezer phase change material in the open cell heat conductive metal foam of the freezer phase change evaporator, and the fresh food compartment having a fresh food phase change material in the open cell heat conductive metal foam of the fresh food phase change evaporator. 
     
     
         21 . The method of  claim 20 , further comprising the step of providing the freezer refrigeration compartment with a freezer phase change evaporator comprising a defrosting heater array, the defrosting heater array being affixed to an exterior surface of the phase change evaporator housing, the defrosting heater array comprising polyimide heater arrays, and operating the polyimide heater arrays to defrost the freezer refrigeration compartment. 
     
     
         22 . The method of  claim 20 , further comprising the step of providing the fresh food refrigeration compartment with a fresh food phase change evaporator further comprising a defrosting heater array, the defrosting heater array being affixed to an exterior surface of the phase change evaporator housing, the defrosting heater array comprising polyimide heater arrays, and operating the polyimide heater arrays to defrost the fresh food refrigeration compartment. 
     
     
         23 . The method of  claim 20 , further comprising the step of providing a freezer target temperature for the freezer refrigeration compartment, and providing a freezer phase change material that has a phase change temperature within ±5° C. of the freezer target temperature, and providing a fresh food target temperature for the fresh food refrigeration compartment, and providing a fresh food phase change material that has a phase change temperature within ±5° C. of the fresh food target temperature. 
     
     
         24 . The method of  claim 20 , wherein the freezer phase change evaporator comprises a freezer refrigerant conduit and the fresh food phase change evaporator comprises a fresh food refrigerant conduit, and comprising the step of circulating refrigerant first through the freezer refrigerant conduit and then through the fresh food refrigerant conduit during the active cooling cycle. 
     
     
         25 . An evaporator for a refrigeration system comprising a compressor, a condenser and an expansion valve, the evaporator comprising a housing containing an open cell heat conductive foam and a phase change material embedded within the cells of the open cell heat conductive foam, and a refrigerant conduit in thermal contact with the open cell heat conductive foam, the refrigerant conduit capable of transferring heat with the metal foam and the phase change material.