High performance refrigerator having dual evaporator

Abstract

A high performance refrigerator includes a cabinet with a unitary refrigerated interior and a refrigeration fluid circuit having first and second evaporators located within the cabinet and separated from the refrigerated interior by respective first and second evaporator covers. The refrigerator also includes a first damper controlling flow between the first evaporator and the refrigerated interior, and a second damper controlling flow between the second evaporator and the refrigerated interior. A controller directs the refrigerator to operate a three-way valve in the refrigeration fluid circuit so as to direct refrigerant to only one of the evaporators when the other requires defrosting. Both evaporators may be used to remove heat from the unitary refrigerated interior during an initial cooling or immediately after the cabinet is opened.

What is claimed is: 
     
         1 . A refrigerator, comprising:
 a cabinet having a unitary refrigerated interior;   a refrigeration fluid circuit for circulating a refrigerant, the refrigeration fluid circuit including a compressor, a condenser, an expansion device, a first evaporator located within the cabinet, a second evaporator located within the cabinet, and a three-way valve enabling selective communication of the refrigerant through one or both of the first and second evaporators;   the first evaporator including a first evaporator coil, a first evaporator fan producing air flow through the first evaporator coil, and a first evaporator cover separating a first evaporator compartment from the refrigerated interior;   the second evaporator including a second evaporator coil, a second evaporator fan producing air flow through the second evaporator coil, and a second evaporator cover separating a second evaporator compartment from the refrigerated interior;   at least one first damper that may open to permit air circulation through the first evaporator cover from the refrigerated interior through the first evaporator; and   at least one second damper that may open to permit air circulation through the second evaporator cover from the refrigerated interior through the second evaporator,   wherein the three-way valve directs refrigerant into only one of the first and second evaporators when the other evaporator requires defrosting.   
     
     
         2 . The refrigerator of  claim 1 , wherein the first evaporator includes a first defrost heater, and the refrigerator further comprises:
 a controller operable to command the refrigerator to perform the following steps when the first evaporator requires defrosting:   direct refrigerant with the three-way valve through only the second evaporator;   remove heat from the refrigerated interior with the second evaporator;   stop operation of the first evaporator fan;   close the at least one first damper to isolate the first evaporator from the refrigerated interior; and   start operation of the first defrost heater.   
     
     
         3 . The refrigerator of  claim 2 , wherein the second evaporator includes a second defrost heater, and the controller is further operable to command the refrigerator to perform the following steps when the second evaporator requires defrosting:
 direct refrigerant with the three-way valve through only the first evaporator;   remove heat from the refrigerated interior with the first evaporator;   stop operation of the second evaporator fan;   close the at least one second damper to isolate the second evaporator from the refrigerated interior; and   start operation of the second defrost heater.   
     
     
         4 . The refrigerator of  claim 3 , wherein the controller is further operable to command the refrigerator to perform the following steps during an initial cooling of the refrigerated interior or immediately after the cabinet is opened:
 direct refrigerant with the three-way valve through both of the first and second evaporators; and   remove heat from the refrigerated interior with both of the first evaporator and the second evaporator simultaneously.   
     
     
         5 . The refrigerator of  claim 3 , wherein the controller is operable to modify an amount of time between defrost cycles and to modify an amount of time the first or second defrost heater is operating during a defrost cycle based on at least one measurable operating parameter. 
     
     
         6 . The refrigerator of  claim 1 , further comprising:
 a controller operable to command the refrigerator to perform the following steps during an initial cooling of the refrigerated interior or immediately after the cabinet is opened:   direct refrigerant with the three-way valve through both of the first and second evaporators; and   remove heat from the refrigerated interior with both of the first evaporator and the second evaporator simultaneously.   
     
     
         7 . The refrigerator of  claim 1 , wherein the expansion device includes at least one of a capillary tube or a valve. 
     
     
         8 . The refrigerator of  claim 7 , wherein the expansion device includes a first capillary tube disposed between the three-way valve and the first evaporator, and a second capillary tube disposed between the three-way valve and the second evaporator. 
     
     
         9 . The refrigerator of  claim 1 , wherein the refrigeration fluid circuit further includes an accumulator operatively connected to the first and second evaporators and the compressor. 
     
     
         10 . The refrigerator of  claim 1 , wherein the refrigeration fluid circuit further includes a filter/dryer operatively connected to the condenser and the expansion device. 
     
     
         11 . The refrigerator of  claim 1 , wherein the at least one first damper includes two first damper portions, one of the first damper portions in an open position permitting air flow into the first evaporator from the refrigerated interior, the other first damper portion in an open position permitting air flow from the first evaporator into the refrigerated interior. 
     
     
         12 . The refrigerator of  claim 11 , wherein the at least one second damper includes two second damper portions, one of the second damper portions in an open position permitting air flow into the second evaporator from the refrigerated interior, the other second damper portion in an open position permitting air flow from the second evaporator into the refrigerated interior. 
     
     
         13 . The refrigerator of  claim 1 , wherein the first and second evaporator compartments are adjacent and are separated by a divider wall. 
     
     
         14 . The refrigerator of  claim 1 , wherein each of the first and second evaporator covers includes a plurality of insulated panels. 
     
     
         15 . A method of operating a refrigerator including a cabinet having a unitary refrigerated interior; a refrigeration fluid circuit including a compressor, a condenser, a first evaporator located within the cabinet and having a first evaporator fan and a first defrost heater, a second evaporator located within the cabinet and having a second evaporator fan and a second defrost heater, and a three-way valve enabling selective communication of a refrigerant between the compressor/condenser and one or both of the first and second evaporators; at least one first damper configured to isolate the first evaporator from the refrigerated interior; and at least one second damper configured to isolate the second evaporator from the refrigerated interior, and the method comprises:
 when the first evaporator requires defrosting, directing refrigerant with the three-way valve through only the second evaporator;   removing heat from the refrigerated interior with the second evaporator;   stopping operation of the first evaporator fan;   closing the at least one first damper to isolate the first evaporator from the refrigerated interior; and   starting operation of the first defrost heater.   
     
     
         16 . The method of  claim 15 , further comprising:
 when the second evaporator requires defrosting, directing refrigerant with the three-way valve through only the first evaporator;   removing heat from the refrigerated interior with the first evaporator;   stopping operation of the second evaporator fan;   closing the at least one second damper to isolate the second evaporator from the refrigerated interior; and   starting operation of the second defrost heater.   
     
     
         17 . The method of  claim 16 , further comprising:
 during initial cool down of the refrigerated interior or immediately after the cabinet is opened, directing refrigerant with the three-way valve through both of the first and second evaporators; and   removing heat from the refrigerated interior with both of the first evaporator and the second evaporator simultaneously.