High performance refrigerator having evaporator outside cabinet

Abstract

A high performance refrigerator includes a cabinet with a refrigerated interior, a refrigeration fluid circuit having an evaporator located within an insulated evaporator compartment outside the cabinet, and at least one damper that opens to permit air circulation from the refrigerated interior through the evaporator compartment. The refrigerator also includes a eutectic member configured to melt at an operating temperature of the refrigerator. The evaporator cools the refrigerated interior to a temperature below the operating temperature so that the eutectic member melts to cool the refrigerated interior or the evaporator compartment during a defrost cycle. The insulated evaporator cover limits heat transfer into the refrigerated interior during the defrost cycle to avoid temperature spikes in the refrigerated interior.

What is claimed is: 
     
         1 . A refrigerator, comprising:
 a cabinet having a refrigerated interior;   a refrigeration fluid circuit for circulating a refrigerant, the circuit including a compressor, a condenser, an expansion device, and an evaporator located within an insulated evaporator compartment outside the cabinet, and including an evaporator coil and an evaporator fan producing air flow through the evaporator coil;   at least one damper that may open to permit air circulation from the refrigerated interior through the evaporator compartment; and   a eutectic member configured to melt at an operating temperature of the refrigerator,   wherein the evaporator cools the refrigerated interior to a temperature below the operating temperature such that when the at least one damper is closed for a defrost cycle, the eutectic member cools at least one of the refrigerated interior and the evaporator compartment by melting.   
     
     
         2 . The refrigerator of  claim 1 , wherein the cabinet includes side walls and a top wall, the at least one damper is formed in the top wall, and the eutectic member is mounted along one of the side walls. 
     
     
         3 . The refrigerator of  claim 1 , wherein the eutectic member is a plate-shaped member. 
     
     
         4 . The refrigerator of  claim 1 , wherein the operating temperature is about −32° C. 
     
     
         5 . The refrigerator of  claim 1 , wherein the cabinet includes a top wall, the at least one damper is formed in the top wall, and the eutectic member is mounted along the top wall. 
     
     
         6 . The refrigerator of  claim 1 , wherein the eutectic member is mounted within the evaporator compartment such that the eutectic member cools the evaporator compartment by melting during a defrost cycle. 
     
     
         7 . The refrigerator of  claim 1 , wherein the cabinet further includes:
 a top wall adjacent the insulated evaporator compartment,   a door,   a rear wall including an inlet duct in communication with the evaporator and a plurality of inlet ports leading into the refrigerated interior, and   side walls extending between the rear wall and the door, each side wall including an outlet duct in communication with the evaporator and a plurality of outlet ports leading from the refrigerated interior,   wherein the at least one damper is a valve controlling flow between the evaporator and the refrigerated interior via the inlet duct and the outlet ducts.   
     
     
         8 . A refrigerator, comprising:
 a cabinet having a refrigerated interior;   a refrigeration fluid circuit for circulating a refrigerant, the circuit including a compressor, a condenser, an expansion device, and an evaporator located within an insulated evaporator compartment outside the cabinet and including an evaporator coil, an evaporator fan producing air flow through the evaporator coil, and a defrost heater;   at least one damper that may open to permit air circulation from the refrigerated interior through the evaporator compartment; and   a controller operable to command the refrigerator to perform the following steps when the evaporator coil requires defrosting:
 stop operation of the compressor and the evaporator fan; 
 close the at least one damper to thermally isolate the evaporator compartment from the refrigerated interior; and 
 start operation of the defrost heater, 
   wherein the refrigerated interior remains thermally isolated from the evaporator during operation of the defrost heater.   
     
     
         9 . The refrigerator of  claim 8 , further comprising a temperature sensor for detecting the temperature of the evaporator, and wherein the controller is further operable to command the refrigerator to perform the following steps during defrosting of the evaporator:
 when the temperature sensor detects that the evaporator has reached a first target temperature above the freezing point of water, stopping operation of the defrost heater and allowing for any remaining moisture to drip off the evaporator coil;   starting the compressor after the remaining moisture drips off the evaporator coil; and   when the temperature sensor detects that the evaporator has reached a second target temperature below the freezing point of water, opening the at least one damper and starting operation of the evaporator fan.   
     
     
         10 . The refrigerator of  claim 9 , wherein the first target temperature is about 10° C. and the second target temperature is about −25° C. 
     
     
         11 . The refrigerator of  claim 8 , wherein the at least one damper includes a first damper and a second damper, the first damper in an open position permitting air flow into the evaporator compartment from the refrigerated interior, the second damper in an open position permitting air flow from the evaporator compartment into the refrigerated interior. 
     
     
         12 . The refrigerator of  claim 8 , wherein the insulated evaporator compartment further includes a plurality of vacuum insulated panels. 
     
     
         13 . The refrigerator of  claim 8 , further comprising:
 a eutectic member located within the cabinet and configured to melt at an operating temperature of the refrigerator,   wherein the evaporator cools the refrigerated interior to a temperature below the operating temperature such that when the at least one damper is closed for a defrost cycle, the eutectic member cools the refrigerated interior by melting.   
     
     
         14 . The refrigerator of  claim 13 , wherein the cabinet includes side walls and a top wall, the at least one damper is formed in the top wall, and the eutectic member is mounted along one of the side walls. 
     
     
         15 . The refrigerator of  claim 13 , wherein the cabinet includes a top wall, the at least one damper is formed in the top wall, and the eutectic member is mounted along the top wall. 
     
     
         16 . The refrigerator of  claim 13 , wherein the operating temperature is about −30° C. 
     
     
         17 . The refrigerator of  claim 8 , further comprising:
 a eutectic member located within the evaporator compartment and configured to melt at an operating temperature of the refrigerator,   wherein the evaporator cools the refrigerated interior to a temperature below the operating temperature such that when the at least one damper is closed for a defrost cycle, the eutectic member cools the evaporator compartment by melting.   
     
     
         18 . The refrigerator of  claim 8 , wherein the cabinet further includes:
 a top wall adjacent the insulated evaporator compartment,   a door,   a rear wall including an inlet duct in communication with the evaporator and a plurality of inlet ports leading into the refrigerated interior, and   side walls extending between the rear wall and the door, each side wall including an outlet duct in communication with the evaporator and a plurality of outlet ports leading from the refrigerated interior,   wherein the at least one damper is a valve controlling flow between the evaporator and the refrigerated interior via the inlet duct and the outlet ducts.   
     
     
         19 . A method of operating a refrigerator including a cabinet having a refrigerated interior, a refrigeration fluid circuit including a compressor, a condenser, and an evaporator located within an insulated evaporator compartment outside the cabinet and having an evaporator fan and defrost heater, the refrigerator further including at least one damper configured to separate the evaporator compartment from the refrigerated interior of the cabinet, and the method comprises:
 stopping operation of the compressor and the evaporator fan;   closing the at least one damper to thermally isolate the evaporator compartment from the refrigerated interior; and   starting operation of the defrost heater,   wherein the refrigerated interior remains thermally isolated from the evaporator during operation of the defrost heater.   
     
     
         20 . The method of  claim 19 , further comprising:
 when the evaporator has reached a first target temperature above the freezing point of water, stopping operation of the defrost heater and allowing for any remaining moisture to drip off the evaporator coil;   starting operation of the compressor after the remaining moisture drips off the evaporator coil; and   when the evaporator has reached a second target temperature below the freezing point of water, opening the at least one damper and starting operation of the evaporator fan.   
     
     
         21 . The method of  claim 20 , wherein the first target temperature is about 10° C. and the second target temperature is about −25° C. 
     
     
         22 . The method of  claim 19 , wherein the system further includes a eutectic member located within the cabinet or the evaporator compartment and configured to melt at an operating temperature of the refrigerator, and the method further comprises:
 cooling the refrigerated interior with the evaporator to a temperature below the operating temperature before a defrost cycle; and   melting the eutectic member to cool at least one of the refrigerated interior and the evaporator compartment during the defrost cycle.   
     
     
         23 . A refrigerator, comprising:
 a cabinet having a refrigerated interior;   a refrigeration fluid circuit for circulating a refrigerant, the circuit including a compressor, a condenser, an expansion device, and an evaporator located within an evaporator compartment outside the cabinet and including an evaporator coil and an evaporator fan producing air flow through the evaporator coil; and   at least one valve that may open to permit air circulation from the refrigerated interior through the evaporator compartment,   wherein the cabinet further includes:
 a top wall adjacent the evaporator compartment, 
 a door, 
 a rear wall including an inlet duct in communication with the evaporator and a plurality of inlet ports leading into the refrigerated interior, and 
 side walls extending between the rear wall and the door, each side wall including an outlet duct in communication with the evaporator and a plurality of outlet ports leading from the refrigerated interior, wherein the at least one valve controls flow between the evaporator and the refrigerated interior via the inlet duct and the outlet ducts. 
   
     
     
         24 . The refrigerator of  claim 23 , wherein the cabinet includes a bottom wall, and the inlet duct and outlet ducts each extend between the top wall and the bottom wall.