Refrigeration system with thermal conductive defrost

Abstract

A refrigeration system including a compressor, a condenser, and an evaporator in heat exchange relationship with a fluid deliverable to a space. The evaporator is connected to the condenser via an inlet line and to the compressor via a suction line. A refrigeration circuit is defined by the compressor, condenser, inlet line, evaporator, and suction line. A refrigeration mode of the refrigeration circuit transfers heat from the fluid to a refrigerant in the evaporator and accumulates frost on the evaporator. The evaporator, a bypass line connected to the suction line and to the inlet line, a portion of the suction line, and a portion of the inlet line define a defrost circuit that circulates refrigerant in a defrost mode to transfer heat from the refrigerant to the frost on the evaporator. The refrigerant flows by gravity from the evaporator to one of the portion of the suction line and the portion of the inlet line in the defrost mode.

1 . A refrigeration system comprising:
 a compressor;   a condenser fluidly connected to the compressor;   an evaporator fluidly connected to the condenser via an inlet line and fluidly connected to the compressor via a suction line, the evaporator in heat exchange relationship with a fluid deliverable to a space, wherein the compressor, condenser, inlet line, evaporator, and suction line define a refrigeration circuit, wherein the system includes a refrigeration mode operable to circulate refrigerant through the refrigeration circuit to transfer heat from the fluid to the refrigerant in the evaporator to cool the space and accumulate frost on the evaporator; and   a bypass line having a first end fluidly connected to the suction line between the evaporator and the compressor and a second end fluidly connected to the inlet line between the condenser and the evaporator, wherein the evaporator, a portion of the suction line between the evaporator and the first end, the bypass line, and a portion of the inlet line between the second end and the evaporator define a defrost circuit, wherein the system includes a defrost mode operable to circulate refrigerant through the defrost circuit to transfer heat from the refrigerant to the frost on the evaporator, and wherein the evaporator is configured to allow the refrigerant to flow by gravity from the evaporator to one of the portion of the suction line and the portion of the inlet line in the defrost mode.   
   
   
       2 . The refrigeration system of  claim 1 , further comprising a valve disposed on the suction line wherein the valve is operable to open in the refrigeration mode and to close in the defrost mode. 
   
   
       3 . The refrigeration system of  claim 1 , further comprising a valve disposed on the bypass line, wherein the valve is operable to close in the refrigeration mode and to open in the defrost mode. 
   
   
       4 . The refrigeration system of  claim 1 , further comprising a first valve in fluid communication with the suction line and a second valve in fluid communication with the bypass line, wherein the first valve is operable to open in the refrigeration mode and to close in the defrost mode, and the second valve is operable to close in the refrigeration mode and to open in the defrost mode. 
   
   
       5 . The refrigeration system of  claim 1 , further comprising a heat source in heat transfer relationship with the defrost circuit, the heat source operable to transfer heat to the refrigerant in the defrost circuit. 
   
   
       6 . The refrigeration system of  claim 5 , wherein the heat source is adjacent at least one of the portion of the suction line and the bypass line to superheat refrigerant in the defrost mode. 
   
   
       7 . The refrigeration system of  claim 6 , wherein the evaporator is configured and oriented to allow the superheated refrigerant to at least partially displace refrigerant in the evaporator. 
   
   
       8 . The refrigeration system of  claim 5 , wherein the heat source includes a first heat source adjacent the portion of the suction line and a second heat source adjacent the bypass line to superheat refrigerant in the defrost mode. 
   
   
       9 . A refrigeration system comprising:
 a compressor;   a condenser fluidly connected to the compressor;   an evaporator fluidly connected to the condenser via an inlet line and fluidly connected to the compressor via a suction line, the evaporator in heat exchange relationship with a fluid deliverable to a space, wherein the compressor, condenser, inlet line, evaporator, and suction line define a refrigeration circuit, wherein the system includes a refrigeration mode operable to circulate refrigerant through the refrigeration circuit to transfer heat from the fluid to the refrigerant in the evaporator to cool the space and accumulate frost on the evaporator;   a bypass line having a first end fluidly connected to the suction line between the evaporator and the compressor and a second end fluidly connected to the inlet line between the condenser and the evaporator, wherein the evaporator, a portion of the suction line between the evaporator and the first end, the bypass line, and a portion of the inlet line between the second end and the evaporator define a defrost circuit; and   a heat source in heat transfer relationship with the defrost circuit, the heat source operable to transfer heat to the refrigerant in the defrost circuit, wherein the system includes a defrost mode operable to circulate refrigerant through the defrost circuit to transfer heat from the refrigerant to the frost on the evaporator.   
   
   
       10 . The refrigeration system of  claim 9 , wherein the heat source is adjacent at least one of the portion of the suction line and the bypass line to evaporate refrigerant in one of the portion of the suction line and the bypass line. 
   
   
       11 . The refrigeration system of  claim 9 , wherein the heat source includes a first heat source adjacent the portion of the suction line and a second heat source adjacent the bypass line. 
   
   
       12 . The refrigeration system of  claim 9 , further comprising a valve disposed on the suction line, wherein the valve is operable to open in the refrigeration mode and to close in the defrost mode. 
   
   
       13 . The refrigeration system of  claim 9 , further comprising a valve disposed on the bypass line, wherein the valve is operable to close in the refrigeration mode and to open in the defrost mode. 
   
   
       14 . The refrigeration system of  claim 9 , further comprising a first valve in fluid communication with the suction line and a second valve in fluid communication with the bypass line. 
   
   
       15 . The refrigeration system of  claim 9 , wherein the heat transfer from the refrigerant to the frost is operable to liquefy the refrigerant, and wherein the evaporator is configured and oriented to allow the liquefied refrigerant to flow by gravity from the evaporator to one of the portion of the suction line and the portion of the inlet line in the defrost mode. 
   
   
       16 . A method of operating a refrigeration system to cool a space, the refrigeration system including a compressor, a condenser fluidly connected to the compressor, an evaporator fluidly connected to the condenser via an inlet line and fluidly connected to the compressor via a suction line, and a bypass line having a first end fluidly connected to the suction line between the evaporator and the compressor and a second end fluidly connected to the inlet line between the condenser and the evaporator, the evaporator in heat transfer relationship with a fluid that is in fluid communication with the space, the method comprising:
 providing a refrigeration circuit including the compressor, condenser, inlet line, evaporator, and suction line;   operating the refrigeration system in a refrigeration mode;   circulating refrigerant through the refrigeration circuit in the refrigeration mode;   transferring heat in the refrigeration mode from the fluid to the refrigerant in the evaporator;   cooling a space in the refrigeration mode;   accumulating frost on the evaporator in the refrigeration mode;   providing a defrost circuit including the evaporator, a portion of the suction line between the evaporator and the first end, the bypass line, and a portion of the inlet line between the second end and the evaporator,   providing a heat source in heat transfer relationship with the defrost circuit;   operating the refrigeration system in a defrost mode;   circulating refrigerant through the defrost circuit in the defrost mode;   transferring heat in the defrost mode from the heat source to the refrigerant in the defrost circuit; and   transferring heat in the defrost mode from the refrigerant to the frost on the evaporator.   
   
   
       17 . The method of  claim 16 , wherein transferring heat in the defrost mode from the refrigerant to the frost further includes melting the frost on the evaporator and condensing the refrigerant. 
   
   
       18 . The method of  claim 16 , further comprising
 providing a valve between the evaporator and the compressor;   opening the valve in the refrigeration mode; and   closing the valve in the defrost mode.   
   
   
       19 . The method of  claim 16 , further comprising
 providing a valve in the bypass line;   opening the valve in the defrost mode; and   closing the valve in the refrigeration mode.   
   
   
       20 . The method of  claim 16 , further comprising providing a first valve between the suction line and the compressor and providing a second valve in the bypass line. 
   
   
       21 . The method of  claim 20 , wherein operating the refrigeration system in the refrigeration mode further includes opening the first valve and closing the second valve. 
   
   
       22 . The method of  claim 20 , wherein operating the refrigeration system in the defrost mode further includes closing the first valve and opening the second valve. 
   
   
       23 . The method of  claim 16 , wherein providing a heat source in heat transfer relationship with the defrost circuit further includes providing a heat source in heat transfer relationship with the portion of the suction line. 
   
   
       24 . The method of  claim 16 , wherein providing a heat source in heat transfer relationship with the defrost circuit further includes providing a heat source in heat transfer relationship with the bypass line. 
   
   
       25 . The method of  claim 16 , wherein transferring heat in the defrost mode from the heat source to the refrigerant further includes evaporating the refrigerant in the portion of the suction line. 
   
   
       26 . The method of  claim 16 , wherein evaporating the refrigerant in the portion of the suction line further includes displacing the refrigerant in the evaporator to the suction line.