Refrigeration system having heat pump and multiple modes of operation

Abstract

The present invention provides a refrigeration system including a first refrigerant circuit including a first heat exchanger for transferring heat from refrigerant, a second refrigerant circuit including a second heat exchanger for transferring heat to refrigerant, and a third refrigerant circuit. The third refrigerant circuit includes a compressor, a condenser connected to the first refrigerant circuit such that heat exchange can occur between the refrigerants of the first and refrigerant circuits, an expansion device, and an evaporator connected to the second refrigerant circuit such that heat exchange can occur between the refrigerant of the second and third refrigerant circuits. The refrigerant can travel along the third refrigerant circuit in a common direction during operation in both heating and cooling modes. Refrigerant can be prevented from moving between first, second, and third refrigerant circuits during operation in heating and cooling modes.

1 . A refrigeration system having both a heating mode for providing heat to a load space and a cooling mode for removing heat from the load space, the system comprising:
 a first refrigerant circuit including a first heat exchanger for transferring heat from refrigerant of the first refrigerant circuit to air;   a second refrigerant circuit including a second heat exchanger for transferring heat from air to refrigerant of the second refrigerant circuit; and   a third refrigerant circuit including:
 a compressor for increasing pressure of refrigerant of the third refrigerant circuit; 
 a third heat exchanger connected to the compressor for receiving refrigerant from the compressor, and connected to the first refrigerant circuit such that heat exchange can occur between the refrigerant traveling through the first refrigerant circuit and the refrigerant traveling through the third refrigerant circuit; 
 an expansion device for reducing the pressure of the refrigerant of the third refrigerant circuit; and 
 an evaporator connected to the expansion device, and connected to the second refrigerant circuit such that heat exchange can occur between the refrigerant traveling through the second refrigerant circuit and the refrigerant traveling through the third refrigerant circuit, the refrigerant traveling along the third refrigerant circuit in a common direction during operation in both the heating mode and the cooling mode; 
 wherein refrigerant is prevented from moving between the first refrigerant circuit, the second refrigerant circuit, and the third refrigerant circuit during operation in the heating and cooling modes. 
   
   
   
       2 . The refrigeration system of  claim 1 , wherein the third heat exchanger is a liquid-cooled gas cooler. 
   
   
       3 . The refrigeration system of  claim 2 , further comprising an air-cooled gas cooler connected in series with the liquid-cooled gas cooler and to at least one of the compressor and the expansion device. 
   
   
       4 . The refrigeration system of  claim 1 , wherein the evaporator is a liquid-heated evaporator. 
   
   
       5 . The refrigeration system of  claim 4 , further comprising an air-heated evaporator connected in series with the liquid heated evaporator and to at least one of the expansion device and the compressor. 
   
   
       6 . The refrigeration system of  claim 1 , further comprising a suction line heat exchanger connected to the third heat exchanger, the expansion valve, the evaporator, and the compressor along the third refrigerant circuit. 
   
   
       7 . The refrigeration system of  claim 1 , wherein the refrigerant of the third refrigerant circuit is carbon dioxide. 
   
   
       8 . The refrigeration system of  claim 1 , wherein the first heat exchanger and the second heat exchanger are combined in a single heat exchanger. 
   
   
       9 . The refrigeration system of  claim 1 , further comprising a heat source separate from the first, second, and third refrigerant circuits for providing heat to the refrigeration system during operation in the heating mode. 
   
   
       10 . A refrigeration system having both a heating mode for providing heat to a load space and a cooling mode for removing heat from the load space, the refrigeration system comprising:
 a first refrigerant circuit extending between a compressor, an evaporator, an expansion device, and a first heat exchanger, the first refrigerant circuit defining a flow path for a refrigerant traveling in a direction along the refrigerant circuit during operation of the refrigeration system in the heating mode and the cooling mode;   a second refrigerant circuit extending between the condenser and a second heat exchanger, the second refrigerant circuit including a first refrigerant pump; and   a third refrigerant circuit extending between the evaporator and the second heat exchanger, the third refrigerant circuit including a second refrigerant pump, the second refrigerant pump being operational during operation in the heating mode and being idle during operation in the cooling mode.   
   
   
       11 . The refrigeration system of  claim 10 , wherein the second refrigerant circuit is separated from the first refrigerant circuit such that refrigerant is prevented from moving between the first and second refrigerant circuits, the second refrigerant circuit extending through the first heat exchanger such that heat exchange can occur between the refrigerant traveling through the first refrigerant circuit and a refrigerant traveling through the second refrigerant circuit. 
   
   
       12 . The refrigeration system of  claim 10 , wherein the third refrigerant circuit is separated from the first refrigerant circuit such that refrigerant is prevented from moving between the first and third refrigerant circuits, the third refrigerant circuit extending through the evaporator such that heat exchange can occur between the refrigerant traveling through the first refrigerant circuit and a refrigerant traveling through the third refrigerant circuit. 
   
   
       13 . The refrigeration system of  claim 10 , wherein the first refrigerant circuit includes a suction line heat exchanger. 
   
   
       14 . The refrigeration system of  claim 10 , wherein the second heat exchanger includes a first heat exchanger core and a second heat exchanger core, the first heat exchanger core being associated with the second refrigerant circuit, the second heat exchanger core being associated with the third refrigerant circuit. 
   
   
       15 . The refrigeration system of  claim 10 , further comprising a heat source separate from the first, second, and third refrigerant circuits for providing heat to the refrigeration system during operation in the heating mode. 
   
   
       16 . The refrigeration system of  claim 10 , wherein the evaporator is a liquid-heated evaporator and the first heat exchanger is a liquid-cooled gas cooler. 
   
   
       17 . The refrigeration system of  claim 16 , further comprising an air-cooled gas cooler connected in series with the liquid-cooled gas cooler. 
   
   
       18 . The refrigeration system of  claim 16 , further comprising an air-heated evaporator connected in series with the liquid-heated evaporator. 
   
   
       19 . A method of operating a refrigeration system, the method comprising the acts of:
 directing a refrigerant along a refrigerant circuit in a direction between a compressor, an evaporator, an expansion device, and a first heat exchanger during operation of the refrigeration system in a cooling mode;   operating a first pump when the refrigeration system is operating in the cooling mode to circulate refrigerant through a second heat exchanger;   transferring heat from a load space to the refrigerant in the refrigerant circuit when the refrigeration system is operating in the cooling mode;   stopping the first pump when the refrigeration system is operating in a heating mode;   directing the refrigerant along the refrigerant circuit in the direction during operation of the refrigeration system in the heating mode;   operating a second pump when the refrigeration system is operating in the heating mode to circulate refrigerant through the second heat exchanger in heat exchange relation with the refrigerant of the refrigerant circuit; and   transferring heat to the load space from the refrigerant in the refrigerant circuit when the refrigeration system is operating in the heating mode.   
   
   
       20 . The method of  claim 19 , further comprising heating the refrigerant with a heat source separate from the refrigerant circuit when the refrigeration system is operating in the heating mode. 
   
   
       21 . The method of  claim 19 , further comprising cooling the refrigerant using a suction line heat exchanger included along the refrigerant circuit. 
   
   
       22 . The method of  claim 19 , further comprising heating the refrigerant with an air-heated evaporator and a liquid-heated evaporator when the refrigeration system is operating in the cooling mode. 
   
   
       23 . The method of  claim 19 , further comprising cooling the refrigerant with an air-cooled condenser and a liquid-cooled condenser when the refrigeration system is operating in the heating mode.