Refrigeration arrangement and methods for reducing charge migration losses

Abstract

A method of operating a refrigeration appliance, comprising the steps: operating a compressor and a valve system to cause refrigerant to flow through a refrigerant circuit to chill an evaporator during a compressor ON-cycle; operating the valve system to direct the refrigerant through a secondary pressure reducing device in response to the initiation of the compressor ON-cycle for a duration that lasts until a nominal operation condition has been reached; operating the valve system during the compressor ON-cycle to direct the refrigerant through a primary pressure reducing device in response to the nominal operation condition; and transferring thermal energy from the primary pressure reducing device to a suction line heat exchanger.

What is claimed is: 
     
         1 . A method of operating a refrigeration appliance, comprising the steps:
 operating a compressor and a valve system to cause refrigerant to flow through a refrigerant circuit to chill an evaporator during a compressor ON-cycle;   operating the valve system to direct the refrigerant through a secondary pressure reducing device in response to the initiation of the compressor ON-cycle for a duration that lasts until a nominal operation condition has been reached;   operating the valve system during the compressor ON-cycle to direct the refrigerant through a primary pressure reducing device in response to the nominal operation condition; and   transferring thermal energy from the primary pressure reducing device to a suction line heat exchanger.   
     
     
         2 . The method of  claim 1 , wherein the method further comprises the step of:
 passing a higher mass flow rate of refrigerant through the secondary pressure reducing device than the primary pressure reducing device until the nominal operation condition has been reached.   
     
     
         3 . The method of  claim 1 , wherein the method further comprises the step of:
 dropping a temperature across the primary pressure reducing device by a greater amount than a temperature drop across the secondary pressure reducing device.   
     
     
         4 . The method of  claim 1 , wherein the method further comprises the step of:
 flowing the refrigerant through the refrigerant circuit to bypass the suction line heat exchanger during the compressor ON-cycle.   
     
     
         5 . The method of  claim 1 , wherein the method further comprises the step of:
 flowing the refrigerant through the suction line heat exchanger in response to the nominal operation condition.   
     
     
         6 . The method of  claim 1 , wherein the step of operating the valve to direct the refrigerant through the primary pressure reducing device in response to the nominal operation condition, further comprises:
 operating the valve to direct the refrigerant through the primary pressure reducing device after a predetermined time.   
     
     
         7 . The method of  claim 1 , wherein the step of operating the valve to direct the refrigerant through the primary pressure reducing device in response to the nominal operation condition, further comprises:
 operating the valve to direct the refrigerant through the primary pressure reducing device after a superheat condition is calculated at the evaporator.   
     
     
         8 . The method of  claim 1 , wherein the step of operating the valve to direct the refrigerant through the primary pressure reducing device in response to the nominal operation condition, further comprises:
 operating the valve to direct the refrigerant through the primary pressure reducing device after a sub-cooling condition is calculated at a condenser.   
     
     
         9 . A method of operating a refrigeration appliance, comprising the steps:
 operating a compressor and a valve system to cause refrigerant to flow through a refrigerant circuit to chill an evaporator during a compressor ON-cycle;   operating the valve system to direct the refrigerant through a secondary pressure reducing device in response to the initiation of the compressor ON-cycle for a duration that lasts until a nominal operation condition has been reached;   operating the valve system during the compressor ON-cycle to direct the refrigerant through the primary pressure reducing device in response to the nominal operation condition; and   flowing the refrigerant through the refrigerant circuit to bypass a suction line heat exchanger.   
     
     
         10 . The method of  claim 9 , further comprising the step:
 operating the valve system in response to a transient condition to allow simultaneous flow of the refrigerant through the primary and secondary pressure reducing devices.   
     
     
         11 . The method of  claim 9 , further comprising the step:
 operating the valve system to equalize pressure in the refrigerant circuit before the initiation of the compressor ON-cycle.   
     
     
         12 . The method of  claim 9 , further comprising the step:
 operating the valve system during the compressor ON-cycle to restrict flow of the refrigerant through the primary and secondary pressure reducing devices in response to a cycle end condition.   
     
     
         13 . The method of  claim 9 , further comprising the step:
 transferring thermal energy from the primary pressure reducing device to the suction line heat exchanger.   
     
     
         14 . A method of operating a refrigeration appliance, comprising the steps:
 operating a compressor and a valve system to cause refrigerant to flow through a refrigerant circuit to chill an evaporator during a compressor ON-cycle;   operating the valve system to direct the refrigerant through a secondary pressure reducing device in response to the initiation of the compressor ON-cycle for a duration that lasts until a nominal operation condition has been reached;   operating the valve system during the compressor ON-cycle to direct the refrigerant through the primary pressure reducing device in response to the nominal operation condition; and   flowing a higher mass flow rate of refrigerant through the secondary pressure reducing device than the primary pressure reducing device until the nominal operation condition has been reached.   
     
     
         15 . The method of  claim 14 , wherein the method further comprises the step of:
 dropping a temperature across the primary pressure reducing device by a greater amount than a temperature drop across the secondary pressure reducing device.   
     
     
         16 . The method of  claim 14 , wherein the method further comprises the step of:
 flowing the refrigerant through the refrigerant circuit to bypass a suction line heat exchanger during the compressor ON-cycle.   
     
     
         17 . The method of  claim 16 , wherein the method further comprises the step of:
 flowing the refrigerant through the suction line heat exchanger in response to the nominal operation condition.   
     
     
         18 . The method of  claim 14 , wherein the step of operating the valve to direct the refrigerant through the primary pressure reducing device in response to the nominal operation condition, further comprises:
 operating the valve to direct the refrigerant through the primary pressure reducing device after a predetermined time.   
     
     
         19 . The method of  claim 14 , wherein the step of operating the valve to direct the refrigerant through the primary pressure reducing device in response to the nominal operation condition, further comprises:
 operating the valve to direct the refrigerant through the primary pressure reducing device after a superheat condition is calculated at the evaporator.   
     
     
         20 . The method of  claim 14 , wherein the step of operating the valve to direct the refrigerant through the primary pressure reducing device in response to the nominal operation condition, further comprises:
 operating the valve to direct the refrigerant through the primary pressure reducing device after a sub-cooling condition is calculated at a condenser.