Low pressure refrigerant system

Abstract

Disclosed is a refrigeration system including a heat transfer fluid circulation loop configured to allow a refrigerant to circulate therethrough, a purge outlet from the heat transfer fluid circulation loop, and at least one gas permeable membrane having a first side in communication with the purge outlet. The membrane includes a porous inorganic material with pores of a size to allow passage of contaminants through the membrane and restrict passage of the refrigerant through the membrane. A retentate return flow path connects the first side of the membrane to the heat transfer fluid circulation loop.

1 . A refrigeration system comprising
 a heat transfer fluid circulation loop configured to allow a refrigerant to circulate therethrough;   a purge outlet from the heat transfer fluid circulation loop;   at least one gas permeable membrane comprising a porous inorganic material with pores of a size to allow passage of contaminants through the membrane and restrict passage of the refrigerant through the membrane, said membrane having a first side in communication with the purge outlet; and   a retentate return flow path from the first side of the membrane to the heat transfer fluid circulation loop.   
     
     
         2 . The refrigeration system of  claim 1 , wherein the heat transfer fluid circulation loop comprises a compressor, a heat rejection heat exchanger, an expansion device, and a heat absorption heat exchanger, connected together in order by conduit. 
     
     
         3 . The refrigeration system of  claim 1 , wherein the retentate return flow path includes a control device. 
     
     
         4 . The refrigeration system of  claim 1 , wherein the purge system is configured for continuous operation. 
     
     
         5 . The refrigeration system of  claim 1 , further comprising a prime mover configured to move gas from a second side of the membrane to an exhaust port leading outside the refrigeration system, and a controller configured to operate the refrigeration system in response to a cooling demand signal, and to operate the prime mover in response to a purge signal. 
     
     
         6 . The refrigeration system of  claim 5 , wherein the retentate return flow path includes a control device, and the controller is further configured to operate the control device in response to the purge signal. 
     
     
         7 . The refrigeration system of  claim 1 , wherein the prime mover comprises a vacuum pump in communication with the second side of the membrane. 
     
     
         8 . The refrigeration system of  claim 1 , further comprising a purge gas collector between the purge outlet and the membrane. 
     
     
         9 . The refrigeration system of  claim 3 , wherein the control device comprises an expansion device and returns retentate to the fluid circulation loop to the heat absorption heat exchanger or to the compressor inlet. 
     
     
         10 . The refrigeration system of  claim 1 , wherein the at least one gas permeable membrane comprises a plurality of gas permeable membranes in serial or parallel communication between the purge outlet and the exhaust port. 
     
     
         11 . The refrigeration system of  claim 10 , comprising a retentate return flow path operably coupling the first side of each of plurality of membranes to the fluid circulation loop. 
     
     
         12 . (canceled) 
     
     
         13 . The refrigeration system of  claim 5 , wherein the system further comprises a pressure sensor operably coupled to the fluid circulation loop, and the controller generates the purge signal in response to output from the pressure sensor. 
     
     
         14 . (canceled) 
     
     
         15 . The refrigeration system of  claim 5 , wherein the system further comprises a temperature sensor operably coupled to the fluid circulation loop, and the controller generates the purge signal in response to output from the temperature sensor. 
     
     
         16 . (canceled) 
     
     
         17 . The refrigeration system of  claim 5 , wherein the system further comprises a refrigerant gas detection sensor operably coupled to second side of the membrane, and the controller generates the purge signal in response to output from the refrigerant gas detection sensor. 
     
     
         18 . The refrigeration system of  claim 5 , wherein the controller is configured to generate the purge signal based at least in part on a timer setting. 
     
     
         19 . (canceled) 
     
     
         20 . The refrigeration system of  claim 6 , wherein the controller is configured, in response to the purge signal, to operate the control device to provide a varying flow rate or pressure drop through the control device, or to vary prime mover pressure in coordination with varying the control device setting, or to operate the control device to provide a varying flow rate or pressure drop through the control device and vary prime mover pressure in coordination with varying the control device setting. 
     
     
         21 . The refrigeration system of  claim 20 , wherein the control device includes a control valve, and the controller is configured, in response to the purge signal, to alternately operate the prime mover with the control valve closed and suspend operation of the prime mover with the control valve open. 
     
     
         22 . (canceled) 
     
     
         23 . (canceled) 
     
     
         24 . The refrigeration system of  claim 1 , wherein the purge outlet is operably coupled to the condenser. 
     
     
         25 . A method of operating the refrigeration system of  claim 5 , comprising
 circulating the refrigerant through the vapor compression heat transfer fluid circulation loop in response to the cooling demand signal under conditions in which the refrigerant is at a pressure less than atmospheric pressure in at least a portion of the fluid circulation loop; and   operating the prime mover and the control device, if present, with the controller as configured.