Systems and methods for purging a chiller system

Abstract

Embodiments of the present disclosure relate to a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system having a purge system configured to purge a vapor compression system of non-condensable gases (NCG). The purge system includes a refrigerant loop configured to circulate a purge refrigerant and a purge heat exchanger configured to place the purge refrigerant in a heat exchange relationship with a mixture of vapor refrigerant and NCG received from the vapor compression system. The purge system further includes a pump configured to draw the mixture from the vapor compression system, increase a pressure of the mixture, and deliver the mixture to the purge heat exchanger. The pump is disposed upstream of the purge heat exchanger, relative to a flow path of the mixture from the vapor compression system to the purge heat exchanger.

1 . A heating, ventilation, air conditioning, and refrigeration (HVAC&R) system, comprising:
 a purge system configured to purge a vapor compression system of non-condensable gases (NCG), comprising:
 a refrigerant loop configured to circulate a purge refrigerant; 
 a purge heat exchanger configured to place the purge refrigerant in a heat exchange relationship with a mixture received from the vapor compression system, wherein the mixture comprises vapor refrigerant and the NCG; and 
 a pump configured to draw the mixture from the vapor compression system, increase a pressure of the mixture, and deliver the mixture to the purge heat exchanger, wherein the pump is disposed upstream of the purge heat exchanger, relative to a flow path of the mixture from the vapor compression system to the purge heat exchanger. 
   
     
     
         2 . The HVAC&R system of  claim 1 , wherein the purge system comprises an expansion device disposed upstream of the purge heat exchanger, relative to the flow path of the mixture from the vapor compression system to the purge heat exchanger, wherein the expansion device is configured to receive the mixture from the pump and decrease the pressure of the mixture. 
     
     
         3 . The HVAC&R system of  claim 1 , wherein the purge heat exchanger comprises a fixed exit orifice, wherein the purge system is configured to drain condensed refrigerant through the fixed exit orifice to the vapor compression system, and wherein the fixed exit orifice is configured to provide a liquid seal between the purge heat exchanger and the vapor compression system. 
     
     
         4 . The HVAC&R system of  claim 1 , wherein the purge system comprises an expansion device disposed downstream of the purge heat exchanger, relative to a flow path of the mixture from the purge heat exchanger to the vapor compression system, wherein the purge system is configured to drain condensed refrigerant through the expansion device, and wherein the expansion device is configured to receive the condensed refrigerant from the purge heat exchanger and decrease a refrigerant pressure of the condensed refrigerant. 
     
     
         5 . The HVAC&R system of  claim 1 , wherein the purge heat exchanger comprises a valve configured to release the NCG into an atmosphere surrounding the HVAC&R system. 
     
     
         6 . The HVAC&R system of  claim 5 , wherein the valve comprises a solenoid valve. 
     
     
         7 . The HVAC&R system of  claim 5 , wherein the pump is configured to induce a pressure differential between the mixture and the atmosphere, such that a first pressure of the NCG within the purge heat exchanger is greater than a second pressure of the atmosphere. 
     
     
         8 . The HVAC&R system of  claim 1 , wherein the pump comprises a first pump and a second pump arranged in series along the flow path of the mixture from the vapor compression system to the purge heat exchanger. 
     
     
         9 . The HVAC&R system of  claim 1 , wherein the purge heat exchanger comprises a shell configured to receive the mixture from the pump and a coil disposed within the shell, wherein the purge heat exchanger is configured to direct the purge refrigerant through the coil. 
     
     
         10 . The HVAC&R system of  claim 1 , wherein the pump is configured to draw the mixture from a condenser of the vapor compression system, and wherein the purge system is configured to direct condensed refrigerant from the purge heat exchanger to the condenser, to an evaporator of the vapor compression system, or to a liquid line of the vapor compression system. 
     
     
         11 . A purge system for a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system, comprising:
 a refrigerant circuit configured to circulate a purge refrigerant;   a purge heat exchanger disposed along the refrigerant circuit and configured to place the purge refrigerant in a heat exchange relationship with a mixture received from a chiller of the HVAC&R system, wherein the mixture comprises vapor refrigerant and non-condensable gases (NCG);   a pump configured to increase a pressure of the mixture upstream of the purge heat exchanger relative to a flow of the mixture from the chiller to the purge heat exchanger; and   a controller configured to regulate operation of the purge system such that the pressure of the mixture within the purge heat exchanger is above a threshold value.   
     
     
         12 . The purge system of  claim 11 , wherein the controller is configured to regulate operation of the pump such that the pressure of the mixture within the purge heat exchanger is above the threshold value, wherein the threshold value is greater than or equal to an ambient pressure. 
     
     
         13 . The purge system of  claim 12 , wherein the threshold value is greater than the ambient pressure by a threshold differential value. 
     
     
         14 . The purge system of  claim 11 , comprising an electronic expansion valve disposed along a conduit extending between the pump and the purge heat exchanger. 
     
     
         15 . The purge system of  claim 14 , wherein the controller is configured to regulate operation of the pump and the electronic expansion valve such that the pressure of the mixture within the purge heat exchanger is above the threshold value. 
     
     
         16 . The purge system of  claim 11 , comprising a solenoid valve configured to release the NCG into an atmosphere surrounding the HVAC&R system. 
     
     
         17 . The purge system of  claim 11 , wherein the pump is configured to draw the mixture from a condenser of the chiller, and wherein the purge system is configured to direct condensed refrigerant from the purge heat exchanger to the condenser, to an evaporator of the chiller, or to a liquid line of the chiller. 
     
     
         18 . A heating, ventilation, air conditioning, and refrigeration (HVAC&R) system, comprising:
 a vapor compression system; and   a purge system configured to purge the vapor compression system of non-condensable gases (NCG), comprising:
 a refrigerant circuit configured to circulate a purge refrigerant; 
 a purge heat exchanger configured to place the purge refrigerant in a heat exchange relationship with a mixture received from the vapor compression system, wherein the mixture comprises vapor refrigerant and the NCG; 
 a first conduit extending from the vapor compression system to the purge heat exchanger and configured to direct the mixture from the vapor compression system to the purge heat exchanger; 
 a pump disposed along the first conduit and configured to increase a pressure of the mixture above an ambient pressure; and 
 a second conduit extending from the purge heat exchanger to the vapor compression system, wherein the second conduit is configured to direct condensed refrigerant from the purge heat exchanger to the vapor compression system. 
   
     
     
         19 . The HVAC&R system of  claim 18 , comprising a solenoid valve coupled to the purge heat exchanger and configured to cycle on and off to release the NCG from the purge heat exchanger. 
     
     
         20 . The HVAC&R system of  claim 18 , comprising an electronic expansion valve of the purge system, wherein the electronic expansion valve is disposed along the first conduit between the pump and the purge heat exchanger or is disposed along the second conduit between the purge heat exchanger and the vapor compression system.