Automatic refill system for an air conditioning system

Abstract

An automatic recharge system ( 22 ) is provided for a transcritical cooling system ( 10 ). The recharge system ( 22 ) includes a refrigerant container ( 30 ) capable of storing a refrigerant charge at a higher pressure that can be accommodated on the low pressure side of the cooling system ( 10 ), and a control valve ( 34 ) connected between an outlet ( 36 ) of the container ( 30 ) and the low pressure side of the cooling system ( 10 ) to automatically control the release of refrigerant form the refrigerant container ( 30 ) for circulation in the cooling system ( 10 ).

1 . A transcritical cooling system comprising:
 a compressor to provide pressurized refrigerant to the system;   a gas cooler connected downstream from the compressor to receive pressurized refrigerant therefrom and to supply cooled, pressurized refrigerant to the system;   an expansion device connected downstream from the gas cooler to receive cooled, pressurized refrigerant therefrom and to supply reduced pressure, two-phase refrigerant to the system;   an evaporator connected downstream from the expansion device to receive reduced pressure, two-phase refrigerant therefrom and connected upstream from the compressor to supply heated, reduced pressure refrigerant thereto; and   an automatic refrigerant recharge system connected to the cooling system downstream from the evaporator and upstream from the compressor to automatically supply additional refrigerant for circulation through the system; the refrigerant recharge system comprising   a refrigerant container for storing a charge of refrigerant at a pressure greater than a pressure of the refrigerant exiting the evaporator, and   a control valve connected between the container and the remainder of the system to control the release of refrigerant from the refrigerant container for circulation in the cooling system.   
     
     
         2 . The system of  claim 1  further comprising an accumulator connected downstream from the evaporator to receive heated refrigerant therefrom and upstream from the compressor to supply gas phase refrigerant thereto; and wherein the control valve is connected to the accumulator to supply refrigerant thereto from the refrigerant container. 
     
     
         3 . The system of  claim 2  wherein the refrigerant recharge system is carried by the accumulator. 
     
     
         4 . The system of  claim 1  further comprising a low pressure conduit connected between the evaporator and the compressor to transfer refrigerant from the evaporator to the compressor; and wherein the refrigerant container is a cylindrical tube extending along an exterior of the low pressure conduit. 
     
     
         5 . The system of  claim 1  wherein the control valve comprises a bleed valve having a preselected bleed rate into the cooling system based on anticipated refrigerant leakage from the system. 
     
     
         6 . The system of  claim 1  wherein the control valve comprises a normally off valve that is responsive to a signal from the cooling system to temporarily open and supply a discrete amount of refrigerant to the cooling system. 
     
     
         7 . The system of  claim 6  further comprising a plurality of sensors to monitor system parameters, and a control connected to the sensors and the control valve to provide the signal to the control valve in response to information from the sensors. 
     
     
         8 . The system of  claim 1  wherein the compressor is a variable displacement compressor. 
     
     
         9 . A method of automatically recharging a transcritical cooling system that has leaked refrigerant, the cooling system comprising a compressor, a gas cooler, an expansion device, an evaporator and an accumulator volume all connected in series in a refrigerant loop, the method comprising the steps of:
 a) storing a refrigerant in a recharge volume that is hydraulically isolated from the accumulator volume and at a pressure that is greater than the refrigerant pressure in the accumulator volume, the recharge volume being part of the cooling system during normal operation of the cooling system; and   b) automatically releasing refrigerant from the recharge volume into the system to replace refrigerant that has leaked from the system.   
     
     
         10 . The method of  claim 9  wherein step b) comprises continuously bleeding refrigerant into the cooling system from the recharge volume during normal operation of the cooling system. 
     
     
         11 . The method of  claim 9  further comprising the step of automatically monitoring the cooling system to determine if refrigerant should be released from the recharge volume into the cooling system; and wherein step b) further comprises releasing the refrigerant into the cooling system in response to the step of automatically monitoring. 
     
     
         12 . The method of  claim 9  wherein the step of monitoring comprises monitoring a suction line pressure of the cooling system, monitoring an ambient temperature, and monitoring a displacement of the compressor. 
     
     
         13 . The method of  claim 9  further comprising the step of periodically replacing the recharge volume after the refrigerant has been depleted therefrom. 
     
     
         14 . A method of automatically recharging a transcritical cooling system that has leaked refrigerant, the cooling system comprising a compressor, a gas cooler, an expansion device, and an evaporator all connected in series in a refrigerant loop, the method comprising the steps of:
 a) storing a refrigerant in a recharge volume at a pressure that is greater than the refrigerant pressure in a suction side of the refrigerant loop, the recharge volume being part of the cooling system during normal operation of the cooling system; and   b) automatically releasing refrigerant from the recharge volume into the system to replace refrigerant that has leaked from the system.   
     
     
         15 . The method of  claim 14  wherein step b) comprises continuously bleeding refrigerant into the cooling system from the recharge volume during normal operation of the cooling system. 
     
     
         16 . The method of  claim 14  further comprising the step of automatically monitoring the cooling system to determine if refrigerant should be released from the recharge volume into the system; and wherein step b) further comprises releasing the refrigerant into the cooling system in response to the step of automatically monitoring. 
     
     
         17 . The method of  claim 14  wherein the step of monitoring comprises monitoring a suction line pressure of the cooling system, monitoring an ambient temperature, and monitoring a displacement of the compressor. 
     
     
         18 . The method of  claim 14  further comprising the step of periodically replacing the recharge volume after the refrigerant has been depleted therefrom.