Cooling system

Abstract

An apparatus includes a high side heat exchanger, a flash tank, a load, a compressor, and a heat exchanger. The high side heat exchanger removes heat from a refrigerant. The flash tank stores the refrigerant from the high side heat exchanger and to discharge a flash gas. The load uses the refrigerant from the cool a space proximate the load. The compressor compresses the refrigerant from the load. The heat exchanger transfers heat from the refrigerant from the compressor to the flash gas before the refrigerant from the compressor reaches the high side heat exchanger. The heat exchanger directs the flash gas to the compressor after heat from the refrigerant from the compressor is transferred to the flash gas and directs the refrigerant from the compressor to the high side heat exchanger after heat from the refrigerant from the compressor is transferred to the flash gas.

What is claimed is: 
     
         1 . An apparatus comprising:
 a high side heat exchanger configured to remove heat from a refrigerant;   a flash tank configured to store the refrigerant from the high side heat exchanger and to discharge a flash gas having a liquid component and a gaseous component;   a first load configured to use the refrigerant to cool a first space proximate the first load;   a first compressor having a first compressor suction side and a first compressor discharge side;   a heat exchanger configured to:
 transfer heat from the refrigerant to the flash gas before the refrigerant from the first compressor reaches the high side heat exchanger; 
 direct the flash gas to the first compressor after heat from the refrigerant from the first compressor is transferred to the flash gas; and 
 direct the refrigerant from the first compressor to the high side heat exchanger after heat from the refrigerant from the first compressor is transferred to the flash gas; 
   a gas bypass valve operable to direct the liquid component and the gaseous component of the flash gas from the flash tank to the suction side of the first compressor;   a first valve positioned between the gas bypass valve and the heat exchanger; and   a second valve positioned between the gas bypass valve and the first compressor, the second valve is disposed in parallel to the first valve, wherein:
 during a first mode of operation, the first valve directs the flash gas from the gas bypass valve to the heat exchanger, the second valve is closed to prevent flash gas from flowing from the flash tank to the first compressor suction side, the first compressor configured to compress the refrigerant received on the first compressor suction side from both the first load and the heat exchanger and provide compressed refrigerant on the first compressor discharge side, wherein compressed refrigerant from the first compressor discharge side flows through the heat exchanger to the first compressor suction side; and 
 during a second mode of operation, the first valve is closed to prevent the flash gas from flowing from the gas bypass valve to the heat exchanger, the second valve is open to direct flash gas from the flash tank to the first compressor suction side such that the flash gas bypasses the heat exchanger, compressed refrigerant from the first compressor discharge side flows through the heat exchanger to the high side heat exchanger and to the flash tank. 
   
     
     
         2 . The apparatus of  claim 1 , wherein:
 the first valve is a check valve configured to direct the flash gas from the flash tank to the first compressor if a pressure of the flash gas exceeds a threshold.   
     
     
         3 . The apparatus of  claim 1 , further comprising:
 an oil separator configured to separate an oil from the refrigerant from the first compressor before the refrigerant from the first compressor reaches the heat exchanger.   
     
     
         4 . The apparatus of  claim 3 , wherein:
 the oil separator is positioned between the first compressor and the heat exchanger.   
     
     
         5 . The apparatus of  claim 1 , wherein:
 the flash gas liquid component transitions to a gas when the heat exchanger transfers heat from the refrigerant from the first compressor to the flash gas.   
     
     
         6 . The apparatus of  claim 1 , wherein:
 the gas bypass valve is disposed downstream of the flash tank.   
     
     
         7 . The apparatus of  claim 1 , further comprising:
 a second load configured to use the refrigerant from the flash tank to cool a second space proximate the second load; and   a second compressor having a second compressor suction side and a second compressor discharge side, the second compressor configured to compress the refrigerant received on the second compressor suction side from the second load and provide compressed refrigerant on the second compressor discharge side to the first compressor suction side.   
     
     
         8 . A method comprising:
 removing, by a high side heat exchanger, heat from a refrigerant;   storing, by a flash tank, the refrigerant from the high side heat exchanger;   discharging, by the flash tank, a flash gas having a liquid component and a gaseous component;   using, by a first load, the refrigerant to cool a first space proximate the first load;   transferring, by a heat exchanger, heat from the refrigerant to the flash gas before the refrigerant from a first compressor reaches the high side heat exchanger;   directing, by the heat exchanger, the flash gas to the first compressor after heat from the refrigerant from the first compressor is transferred to the flash gas; and   directing, by the heat exchanger, the refrigerant from the first compressor to the high side heat exchanger after heat from the refrigerant from the first compressor is transferred to the flash gas,   wherein during a first mode of operation, the method further comprises:
 directing the flash gas from the flash gas and a gas bypass valve to the heat exchanger; 
 preventing flash gas from flowing from the flash tank to a first compressor suction side; and 
 compressing the refrigerant received on the first compressor suction side from both the first load and the heat exchanger and provide compressed refrigerant on a first compressor discharge side, wherein compressed refrigerant from the first compressor discharge side flows through the heat exchanger to the first compressor suction side, 
   wherein during a second mode of operation, the method further comprises:
 directing flash gas from the flash tank to the first compressor suction side such that the flash gas bypasses the heat exchanger; 
 preventing the flash gas from flowing from the gas bypass valve to the heat exchanger; and 
 compressing the refrigerant received on the first compressor suction side from both the first load and the flash tank and provide compressed refrigerant on the first compressor discharge side, herein compressed refrigerant from the first compressor discharge side flows through the heat exchanger to the high side heat exchanger and to the flash tank. 
   
     
     
         9 . The method of  claim 8 , further comprising:
 directing, by a gas bypass valve, the flash gas from the flash tank to the first compressor if a pressure of the flash gas exceeds a threshold, wherein the gas bypass valve is a check valve.   
     
     
         10 . The method of  claim 8 , further comprising:
 separating, by an oil separator, an oil from the refrigerant from the first compressor before the refrigerant from the first compressor reaches the heat exchanger.   
     
     
         11 . The method of  claim 8 , further comprising:
 using, by a second load, the refrigerant from the flash tank to cool a second space proximate the second load;   compressing, by a second compressor, the refrigerant from the second load; and   compressing, by the first compressor, the refrigerant from the second compressor.   
     
     
         12 . The method of  claim 8 , wherein:
 a flash gas liquid component transitions to a gas when the heat exchanger transfers heat from the refrigerant from the first compressor to the flash gas.   
     
     
         13 . A system comprising:
 a high side heat exchanger configured to remove heat from a refrigerant;   a flash tank configured to store the refrigerant from the high side heat exchanger and to discharge a flash gas having a liquid component and a gaseous component;   a first load configured to use the refrigerant from the flash tank to cool a first space proximate the first load;   a first compressor having a first compressor suction side and a first compressor discharge side, the first compressor configured to compress the refrigerant received on the first compressor suction side from the first load and provide compressed refrigerant on the first compressor discharge side;   a second load configured to use the refrigerant from the flash tank to cool a second space proximate the second load;   a second compressor having a second compressor suction side and a second compressor discharge side, the second compressor configured to compress the refrigerant received on the second compressor suction side from the second load and provide compressed refrigerant on the second compressor discharge side;   a heat exchanger configured to:
 transfer heat from the refrigerant to the flash gas before the refrigerant from the first compressor reaches the high side heat exchanger; 
 direct the flash gas to the first compressor after heat from the refrigerant from the first compressor is transferred to the flash gas; and 
 direct the refrigerant from the first compressor to the high side heat exchanger after heat from the refrigerant from the first compressor is transferred to the flash gas; 
   a gas bypass valve disposed downstream of the flash tank operable to direct the liquid component and the gaseous component of the flash gas from the flash tank to a suction side of the first compressor; and   a first valve positioned between the gas bypass valve and the heat exchanger; and   a second valve positioned between the gas bypass valve and the first compressor, the second valve is disposed in parallel to the first valve, wherein:
 during a first mode of operation, the first valve directs the flash gas from the gas bypass valve to the heat exchanger, the second valve is closed to prevent flash gas from flowing from the flash tank to the first compressor suction side, compressed refrigerant from the first compressor discharge side flows through the heat exchanger to the first compressor suction side; and 
 during a second mode of operation, the first valve is closed to prevent the flash gas from flowing from the gas bypass valve to the heat exchanger, the second valve is open to direct flash gas from the flash tank to the first compressor suction side such that the flash gas bypasses the heat exchanger, compressed refrigerant from the first compressor discharge side flows through the heat exchanger to the high side heat exchanger and to the flash tank. 
   
     
     
         14 . The system of  claim 13 , wherein:
 the first valve is a check valve configured to direct the flash gas from the flash tank to the first compressor if a pressure of the flash gas exceeds a threshold.   
     
     
         15 . The system of  claim 13 , further comprising:
 an oil separator configured to separate an oil from the refrigerant from the first compressor before the refrigerant from the first compressor reaches the heat exchanger.   
     
     
         16 . The system of  claim 15 , wherein:
 the oil separator is positioned between the first compressor and the heat exchanger.   
     
     
         17 . The system of  claim 13 , wherein:
 the flash gas liquid component transitions to a gas when the heat exchanger transfers heat from the refrigerant from the first compressor to the flash gas.   
     
     
         18 . The system of  claim 13 , wherein:
 the gas bypass valve is disposed downstream of the flash tank.