Cooling system

An apparatus comprising:

• a high side heat exchanger configured to remove heat from a refrigerant;
• a heat exchanger;
• a flash tank configured to store the refrigerant;
• a first expansion valve;
• a second expansion valve, wherein the second expansion valve is configured to reduce the temperature of a larger volume of refrigerant per unit time than the first expansion valve and to reduce the temperature of the refrigerant to a lower temperature than the first expansion valve;
• a load, wherein the first expansion valve and the second expansion valve are disposed between the flash tank and the load;
• a first compressor;
• and
• a second compressor;
• wherein, during a first mode of operation:
• the first expansion valve is closed;
• the second expansion valve directs refrigerant from the flash tank to the load;
• the load uses the refrigerant from the second expansion valve to cool a space proximate the load;
• the first compressor is off, the refrigerant from the load bypasses the first compressor;
• the heat exchanger transfers heat from the refrigerant from the high side heat exchanger to the refrigerant from the load, the heat exchanger directs the refrigerant from the load to the second compressor after heat from the refrigerant from the high side heat exchanger is transferred to the refrigerant from the load;
• and
• the second compressor compresses the refrigerant from the heat exchanger.

An apparatus comprising:

• a high side heat exchanger configured to remove heat from a refrigerant;
• a heat exchanger;
• a flash tank configured to store the refrigerant;
• a first expansion valve;
• a second expansion valve, wherein the second expansion valve is configured to reduce the temperature of a larger volume of refrigerant per unit time than the first expansion valve and to reduce the temperature of the refrigerant to a lower temperature than the first expansion valve;
• a load, wherein the first expansion valve and the second expansion valve are disposed between the flash tank and the load;
• a first compressor;
• and
• a second compressor;
• wherein, during a second mode of operation:
• the first expansion valve directs refrigerant from the flash tank to the load;
• the second expansion valve is closed;
• the load uses the refrigerant from the first expansion valve to cool the space;
• the first compressor compresses the refrigerant from the load;
• the refrigerant from the first compressor flows to the second compressor through the heat exchanger;
• and
• the second compressor compresses the refrigerant from the first compressor before the refrigerant from the first compressor reaches the high side heat exchanger.