Cooling system

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;

a first load;

a first compressor;

an expansion valve;

a subcooler heat exchanger configured to receive the refrigerant from the flash tank, wherein:

the subcooler heat exchanger is coupled to an input of the first load; and

the subcooler heat exchanger is coupled to an input of the expansion valve;

during a first mode of operation:

the subcooler heat exchanger is configured to direct the refrigerant from the flash tank to the input of the first load;

the first load configured to use the refrigerant from the subcooler heat exchanger to cool a first space proximate the first load;

the first compressor configured to compress the refrigerant from the first load; and

during a second mode of operation:

the subcooler heat exchanger configured to:

direct the refrigerant from the flash tank to the input of the expansion valve;

generate a heated refrigerant by transferring transfer heat from the refrigerant from the flash tank to the refrigerant from the expansion valve;

direct a first portion of the heated refrigerant to the input of the first load; and

direct a second portion of the heated refrigerant to the first compressor;

the first compressor configured to:

compress the heated refrigerant from the subcooler heat exchanger; and

direct the compressed refrigerant from the subcooler heat exchanger to the first load to defrost the first load.

2. The apparatus of claim 1 , wherein the subcooler heat exchanger is positioned within the flash tank.

3. 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 during the second mode of operation.

4. 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 during the first mode of operation; and

a second compressor configured to compress a mixture of the refrigerant from the second load and the refrigerant from the first compressor during the first mode of operation.

5. The apparatus of claim 1 , wherein during the second mode of operation:

the first load is configured to direct the compressed refrigerant from the first compressor to the flash tank; and

the flash tank is configured to direct the compressed refrigerant from the first load to a second compressor.

6. The apparatus of claim 1 , further comprising an oil separator configured to separate an oil from the refrigerant from a second compressor.

7. The apparatus of claim 1 , wherein the flash tank is further configured to direct a flash gas to a second compressor.

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;

receiving, by a subcooler heat exchanger, the refrigerant from the flash tank;

during a first mode of operation:

directing, by the subcooler heat exchanger, refrigerant from the flash tank to an input of a first load;

using, by the first load, the refrigerant from the subcooler heat exchanger to cool a first space proximate the first load; and

compressing, by a first compressor, the refrigerant from the first load;

during a second mode of operation:

directing, by the subcooler heat exchanger, the refrigerant from the flash tank to an input of an expansion valve;

generating, by the subcooler heat exchanger, a heated refrigerant by transferring heat from the refrigerant from the flash tank to the refrigerant from the expansion valve;

directing, by the subcooler heat exchanger, a first portion of the heated refrigerant to the input of the first load;

directing, by the subcooler heat exchanger, a second portion of the heated refrigerant to the first compressor;

compressing, by the first compressor, the heated refrigerant from the subcooler heat exchanger; and

directing, by the first compressor, the compressed refrigerant from the subcooler heat exchanger to the first load to defrost the first load.

9. The method of claim 8 , wherein the subcooler heat exchanger is positioned within the flash tank.

10. 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 during the second mode of operation.

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 during the first mode of operation; and

compressing, by a second compressor, a mixture of the refrigerant from the second load and the refrigerant from the first compressor during the first mode of operation.

12. The method of claim 8 , further comprising, during the second mode of operation:

directing, by the first load, the compressed refrigerant from the first compressor to the flash tank; and

directing, by the flash tank, the compressed refrigerant from the first load to a second compressor.

13. The method of claim 8 , further comprising separating, by an oil separator, an oil from the refrigerant from a second compressor.

14. The method of claim 8 , further comprising directing, by the flash tank, a flash gas to a second compressor.

15. 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;

an expansion valve;

a first load;

a second load;

a first compressor;

a second compressor; and

a subcooler heat exchanger configured to receive the refrigerant from the flash tank, wherein:

the subcooler heat exchanger is coupled to an input of the first load; and

the subcooler heat exchanger is coupled to an input of the expansion valve;

during a first mode of operation:

the subcooler heat exchanger is configured to direct the refrigerant from the flash tank to the input of the first load;

the first load configured to use the refrigerant from the subcooler heat exchanger to cool a first space proximate the first load;

the second load configured to use the refrigerant from the subcooler heat exchanger to cool a second space proximate the second load;

the first compressor configured to compress the refrigerant from the first load; and

the second compressor configured to compress a mixture of the refrigerant from the first compressor and the refrigerant from the second load; and

during a second mode of operation:

the subcooler heat exchanger configured to:

direct the refrigerant from the flash tank to the input of the expansion valve;

generate a heated refrigerant by transferring heat from the refrigerant from the flash tank to the refrigerant from the expansion valve;

direct a first portion of the heated refrigerant to the input of the first load; and

direct a second portion of the heated refrigerant to the first compressor;

the first compressor configured to:

compress the heated refrigerant from the subcooler heat exchanger; and

direct the compressed refrigerant from the subcooler heat exchanger to the first load to defrost the first load.

16. The system of claim 15 , wherein the subcooler heat exchanger is positioned within the flash tank.

17. The system of claim 15 , wherein the second load uses the refrigerant from the flash tank to cool the second space during the second mode of operation.

18. The system of claim 15 , wherein during the second mode of operation:

the first load is configured to direct the compressed refrigerant from the first compressor to the flash tank; and

the flash tank is configured to direct the compressed refrigerant from the first load to the second compressor.

19. The system of claim 15 , further comprising an oil separator configured to separate an oil from the refrigerant from the second compressor.

20. The system of claim 15 , wherein the flash tank is further configured to direct a flash gas to the second compressor.