Cooling system

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;
• using, by a first load, the refrigerant from the flash tank to cool a first space proximate the first load;
• during a first mode of operation:
• separating, by an oil separator, an oil from the refrigerant from the first load;
• directing, by the oil separator, the refrigerant to an ejector;
• directing, by the ejector, the refrigerant from the high side heat exchanger and the refrigerant from the first oil separator to the flash tank;
• directing, by the flash tank, the refrigerant from the first oil separator to a first compressor;
• and
• compressing, by the first compressor, the refrigerant from the flash tank;
• and
• during a second mode of operation, directing, by the first oil separator, the oil separated from the refrigerant to the first compressor, wherein a first valve disposed between the first oil separator and the ejector is closed, wherein a second valve disposed between the first oil separator and the high side heat exchanger is open wherein the second valve is configured to direct refrigerant to the high side heat exchanger, and wherein the oil separated from the refrigerant is directed to the first compressor due to an increase in pressure from opening the second valve.

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;
• a first load configured to use the refrigerant from the flash tank to cool a first space proximate the first load;
• a second load configured to use the refrigerant from the flash tank to cool a second space proximate the second load;
• a first oil separator;
• a first valve disposed between the first oil separator and an ejector;
• a second valve disposed between the first oil separator and the high side heat exchanger;
• a first compressor;
• and
• a second compressor configured to compress the refrigerant from the second load;
• during a first mode of operation, wherein the first valve is open and the second valve is closed:
• the first oil separator configured to:
• separate an oil from the refrigerant from the first load;
• direct the refrigerant to the ejector, the ejector configured to direct the refrigerant from the high side heat exchanger and the refrigerant from the first oil separator to the flash tank;
• the flash tank configured to direct the refrigerant from the first oil separator to the first compressor;
• and
• the first compressor configured to compress the refrigerant from the flash tank and the refrigerant from the second compressor;
• and
• during a second mode of operation, wherein the first valve is closed and the second valve is open, the second valve is configured to direct refrigerant to the high side heat exchanger, and the first oil separator is configured to direct the oil separated from the refrigerant to the first compressor, wherein the oil separated from the refrigerant is directed to the first compressor due to an increase in pressure from opening the second valve.