Patent ID: 11933527
Assignee: HEATCRAFT REFRIGERATION PRODUCTS LLC
Field: Thermal processes and apparatus (Mechanical engineering)
Classification: CPC F | IPC F

Claim 14:
15. A system comprising:
a high side heat exchanger configured to remove heat from a primary refrigerant;
a flash tank configured to store the primary refrigerant;
a first low side heat exchanger;
an accumulator disposed downstream of the first low side heat exchanger, wherein the accumulator comprises a U-shaped pipe having an end configured to receive the primary refrigerant, and wherein the U-shaped pipe comprises a hole located towards a bottom of the accumulator;
a first compressor;
a second compressor disposed downstream of the first compressor;
a first valve associated with the first low side heat exchanger and is disposed upstream of the accumulator in parallel with the first low side heat exchanger;
a first cooling system fluidly coupled to the first low side heat exchanger; and
a second valve associated with the first low side heat exchanger and is disposed between a discharge side of the first valve and a suction side of a vessel, wherein the vessel is disposed between the first valve and the accumulator, wherein the second valve is configured to direct primary refrigerant discharged from the first compressor to the first vessel,
wherein during a first mode of operation:
the first and second valves are closed;
the first low side heat exchanger is configured to use primary refrigerant from the flash tank to cool a secondary refrigerant;
the accumulator is configured to receive the primary refrigerant from the first low side heat exchanger;
the first cooling system is configured to receive the cooled secondary refrigerant;
the first compressor is configured to compress the primary refrigerant from the accumulator; and
the second compressor is configured to compress the primary refrigerant from the first compressor,

wherein during a second mode of operation:
the first valve is open and configured to direct the primary refrigerant from the first low side heat exchanger and an oil from the first low side heat exchanger to the vessel; and
the second valve is closed,

wherein during a third mode of operation:
the first valve is closed; and
the second valve is open and directs the primary refrigerant from the first compressor to the vessel, wherein the primary refrigerant from the first compressor pushes the oil in the vessel to the accumulator, and wherein the oil collected at the bottom of the accumulator is sucked through the hole in the U-shaped pipe and directed to the first compressor.