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

Claim 7:
8. A method comprising:
storing, by a flash tank, a primary refrigerant;
during a first mode of operation:
closing a first valve and a second valve;
using, by a first low side heat exchanger, primary refrigerant from the flash tank to cool a secondary refrigerant, wherein both the first valve and the second valve are each associated with the first low side heat exchanger;
receiving, by an accumulator disposed downstream of the first low side heat exchanger, primary refrigerant from 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;
receiving, by a first cooling system fluidly coupled to the first low side heat exchanger, the cooled secondary refrigerant;
compressing, by a first compressor, primary refrigerant from the accumulator; and
compressing, by a second compressor disposed downstream of the first compressor, primary refrigerant from the first compressor,

during a second mode of operation:
opening the first valve, wherein the first valve is disposed upstream of the accumulator in parallel with the first low side heat exchanger;
closing the second valve, wherein the second valve is disposed between a discharge side of the first valve and a suction side of a first vessel, wherein the first vessel is disposed between the first valve and the accumulator; and
directing, by the first valve, primary refrigerant from the first low side heat exchanger and an oil from the first low side heat exchanger to the first vessel; and

during a third mode of operation:
closing the first valve;
opening the second valve;
directing, by the second valve, primary refrigerant from the first compressor to the first vessel; and
pushing, by the primary refrigerant from the first compressor, the oil in the first 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.