A cooling system drains oil from low side heat exchangers to vessels and then uses compressed refrigerant to push the oil in the vessels back towards a compressor. Generally, the cooling system operates any number and combination of three different modes of operation: a normal mode, an oil drain mode, and an oil return mode. During the normal mode, a primary refrigerant is cycled to cool one or more secondary refrigerants. As the primary refrigerant is cycled, oil from a compressor may mix with the primary refrigerant and become stuck in a low side heat exchanger. During the oil drain mode, the oil in the low side heat exchanger is allowed to drain into a vessel. During the oil return mode, compressed refrigerant is directed to the vessel to push the oil in the vessel back towards a compressor.

A refrigerant compressor unit, including a compressor housing and at least one compressor element that is arranged in the compressor housing, is movable by bearing and drive parts, and operates in at least one compressor chamber, at least one lubricant supply point arranged in the compressor housing for at least one of the bearing and drive parts and/or compressor element, and a lubricant supply line to the at least one lubricant supply point, wherein the lubricant supply line has a lubricant storage chamber through which lubricant flows and in which a lubricant presence sensor is arranged for detecting the presence of lubricant in the lubricant storage chamber.

A refrigerant compressor for a refrigeration system comprises a common housing, a compressor unit arranged in the common housing, a mechanical compressor drive unit for the compressor unit, arranged in a drive chamber, a lubricant bath forming in the drive chamber, an intake duct that extends in a manner separated from the drive chamber and through which the compressor unit draws in by suction refrigerant that is to be compressed. The intake duct and the drive chamber are connected by a gas equaliser duct, which allows a permanent equalisation of gas, and which has on one side an opening on the drive chamber side and on the other an opening on the intake side, and of which the duct length between the openings corresponds to at least twice an equivalent duct diameter, in particular a smallest equivalent duct diameter, of the gas equaliser duct.

An oil return control method for a multi-split air conditioner and a system accomplishing the same includes: calculating an average exhaust pressure within an oil return period Pd_AVG; determining whether the average exhaust pressure Pd_AVG≥the set threshold Pd.sub.threshold; if Pd_AVG≥Pd.sub.threshold, maintaining the multi-split air conditioner working in heating mode to ensure an acceptable oil return performance without affecting the air conditioning effect of indoor unit in heating mode; if Pd_AVG<Pd.sub.threshold, switching the multi-split air conditioner to cooling mode, stopping a fan within those power-on indoor units and entering into a cooling oil return process and switching the multi-split air conditioner back to heating mode until the cooling oil return process ends.

A refrigeration cycle apparatus (1) is capable of performing a refrigeration cycle using a small-GWP refrigerant. The refrigeration cycle apparatus (1) includes a refrigerant circuit (10) and a refrigerant enclosed in the refrigerant circuit (10). The refrigerant circuit includes a compressor (21), a condenser (23), a decompressing section (24), and an evaporator (31). The refrigerant contains at least 1,2-difluoroethylene.

This disclosure relates to cold-chain transportation, and more particularly to a refrigerated container refrigeration system capable of preventing freezing of container door, including compressors, oil separators, gas coolers, regenerators, electronic expansion valves, gas-liquid separators, an evaporator, suction pressure regulating valves, oil-level solenoid valves, gas cooler pressure regulating valves, differential pressure regulating valves, an evaporation pressure regulating valve, solenoid valves, check valves, flow meters, pressure sensors, temperature sensors, a door anti-freezing area, a refrigerated container shell, refrigerated container doors, a refrigeration unit, an anti-freezing pipeline and fastening components. Carbon dioxide is selected as refrigerant. A flow two-stage cycle compression refrigeration system with switchable operation pipeline is adopted, and the outlet pipeline of a high-pressure compressor is extended for preventing freezing of container door.

This disclosure relates to cold-chain transportation, and more particularly to a refrigerated container refrigeration system capable of preventing freezing of container door, including compressors, oil separators, gas coolers, regenerators, electronic expansion valves, gas-liquid separators, an evaporator, suction pressure regulating valves, oil-level solenoid valves, gas cooler pressure regulating valves, differential pressure regulating valves, an evaporation pressure regulating valve, solenoid valves, check valves, flow meters, pressure sensors, temperature sensors, a door anti-freezing area, a refrigerated container shell, refrigerated container doors, a refrigeration unit, an anti-freezing pipeline and fastening components. Carbon dioxide is selected as refrigerant. A flow two-stage cycle compression refrigeration system with switchable operation pipeline is adopted, and the outlet pipeline of a high-pressure compressor is extended for preventing freezing of container door.

A refrigeration system includes a compressor, a condenser, a throttling device, and an evaporator, which are connected in sequence to form a cooling circuit, the refrigeration system further includes an oil recovery system which includes: an operation chamber, which includes a first port communicating with an oil-containing position in the refrigeration system through a first pipeline, and a second port communicating with a bearing chamber or a bearing lubrication pipeline of the compressor through a second pipeline; and a main piston in the operation chamber, the main piston reciprocating in the operation chamber to perform an extraction stroke and a discharge stroke; in the extraction stroke, an oil-containing refrigerant in the oil-containing position in the refrigeration system is extracted to the operation chamber; and in the discharge stroke, the oil-containing refrigerant in the operation chamber is delivered to the bearing chamber or the bearing lubrication pipeline of the compressor.

This disclosure is directed to systems and methods for controlling compressor motors, particularly varying the operation parameters of the motor to provide heat to a lubricant of the motor. The operation parameters include one or more of a pulse width modulation switching frequency, a pulse width modulation frequency switching pattern, or a torque/amp ratio of a drive of the compressor. The efficiency of the motor may be reduced to provide heat, with the heat improving lubricant quality and drive efficiency, to increase an overall efficiency of compressor operations. Methods may include determining a lubricant quality, and determining operational parameters that improve lubricant quality.

It is an object of the present invention to provide a fluid stirring and liquefaction promoting apparatus which enables uniform mixture of refrigerator oil with refrigerant, thereby improving the heat exchange efficiency of heat pump systems and reducing the energy consumption.

There is provided a liquefaction promoting apparatus to be disposed on a pipeline of a heat pump system for the purpose of stirring and uniformly mixing the fluid containing refrigerant and refrigerator oil circulating therein. The apparatus comprises a cylindrical casing, one or more channelizing units each composed of a pair of large-diameter disks on its outer side and a pair of small-diameter disks on its inner side disposed in axial alignment inside the cylindrical casing. Each of the large-diameter disks is on its inner surface with a honeycomb panel having polygonal cells and each of the small-diameter disks is formed on its outer surface with a honeycomb panel having polygonal cells such that the honeycomb panels of the large-diameter disks and of the small-diameter disks are arranged to face each other and each polygonal cell communicates with more than one opposing polygonal cells. The fluid containing refrigerant and refrigerator oil is circulated in the heat pump system with a pressure of 0.2 to 10 MPa.