An apparatus includes a conduit coupled to a suction header that is configured to receive a refrigerant and an oil separator that is configured to separate an oil from the refrigerant received from a compressor. During a first mode of operation, the conduit is configured to remove excess oil from the refrigerant that has collected at the suction header. During a second mode of operation, the oil separator is configured to direct to the conduit the oil separated from the refrigerant received from the compressor. The conduit is configured to direct to an oil reservoir the oil from the oil separator and the excess oil removed from the refrigerant.

A refrigeration cycle apparatus includes: a refrigeration cycle circuit in which a compressor, a condenser, a first expansion valve, and an evaporator are connected by refrigerant pipes; an injection pipe having a refrigerant inflow side end and a refrigerant outflow side end, the refrigerant inflow side being connected between the condenser and the first expansion valve, the refrigerant outflow side end being connected to a suction side of the compressor; a second expansion valve provided at the injection pipe; and a controller that controls a rotation speed of the compressor and an opening degree of the second expansion valve. In the case of reducing a heat-exchange capability of the evaporator when the rotation speed of the compressor is a specified rotation speed, the controller performs a low load operation during which refrigeration is caused to flow through the injection pipe.

A cooling system is provided including a two-phase pump loop and a vapor compression system. The two-phase pump loop cools a thermal load with a first coolant. The vapor compression system is configured to circulate a second coolant. The vapor compression system includes a liquid vapor separator which separates the second coolant into a liquid portion and a gaseous portion. The liquid vapor separator is a thermal energy storage for the two-phase pump loop. A condenser of the two-phase pump loop transfers heat from the first coolant to the liquid portion of the second coolant in the liquid-vapor separator.

An oil return control method of a multi-functional multi-split system with double four-way valves. The multi-functional multi-split system includes an outdoor unit, at least one set of hydraulic modules and at least one set of indoor modules. When the multi-split system is switched from a normal operation mode to an oil return mode, a first four-way valve and a second four-way valve are powered down, and operation modes of each set of indoor modules and each set of hydraulic modules, the on/off state of fans of an indoor heat exchanger and a hydraulic heat exchanger, opening degrees of a first electronic expansion valve of the indoor heat exchanger and a first electronic expansion valve of the hydraulic heat exchanger, and the on/off state of a first electromagnetic valve and a second electromagnetic valve are correspondingly adjusted based on the previous operation modes.

A compressor may include a shell, a first scroll, and a second scroll. The shell may include a first inlet, a second inlet, and an outlet. The first scroll may include a first end plate and a first spiral wrap. The second scroll may include a second end plate and a second spiral wrap, the first and second spiral wraps cooperating to define a series of moving compression pockets therebetween. The moving compression pockets decrease in volume as the moving compression pockets move from a radially outer position to a radially inner position. The moving compression pockets may receive working fluid from the first inlet at the radially outer position and provide working fluid to the outlet at the radially inner position. The second end plate may include a fluid cavity receiving working fluid from the second inlet and fluidly isolated from working fluid within the moving compression pockets.

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 in 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 vapor compression system includes a compressor configured to circulate a refrigerant through a refrigerant loop, a sump configured to receive a mixture of lubricant and the refrigerant from the compressor, and a controller having a memory and a processor. The processor is configured to receive a first signal indicative of a temperature of the mixture within the sump, receive a second signal indicative of a pressure of the mixture within the sump, determine a relative amount of the refrigerant in the mixture based on the first signal and the second signal, and output a control signal in response to the relative amount of the refrigerant in the mixture exceeding a threshold value.

A refrigeration cycle apparatus includes: a refrigerant circuit; an oil reservoir; a first pipe that connects the oil separator and the oil reservoir, the first pipe being configured to send the refrigeration oil separated by the oil separator to the oil reservoir; a first valve provided at the first pipe; a second pipe that connects the oil reservoir and a suction side of the compressor; a second valve provided at the second pipe; a third pipe that connects the oil reservoir and the suction side of the compressor at a position lower than a position at which the second pipe is connected to the oil reservoir; and a third valve provided at the third pipe. The first to third valves are closed in a non-operational period of the compressor.

An unconventional oil separator includes a vertical design. Generally, a refrigerant enters the vertical oil separator and spins downwards. The oil separator includes plates within the oil separator that either maintain the spin of the refrigerant or reverse the spin of the refrigerant, which causes oil in the refrigerant to separate from the refrigerant. A vertical outlet allows refrigerant that spins towards the bottom of the oil separator to travel back towards the top and out of the oil separator. Separated oil is collected at the bottom of the oil separator.

Systems, methods, and computer-readable mediums are provided for improving the efficiency of a filter-type oil separator in a cooling system including a compressor that pumps a mixture of lubricating oil and refrigerant through the filter-type oil separator. The filter type oil separator is configured to receive a first portion of the mixture from the compressor, and a bypass line is configured to bypass a second portion of the mixture around the filter-type oil separator. The bypass line ensures a sufficient amount of oil is present in the compressor.