A heating, ventilation, air conditioning, and/or refrigeration (HVAC&R) system includes a refrigerant loop having a compressor configured to circulate a refrigerant therethrough, a motor configured to drive rotation of the compressor, wherein the motor is a permanent magnet assisted synchronous reluctance (PMASR) motor, and a motor cooling system configured to direct a portion of the refrigerant from the refrigerant loop and through a housing of the PMASR motor to place the portion of the refrigerant in thermal communication with components of the PMASR motor.

An air conditioner is provided that may include an outdoor unit having a compressor configured to compress a refrigerant; at least one indoor unit having an indoor heat exchanger, in which the refrigerant is heat exchanged, an indoor expansion valve that expands the refrigerant by adjusting an opening thereof, and a leak sensor that senses leakage of the refrigerant; a gaseous line that connects the outdoor unit and the at least one indoor unit and through which gaseous refrigerant flows; a liquid line that connects the outdoor unit and the at least one indoor unit and through which liquid refrigerant flows; a first shut-off valve disposed adjacent to the at least one indoor unit that opens and closes the gaseous line; a second shut-off valve disposed adjacent to the at least one indoor unit that opens and closes the liquid line; a supercooling pipe branched from the liquid line and connected to an inlet of the compressor; a supercooling expansion valve that expands refrigerant, flowing through the supercooling pipe, by adjusting an opening thereof; and a controller configured to control operation of the compressor and to control opening and closing of the first shut-off valve, the second shut-off valve, the indoor expansion valve, and the supercooling expansion valve. When the leak sensor senses the leakage of the refrigerant, the controller closes the first shut-off valve and the second shut-off valve.

A refrigeration system includes a heat exchanger configured to place a cooling fluid in a heat exchange relationship with a working fluid, a free-cooling circuit having a pump configured to circulate the working fluid through the heat exchanger and a condenser, a flow control valve configured to control a flow rate of the working fluid to the condenser, a condenser bypass valve configured to control a flow rate of the working fluid that bypasses the condenser, and a controller configured to adjust a position of the flow control valve, a position of the condenser bypass valve, a speed of a fan of the condenser, a speed of the pump, and a temperature of a heater based on an ambient temperature, a temperature of the working fluid leaving the condenser, the position of the flow control valve, the position of the condenser bypass valve, or a combination thereof.

An air-conditioning apparatus including heat source apparatuses each including a compressor and an accumulator includes: a refrigerant amount calculation unit that calculates an amount of the refrigerant accumulated in the accumulator in one of the heat source apparatuses that is to be controlled; a refrigerant differential amount calculation unit configured to calculate, when the number of the heat source apparatuses is two, a differential amount between the calculated amount and an amount of the refrigerant in the accumulator in the other heat source apparatus, and calculate, when the number of the heat source apparatuses is three or more, a differential amount between the calculated amount of the refrigerant and an average amount of amounts of the refrigerant accumulated in the accumulators in the heat source apparatuses; and a liquid equalization control unit that controls the heat source apparatus to be controlled, based on the calculated differential amount.

The disclosure describes a system that includes an evaporator, an accumulator downstream of the evaporator, a centrifugal compressor downstream of the accumulator, a first heat exchanger stage downstream of the centrifugal compressor, and a second heat exchanger stage downstream of the first heat exchanger stage. The evaporator is configured to cool a conditioned air stream using a refrigerant. The accumulator is configured to store excess refrigerant. The centrifugal compressor is configured to compress the refrigerant. The first heat exchanger stage is configured to cool the refrigerant using environmental air. The second heat exchanger stage is configured to cool the refrigerant from the first heat exchanger stage using a portion of the excess refrigerant from the accumulator.

A cooling system is designed to operate in two different modes. Generally, in the first mode, when parallel compression is needed, certain valves are controlled to direct gaseous refrigerant from a tank to a compressor in the system and to direct refrigerant from low side heat exchangers towards other compressors. In this manner, a compressor in the system is transitioned to be generally a parallel compressor. In the second mode, when parallel compression is not needed, the valves are controlled to return the refrigerant flow back to normal.

A refrigeration cycle apparatus includes: a refrigerant circuit configured to circulate refrigerant; and a controller configured to control the refrigerant circuit. The refrigerant circuit includes a compressor, a first heat exchanger, a first expansion device, a second expansion device, a third expansion device, a second heat exchanger, and a cooler configured to cool a substrate of the controller. In a first path of the refrigerant circuit, the compressor, the first heat exchanger, the first expansion device, the second expansion device, and the second heat exchanger are connected in order of the compressor, the first heat exchanger, the first expansion device, the second expansion device, and the second heat exchanger. In a second path of the refrigerant circuit, the cooler and the third expansion device are connected in order of the cooler and the third expansion device from a first point between the first expansion device and the second expansion device to a second point between the compressor and the second heat exchanger.

A refrigeration cycle apparatus includes a refrigeration cycle circuit, a liquid receiver, a first valve and a second valve. The refrigeration cycle circuit includes a compressor, an outdoor heat exchanger and an indoor heat exchanger. The liquid receiver is provided in a second section located in the refrigeration cycle circuit. The second section is a section extending between the outdoor heat exchanger and the indoor heat exchanger without extending through the compressor. The first valve is provided in a first section in the refrigeration cycle circuit, and is a solenoid valve or a motor valve. The first section is a section extending between the outdoor heat exchanger and the indoor heat exchanger through the compressor. The second valve is provided in the second section and between the liquid receiver and the indoor heat exchanger, and is an electronic expansion valve, a solenoid valve or a motor valve.

An air conditioning apparatus includes an outdoor device that is configured to circulate refrigerant and that includes a compressor and an outdoor heat exchanger, a plurality of indoor devices configured to circulate water, and a heat exchange device connecting the outdoor device with the indoor device. The heat exchange device includes a heat exchanger configured to exchange heat between the refrigerant and the water, and a switch device configured to control flow of refrigerant between the indoor devices and the heat exchanger.

A cooling system uses P-traps to address the oil return issues that result from a vertical separation between a compressor and a heat exchanger. Generally, the vertical piping that carries the refrigerant from the compressor to the heat exchanger includes P-traps installed at various heights to capture oil in the refrigerant and to prevent that oil from flowing back to the compressor. T-connections are coupled to the P-traps to allow the oil to drain out of the P-traps. The oil may then be collected and returned to the compressor.