A refrigeration cycle apparatus includes: a refrigerant circuit in which a compressor, a heat-source-side heat exchanger, a first expansion device, a second expansion device, and a load-side heat exchanger are sequentially connected by refrigerant pipes and in which refrigerant is circulated; a controller that controls the refrigerant circuit; a bypass pipe extending from a liquid pipe between the first expansion device and the second expansion device toward a suction side of the compressor; a third expansion device provided at the bypass pipe to decompress the refrigerant that flows through the bypass pipe; and a refrigerant cooler provided at the bypass pipe and downstream of the third expansion device to cause heat exchange to be performed between the refrigerant decompressed by the third expansion device and heat generated from the controller.

In an air-conditioning system according to an aspect of the present disclosure, a gaseous refrigerant remaining in a reservoir can be discharged from the reservoir even when a cooling operation has started and the reservoir is being filled with a liquid refrigerant. Therefore, the reservoir can be filled with the liquid refrigerant at a faster speed.

Provided are an air conditioner and a mode switching control method thereof. The air conditioner comprises an outdoor unit and an indoor unit. One end of the outdoor unit is connected to one end of the indoor unit via a throttling element, and the other end of the indoor unit is connected to the other end of the outdoor unit via a liquid storage tank. The mode switching control method comprises the following steps: when the indoor unit switches to a refrigeration mode, acquiring an outlet superheat degree of the liquid storage tank, and determining whether the outlet superheat degree is less than a first preset value; and if the outlet superheat degree is less than the first preset value, controlling to turn down the throttling element until the outlet superheat degree is greater than a second preset value that is greater than the first preset value.

An air-conditioning apparatus includes a refrigeration cycle charged with non-azeotropic refrigerant mixture and refrigerating machine oil. A suction pipe which is a refrigerant pipe connecting between a suction port of a compressor and an accumulator has an end portion on the side of the accumulator extending into the accumulator. In addition, the suction pipe of the air-conditioning apparatus includes an oil return hole formed in a portion of the suction pipe located inside the accumulator at a position higher than a central portion of the accumulator. A controller of the air-conditioning apparatus controls an opening degree of a pressure reducing device so as to make quality of refrigerant flowing into the accumulator less than 1.

A passive liquid collecting device has a reservoir with an outlet and one or more rigid structures within the reservoir. The rigid structures are configured to collect a liquid and direct the liquid to the outlet. Porous capillary media are supported by the rigid structures. A thermal control loop is also disclosed.

The various embodiments described herein include methods, devices, and systems for determining refrigerant charge level. In one aspect, a refrigeration system includes: (1) a compressor to compress a refrigerant; (2) a condenser disposed downstream of the compressor to condense the refrigerant; (3) an evaporator disposed downstream of the condenser to vaporize the refrigerant; (4) refrigerant lines fluidly connecting the compressor, the condenser and the evaporator in series to form a refrigerant circuit for circulating the refrigerant; (5) at least one sensor configured to measure temperature and pressure of the refrigerant in the refrigerant circuit; and (6) a controller communicatively coupled to the at least one sensor and configured to: (a) determine a sub-cooling level or super-heating level based on the temperature and/or pressure measured by the at least one sensor; and (b) facilitate operation of the refrigeration system based on the sub-cooling level or the super-heating level.

The refrigeration system includes a compressor, a condenser, an evaporator, one or both of a receiver drier unit and an accumulator unit fluidly connected by refrigerant lines to form a refrigerant circuit. The receiver drier unit includes a receiver drier and a first sensor, and the accumulator unit includes an accumulator and a second sensor. A controller is electrically connected to the first and second sensors and in some cases electrically connected to an electrical valve. The electrical valve is fluidly connected to a refrigerant reservoir. The controller determines the refrigerant charge level, and selectively controls the electrical valve to allow the refrigerant to flow from the refrigerant reservoir to the refrigerant circuit when the refrigerant charge level is below the predetermined refrigerant charge level.

The refrigeration system includes a compressor, a condenser, an evaporator, one or both of a receiver drier unit and an accumulator unit fluidly connected by refrigerant lines to form a refrigerant circuit. The receiver drier unit includes a receiver drier and a first sensor, and the accumulator unit includes an accumulator and a second sensor. A controller is electrically connected to the first and second sensors and in some cases electrically connected to an electrical valve. The electrical valve is fluidly connected to a refrigerant reservoir. The controller determines the refrigerant charge level, and selectively controls the electrical valve to allow the refrigerant to flow from the refrigerant reservoir to the refrigerant circuit when the refrigerant charge level is below the predetermined refrigerant charge level.

A refrigeration and air-conditioning apparatus rapidly varies the pressure or the temperature inside a liquid reserve container to identify a liquid level position inside the liquid reserve container on the basis of the surface temperature of the liquid reserve container.

A heat-source-side circuit of a heat source unit includes a low-stage compressor, a high-stage compressor, a heat-source-side heat exchanger, a receiver, and a venting passage. The venting passage connects an upper portion of the receiver with an inlet of the high-stage compressor. A determination unit of the heat source unit determines that the amount of the refrigerant charged in a refrigerant circuit is excessive based on the pressure and the degree of superheat of the refrigerant sucked into the high-stage compressor.