An apparatus includes a first compressor, a first load, a second compressor, a second load, a first heat exchanger, and a second heat exchanger. The first compressor compresses a first refrigerant. The first load uses the first refrigerant to remove heat from a space proximate the first load. The first load sends the first refrigerant to the first compressor. The second compressor compresses a second refrigerant. The second load uses the second refrigerant to remove heat from a space proximate the second load. The second load sends the second refrigerant to the second compressor. The first heat exchanger receives the first refrigerant from the first compressor. The first heat exchanger transfers heat from the first refrigerant to a fluid. The second heat exchanger receives the second refrigerant from the second compressor. The second heat exchanger transfers heat from the fluid to the second refrigerant.

The refrigerant device includes a refrigerant circuit, an injection circuit, an inlet temperature sensor, an outlet temperature sensor, and a controller configured to control the operation of the refrigerant circuit. The controller includes an evaluation value calculation unit and a refrigerant amount detection unit. The evaluation value calculation unit calculates an evaluation value indicating a capability of a subcooling heat exchanger in accordance with an inlet temperature detected by the inlet temperature sensor and an outlet temperature detected by the outlet temperature sensor. The refrigerant amount detection unit determines whether there is a shortage of refrigerant in accordance with the evaluation value calculated by the evaluation value calculation unit.

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 heat pump system includes a first heat pump arrangement configured to operate with a first heat pump medium including CO2; a second heat pump arrangement configured to operate with a second heat pump medium including water; and a coupler for thermally coupling the first heat pump arrangement to the second heat pump arrangement.

An apparatus includes a compressor, a load, a heat exchanger, and a heater. The compressor compresses a refrigerant. The load uses the refrigerant to remove heat from a space proximate the load. The load sends the refrigerant to the compressor. The heat exchanger receives the refrigerant from the compressor. The heat exchanger transfers heat from a fluid to the refrigerant. The heat exchanger discharges the refrigerant to the compressor. The heater adds heat to the fluid.

A refrigeration system, including: an electronic control unit, including a housing and an electronic device arranged in the housing; a refrigeration loop, including a compressor, a condenser, a primary throttling element, and an evaporator sequentially connected through a pipeline and forming a closed loop; and an electronic device cooling branch connected into the refrigeration loop from the condenser, and connected back to the refrigeration loop from the evaporator; the electronic device cooling branch including an electronic device cooling unit, a secondary throttling element, and an electromagnetic valve; and the electronic device cooling unit being arranged in the housing and spaced apart from the electronic device, for reducing the temperature and humidity of the electronic device and an environment in the housing.

An air-conditioning apparatus includes an internal heat exchanger in which refrigerant flowing through a refrigerant pipe between an outdoor heat exchanger and an expansion device and refrigerant flowing through a refrigerant pipe between the expansion device and an indoor heat exchanger exchange heat, a pressure sensor, a first temperature sensor that detects temperature of the refrigerant flowing into the expansion device in the cooling operation, and a control unit configured to control the opening degree of the expansion device based on results of detection by the pressure sensor and the first temperature sensor in the cooling operation.

An outdoor unit includes at least a compressor, a gas-liquid separator, and an outdoor heat exchanger of a refrigerant circuit, the refrigerant circuit being formed by connecting, by pipes, the compressor, a condenser, a pressure reducing device, the gas-liquid separator, and the outdoor heat exchanger that acts as an evaporator including at least a plurality of heat transfer tubes and an inlet header that distributes incoming refrigerant to the heat transfer tubes. The outdoor unit further includes a gas-liquid-separator bypass pipe, a gas-liquid-separator-side flow control valve, a header bypass pipe, a header-side flow control valve, and a determination device.

Embodiments of the present disclosure are directed to a controller for a heating, ventilation, and/or air conditioning (HVAC) system. The controller is configured to operate in a first defrost mode or a second defrost mode, determine that feedback from a first sensor of the HVAC system is unavailable, receive feedback from a second sensor of the HVAC system, and operate the HVAC system in the second defrost mode instead of the first defrost mode in response to unavailability of the feedback from the first sensor and based on the feedback from the second sensor.

The invention relates to a flow circuit system (1) for a vehicle, with a first flow circuit (10) guiding a first fluid and operable as a heat pump, and a second flow circuit (50) with a conveying device (31) guiding a second fluid, and a switching device (35), wherein in the provided flow direction of the first fluid downstream of a compressor (3) and upstream of an expansion element (15), at least one first heat exchanger (7) between the first and second fluids, wherein the second flow circuit (50) has at least two flow circuit modes, wherein in the first flow circuit mode, apart from the at least one conveying device (31) for the second fluid and the at least one first heat exchanger (7), at least one outside heat exchanger (37) which may be flowed through by the second fluid and is configured as a radiator is connected to the second flow circuit (50), and in the second flow circuit mode this at least one outside heat exchanger (37) is not connected to the at least second flow circuit (50) containing the conveyor device (31) and the first heat exchanger (7), and preferably is also a heating flow circuit. In this way more flexibility is created in the flow circuit system (1) for a vehicle.