No studies have been made regarding what kinds of refrigerants should be used in a refrigeration cycle device for a vehicle. An air conditioner (1) for a vehicle includes a refrigerant circuit (10) and a refrigerant that is sealed in the refrigerant circuit (10). The refrigerant circuit (10) includes a compressor (80), a first heat exchanger (85), which serves as a heat dissipater in a dehumidifying heating mode, an outside-air heat exchanger (82), a cooling control valve (87), and a second heat exchanger (86), which serves as an evaporator in the dehumidifying heating mode. The refrigerant is a refrigerant having a low GWP.

Provided is an air conditioning apparatus. The air conditioning apparatus includes an outdoor unit through which a refrigerant is circulated, an indoor unit through which water is circulated, and a heat exchange device including a heat exchanger in which the refrigerant and the water are heat-exchanged with each other. The heat exchanger includes a high-pressure guide tube, a low-pressure guide tube, a liquid guide tube, a bypass tube configured to connect a bypass branch point of the high-pressure gas tube of the outdoor unit to a bypass combination point of the liquid guide tube to bypass a high-pressure refrigerant existing in the high-pressure tube to the liquid guide tube, and a bypass valve installed in the bypass tube. The outdoor unit includes a first valve device configured to guide a refrigerant compressed in the compressor to the outdoor heat exchanger and a second valve device configured to guide the refrigerant compressed in the compressor to the high-pressure guide tube of the heat exchange device.

Provided is an air conditioning apparatus. The air conditioning apparatus includes an outdoor unit which includes a compressor and an outdoor heat exchanger and through which a refrigerant is circulated, an indoor unit through which water is circulated, a heat exchanger in which the refrigerant and the water are heat-exchanged with each other, a water tube configured to guide the water circulated through the indoor unit and the heat exchanger, a pump installed in the water tube, and a controller configured to analyze an output signal of the pump so as to calculate a ration of an air layer in the water tube, the controller being configured to control a target supercooling degree or target superheating degree of the heat exchanger according to the calculated ratio of the air layer.

An air-conditioning system includes a plurality of indoor units, an outdoor unit, a refrigerant pipe including a branch portion and being divided into a plurality of flow sections, a plurality of control valves, a plurality of pressure sensors, and a controller. The control valves include indoor-unit control valves, and a plurality of pipe control valves. The pipe control valves include a plurality of indoor-side pipe control valves provided between the branch portion and the indoor units. The pressure sensors include a plurality of indoor-side pressure sensors connected to the controller and provided between the indoor-unit control valves and the indoor-side pipe control valves. The controller opens or closes the control valves, compares a pressure of refrigerant to a predetermined threshold, and detects refrigerant leaking in the flow section where a pressure of refrigerant measured is determined to be lower than the predetermined threshold.

A heat source controller performs a first operation when a compression element is in a stopped state and a pressure in a receiver exceeds a predetermined first pressure. The heat source controller allows an inlet of the compression element to communicate with the receiver, and drives the compression element in the first operation.

Example embodiments of the present disclosure relate to an HVAC system, and methods for controlling the system, that mitigate the impact of refrigerant leaks before the leaks are even detected. Some embodiments include an HVAC system operable to mitigate refrigerant leaks, the system including an indoor unit including an indoor fan and an indoor heat exchanger, an outdoor unit including an outdoor heat exchanger and a compressor, a refrigerant circuit including a refrigerant circulated between the indoor unit and the outdoor unit, a mass control valve coupled to the refrigerant circuit, and control circuitry configured to: operate the HVAC system to satisfy a conditioning load by circuiting the refrigerant through the refrigerant circuit and operating the indoor fan, and completely close the mass control valve to at least partially isolate the refrigerant circuit at the indoor heat exchanger in response to the indoor fan being shut off.

A heat medium relay device includes: a valve block provided in a third space, and including a plurality of valves to allow a secondary heat medium subjected to the heat exchange at a first heat exchanger and a secondary heat medium subjected to the heat exchange at a second heat exchanger to flow to at least one indoor unit, the valve block being lighter in weight than each of the first heat exchanger, a first pump, the second heat exchanger, and a second pump.

An air-conditioning apparatus includes a suction-injection pipe that introduces a refrigerant in a liquid or two-phase state into a suction side of a compressor, an expansion device that is arranged at the suction-injection pipe, and a controller that regulates the suction-injection flow rate of a refrigerant introduced into the suction side of the compressor through the suction-injection pipe by controlling the opening degree of the expansion device.

An air-conditioning apparatus is capable of completing heat medium freeze prevention control more quickly by performing heat medium temperature rise control for raising the temperature of a cooled heat medium and includes a controller that adjusts a current opening degree of a bypass device at a bypass pipe to an opening degree, and that makes an adjustment such that the flow passage resistance in the case of the opening degree becomes equal to the flow passage resistance in the case of an opening degree before an expansion device is adjusted to a minimum opening degree.

An air-conditioning apparatus includes a temperature sensor for detecting a temperature of the heat medium sent from each of the intermediate heat exchangers to each of the use-side heat exchangers, and a temperature of the heat medium that has exited each of the use-side heat exchangers, an opening degree controller for regulating a flow rate of the heat medium through each of the heat medium flow control devices, and a computing unit for computing a usage capacity of each of the indoor units from a rotation speed of the pump, an opening degree of each of the heat medium flow control devices, temperatures detected by the temperature sensors, and power consumption of each of the indoor units, and proportionally dividing the power consumption for a common portion among each of the indoor units based on the computed usage capacity and the power consumption of the common portion.