An air conditioner includes: an outdoor unit; a liquid-refrigerant connection pipe and a gas-refrigerant connection pipe; an indoor unit; a gas-side shutoff valve; a refrigerant sensor; and a controller. The indoor unit is connected to the outdoor unit via the liquid-refrigerant and gas-refrigerant connection pipes, is arranged in an air-conditioning target space, and includes: an indoor heat exchanger that performs heat exchange between a refrigerant circulated between the indoor unit and the outdoor unit via the liquid-refrigerant and gas-refrigerant connection pipes and air sent to the air-conditioning target space; an indoor expansion valve that decompresses the refrigerant; a heat-exchange-side indoor liquid-refrigerant pipe that connects a liquid side of the indoor heat exchanger to the indoor expansion valve; and a connection-side indoor liquid-refrigerant pipe that connects the indoor expansion valve to the liquid-refrigerant connection pipe.

Provided is a system for air-conditioning and hot-water supply configured to selectively perform cooling and heating operations, comprising: an outdoor unit having a compressor and an outdoor heat exchanger; at least one or more indoor units each of which is connected to the outdoor unit and includes an indoor heat exchanger; a hot-water supply unit connected to the outdoor unit so as to be arranged in parallel to the indoor unit and including a refrigerant-water heat exchanger; a controller configured to monitor for a request for hot-water supply from the hot-water supply unit while a cooling operation is being performed in at least one of the indoor units, and then to start the heating operation in accordance with the request; wherein the controller transmits to all of the indoor units, which are turned on for said cooling operation, a fan-stop command to stop a fan arranged at each indoor unit.

A multi-connected heat recovery air conditioning system and a control method thereof. The multi-connected heat recovery air conditioning system includes an indoor unit, an outdoor unit and a hydraulic module, wherein the outdoor unit comprises a compressor, an outdoor heat exchanger, a first four-way valve and a second four-way valve. The multi-connected heat recovery air conditioning system further comprises an indoor unit temperature unit, a water temperature unit, a high-pressure sensor and a low-pressure sensor. The indoor unit temperature unit is arranged in the indoor unit for detecting and obtaining the outlet temperature value of the indoor unit, the water temperature unit is arranged at a heat exchange water tank for detecting and obtaining water temperature, and the high-pressure sensor and the low-pressure sensor are arranged at the output end and the air return end of the compressor respectively.

A refrigeration cycle apparatus includes a compressor, a four-way valve, a second flow path switching unit, a first outdoor heat exchanger, a second outdoor heat exchanger, a first indoor heat exchanger and a second flow path switching unit. The second flow path switching unit switches between a third state in which the first port, the second port, the first outdoor heat exchanger, the fourth port, the third port, the second heat exchanger, the fifth port and the sixth port are successively connected in series, and a fourth state in which the sixth port, the fourth port, the first heat exchanger, the second port and the first port are successively connected in series, and the sixth port, the fifth port, the second heat exchanger, the third port and the first port are successively connected in series.

A refrigeration apparatus includes a heat source unit, a utilization unit, and a liquid refrigerant pipe and gas refrigerant pipe. The utilization unit has utilization unit internal pipelines. The liquid refrigerant pipe and the gas refrigerant pipe connect the heat source unit and the utilization unit internal pipelines. A refrigerant circulates through the heat source unit, the utilization unit, the liquid refrigerant pipe, and the gas refrigerant pipe. The refrigerant contains a compound represented by a molecular formula having one or more carbon-carbon unsaturated bonds. A disproportionation inhibitor for reducing a disproportionation reaction of the refrigerant is applied to at least a part of inner surfaces of the liquid refrigerant pipe, the gas refrigerant pipe, and the utilization unit internal pipelines.

A refrigeration apparatus includes a heat source unit, a utilization unit, and a liquid refrigerant pipe and gas refrigerant pipe. The utilization unit has utilization unit internal pipelines. The liquid refrigerant pipe and the gas refrigerant pipe connect the heat source unit and the utilization unit internal pipelines. A refrigerant circulates through the heat source unit, the utilization unit, the liquid refrigerant pipe, and the gas refrigerant pipe. The refrigerant contains a compound represented by a molecular formula having one or more carbon-carbon unsaturated bonds. A disproportionation inhibitor for reducing a disproportionation reaction of the refrigerant is applied to at least a part of inner surfaces of the liquid refrigerant pipe, the gas refrigerant pipe, and the utilization unit internal pipelines.

As a shut-off valve inspection process for checking operation of a liquid side shut-off valve and a gas side shut-off valve, an air conditioning system operates a compressor in a cooling cycle state, performs opening and closing operation of the liquid side shut-off valve and the gas side shut-off valve, and determines whether the liquid side shut-off valve and the gas side shut-off valve properly operate on the basis of a temperature value detected by a temperature sensor provided in an indoor unit.

An air-conditioning apparatus includes a refrigerant circuit in which pipes sequentially connect a compressor, a flow switching device, a heat source side heat exchanger, an expansion device, a load side heat exchanger, and the flow switching device, and configured to perform a cooling operation and a heating operation switched by the flow switching device, an oil separator configured to separate refrigerating machine oil from refrigerant discharged from the compressor, a first bypass passage in which fluid flowing out of the oil separator flows, an auxiliary heat exchanger configured to cool the fluid, a first flow control device configured to control passing of the fluid, a second bypass passage in which liquid refrigerant or two-phase gas-liquid refrigerant flowing through one of the pipes connecting the heat source side heat exchanger and the expansion device flows, and a second flow control device configured to control passing of refrigerant.

An apparatus using a heat pump includes a refrigerant circuit and a heat medium circuit. The refrigerant circuit is allowed to perform a first operation, in which a load-side heat exchanger is used as a condenser, and a second operation, in which the load-side heat exchanger is used as an evaporator. A container is provided to a suction pipe provided between a refrigerant flow switching device and a compressor. To the heat medium circuit, an overpressure protection device and a refrigerant leakage detecting device are connected. When leakage of refrigerant into the heat medium circuit is detected, the refrigerant flow switching device is switched to a second state, an expansion device is set to a closed state, and the compressor is made in operation. When a requirement for ending the operation of the compressor is satisfied after the leakage of the refrigerant into the heat medium circuit is detected, the compressor is set to a stopped state, and the refrigerant flow switching device is switched to a first state.

A motor drive apparatus includes a power converter including an inverter having an upper arm and a lower arm, the inverter being configured to control an operation of an electric motor, and a drive controller configured to apply a dead time for preventing a short circuit between the upper arm and the lower arm, and to control the power converter. The drive controller is configured to control the power converter by switching a first mode in which a first correction value representing a time used to correct a voltage drop due to the dead time is employed to control the power converter, and a second mode in which a second correction value smaller than the first correction value is employed to control the power converter.