A multi-split system and a medium-pressure controlling method thereof are provided. The multi-split system includes an outdoor unit, a distribution device, and a plurality of indoor units. The distribution device includes a gas-liquid separator, a first heat exchange assembly, a first electronic expansion valve, a second heat exchange assembly and a second electronic expansion valve. The distribution device is configured to perform a routine correction on a medium-pressure control target value of the first electronic expansion valve according to the subcooling degree of the heating indoor unit, the outlet air temperature of the heating indoor unit and the opening of the throttling element in the heating indoor unit, and to correct a current medium-pressure control target value of the first electronic expansion valve according to a preset step when the opening of the throttling element reaches a maximum opening or a minimum opening and lasts for a first preset time.

A valve body in each of heat medium flow switching devices has an open portion. When the length from a connection between a first passage pipe and a third passage pipe to a connection between a second passage pipe and the third passage pipe is defined as a casing passage width, a valve body passage width of the open portion in a direction substantially perpendicular to the axis of the valve body is smaller than the casing passage width.

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.

An air-conditioning apparatus includes a refrigerant circuit, a heat medium circuit, and a controller. In the refrigerant circuit, a compressor, a heat-source-side heat exchanger, an expansion unit, and a load-side heat exchanger are connected by refrigerant pipes, and refrigerant flows. The heat-source-side heat exchanger causes heat exchange to be performed between the refrigerant and a heat-source heat medium. The load-side heat exchanger causes heat exchange to be performed between the refrigerant and a load heat medium, and refrigerant flows. In the heat medium circuit, a flow control valve that regulates the flow rate of the heat-source heat medium and the heat-source-side heat exchanger are connected by a heat medium pipe, and the heat-source heat medium flows. The controller includes a storage unit that stores data indicating a defined maximum flow rate and a defined minimum flow rate of the heat-source heat medium that flows in the heat medium circuit.

A first valve is connected between a compressor and a first heat exchanger. A second valve is connected between the first heat exchanger and a expansion valve. When a start condition of the heating operation is satisfied and when a specific condition is satisfied, a controller starts supplying refrigerant from the compressor to the first valve, and then, opens the first and second valves. The specific condition is a condition indicating that a first heat exchange capability of the first heat exchanger is higher than a second heat exchange capability of a second heat exchanger. When the start condition of the heating operation is satisfied and when the specific condition is not satisfied, the controller opens the first and second valves, and then starts supplying the refrigerant from the compressor to the first valve.

A refrigeration cycle device that includes a main refrigerant circuit and a sub-refrigerant circuit cools or heats a main refrigerant that flows between a main heat-source-side heat exchanger and a main usage-side heat exchanger by causing a sub-usage-side heat exchanger to function as an evaporator or a radiator of a sub-refrigerant. A first main expansion mechanism and a second main expansion mechanism that decompress the main refrigerant are provided on an upstream side and a downstream side of the sub-usage-side heat exchanger of the main refrigerant circuit.

An air-conditioning apparatus includes an outdoor unit and a relay unit. The outdoor unit includes a compressor compressing and discharging refrigerant and a heat-source-side heat exchanger performing heat exchange between the refrigerant and outside air. The relay unit and the outdoor unit form a refrigerant circuit. The outdoor unit includes first and flow switching devices each switching an associated flow passage for the refrigerant between a plurality of flow passages, according to an operation mode. An outflow pipe and an inflow pipe through which refrigerant flows from the outdoor unit to the relay unit and from the relay unit into the outdoor unit, respectively, are between the outdoor unit and the relay unit. The first flow switching device is connected to the compressor, the second flow switching device, and the outflow pipe. The second flow switching device is connected to the first flow switching device and the inflow pipe.

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.

An air conditioning apparatus is provided that may include an outdoor unit including a compressor and an outdoor heat exchanger and through which a refrigerant is circulated, an indoor unit through which a fluid, such as water is circulated, and at least one heat exchange device including a heat exchanger in which the refrigerant and the fluid are heat-exchanged with each other. The at least one heat exchange device may include a high-pressure guide tube that extends from a high-pressure gas tube of the outdoor unit so as to be connected to a first side of the heat exchanger, a low-pressure guide tube that extends from a low-pressure gas tube of the outdoor unit so as to be combined with the high-pressure guide tube, a liquid guide tube that extends from a liquid tube of the outdoor unit so as to be connected to a second side of the heat exchanger, and a solenoid valve installed in the high-pressure guide tube or the low-pressure guide tube to perform an opening and closing operation so as to allow the refrigerant to flow in a first direction. The high-pressure gas tube and the low-pressure gas tube may be connected to each other by a single gas tube, and when the indoor unit performs a cooling operation or a heating operation, flow of refrigerant in the first direction may be blocked in a state in which power is applied to the solenoid valve.

An air-conditioning apparatus includes an outdoor unit including an outdoor heat exchanger; an indoor unit including an indoor heat exchanger; and a relay unit provided between the outdoor unit and the indoor unit and including one or more first refrigerant supply pipes and one or more second refrigerant supply pipes that are connected to the indoor heat exchanger of the indoor unit. The one or more first refrigerant supply pipes and the one or more second refrigerant supply pipes protrude from the same side surface of the relay unit. The one or more first refrigerant supply pipes are each provided above an associated one of the one or more second refrigerant supply pipes. Part of the one or more first refrigerant supply pipes that protrudes from the side surface is longer than part of the one or more second refrigerant supply pipes that protrudes from the side surface.