A heat-pump system may include an outdoor heat exchanger, an expansion device, an indoor heat exchanger, a compressor, and a multiway valve. The expansion device is in fluid communication with the outdoor heat exchanger. The indoor heat exchanger is in fluid communication with the expansion device. The compressor circulates working fluid through the indoor and outdoor heat exchangers. The multiway valve may be movable between a first position corresponding to a cooling mode of the heat-pump system and a second position corresponding to a heating mode of the heat-pump system. The working fluid flows in the same direction through the outdoor heat exchanger in the cooling mode and in the heating mode, and the working fluid flows in the same direction through the indoor heat exchanger in the cooling mode and in the heating mode.

An air conditioner (1A) as a refrigeration apparatus includes: a refrigerant circuit (2) including an evaporator (25), a first compressor (21), a vapor cooler (3), a second compressor (22), and a condenser (23) that are connected in this order; a heat release circuit (4) that allows a heat medium to circulate between the condenser (23) and a first heat exchanger (5) that releases heat to the atmosphere; and a heat absorption circuit (6) that allows a heat medium to circulate between the evaporator (25) and a second heat exchanger (7). The vapor cooler (3) is a heat exchanger that exchanges heat between a refrigerant vapor compressed by the first compressor (21) and the heat medium flowing in the heat release circuit (4) or the heat medium flowing in the heat absorption circuit (6).

An HVAC system includes an outdoor heat exchanger. A first indoor heat exchanger is fluidly coupled to the outdoor heat exchanger and disposed in a first zone. A second indoor heat exchanger is fluidly coupled to the outdoor heat exchanger and disposed in a second zone. A compressor is fluidly coupled to the outdoor heat exchanger, the first indoor heat exchanger, and the second indoor heat exchanger. A first zone controller is electrically coupled to the first indoor heat exchanger. The first zone controller is configured to measure a temperature in the first zone, compare the measured temperature to a setpoint temperature of the first zone, and responsive to a difference between the measured temperature and the setpoint temperature, adjust a speed of a first circulation fan independent of the speed of a second circulation fan.

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 device including multiple outdoor units and an indoor unit through a pipe includes a control section that obtains a degree of subcooling at an outlet of a subcooling circuit of each outdoor unit based on a temperature detected by a temperature sensor that detects the temperature of refrigerant having passed through the subcooling circuit of each outdoor unit, obtain a target value of the degree of subcooling based on the obtained multiple degrees of subcooling, and perform the control of increasing the rotation speed of a compressor of an outdoor unit having a higher degree of subcooling than the target value and decreasing the rotation speed of a compressor of an outdoor unit having a lower degree of subcooling than the target value such that a difference in the degree of subcooling at the outlet of the subcooling circuit of each outdoor unit is decreased.

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 defrosting control method of a multi-functional multi-split system with double four-way valves. The multi-functional multi-split system includes an outdoor unit, at least one set of hydraulic modules, and at least one set of indoor modules. When the multi-split system is switched from a normal operation mode to a defrosting mode, a first four-way valve and a second four-way valve are powered down, and operation modes of each set of indoor modules and each set of hydraulic modules, the on/off state of fans of an indoor heat exchanger and a hydraulic heat exchanger, opening degrees of a first electromagnetic valve of the indoor heat exchanger and a second electromagnetic valve of the hydraulic heat exchanger, and the on/off state of the first electromagnetic valve and the second electromagnetic valve are correspondingly adjusted based on the previous operation modes of each set of indoor modules and each set of hydraulic modules.

An oil return control method of a multi-functional multi-split system with double four-way valves. The multi-functional multi-split system includes an outdoor unit, at least one set of hydraulic modules and at least one set of indoor modules. When the multi-split system is switched from a normal operation mode to an oil return mode, a first four-way valve and a second four-way valve are powered down, and operation modes of each set of indoor modules and each set of hydraulic modules, the on/off state of fans of an indoor heat exchanger and a hydraulic heat exchanger, opening degrees of a first electronic expansion valve of the indoor heat exchanger and a first electronic expansion valve of the hydraulic heat exchanger, and the on/off state of a first electromagnetic valve and a second electromagnetic valve are correspondingly adjusted based on the previous operation modes.

A three-pipe, multi-split system and a control method thereof. The three-pipe multi-split system includes an outdoor unit, a multi-split indoor unit, and a hydraulic module. By optimizing a refrigerant system, the phenomenon that a refrigerant is throttled before flowing through a refrigerant heat dissipation module or supercooled when passing through a plate heat exchanger which causes a relatively low temperature of the refrigerant entering the refrigerant heat dissipation module and consequent condensation on the refrigerant heat dissipation module to produce condensate water and then causes a damage to a compressor frequency conversion module can be avoided. In addition, more refrigerant is caused to flow through the refrigerant heat dissipation module to reduce the temperature of the module.