An air-conditioning apparatus that includes a compressor, a flow switching device, an outdoor heat exchange unit, an expansion section and an indoor heat exchanger, which are connected by pipes, in which the outdoor heat exchange unit includes a first outdoor heat exchanger, a first flow rate control device, a second outdoor heat exchanger, a second flow rate control device, a bypass pipe, the second outdoor heat exchanger, the second flow rate control device, a third flow rate control device, and a flow control device.

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

Disclosed are an oil return control method and device of an air conditioning system, a storage medium and an air conditioning system, wherein the oil return control method is used for a three-pipe air conditioning system, and the three-pipe air conditioning system comprises a compressor, an outdoor heat exchanger, an indoor heat exchanger, a gas-liquid separator, a first pipeline, a second pipeline and a third pipeline; the oil return control method comprises the following steps: controlling the compressor to operate at a first frequency in a refrigerating mode; judging whether the operation duration of the refrigerating mode reaches a first preset time or not; if so, the air conditioning system enters an oil return state, and the compressor, the third pipeline, the second pipeline and the gas-liquid separator are controlled to be communicated in sequence to form a refrigerant circulation loop. The present disclosure aims to quickly and smoothly realize the oil return process of a three-pipe air conditioning system in a refrigerating mode or a heating mode.

It is provided a refrigeration apparatus that uses liquid fluid as a heat source and is highly reliably configured to reduce the occurrence of dew condensation and freezing at a utilization unit during cooling operation in which a liquid fluid heat exchanger in a heat source unit functions as a radiator. An air conditioner (10) includes a heat source unit (100) having a compressor (110), a first heat exchanger (140) configured to cause heat exchange between a refrigerant and liquid fluid, a second heat exchanger (160) configured to cause heat exchange between the refrigerant and air, and a valve (162) configured to switch to supply or not to supply the second heat exchanger with the refrigerant, a utilization unit (300) constituting a refrigerant circuit (50) along with the heat source unit, and a controller (406) configured to control to operate the compressor and to open or close the valve (162). The controller opens the valve (162) to supply the second heat exchanger with the refrigerant to cause the second heat exchanger to function as a heat absorber when assessing that the refrigerant sent to the utilization unit needs to be decreased in quantity during cooling operation in which the first heat exchanger functions as a radiator.

A heat exchange apparatus includes a first heat exchanger configured to transfer heat between a refrigerant and another medium, a plurality of second heat exchangers configured to transfer heat between the refrigerant and the liquid, a compressor configured to pressurize the refrigerant and a plurality of expansion devices for each of the plurality of second heat exchangers and configured to expand the refrigerant pressurized by the compressor, wherein the refrigerant flows through the plurality of second heat exchangers in parallel, and the liquid flows through the plurality of second heat exchangers in series.

A heat pump includes a control device configured to control conduction and shutting-off of electric power to a first compressor heater, and to control whether or not an alarm unit notifies an alarm. The control device causes the alarm unit to notify the alarm when the control device determines that duration of electric conduction to the first compressor heater is a predetermined period or longer. With this, it is possible to provide a heat pump that can control electric conduction to the heater to enable saving of electricity, and that can detect a problem in the controlling of the electric conduction to the heater.

In a heat source-side unit according to the present invention, a temperature sensor is installed on an inter-column connecting part included in a plurality of inter-column connecting parts and located higher than an intermediate position in a vertical direction of a heat exchanger.

A heat pump system includes a first heat pump and a second heat pump. The first heat pump includes a first outdoor unit. The first outdoor unit includes a compressor, an outdoor-unit connecting pipe, and a refrigerant filling port. The outdoor-unit connecting pipe connects an intake path of the compressor and a second outdoor unit of the second heat pump for supplying a refrigerant to the second outdoor unit of the second heat pump. The refrigerant filling port is provided in a portion of the outdoor-unit connecting pipe.

A chilling unit and a temperature control system using water circulation includes a refrigerant circuit, a pipe through which a heat medium flows, a flow switching device, a temperature sensor, a pressure sensor, and a controller. The refrigerant circuit includes a compressor, a pair of air-side heat exchangers, an expansion valve, and a heat-medium-side heat exchanger that are connected to each other by pipes, thereby enabling refrigerant to circulate in the refrigerant circuit. The flow switching device switches between refrigerant-circulation routes. The controller controls the compressor in accordance with a target outlet temperature, the temperature of the heat medium detected by the temperature sensor, and a pressure difference in the heat medium detected by the pressure sensor. When a load on a loading device decreases to a low level and the load is equal to or less than the lowest capacity of the compressor, the controller performs control to avoid starts and stops while keeping the compressor operating at the lowest capacity and controls the flow switching device so that one of the pair of air-side heat exchangers and the heat-medium-side heat exchanger are connected in parallel.

A method for controlling a multi-split air conditioner. The method comprises: detecting whether the degree of superheat of an outdoor unit meets a target requirement, if yes, determining whether a difference value between an average exhaust temperature of the outdoor unit and the average exhaust temperature of an outdoor unit system reaches a preset value, if yes, comparing the average exhaust temperature of the outdoor unit with the average exhaust temperature of the outdoor unit system, reducing operating frequency of a compressor of the outdoor unit if the average exhaust temperature of the outdoor unit is greater than the average exhaust temperature of the outdoor unit system; and increasing the operating frequency of the compressor of the outdoor unit if the average exhaust temperature of the outdoor unit is less than the average exhaust temperature of the outdoor unit system.