This air conditioner performs a cooling operation and a heating operation in parallel with each other with an outdoor unit and indoor units connected together through two communication pipes. The air conditioner includes a switching mechanism changing the directions of refrigerants flowing through the communication pipes depending on whether a heating dominant operation is being performed in a first load region where a cooling load is relatively light or a second load region where the cooling load is heavier than in the first load region. In the second load region, the switching mechanism allows a low-pressure refrigerant to flow from the indoor units to the outdoor unit through the second communication pipe thicker than the first communication pipe to reduce a performance deterioration due to the pressure loss involved with the heating dominant operation.

An air-conditioning apparatus includes a low-pressure-side pressure sensor that detects the pressure of heat-source-side refrigerant that flows into a compressor and outputs it as a first detection value and a high-pressure-side pressure sensor that detects the pressure of heat-source-side refrigerant discharged from the compressor and outputs it as a second detection value. When switching the operation mode of the apparatus, a controller determines whether the ratio of the first detection value to the second detection value is higher than a first threshold. When the ratio is higher than the threshold, the controller causes a second refrigerant flow switching device to perform a switching operation. When the ratio is less than or equal to the threshold, the controller makes an adjustment such that an opening degree of an expansion device is less than a second threshold, and then causes the second refrigerant flow switching device to perform the switching operation.

A dynamic receiver is included in parallel to an expander of a heating, ventilation, air conditioning, and refrigeration (HVACR) system. The dynamic receiver allows control of the refrigerant charge of the HVACR system to respond to different operating conditions. The dynamic receiver can be filled or emptied in response to the subcooling observed in the HVACR system compared to desired subcooling for various operating modes. The HVACR system can include a line directly conveying working fluid from compressor discharge to the dynamic receiver to allow emptying of the dynamic receiver to be assisted by injection of the compressor discharge.

A refrigerant charge controller for heating, ventilation, or air conditioning (HVAC) equipment includes a processing circuit configured to analyze usage data for the HVAC equipment using a machine learning model to estimate an amount of refrigerant used by the HVAC equipment, identify a refrigerant deficiency based on the amount of refrigerant, and initiate a corrective action in response to identifying the refrigerant deficiency.

A refrigeration apparatus includes a heat source-side unit and a utilization-side unit that are connected to each other, and performs a refrigeration cycle in which a high pressure of a refrigerant reaches or exceeds a critical pressure. The refrigeration apparatus also includes a control unit configured to perform a first action of returning the refrigerant to the heat source-side unit when a stop condition of the utilization-side unit is satisfied, and a second action of prohibiting the first action when a pressure at the heat source-side unit is equal to or more than the critical pressure of the refrigerant. This configuration suppresses damage to a refrigerant storage reservoir and the like in returning the refrigerant to the heat source-side unit.

In an air-conditioning apparatus including a refrigerant circulating circuit A and a heat medium circulating circuit B that performs passing of heat to and from the refrigerant circulating circuit A, the heat medium circulating circuit is a closed circuit, the maximum pump head Pp of a pump of the heat medium circulating circuit is 150 kPa or more, and a pressure near at least a suction side of the pump is set to a charged pressure that is maintained equal to or higher than the atmospheric pressure during operation of the pump.

A refrigerant circuit is configured by connecting, by pipes, a compressor that compresses a heat-source-side refrigerant, a first refrigerant flow switching device, a heat-source-side heat exchanger, an expansion device, and one or more intermediate heat exchangers that exchange heat between a heat-source-side refrigerant and a heat medium that is different from the heat-source-side refrigerant. A controller performs control of pumps to drive the pumps at a specific pump capacity or higher to circulate the heat medium at a time when a heat recovery defrosting operation for causing the heat-source-side refrigerant that has been heated by the heat medium in the intermediate heat exchangers to flow into the heat-source-side heat exchanger for defrosting purposes.

An air-conditioning apparatus includes a refrigerant circuit formed by connecting, with pipes, a compressor, a first refrigerant flow switching device, a heat-source-side heat exchanger, an expansion device, and a plurality of intermediate heat exchangers. A heat medium circuit is formed by connecting, with pipes, a plurality of pumps configured to pressurize and circulate the heat medium subjected to heat exchange in the plurality of intermediate heat exchangers, a plurality of use-side heat exchangers each configured to exchange heat between the heat medium and air in an air-conditioned space, and a heat-medium flow switching/control device configured to switch which of the heat medium is to be allowed to flow into and out of each of the use-side heat exchangers; and a controller configured to perform processing for controlling the switching performed by the heat-medium flow switching/control device, in accordance with a capacity of each of the use-side heat exchangers.

A refrigeration cycle apparatus including a heat source side heat exchanger including a first heat exchanger and a second heat exchanger connected in parallel; an air-sending device that supplies air, which is an object to be heat exchanged in the first heat exchanger and the second heat exchanger, in a variable manner; solenoid valves that each opens and closes a refrigerant passage of the first heat exchanger and the second heat exchanger; a third refrigerant circuit that is parallelly connected to the first heat exchanger and the second heat exchanger; and a flow control valve that controls the flow rate of the refrigerant flowing in the third refrigerant circuit. The refrigeration cycle apparatus can improve continuity of control of a heat exchange capacity of a heat source side heat exchanger.

An air conditioning system includes a storage medium and an air conditioning system, for a three-pipe air conditioning system, the three-pipe air conditioning system includes 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.