An air-conditioner includes: a refrigerant circuit through which a refrigerant flows, the refrigerant circuit being formed of a compressor, a switching valve, a first heat exchanger, an expansion valve, and a second heat exchanger connected to one another by a first pipe; a heat-transfer medium circuit through which a heat-transfer medium flows, the heat-transfer medium circuit being formed of a pump, the first heat exchanger, and a third heat exchanger connected to one another by a second pipe; and control device that controls the compressor and the pump. In an operation of the air-conditioner performed before entering a defrosting operation, the control device increases a frequency of the compressor, as compared to the frequency of the compressor in a heating operation, and reduces a rotational speed of the pump, as compared to the rotational speed of the pump in the heating operation.

A controller of a heating, ventilation, and air conditioning (HVAC) system, the controller comprising instructions that cause the controller to determine an air flowrate of an air blower of the HVAC system and calculate a threshold value based on a minimum required air flowrate. The controller further comprises instructions that cause the controller to send a notification to an operator of the HVAC system indicating that the air flowrate of the air blower is less than the threshold value in response to determining that the air flowrate of the air blower is less than the threshold value and shut down the HVAC system such that the refrigerant is no longer circulated by the componentry of the HVAC system in response to determining that the air flowrate of the air blower is less than the minimum required air flowrate.

Systems and methods for controlling pressure in a CO.sub.2 refrigeration system are provided. The pressure control system includes a pressure sensor, a gas bypass valve, a parallel compressor, and a controller. The pressure sensor is configured to measure a pressure within a receiving tank of the CO.sub.2 refrigeration system. The gas bypass valve is fluidly connected with an outlet of the receiving tank and arranged in series with a compressor of the CO.sub.2 refrigeration system. The parallel compressor is fluidly connected with the outlet of the receiving tank and arranged in parallel with both the gas bypass valve and the compressor of the CO.sub.2 refrigeration system. The controller is configured to receive a pressure measurement from the pressure sensor and operate both the gas bypass valve and the parallel compressor, in response to the pressure measurement, to control the pressure within the receiving tank.

An economizer control system includes a compressor including a compression area, a piston chamber, and an economizer inlet configured to receive economizer vapor into the compression area via a flow path that extends between the economizer inlet and the compression area. At least a portion of the flow path traverses the piston chamber. The economizer control system also includes a piston disposed within the piston chamber and configured to contact the economizer vapor. The piston is moveable between an open position that opens the flow path and a closed position that closes the flow path. Additionally, the economizer control system includes a biasing system configured to apply force to the piston to bias the piston toward the closed position.

An air-conditioning system includes a heat-source device that includes a compressor and a heat-source-side heat exchanger, a relay device that includes a pump and an intermediate heat exchanger, and a plurality of indoor units that each include a load-side heat exchanger. The air-conditioning system includes a refrigerant circuit through which refrigerant circulates and a heat medium circuit through which a heat medium circulates. The air-conditioning system includes a flow rate detection unit configured to detect flow rate information associated with a flow rate of a heat medium that flows through each of the plurality of indoor units and a controller configured to control the compressor and the pump. The controller controls operation of at least either the compressor or the pump on the basis of the flow rate information detected by the flow rate detection unit.

A processing apparatus includes a first temperature measuring unit configured to measure a surface temperature of a first member exposed in a first closed space, a supply line configured to supply a low-dew point gas into the first closed space and a control unit configured to control a flow rate of the low-dew point gas. The control unit performs a first process to a third process. In the first process, an absolute humidity of a gas within the first closed space at a position of a surface of the first member is specified for the flow rate of the low-dew point gas. In the second process, a saturated absolute humidity at the surface temperature of the first member is specified. In the third process, the flow rate of the low-dew point gas is controlled based on the absolute humidity of the gas and the saturated absolute humidity.

An air-conditioning system includes a heat-source device that includes a compressor and a heat-source-side heat exchanger, a relay device that includes a pump and an intermediate heat exchanger, and a plurality of indoor units that each include a load-side heat exchanger. The air-conditioning system includes a refrigerant circuit through which refrigerant circulates and a heat medium circuit through which a heat medium circulates. The air-conditioning system includes a flow rate detection unit configured to detect flow rate information associated with a flow rate of a heat medium that flows through each of the plurality of indoor units and a controller configured to control the compressor and the pump. The controller controls operation of at least either the compressor or the pump on the basis of the flow rate information detected by the flow rate detection unit.

In various implementations, an air conditioner may include more than one expansion device. Refrigerant flow through the expansion device(s) may be controlled based at least partially on an operational property of the air conditioner.

A refrigerant-amount determination kit includes a sensor and a processor. The sensor is mounted at least temporarily on at least one of a portion of a refrigeration cycle apparatus and the periphery of the refrigeration cycle apparatus. The refrigeration cycle apparatus is an apparatus having a refrigerant circuit that includes a compressor, a condenser, and an evaporator. The processor determines the amount of a refrigerant in the refrigerant circuit based on a detection result detected by the sensor during operation of the refrigeration cycle apparatus.

A refrigeration apparatus including a compressor (301), a condenser (302), an expansion device (304), and an evaporator (305), fluidly connected to form a refrigeration cycle for a refrigerant, wherein the compressor (301) has a variable working capacity, and wherein the expansion device (304) has a configurable flow resistance with respect to the refrigerant passing through the expansion device. The apparatus further includes a controller (300) which is configured to determine a current working capacity of the compressor (301) and to control the resistance of the expansion device (304) in dependence on the current working capacity of the compressor (301). The controller (300) is further configured to control the resistance of the expansion device (304) in order to achieve a mass flow of the refrigerant through the expansion device (304), which mass flow corresponds to a mass flow of the refrigerant through the compressor (301).