An air-conditioning apparatus includes a plurality of indoor units. Each of the indoor units includes a heat-medium flow adjusting valve and a heat exchanger. The heat-medium flow adjusting valve adjusts the flow rate of a heat medium that flows into the heat-medium flow adjusting valve, and causes the heat medium to flow out of the heat-medium flow adjusting valve. The heat exchanger causes heat exchange to be performed between the heat medium and air. The heat medium flows into the heat exchanger from an inflow side of the heat exchanger. The inflow side of the heat exchanger is connected to an outflow side of the heat-medium flow adjusting valve. The plurality of indoor units are connected in series.

An air conditioner includes an ejector that raises a pressure of refrigerant by using energy for refrigerant decompression and expansion. A switching mechanism switches between a refrigerant flow in a first operation and a refrigerant flow in a second operation. The air conditioner is configured such that in the first operation, refrigerant compressed by a compression mechanism radiates heat in a use-side heat exchanger and is decompressed and expanded by the ejector while refrigerant evaporated in a heat-source-side heat exchanger is raised in pressure by the ejector. The air conditioner is configured such that in the second operation, refrigerant compressed by the compression mechanism radiates heat in the heat-source-side heat exchanger and is decompressed and expanded by a first expansion valve before being evaporated in the use-side heat exchanger while refrigerant does not flow through the ejector.

An air conditioning apparatus is an air conditioning apparatus dedicated to cooling and includes a first circuit and a second circuit. The first circuit has an outdoor heat exchanger that cools a first refrigerant by outdoor air. In the second circuit, a first heat transfer medium that is cooled by exchanging heat with the first refrigerant that flows in the first circuit flows. The first refrigerant is a HFO refrigerant having a critical temperature higher than that of R32.

At least one heat-source side cycle and at least one load side cycle share a cascade heat exchanger. A total number of cycles provided by the at least one heat-source side cycle and the at least one load side cycle is three or more, such that there is a first cycle, a second cycle and a third cycle. The first cycle circulates a first refrigerant or heat medium. The second cycle circulates a second refrigerant or heat medium. The third cycle circulates a third refrigerant or heat medium. The first refrigerant or heat medium, the second refrigerant or heat medium, and the third refrigerant or heat medium are different from one another.

A motor drive apparatus includes a reactor, a converter connected to an alternating current power supply via the reactor, a smoothing capacitor connected between output terminals of the converter, and an inverter that converts a direct current voltage output from the smoothing capacitor into an alternating current voltage to be applied to a motor and outputs the alternating current voltage. The motor drive apparatus includes a plurality of operation modes for controlling conduction of switching elements of the converter and causing the converter to operate in different modes of operation, and changes operation of at least one of the switching elements of the converter and the inverter according to the operation mode when a bus voltage indicates an excessive value.

A heating, ventilation, and air conditioning system includes first and second fluids, a heat exchanger, a refrigerant sub-system, and at least one closed loop sub-system. The heat exchanger includes a membrane for channeling the first fluid through the heat exchanger and is disposed for heat transfer between the first fluid and the second fluid. The membrane defines an inlet having an inlet height relative to grade. The closed loop sub-system transfers heat from the heat exchanger to the refrigerant sub-system and includes an expansion tank containing the first fluid. A level of the first fluid within the expansion tank has a level height relative to grade. The expansion tank is positioned relative to the heat exchanger such that the inlet height is greater than the level height and the membrane is maintained in a collapsed configuration.

The present disclosure provides an air conditioner, a control strategy of the air conditioner and an air conditioning system. The air conditioner includes a compressor, a first heat exchanger, a phase-change thermal-storage heat exchanger, a throttling device and a box. The throttling device is provided between the first heat exchanger and the phase-change thermal-storage heat exchanger. One of the first heat exchanger and phase-change thermal-storage heat exchanger functions as an evaporator and the other functions as a condenser. The box includes an air supply port and an air return port. The compressor, the first heat exchanger, the phase-change thermal-storage heat exchanger and the throttling device are mounted in the box, thereby facilitating installation of the air conditioner.

An air-conditioning system that optimizes operation capacity of an outside air conditioning unit and operation capacity of an air conditioning unit is provided. An air-conditioning system includes an outside air conditioning device, an air conditioning device, and a machine learning apparatus, and includes a state variable acquiring unit configured to acquire state variables including a condition of outside air, a condition of inside air, an operation condition of the outside air conditioning device, an operation condition of the air conditioning device, and a temperature or humidity set for a target space, a learning unit configured to perform learning by associating the state variables with at least either the operating capacity of the outside air conditioning device or the operating capacity of the air conditioning device, and a reward calculating unit configured to calculate a reward that correlates with a total of energy consumption of the outside air conditioning device and energy consumption of the air conditioning device. The learning unit performs the learning by using the reward.

A heating, ventilation, and air conditioning system includes first and second fluids, a heat exchanger, a refrigerant sub-system, and at least one closed loop sub-system. The heat exchanger includes a membrane for channeling the first fluid through the heat exchanger and is disposed for heat transfer between the first fluid and the second fluid. The membrane defines an inlet having an inlet height relative to grade. The closed loop sub-system transfers heat from the heat exchanger to the refrigerant sub-system and includes an expansion tank containing the first fluid. A level of the first fluid within the expansion tank has a level height relative to grade. The expansion tank is positioned relative to the heat exchanger such that the inlet height is greater than the level height and the membrane is maintained in a collapsed configuration.

A refrigerant sub-system includes a compressor, a condenser, an expansion valve, an evaporator, and a refrigerant-air heat exchanger. The compressor receives and compresses refrigerant. The condenser condenses the refrigerant and transfers heat from the refrigerant to a first fluid. The expansion valve expands the refrigerant. The evaporator vaporizes the refrigerant at the first pressure and transfers heat from a second fluid to the refrigerant. The refrigerant-air heat exchanger has a first operating mode and a second operating mode. In the first operating mode, the condenser is adapted to condense a first portion of the refrigerant from a vapor to a liquid, and the refrigerant-air heat exchanger is adapted to condense a second portion of the refrigerant from a vapor to a liquid and transfer heat from the second portion of the refrigerant to air.