An air conditioning apparatus includes a heat exchange device that connects an outdoor unit to an indoor unit and that includes a heat exchanger configured to perform heat exchange between refrigerant and water, thereby reducing an amount of refrigerant used to perform a cooling operation or a heating operation. The apparatus further includes a switching mechanism that connects the outdoor unit to the heat exchange device and that is configured to be connected to both a simultaneous outdoor unit and a switchable outdoor unit to thereby allow the heat exchange device to be installed regardless of the type of the outdoor unit.

A refrigeration system includes a rotary pressure exchanger fluidly coupled to a low pressure loop and a high pressure loop. The rotary pressure exchanger replaces a traditional bulk flow compressor. The rotary pressure exchanger is configured to receive the refrigerant at high pressure from the high pressure loop, to receive the refrigerant at low pressure from the low pressure loop, and to exchange pressure between the refrigerant at high pressure and the refrigerant at low pressure, and wherein a first exiting stream from the rotary pressure exchanger includes the refrigerant at high pressure in the supercritical state or the subcritical state and a second exiting stream from the rotary pressure exchanger includes the refrigerant at low pressure in the liquid state or the two-phase mixture of liquid and vapor.

A refrigerant flow path switching unit, disposed between a heat source unit and a utilization unit and that switches a refrigerant flow in the utilization unit, includes: a flow path switching valve; a case that houses the flow path switching valve; and an electric component box that houses an electric component that controls the flow path switching valve. At least two surfaces of the case include a box attachment part that is configured to attach the electric component box to the case.

A refrigerant flow path switching device includes: a first header pipe that is connected to a high-and-low-pressure gas connection pipe of a heat source unit in an air conditioner; a second header pipe that is connected to a sucked-gas connection pipe of the heat source unit; a third header pipe that is connected to a liquid connection pipe of the heat source unit; switching units that each correspond respectively to utilization units in the air conditioner and include valves that control refrigerant flows; and a casing accommodating the first header pipe, the second header pipe, the third header pipe, and switching units. The refrigerant flow path switching device switches among refrigerant flow paths, each of which is between the heat source unit and one of the utilization units.

A refrigeration apparatus includes a gas-liquid separator on a downstream side of a radiator, and a refrigerant circuit in which a high pressure of a refrigeration cycle is equal to or higher than a critical pressure. The refrigeration apparatus includes a gas passage that communicates with the gas-liquid separator and at least one of a plurality of heat exchangers provided in the refrigerant circuit, and an opening and closing device that opens and closes the gas passage. There is provided a controller that opens the opening and closing device when a pressure in the gas-liquid separator is equal to or higher than a predetermined value in a state where a compression unit of the refrigerant circuit is stopped to suppress occurrence of pressure abnormality inside the gas-liquid separator in a state where a compressor is stopped.

A heat source-side unit (10) includes a heat source-side circuit (11). The heat source-side circuit (11) includes a compression unit (20) including a lower-stage compression element (23) and a higher-stage compression element (21), an intermediate heat exchanger (17) disposed on a refrigerant path between the lower-stage compression element (23) and the higher-stage compression element (21), and a bypass passage (23c) connected to a suction pipe (23a) and a discharge pipe (23b) each connected to the lower-stage compression element (23). At startup of the compression unit (20), a first action is performed for stopping the lower-stage compression element (23) and operating the higher-stage compression element (21). This configuration thus suppresses occurrence of liquid compression at startup of a compressor.

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.

An air conditioning apparatus is provided that may include an outdoor unit including a compressor and an outdoor heat exchanger and through which a refrigerant is circulated, an indoor unit through which a fluid, such as water is circulated, and at least one heat exchange device including a heat exchanger in which the refrigerant and the fluid are heat-exchanged with each other. The at least one heat exchange device may include a high-pressure guide tube that extends from a high-pressure gas tube of the outdoor unit so as to be connected to a first side of the heat exchanger, a low-pressure guide tube that extends from a low-pressure gas tube of the outdoor unit so as to be combined with the high-pressure guide tube, a liquid guide tube that extends from a liquid tube of the outdoor unit so as to be connected to a second side of the heat exchanger, and a solenoid valve installed in the high-pressure guide tube or the low-pressure guide tube to perform an opening and closing operation so as to allow the refrigerant to flow in a first direction. The high-pressure gas tube and the low-pressure gas tube may be connected to each other by a single gas tube, and when the indoor unit performs a cooling operation or a heating operation, flow of refrigerant in the first direction may be blocked in a state in which power is applied to the solenoid valve.

The invention provides a refrigeration apparatus configured to cool the interior of a casing of a heat source unit by a refrigerant. An air conditioner includes a heat source unit, a utilization unit having a utilization heat exchanger and constituting a refrigerant circuit along with the heat source unit, and a controller. The heat source unit causes heat exchange between a refrigerant and a heat source, and cools the interior of the casing, and causes a valve to switch to supply or not to supply the cooling heat exchanger with the refrigerant. The controller assesses, before the refrigerant is supplied to the cooling heat exchanger, whether or not the refrigerant flowing from the cooling heat exchanger toward the compressor comes into a wet state when the refrigerant is supplied, and determines whether or not to open the valve in accordance with an assessment result.

A heat source unit constitutes a refrigeration apparatus by being connected to a utilization-side unit. The heat source unit includes a low-stage compression element, a high-stage compression element, and a heat exchanger. The low-stage compression element has a discharge pipe provided with a pressure switchgear. The high-stage compression element compresses a refrigerant discharged from the low-stage compression element. When the low-stage compression element is paused in response to activation of the pressure switchgear, the high-stage compression element operates while the low-stage compression element is kept paused.