A HVAC system having an indoor heat exchanger having a first refrigerant passage extending in a first direction and a second refrigerant extending in a second direction opposite from the first direction, a first refrigerant circuit comprising a first compressor, a first expansion valve, a first outdoor heat exchanger, the first refrigerant passage, and a first reversing valve operable to control a direction of first refrigerant in the first refrigerant circuit, and a second refrigerant circuit comprising a second compressor, a second expansion valve, a second outdoor heat exchanger, the second refrigerant passage, and a second reversing valve operable to control a direction of second refrigerant in the second refrigerant circuit.

A system includes a pressure exchanger (PX). The PX is coupled to a motor that controls an operating speed of the PX. The system further includes a first pressure gauge configured to generate first pressure data indicative of a pressure of a fluid of a condenser. A first controller is to generate a first control signal based on the first pressure data. The motor of the PX is configured to adjust the operating speed of the PX based on the first control signal. The system further includes a pump. The system further includes a fluid density sensor for generating fluid density data associated with a first output fluid of the PX. A second controller is to generate a second control signal based on at least the fluid density data. The pump is to adjust an operating speed of the pump based on the second control signal.

When heating is being performed, and a temperature detected by a temperature sensor is lower than a first determination value, a controller opens the flow rate control valve corresponding to a heat exchanger, of the third heat exchangers, to which a request for air conditioning has not been made, and closes the flow rate control valve corresponding to a heat exchanger, of the third heat exchangers, to which the request for air conditioning has been made. When heating is being performed, and the temperature detected by the temperature sensor is higher than a second determination value, the controller opens the flow rate control valve corresponding to the heat exchanger to which the request for air conditioning has been made, and closes the flow rate control valve corresponding to the heat exchanger to which the request for air conditioning has not been made.

The storage device is adapted to store a plurality of objects, such as sample tube holders, at several low temperatures, e.g., at −80° C. and at −110° C. The storage device includes a storage chamber with a plurality of storage cassettes arranged in its bottom section. A cassette lift in its top section can be used to lift individual storage cassettes up and to move them to an access opening, where the contents of the storage cassette can be accessed. The bottom section is divided into several, concentric storage zones, with the innermost, first storage zone being colder than the outer, second storage zone. A first insulating wall separates the two storage zones. This design reduces the thermal losses of the storage device. A refrigerant circuit with a non-inflammable cryo-liquid is provided for carrying off heat from the first storage zone.

The storage device is adapted to store a plurality of objects, such as sample tube holders, at several low temperatures, e.g., at −80° C. and at −110° C. The storage device includes a storage chamber with a plurality of storage cassettes arranged in its bottom section. A cassette lift in its top section can be used to lift individual storage cassettes up and to move them to an access opening, where the contents of the storage cassette can be accessed. The bottom section is divided into several, concentric storage zones, with the innermost, first storage zone being colder than the outer, second storage zone. A first insulating wall separates the two storage zones. This design reduces the thermal losses of the storage device. A refrigerant circuit with a non-inflammable cryo-liquid is provided for carrying off heat from the first storage zone.

A hydrogen cooling apparatus according to an embodiment includes: a binary refrigeration unit including a high-temperature-side refrigerator and a low-temperature-side refrigerator; and a hydrogen-cooling-fluid circulation unit. The binary refrigeration unit cools a hydrogen cooling fluid circulated by the hydrogen-cooling-fluid circulation unit by means of a low-temperature-side evaporator of the low-temperature-side refrigerator. The high-temperature-side refrigerator includes: a high-temperature-side refrigeration circuit; and a high-temperature-side bypass circuit including: a high-temperature-side bypass flow path that extends from a part, which is downstream of a high-temperature-side compressor and upstream of a high-temperature-side condenser in the high-temperature-side refrigeration circuit, to a part, which is downstream of a high-temperature-side expansion valve and upstream of a high-temperature-side evaporator in the high-temperature-side refrigeration circuit; and a high-temperature-side opening and closing valve provided on the high-temperature-side bypass flow path. The high-temperature-side refrigerator opens the high-temperature-side opening and closing valve when a high-temperature-side refrigerant has an abnormal pressure.

A heat exchanger includes: a first layer including first flow channels that are microchannels and arranged to extend side by side; and a second layer that is laminated on the first layer and that includes second flow channels that are microchannels and arranged to extend side by side. A first one end-side collective flow channel is in fluid communication with first ends of the first flow channels. A first other end-side collective flow channel is in fluid communication with second ends of the first flow channels. A second one end-side collective flow channel is in fluid communication with first ends of the second flow channels. A second other end-side collective flow channel is in fluid communication with second ends of the second flow channels.

A refrigeration cycle apparatus includes a first refrigerant circuit including a first compressor, a first heat exchanger, a first refrigerant flow path of a second heat exchanger, a first expansion device, a third heat exchanger, and a second refrigerant flow path of a fourth heat exchanger, and a second refrigerant circuit including a second compressor, a fifth heat exchanger, a second expansion device, a third refrigerant flow path of the second heat exchanger, and a fourth refrigerant flow path of the fourth heat exchanger, a first refrigerant flows through, in order, the first compressor, the first heat exchanger, the first refrigerant flow path, the first expansion device, the third heat exchanger, and the second refrigerant flow path, the second refrigerant flows through, in order, the second compressor, the fifth heat exchanger, the second expansion device, the third refrigerant flow path, and the fourth refrigerant flow path.

A refrigeration cycle apparatus includes a first refrigerant circuit including a first compressor, a first heat exchanger, a first refrigerant flow path of a second heat exchanger, a first expansion device, a third heat exchanger, and a second refrigerant flow path of a fourth heat exchanger, and a second refrigerant circuit including a second compressor, a fifth heat exchanger, a second expansion device, a third refrigerant flow path of the second heat exchanger, and a fourth refrigerant flow path of the fourth heat exchanger, a first refrigerant flows through, in order, the first compressor, the first heat exchanger, the first refrigerant flow path, the first expansion device, the third heat exchanger, and the second refrigerant flow path, the second refrigerant flows through, in order, the second compressor, the fifth heat exchanger, the second expansion device, the third refrigerant flow path, and the fourth refrigerant flow path.

A process for conditioning air, by means of a main circuit, the main circuit being a vapor compression circuit, wherein a first refrigerant circulates, and a secondary circuit with no compressor, wherein a non-flammable second refrigerant including a hydrofluoroolefin and/or a hydrochlorofluoroolefin circulates, the main circuit and the secondary circuit being coupled to one another; the process including a heat exchange between the surroundings and the first refrigerant, a heat exchange between the first and second refrigerants, and a heat exchange between the second refrigerant and the air to be conditioned. Also, an air conditioning plant for implementing the process.