A refrigerator includes a compressor configured to compress a refrigerant, a condenser configured to condense the refrigerant compressed in the compressor, an expander configured to depressurize the refrigerant condensed in the condenser, a plurality of evaporators configured to evaporate the refrigerant depressurized in the expander, a first valve configured to be operated to introduce the refrigerant into at least one of the plurality of evaporators, a hot gas valve device disposed at an inlet side of the first valve and configured to guide the refrigerant passed through the compressor or the condenser to the plurality of evaporators, and a hot gas path configured to extend from the hot gas valve device to the plurality of evaporators.

A heat exchanger, a heat exchanger unit, and a refrigeration cycle apparatus improve a heat exchange performance, a discharge performance, and a frosting resistance, and each include: a flat tube; a fin formed in the shape of a plate having a plate surface extending in a longitudinal direction of the fin that is perpendicular to a width direction thereof, coincides with an up/down direction, and crosses the tube axis of the flat tube; and a first water conveyance member provided below the fin. The first water conveyance member has: a first upper surface facing a lower end portion of the fin; a first ridge located at one end portion of the first upper surface; and a second ridge located at the other end portion of the first upper surface.

The refrigeration cycle apparatus includes a refrigerant circuit, a controller to control the refrigerant circuit, a bypass flow path, and a flow control valve. The bypass flow path communicates between the discharge side of the compressor and the first outdoor heat exchanger or between the discharge side of the compressor and the second outdoor heat exchanger. The flow control valve is provided to the bypass flow path. The refrigerant circuit is configured to be able to perform a heating defrosting simultaneous operation. The heating defrosting simultaneous operation is an operation of supplying part of the refrigerant discharged from the compressor to one of the first outdoor heat exchanger and the second outdoor heat exchanger via the bypass flow path, causing the other of the first outdoor heat exchanger and the second outdoor heat exchanger to serve as an evaporator, and causing the indoor heat exchanger to serve as a condenser.

A refrigerator and method utilize a pair of tandem evaporators to provide cooling for both a compartment and an ice making system of a refrigerator. An upstream evaporator in the pair of tandem evaporators provides cooling for a compartment such as a freezer, fresh food, flexible cooling, or quick cooling compartment, while a downstream evaporator is in fluid communication with the upstream evaporator to receive a portion of the air cooled by the upstream evaporator and further cool the received portion for use in cooling one or more components of the ice making system.

A refrigeration system includes a dedicated defrost-mode compressor that delivers high pressure, high temperature refrigerant to one or more evaporators to defrost the evaporators.

A refrigeration system includes an expansion valve downstream of one or more medium temperature compressors. The expansion valve is configured to decrease pressure of a portion of refrigerant output by the one or more medium temperature compressors. When defrost operation of an evaporator is indicated, the refrigerant with decreased pressure from the expansion valve is provided to the evaporator for at least a period of time sufficient to defrost the evaporator.

A refrigeration cycle apparatus includes a refrigerant circuit including a compressor, an indoor heat exchanger, an expansion device, and an outdoor heat exchanger connected to each other via refrigerant pipes. The outdoor heat exchanger includes a heat transfer pipe, and a plurality of fins. The outdoor heat exchanger is configured so that a ratio of a heat capacity of the plurality of fins to a total of heat capacities of the heat transfer pipe and the plurality of fins is not more than 50%. The refrigeration cycle apparatus has a mixed defrosting operation mode in which a hot gas defrosting operation and a reverse-defrosting operation are performed in sequence. In the hot gas defrosting operation, hot gas discharged from the compressor is supplied to the outdoor heat exchanger. In the reverse-defrosting operation, refrigerant passing through the indoor heat exchanger is supplied from the compressor to the outdoor heat exchanger.

A refrigeration cycle apparatus including a refrigerant circuit including a compressor, an indoor heat exchanger, an expansion device, an outdoor heat exchanger, an outside air temperature sensor, and a controller configured to perform a hot gas defrosting operation and a reverse-defrosting operation based on a temperature obtained by the outside air temperature sensor. In the hot gas defrosting operation, hot gas discharged from the compressor without passing through the indoor heat exchanger is supplied to the outdoor heat exchanger. In the reverse-defrosting operation, refrigerant passing through the indoor heat exchanger is supplied from the compressor to the outdoor heat exchanger. The controller has at least a mixed defrosting operation mode in which the hot gas defrosting operation and the reverse-defrosting operation are performed in sequence. The controller is configured to start the mixed defrosting operation mode when the temperature obtained by the outside air temperature sensor satisfies a preset condition.

An air-conditioning apparatus includes a refrigerant circuit, an air-conditioning load state detection unit, an operation-state detection unit, and a controller. The refrigerant circuit includes a main circuit and a bypass circuit. The air-conditioning apparatus has a simultaneous heating and defrosting operation mode. In the simultaneous heating and defrosting operation mode, the controller controls a compressor, a pressure reducing device, and a defrosting refrigerant pressure-reducing device such that control amounts of the compressor, the pressure reducing device, and the defrosting refrigerant pressure-reducing device reach respective normal-time control target values that are set based on an air-conditioning load state and an operation state.

A hybrid heating system is disclosed. The hybrid heating system includes a compressor that is configured to compress refrigerant. The hybrid heating system further includes a first heat exchanger that is configured to adjust a temperature of water by exchanging heat between the water and refrigerant compressed by the compressor. The hybrid heating system further includes a second heat exchanger that is configured to evaporate refrigerant by exchanging heat exchange with exterior air. The hybrid heating system further includes a first boiler heat exchanger that is configured to increase a temperature of water using heat generated by combustion. The hybrid heating system further includes a second boiler heat exchanger that is configured to exchange heat between exhaust gas discharged from the first boiler heat exchanger and refrigerant flowing into the second heat exchanger.