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 refrigerant system includes a condenser and a plurality of evaporators each connected to the condenser. Each of the plurality of evaporators receives fluid from the condenser in a harvest mode, and at least two of the plurality of evaporators are in a harvest mode at different times.

An air conditioner, and a control method, including a compressor to compress a refrigerant; an outdoor heat exchanger; a first four-way valve between a discharge port of the compressor and an upper inlet of the outdoor heat exchanger; a second four-way valve between the discharge port of the compressor and a lower inlet of the outdoor heat exchanger; and a controller electrically connected to the compressor and the first four-way valve and the second four-way valve to control the first and second four-way valves to perform a first defrosting operation which defrosts an upper and a lower portion of the outdoor heat exchanger during a heating operation, and control the first and second four-way valves to perform a second defrosting operation which operates the upper portion as an evaporator, and operates the lower portion as a condenser, based on a detected need for additional defrosting of the lower portion.

A device having a heat exchanger, wherein the heat exchanger has pipes which carry a cooling medium, wherein the heat exchanger has a fin arrangement which is penetrated by the pipes, and wherein the heat exchanger has a heating device integrated in the heat exchanger, with a control device for controlling the heating device, wherein the heating device has two or more separately controllable heating sections, wherein each heating section is assigned a defrosting area of the heat exchanger, and wherein the heating device is set up for the separate defrosting of individual defrosting areas of the heat exchanger by the separately controllable heating sections.

An air-to-water heat pump system is disclosed comprising a lower heat source unit and an upper heat source unit connected in a thermodynamic cycle, wherein the lower heat source unit is supplied with external air and the lower heat source has at least two alternating evaporators (1, 2) forming the lower heat source with a fan mounted axially in relation to the lower heat source unit in its upper part, provided with a defrosting unit in which it is possible to implement the defrosting and drying process of the evaporator heat exchange surface, as well as improve the energy efficiency of the heat pump system.