Vapourcompressioncykeln

Vapour compression refrigeration is a thermodynamic cycle used to move heat from a cooler space to the surrounding environment by circulating a working refrigerant through a closed loop. The cycle relies on four main components: an evaporator, a compressor, a condenser, and a throttling expansion device. In operation, low-pressure refrigerant evaporates in the evaporator, absorbing latent heat from the cooled space. The resulting vapour is compressed to a high-pressure, high-temperature state in the compressor, then released to the condenser where it rejects heat to the surroundings and condenses to a liquid. The liquid experiences a rapid pressure drop in the expansion device, cooling it and allowing it to enter the evaporator again to absorb heat.

Variations exist in compressor type (piston, screw, scroll; with fixed-speed or variable-speed drives), condensation method (air-cooled or water-cooled), and refrigerants used. The cycle is widely used in domestic and commercial air conditioning, refrigerators and freezers, heat pumps, and industrial cooling. Refrigerants have ranged from chlorofluorocarbons historically to hydrochlorofluorocarbons, then hydrofluorocarbons, and now lower-GWP alternatives such as R-32, R-410A (mixtures) or CO2 (R-744) and ammonia (R-717) in specialised systems.

Performance is described by the coefficient of performance (COP) for cooling and the energy efficiency ratio (EER) or seasonal performance factor (SPF) for heating. System efficiency is affected by ambient conditions, part-load operation, and component design; modern systems use variable-speed drives and advanced controls to improve efficiency.

Environmental considerations include potential ozone depletion and greenhouse warming depending on the refrigerant; regulatory trends favour low-GWP and natural refrigerants, with lifecycle considerations and safety requirements guiding selection.