vaporcompressionkølesystemet

Vapor-compression refrigeration is a thermodynamic cycle used to transfer heat from a low-temperature region to a higher-temperature environment by circulating a refrigerant that alternates between vapor and liquid phases. The cycle typically consists of an evaporator, a compressor, a condenser, and an expansion device. In the evaporator, low-pressure liquid refrigerant absorbs heat and vaporizes. The resulting vapor is compressed by the compressor, increasing both its pressure and temperature. The high-temperature vapor then releases heat in the condenser, condensing to a liquid. The liquid is depressurized by the expansion device, cooling again and returning to the evaporator to repeat the cycle. The net effect is to remove heat from the cooled space or substance.

Most systems operate with refrigerants chosen for favorable thermodynamic properties and acceptable environmental impact. Historically common refrigerants included chlorofluorocarbons and hydrochlorofluorocarbons, which were phased out due to ozone depletion; modern systems use hydrofluorocarbons or natural alternatives. Examples include R-134a, R-410A, and, in some applications, carbon dioxide (R-744) in transcritical cycles, ammonia, and hydrocarbons in small appliances. The choice of refrigerant affects efficiency, safety, and climate impact.

Efficiency is described by the coefficient of performance (COP), which is the ratio of cooling effect to input work. Equipment ratings such as EER or SEER express performance under standardized conditions. Advances focus on reducing refrigerant charge, improving compressor efficiency, and enabling low-GWP refrigerants while avoiding flammability or toxicity risks.

Vapor-compression systems are widely used in domestic refrigerators, air conditioners, commercial freezers, and industrial cooling. They remain a central technology in climate-control and industrial process cooling, subject to regulatory evolution and ongoing research into sustainable refrigerants and component design.