Kjølemedie

Kjølemedie is a Norwegian term that translates to "refrigerant" in English. It refers to a substance or a mixture of substances used in refrigeration and air conditioning cycles to absorb heat from a low-temperature reservoir and release it to a high-temperature reservoir. This process is fundamental to how refrigerators, freezers, air conditioners, and heat pumps operate.

The working principle of a kølemedie involves a phase change. Typically, it circulates through a closed loop, undergoing evaporation at low pressure and temperature, absorbing heat from the space being cooled. It then moves to a compressor, where its pressure and temperature are increased. Subsequently, it condenses at high pressure and temperature, releasing the absorbed heat to the surroundings. Finally, it passes through an expansion valve, reducing its pressure and temperature before returning to the evaporator to repeat the cycle.

Historically, various substances have been used as kjølemedie, including ammonia, sulfur dioxide, and chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). However, due to environmental concerns, particularly their ozone-depleting potential and high global warming potential (GWP), many of these have been phased out or are being phased out. Modern kjølemedier are often hydrofluorocarbons (HFCs), hydrofluoroolefins (HFOs), or natural refrigerants like propane, carbon dioxide, and ammonia, chosen for their improved environmental profiles and thermodynamic properties. The selection of a specific kjølemedie depends on the application, safety requirements, efficiency considerations, and environmental regulations.