Absorptiokylmäys

Absorptiokylmäys is a refrigeration process that uses a heat source to provide the energy needed to drive the cooling cycle, rather than an electric compressor like in conventional vapor-compression refrigeration. This method is particularly attractive in situations where waste heat is available or where electricity is expensive or unreliable. The core of an absorption refrigeration system consists of an absorbent, a refrigerant, and a heat source. Common refrigerant-absorbent pairs include ammonia-water and lithium bromide-water.

The cycle begins with the refrigerant being absorbed into the absorbent, usually in an absorber. This absorption process generates heat. The mixture is then pumped to a generator where the heat source is applied, causing the refrigerant to evaporate. The refrigerant vapor then travels to a condenser, where it releases heat and turns back into a liquid. This liquid refrigerant then flows through an expansion valve, reducing its pressure and temperature, before entering the evaporator. In the evaporator, the cold liquid refrigerant absorbs heat from the space to be cooled, thereby producing the desired cooling effect. The refrigerant vapor then returns to the absorber, completing the cycle.

Absorptiokylmäys systems are often quieter and have fewer moving parts than compressor-based systems, leading to potentially lower maintenance requirements. Their efficiency is generally lower than vapor-compression systems, but their ability to utilize waste heat makes them economically viable in specific applications, such as industrial processes, combined heat and power (CHP) plants, and solar cooling. The energy efficiency is measured by the Coefficient of Performance (COP), which is typically lower for absorption systems compared to compression systems.