Absorptiojäähdytys

Absorptiojäähdytys is a refrigeration process that uses a heat source to drive the refrigeration cycle, rather than an electrical compressor as in conventional vapor-compression refrigeration. This method is particularly useful in situations where waste heat is available, such as from industrial processes or solar thermal collectors. The core of an absorption refrigeration system consists of an absorbent fluid and a refrigerant fluid.

The cycle begins with the refrigerant being evaporated at low pressure, which creates the cooling effect. This refrigerant vapor then moves to an absorber, where it is dissolved by the absorbent fluid. The resulting solution is then pumped to a generator, where it is heated. The heat causes the refrigerant to separate from the absorbent, becoming a high-pressure vapor. This vapor is then condensed back into a liquid and passed through an expansion valve, reducing its pressure and temperature, before returning to the evaporator to repeat the cycle.

Common working fluid pairs include ammonia and water, or lithium bromide and water. Ammonia-water systems are typically used for lower temperature refrigeration, while lithium bromide-water systems are suited for air conditioning applications. The primary advantage of absorption refrigeration is its ability to utilize low-grade heat, making it an energy-efficient option in specific contexts. However, absorption systems generally have lower coefficients of performance compared to vapor-compression systems and can be more complex.