Absorptionskølesystemer

Absorptionskøl, or absorption cooling, is a method of refrigeration that uses the absorption of a refrigerant by a secondary liquid (the absorbent) instead of a mechanical compressor to move heat. In a typical absorption chiller, heat supplied to a generator drives off refrigerant vapor from a solution; the vapor is condensed and releases heat as it returns to a liquid, then evaporates in an evaporator at low pressure to absorb heat from the space being cooled. The resulting vapor is absorbed by the absorbent, and the resulting solution cycles back to the generator, continuing the process.

The two most common working pairs are ammonia–water and water–lithium bromide. Ammonia–water is effective at lower cooling temperatures and is often used in smaller or industrial systems, while water–LiBr is favored for large, quiet, and efficient installations in buildings. Key components of an absorption chiller include the generator, absorber, condenser, evaporator, and a means to circulate the absorbent solution, which may be a pump or natural circulation.

Absorption cooling can utilize low-grade or waste heat, solar thermal energy, or cogenerated heat, making it attractive where heat is readily available and electricity is expensive or limited. Advantages include quiet operation, fewer moving parts, and the ability to run on heat sources other than electricity. Disadvantages include generally lower coefficients of performance than electric vapor-compression systems, larger size, and challenges related to ammonia safety or LiBr crystallization and corrosion. Absorption chillers find use in commercial buildings, hotels, hospitals, ships, and industrial processes, especially when waste heat or solar energy is accessible.