Absorption Chiller

An absorption chiller produces cooling using heat as its main energy input instead of an electrically driven compressor. By running on waste heat, steam or hot water, it lets facilities turn surplus thermal energy into useful refrigeration or air conditioning.

A conventional vapour-compression chiller uses an electric compressor to circulate refrigerant. An absorption chiller replaces the compressor with a thermochemical process: a refrigerant (often water) is absorbed into and then driven out of a solution (often lithium bromide) using heat, accomplishing the same evaporation-and-condensation cooling cycle with very little electricity.

This makes absorption chillers attractive wherever low-grade heat is available cheaply or would otherwise be wasted — for example exhaust or jacket heat from engines and turbines, or steam from a boiler. They are a common companion to combined-heat-and-power plants, turning recovered heat into cooling.

The trade-off is lower coefficient of performance and larger physical size than electric chillers, so the case rests on the availability of essentially free heat. Where it exists, absorption cooling improves overall energy use and reduces peak electrical demand for cooling.

Related terms

Waste Heat Recovery · CHP / Cogeneration · Industrial Heat Pump · Heat Exchanger