An absorption cycle is a heat-activated thermal cycle. It exchanges only thermal energy with its surroundings; no appreciable mechanical energy is exchanged. Furthermore, no appreciable conversion of heat to work or work to heat occurs in the cycle.
Absorption cycles find use in applications where one or more of the heat exchanges with the surroundings is the useful product. This includes refrigeration, air conditioning, and heat pumping. The two great advantages of this type of cycle in comparison to other cycles with similar product are:
• No large rotating mechanical equipment is required
• Any source of heat can be used, including low-temperature sources.