ABSTRACT
The chapter starts with a discussion of liquid-vapor absorption heat pumps, the most frequently applied thermally driven systems in practice. The working fluids in these cycles are ammonia-water mixtures, with ammonia as the refrigerant, and water-lithium bromide mixtures, with water as the refrigerant. Other mixtures have been proposed and investigated but are not yet applied on a commercial scale. Absorption has been a topic discussed in the refrigeration courses at the Delft University of Technology in the Netherlands for many years (Stolk, 1990). The topics discussed in these courses form the basis of the section about liquid-vapor absorption: determination of cycles based on equilibrium conditions and effect of irreversibilities and deviation from equilibrium in the different components of the cycle. Sorption cycles were extensively discussed by Niebergall (1981) in the German language, which in fact was a reprint of the original 1959 version. Herold et al. (1996) published a dedicated book that also focused on absorption heat pumps. Bogart (1981) dedicated a whole book specifically to ammonia-water absorption systems.
