Working Pairs for Adsorption Heat Pumps

When designing an adsorption heat pump, one of the critical choices a designer must make is the choice of working pair. The working pair, which consists of a solid adsorbent and a gaseous adsorbate, influences the performance of the cycle through its thermodynamic and thermophysical properties, and its suitability for a given application is additionally governed by other properties. In this chapter, the thermophysical and other properties that are desirable in a high-performing working pair are discussed, along with the reasons for which they are desired. Working pair metrics are suggested to allow quick comparisons between working pairs. Common refrigerants and classes of working pairs are discussed, along with recent developments in these areas. The influence of operating conditions on working pair metrics is demonstrated by calculation of several of the working pair metrics for some common working pairs under different operating conditions.