An Introduction to Heat Pumps

Heat pumps are extremely common in modern society, facilitating thermal comfort and thermal control in residential, commercial, industrial, and mobile applications. Over the past century, electrically driven mechanical vapor compression heat pumps have been the most common technology. In recent years, concerns have been raised about the high electrical load required to drive mechanical vapor compression heat pumps and the global climate change potential associated with both the generation of electricity and the synthetic refrigerants used in these devices. As a result, investigators have considered alternative heat pump technologies, including some that are driven by thermal energy. One of the types of thermally driven heat pumps is the adsorption heat pump. This chapter serves as a prelude to the detailed discussion of adsorption heat pumps throughout the rest of this work by introducing the operating principles of mechanically driven and thermally driven heat pumps and the figures of merit that can be used to evaluate their performance.