ABSTRACT
This chapter presents study of the Joule coefficient and Joule-Kelvin coefficients. After presenting some basic facts about these concepts, the chapter shows how the Joule-Kelvin coefficient is used in refrigeration. The chapter discusses the important Joule-Kelvin effect or throttling process. This is an important effect, because it is widely used in refrigeration and in the liquefaction of gases. It was shown that the process takes place with no change in enthalpy. Before describing the thermodynamics of this irreversible process, it is useful to describe the effect in more detail. Gases might also be cooled by allowing them to expand adiabatically in an engine and indeed, it can be shown that a simple adiabatic expansion produces a bigger temperature drop for a given pressure decrease than a throttling process. Finally, the chapter explains how the throttling process is used in the classic Linde method of liquefying helium.
