Chapter 7 - Transport Properties

Abstract

An accurate knowledge of transport properties of gases is essential for the optimum design of the different items of chemical processing plants, for determination of intermolecular potential functions and for development of accurate theories of transport properties in dense fluid states. The transport properties in a dilute gas or vapor phase can be predicted from the kinetic theory. Existing methods are limited to a specific class of fluids and cannot be applied to various substances. Of the many predictive approaches that have been proposed, the corresponding-states principle has proved to be the most powerful framework, it was the most useful and accurate derivation of the Van der Waals' equation of state and has a firm basis in statistical mechanics and kinetic theory, and has great range and accuracy. The methods based on the corresponding-states principle are theoretically based and predictive, rather than empirical and correlative. The extended corresponding-states theory was established based on the aspherical factor containing highly polar species and species exhibiting specific interactions like associating and hydrogen bonding. The theory of gas transport properties has been reasonably well clarified by the application of the kinetic theory of gases; however, the theory of liquid viscosity is poorly developed. The chapter will briefly present both theories, introduce the extended corresponding states method to describe the transport properties of various real substances, and predict the transport properties over the entire region of different classes of substances with the Enskog hard-sphere dense theory.