Accurate knowledge of transport properties of pure gases and liquids, and of their mixtures, is essential for the optimum design of the different items of chemical process plants, for determination of intermolecular potential energy functions and for development of accurate theories of transport in dense fluids. A previous IUPAC volume, edited by Wakeham et al. (1991), also produced by Commission I.2 through its Subcommittee on Transport Properties, has described experimental methods for the accurate determination of transport properties. However, it is impossible to measure these properties for all industrially important fluids, and their mixtures, at all the thermodynamic states of interest. Measurements therefore need to be supplemented by theoretical calculations.

This present volume, which is complementary to the previous publication, discusses the present state of theory with regard to the dilute–gas state, the initial density dependence, the critical region and the very dense gas and liquid states for pure components and mixtures. In all cases, the intention is to present the theory in usable form and examples are given of its application to nonelectrolyte systems. This will be of particular use to chemical and mechanical engineers. The subtitle of this volume ‘Their correlation, prediction and estimation’ reflects the preferred order of application to obtain accurate values of transport properties. Careful correlation of accurate experimental data gives reliable values at interpolated temperatures and pressures (densities), and at different compositions when the measurements are for mixtures. Unfortunately, there are only a limited number of systems where data of such accuracy are available.