ABSTRACT

Since the 1974 ICHMT Seminar the activity in this field has been continued and even increased. The present interest is exemplified by an international Symposium held in Canberra, August 31 - September 4, 1987. We return to this below, but first remark on combined transfer of heat and moisture in porous media, a topic was not discussed at the Canberra meeting, but has received considerable attention.
The theory published by the authors in 1957/8 is generally applicable, mainly in connection with soils, but also in drying. A review of its present status was presented by de Vries at the Euromech 194 Colloquium on "Simultaneous Heat and Mass Transfer in Porous Media", held at Nancy, 1985 and was recently published. The main unsolved problem is the theoretical incorporation of the influence of hysteresis. Certain criticisms, based on experimental observations interpreted without taking account of latent heat, have been refuted.
A special application is connected with the current rating of buried cables for the transmission of electricity. An international workshop on this subject was held in The Netherlands, 1984. A relatively new subject of interest is the storage of solar heat in a body of soil.
A subject outside the theory of Philip and de Vries is that of free convection in porous media. It has received attention from soil physicists and engineers. Heat transfer in porous media is now a separate subject in the bibliographic reviews published annually in the Int. J. of Heat and Mass Transfer.
The major themes of the Canberra Symposium were: Soil Physics; Physical Ecology; Micrometeorology; and Applications (to physically similar industrial processes). They embrace most subjects treated in the 1974 ICHMT Seminar, and we refer to papers in [1] in discussing developments since 1974. Conveniently, the Canberra Symposium expressly addressed progress over the last 20 years.