The theory of heat and moisture transfer in porous media revisited
De Vries, D. A.
1987 Int. J. Heat Mass Transfer, Vol. 30, No. 7, pp. 1343-1350
De Vries, D. A., (1987), "The theory of heat and moisture transfer in porous media revisited", Int. J. Heat Mass Transfer, Vol. 30, No. 7, pp. 1343-1350.
Abstract:
In this paper a review: presented of the present status of the theory of combined heat and moisture transfer in porous media. developed by J. R. Philip and the author in the mid-1950s. First, attention is drawn to the limitations of the theory and the assumptions underlying it. Next, attempts to test the theory by laboratory and fwld experiments are briefly discussed, leading to the conclusion that the usefulness of the theory in describing and analysing the experiments was proven, but that doubts remain about its predictive value. These doubts are a consequence of: (a) the limitations of the theory; (b) uncertainty about the quality of the experimental procedures and data. Remarks are made on hysteresis and its possible influence. It is concluded that experiments aimed at a study of the behaviour of non-isothermal systems subjected to h%3uit:is are needed. Finally, the problem of the definition and use of an apparent thermal conductivity is analysed. In the original papers two alternatives were presented. An expression for the phase average of the vapour flux density is derived. A numerical example is presented and suggestions are made concerning the proper choice between the alternatives.