Microwave and Radio-Frequency Technologies in Agriculture

14 Simultaneous Heat and Moisture Movement

In experiments using wool fibres, described by Cassie, King and Baxter (1940 in Crank 1979), the isothermal moisture diffusion coefficient predicted that moisture equilibrium should be reached within seconds of a sudden change in external humidity. However their experiments demonstrated that equilibrium was only reached after an hour or more of exposure to the new external conditions (Crank 1979).

Any realistic analysis of microwave heating in moist organic materials must account for simultaneous heat and moisture diffusion through the porous material. The coupling between heat and moisture transfer is well known but not very well understood (Chu and Lee 1993). Henry (1948) was one of the first to propose ...