Study for the standardization of the drying curves of capillary-porous media

A new test apparatus and an analyzing method were developed, and the presence of a simple (well-known but controversial) shape of the falling-rate period in drying curves was experimentally and theoretically verified for capillary-porous media: under exceedingly simplified drying conditions, the first and second falling-rate periods were clearly distinguishable in the drying curves for porous ceramics with submicron-sized to micron-sized pores as well as for a glass filter with larger micron-sized pores. Moreover, some properties in drying such as the moisture content in the pendular state, the effective diffusion coefficient, etc., were estimated by analysis of the data of the simple shape of the falling-rate period in drying curves. These properties could be used as key data on drying characteristics of capillary-porous media.