AIChE Journal, Vol.54, No.2, 475-486, 2008
An analytical model for internal moisture content during the decreasing drying rate period
A system of analytical expressions for internal moisture distribution during the falling drying rate period for porous nonhygroscopic slabs is presented. This model is derived by resolution of thermal balance and mass flux continuity equations and on the assumption of a parabolic internal moisture profile in the liquid transport zone. This study is based on the assumption of the existence of a receding evaporative front within the product during the decreasing drying rate period and on heat transfer being the limiting mechanism. The model addresses the cases where heat transfer is the limiting mechanism during drying and applies to flat slabs which are classified into two groups, namely, thick products and thin products, depending on their thicknesses and drying conditions. Overall, the model predictions were in a slight deviation from experimental data obtained on plaster. (c) 2007 American Institute of Chemical Engineers.