Modelling heat and mass transfer processes during drying: Empirical, theoretical and reaction engineering approach.

Drying is a simultaneous heat and mass transfer operations where heat input from the dryer is supplied to the product to facilitate moisture diffusion from the interior of the product to the surface and it is eventually removed through evaporation. Modelling of drying processes can be carried out by using empirical, theoretical and reaction engineering approaches. Empirical (including semi-empirical) modelling uses thin layer models (Newton, Page, logarithmic and etc.) that can be fitted to any experimental drying data via regression analyses. It is simple to use but lacks theoretical justification. On the other hand, theoretical model uses classical Fick's second law and heat conduction models which is more realistic and fulfill major theoretical considerations in a typical drying operation. Through advancement in drying research, reaction engineering approach enables a normalized activation energy curve is developed from a single accurate drying experiment to predict the moisture content and temperature profiles during drying. This paper attempts to provide a mini review on the above modelling approaches and also to compare the benefits/drawbacks when come to practical use. [ABSTRACT FROM AUTHOR]