Mathematical Modelling of Heat and Mass Transfer in Agricultural Grain Drying

Mathematical modelling and computer simulation of grain drying are now widely used in agricultural engineering research. Several models have been proposed to describe the heat and mass transfer processes involved in the drying of agricultural products. Most of these models, however, have been derived under assumptions that are not explicitly stated and that restrict their applications from the outset. Furthermore, it is not always clear what differences, if any, exist between various models. The purpose of this paper is to provide a general framework from which mathematical models for any type of drier may be derived. We illustrate the use of this framework by deducing equations for the four basic types of convective grain drier, namely fixed bed, crossflow, concurrent flow and counterflow. Finally we discuss some of the differences between the models thus obtained and those of other workers.