DRYING OF SHRINKING CYLINDER-SHAPED BODIES

A mathematical model has been developed for the prediction of sample t emperature, average moisture and moisture distribution in a cylinder-s haped solid during the drying process. The effect of shrinkage was tak en into account. The macroscopic heat balance and the microscopic mass balance combined with Fick's law were simultaneously solved using the Runge-Kutta-Merson method and a numerical finite difference method. T he effective diffusion coefficient was expressed as a function of samp le temperature and local moisture content. Using an experimental dryin g curve determined at 90 degrees C, the diffusional equation was ident ified for broccoli stems, and was used to predict the average and loca l moisture content variations during the process. Good agreement with experimental results was found (average percentage of explained varian ce was 99.8%). (C) 1998 Elsevier Science Limited. All rights reserved.