Development of a mathematical model for predicting moisture changes in pear during convective drying

The efficiency of several theoretical models to predict the moisture content of pear slices during drying were evaluated and compared. Pear slices were dried at 5 different temperatures (30-40-50-60-70oC) and the moisture diffusivity and convective mass transfer coefficient were estimated. In the next step, mass transfer model was developed by using mathematical solution of Fickchr(chr('39')39chr('39'))s second law of diffusion with different numerical and analytical models. The results of the studied models indicated that the both numerical models were substantially more accurate than analytical model in describing the experimental drying curves. However, the best result was obtained with the combined model developed in this study. This model presents the highest coefficient of determination (R2) value (0.999), and the lowest root mean square error (RMSE) value (0.06). The higher accuracy of this model can be attributed to the fact that this model takes into account the term that simulate the convective moisture transport and chooses the appropriate boundary conditions. By applying this model, it is possible to predict moisture variations in pear slices with high accuracy as a function of internal variables (thickness, chemical composition) and external factors (temperature, relative humidity and air velocity).