Mathematical modeling and experimental analysis of potato thin-layer drying in an infrared-convective dryer

In this paper, the thin layer potato drying process by a laboratory scale infrared-convective dryer is investigated. The experiments were accomplished in three levels of slice thickness; 3, 5 and 7 mm, and three levels of infrared power; 500, 700 and 900 W. Drying took place entirely in the falling rate period. The results show that increasing the infrared power leads to a decrease in the moisture content, and drying time of samples, but increased the drying rate, shrinkage, and effective moisture diffusivity. The results also indicated that by increasing the thickness, the effective moisture diffusivity and drying time increased while the drying rate and shrinkage decreased. Eight thin-layer drying models were fitted on the experimental data. The models were compared according to three statistical parameters of the correlation coefficient (R2), root mean square error (RMSE), and reduced chi-square (χ2). The obtained results indicated that the page model could satisfactorily describe the drying curve of potato slices with R2 = 0.9991-0.9997, RMSE = 0.0050-0.0095, and χ2 = 1.3E-05-9.6E-05 under different operational conditions.