Experimental and numerical study of tomatoes drying kinetics using solar dryer equipped with PVT air collector

Abstract

The present work aims to develop a 3D numerical simulation that describes fresh tomatoes' heat- and mass-transfer characteristics using software COMSOL Multiphysics. Besides, a numerical study of the effect of drying parameters (drying temperature, Velocity of air drying and thickness of the slice) on the moisture content elimination from the tomato slice was realized. Also, an experimental study of the effect of the continuity and the discontinuity of the drying process on the water content vaporization is carried out. In contrast, the numerical simulation developed is validated by comparing the experimental data with the numerical results of the temperature distribution and mass transfer inside the tomato slice. The results show that the numerical simulation is agrees with the experimental tests. In addition, the results show that bacteria contamination appears in the tomato slice when the drying temperature decreases under 50 °C. The discontinuity of the drying process harms the quality of the dried product. Furthermore, the results show that the water evaporation rate in the thin slice was faster compared to the thick slice. Consequently, the drying time was reduced by 39 h when the thickness of the product was decreased from 33 mm to 10 mm. Also, the numerical simulation shows that moisture elimination is faster at higher drying air temperatures and increasing the drying air velocity leads to decrease drying time. The results show that the numerical simulation developed in this paper can accurately simulate the drying process characteristics of the agro-food product, especially Tomato, and that it provides a high spatial resolution of the distribution of water content and temperature inside the slice of tomatoes during the drying process.