Integrated CFD simulation and thermal imaging for monitoring convective drying of tomato wedges
The overarching aim of this study was to develop and validate a computational fluid dynamics (CFD) model to predict heat and mass transfer processes during the convective drying of tomato wedges. Experimental drying trials were conducted at three air temperatures (60, 70, and 80 °C) to evaluate model performance by monitoring drying kinetics under controlled conditions. During the drying process, the moisture content of tomato wedges was reduced from an initial value of 15.67 kg water/kg dry matter to a final value of 0.17 kg water/kg dry matter, requiring 21, 13, and 11 h at 60, 70, and 80 °C, respectively. Spatiotemporal surface temperature distributions were continuously obtained from radiometric infrared thermography recorded by a highly sensitive thermal camera and was used for monitoring of temperature changes and for CFD model validation. The results revealed that a close correspondence was observed between experimental data and simulated results across all operating drying temperatures, with improved predictive accuracy observed at lower temperatures. The model also demonstrated good predictive performance for moisture content during drying, with root-mean-square error (RMSE), and chi-square (χ2) values of 0.812 and 0.313, respectively. Additionally, color change, lycopene content, antioxidant activity, and total phenols were determined to evaluate the impact of drying temperatures on tomato quality. Drying air temperature of 70 °C resulted in the highest lycopene retention and lower color change, while a higher temperature of 80 °C showed lower degradation of antioxidant activity and phenols, indicating that drying temperature not only affects drying rate but also influences the nutritional and quality values. Overall, the developed CFD model can serve as a robust tool for analyzing and predicting the drying behavior of tomato wedges, improving process optimization, quality preservation, and enhanced control of drying operations.