Thin layer drying of fenugreek leaves in a solar tunnel dryer: Performance and analysis

Abstract

This study explores the drying behaviour of fenugreek leaves (Trigonella foenum-graecum) in a solar tunnel dryer, comparing two drying methods (solar tunnel drying and sun drying) and varying blanching times (0 min, 3 min, 5 min), with the goal of identifying the most effective model for predicting moisture content dynamics. Experimental data were transformed into moisture ratio values and analysed using six well-established drying models. Statistical evaluation, based on parameters such as the coefficient of determination (R²), chi-square (χ²), and root mean square error (RMSE), was conducted to assess the goodness of fit. Among the models tested, the Midilli model showed the best performance, with R² values ranging from 0.9944 to 0.9999, and the lowest χ² and RMSE values. Residual analysis indicated minimal discrepancies between the actual and predicted moisture ratios, ranging from 0.00010 to 0.00138, demonstrating the model’s accuracy and reliability in describing the thin-layer drying kinetics of fenugreek leaves. By effectively capturing moisture removal behaviour, the Midilli model offers a strong framework for optimizing drying processes, particularly those using renewable energy methods. This study highlights the potential of the Midilli model in guiding the development of energy-efficient and sustainable drying techniques, which not only minimize energy consumption but also help preserve product quality. The results are especially relevant for renewable energy engineering, where efficient drying methods play a key role in reducing post-harvest losses and increasing the value of agricultural products. By incorporating precise modeling into the design of drying systems, this research contributes to advancing environmentally friendly practices and supports the creation of innovative solutions for agricultural preservation. The findings emphasize the importance of accurate models in achieving sustainable and cost-effective drying strategies, driving progress in both renewable energy applications and agricultural engineering.