Enhancing agricultural drying efficiency with a novel hybrid solar-biogas dryer: Mathematical modeling and experimental validation

Drying is a crucial post-harvest process for preserving agricultural products. While previous studies have used empirical methods to develop the solar drying backup with biogas, this study introduces a mathematical modeling approach to develop a novel integrated hybrid solar biogas dryer (HSBD). Mathematical modeling involved deriving equations describing the system's heat transfer mechanisms and energy balance. The model depends on several factors such as solar irradiance, ambient conditions, air velocity and material properties. The mathematical model was implemented in MATLAB R2023b software. The predicted model results were experimentally validated in HSBD using Cavendish bananas with cross-section slices of 5 mm thick. Statistical parameters such as R2, mean absolute error (MAE), and root mean square error (RMSE) were used to evaluate model accuracy. The results showed that Model predictions closely matched experimental data, with an R2 value exceeding 0.98, an MAE of 0.0027, and an RMSE of 0.0157. During experimental validation, the HSBD maintained stable drying temperatures between 58.2 °C and 75.7 °C, reducing dependence on fluctuating solar radiation. Moisture content decreased from 3.07 kg/kg (dry basis) to 0.0849 kg/kg within 14 h, with a drying rate constant of 0.116 h−1. The solar collector achieved a peak thermal efficiency of 27.74 %, outperforming conventional collectors. The mathematical model provides accurate predictions, making it a valuable tool for system optimization recommended for large-scale agricultural and food processing applications. © 2025 Elsevier Ltd