Computational and experimental analysis of a biomass-fueled natural convection dryer and prediction of thermodynamic parameters using machine learning algorithms
摘要
Northeast India, with its abundant rainfall, unreliable electricity, and extensive crop cultivation, necessitates reliable and renewable drying technologies to minimize post-harvest losses. This study focuses on the development and performance evaluation of a biomass-fueled natural convection dryer integrated with thermal energy storage materials—paraffin wax and pebbles—for drying ginger. Experimental and computational analyses reveal consistent airflow and temperature distribution, with the combination of both storage materials offering maximum heat retention and paraffin wax showing the most efficient moisture removal. The system achieves a drying efficiency of approximately 40%. To enhance predictive capabilities, a machine learning approach was employed using experimental data generated under four operational scenarios. Four algorithms—decision tree, K-nearest neighbors (KNNs), random forest and gradient boosting regressor (GBR)—were trained and compared. In single-output regression, GBR provided the most accurate enthalpy prediction (R2 = 0.9820), while KNN outperformed others for energy efficiency (R2 = 0.9423), exergy efficiency (R2 = 0.9714), and exergy loss (R2 = 0.9760). In multi-output regression, GBR yielded the best performance with an R2 of 0.9657. The integration of experimental validation, simulation, and machine learning modeling demonstrates a comprehensive and robust framework for improving the efficiency and applicability of biomass-based drying systems in rural and hilly agricultural regions.