Development of Simple Drying Model for Performance Prediction of Solar Dryer: Theoretical Analysis

An analytical moisture diffusion model which considers the influence of external resistance to mass transfer is developed to predict thermal performance of dryer system. The moisture diffusion coefficient, Deff that is necessary to evaluate the prediction model has been determined in terms of experimental drying parameters. A laboratory model of mixed-mode solar dryer system is tested with cylindrical potato samples of thickness 5 and 18 mm under simulated indoor conditions. The potato samples were dried at a constant absorbed thermal energy of 750 W/m2 and air mass flow rate of 0.011 kg/sec. The proposed model with computed moisture diffusion coefficient, Deff has been utilized to predict dimensionless moisture content, φ for each test condition of a given dryer design. In order to validate the model, statistical test methods such as mean absolute error (MAE), root mean square error (RSME) and standard error (SE) in dimensionless moisture content are also determined. The errors less than 5% between experimental and predicted φ for all tests have confirmed the accuracy and suitability of proposed model in the representation of experimental results.