Thermal performance of a hybrid solar dryer through experimental and CFD investigation

Abstract

AbstractSolar drying comes under clean energy technology that aims to dry food products hygienically. The present work discusses the development of an energy‐efficient and cost‐effective hybrid‐type solar dryer for drying 15 kg of food products. Experiments and CFD modeling of the solar drying system have been carried out for drying tomato slices. The maximum efficiency of the collector has been obtained as 74.1% and 66.96%, respectively with and without using exhaust hot air recirculation. Performance indicators such as convective heat transfer coefficient, overall loss coefficient, drying efficiency, and collector efficiency factor have been obtained as 7.743685 W/m2°C, 5.94189 W/m2°C, 32.89%, and 0.987%, respectively. The coefficient of determination (R2) is calculated as 0.9863, 0.9919, and 0.9755 for the first, second, and third day, respectively, representing a higher order of fit of getting a performance evaluation of the collector. A p‐value is obtained as 0.49375 (>0.05) from a paired sample t‐test signifying no statistical significance difference between the predicted and actual experimental results of collector efficiency. For a constant mass flow rate of air, the maximum temperature inside the drying chamber and wall radiative heat flux obtained from experiments and CFD simulation are in good agreement, thus satisfying the validation. Further, the dryer can be used during the night time by using an electric coil producing a satisfactory drying effect. It is lightweight and easily portable to capture maximum solar radiation.Practical applicationsThe present solar dryer is most suitable for drying applications in food processing industries due to the clean and hygienic process of drying. It is easily portable to any location to capture maximum solar radiation. It is lightweight and has low construction, and maintenance costs. It is the most efficient and fast drying compared to open sun drying and can be used for large‐scale drying in industrial applications. The present study is about CFD simulations of the solar dryers for drying 5 kg of tomato slices. The drying efficiency has been increased by utilizing exhaust hot air circulation. Both the simulation and experimental results have been validated and further dryer has been used during night time by using an auxiliary heating element.