Experimental and Numerical CFD Analysis of a Solar Dryer with Integration of Basalt Thermal Bed for Heat Storage

Solar thermal energy is available in abundance in a country like Senegal where direct solar radiation is on average 1950kWh/m2 per year. Solar drying is the most popular method to preserve food in our country. However, it is limited by the intermittent nature of the sun. The objective of this paper is to overcome the intermittency of the sun by integrating a thermal bed into the solar dryer. The thermal bed is made of basalt and biochar for heat storage and humidity absorption respectively. An experimental study was done using papaya and moringa leaves. The results obtained show that the thermal bed stores heat at the temperature of 39°C at 10p.m. Papaya is dried in two days and moringa leaves are dried in one day. For papaya slices, water content is 15% and was reached at the second day of drying. Also, moringa dry leaves water content is 8%. This value begins to be reached from 3 p.m. in the afternoon. Thus, the thermal bed temperature, the air temperature between the drying racks and the drying chamber outlet air temperature are respectively an average of 48.67°C, 48°C and 47.22°C compared to 34.33°C of the ambient temperature, a difference of more than 4°C. The experimental study is supported by a Computational fluid dynamic (CFD) analysis.