Publication date: April 2019
Source: Renewable Energy, Volume 133
Author(s): Sameh S. Kishk, Ramadan A. ElGamal, Gamal M. ElMasry
The shortages in conventional fuels along with the continuous rise in their prices have led to an increased emphasis on using solar energy as an alternative source of energy. However, establishing reliable and affordable solar collectors for different applications is a great challenge. Therefore, this study aimed to design and fabricate an efficient and cheap solar air collector from recyclable aluminum cans. Two dryers of different configurations (closed and open modes) were then constructed and examined for drying tomatoes under different operating conditions. The results revealed that the thermal efficiency of the designed solar collectors increased considerably from 25 to 63% when the air-flow rate increased from 15 to 45 m3h-1. In comparison to the conventional method of open sun drying, the designed solar dryers enhanced both the drying rate and the overall quality of the final product. In the designed solar dryer, over three days of consecutive drying (30 h of drying), the moisture content of tomato wedges was reduced from 19 to less than 1 kg [H2O] kg−1 [dry matter]. The closed-mode dryer configuration, which recirculates the drying air, showed a considerable increase in the drying rate and weigh loss over the traditional sun dryers and open-mode dryer systems. Among all mathematical models, a non-linear quadratic model (Wang and Singh model) has shown a better fit to the experimental drying data compared to the other models.