Experimental Study and Analysis of a Natural Convection Passive Solar Dryer

This study responds to the growing negative impacts on the environment by developing an indirect-type natural convection solar dryer. It details the system's construction, design, operation, and performance metrics. The solar dryer was made using 16-mm plywood for the chambers, a corrugated iron sheet collector (1.066-inch × 0.762 inch), and a planned PVC chimney (0.102 m diameter, 1.556 m length). Potato drying experiments evaluated its efficiency. The solar intensity was measured at first. Then the dry bulb temperature, relative humidity, airflow rate, sun intensity, and potato weight were measured. Using these data, we measured the efficiency of the solar dryer along with the moisture content of the potatoes. Also, we calculated the weight of the potatoes in the open-sun drying process. The overall results showed that the drying chamber reached 23–41.10 °C, with the solar dryer reducing potato moisture content to 12.9% compared to 15.5% in open-sun drying. Rates for the solar dryer and open-sun methods were 0.0815 kg/hr and 0.075 kg/hr, respectively. The solar dryer exhibited a greater temperature elevation than open-sun drying. At last, we compared our tested solar dryer’s efficiency with another solar dryer project that was used to dry the banana. The results indicated that the collector of our solar dryer achieved 41.49% efficiency, with an overall efficiency of 21.04%. On the other hand, the overall efficiency of the comparable solar dryer was 21.67%, which is slightly higher than our project, but that comparable project showed a lower collector efficiency than our project, which is 31.67%.