Performance analysis of natural and forced convection mixed mode UV tent house solar dryer for potato drying

A solar dryer that uses solar radiation and a mixed mode of operation was installed. The dryer includes a flat plate collector with 1.12 m2 area covered by 5.0 mm glass. It has two trays for holding potato slices in the drying chamber. Meteorological data, including solar intensity, relative humidity, atmospheric temperature, and wind speed, were recorded. The initial moisture content of the potato slices, which were 2.5 mm thick, was 85.90%. In the forced convection drying mode, the moisture content decreased to 14.10% in 8 hours, while the natural convection mode required 14 hours to reach 14.75%. Forced and natural convection dryings were much faster compared to open sun drying. Air moves through the collector at a speed of 1.1 m/s during forced convection. The moisture ratio varied from 0.4750 to 0.0010 for forced convection drying and from 0.4095 to 0.02646 for natural convection drying. The maximum dryer efficiency was 32.95% for forced convection drying and 26.62% for natural convection drying. The little difference attained between natural and forced convections can be due to the fact that the experiments are not made in the same moment.