Design, fabrication and performance analysis of indirect solar dryer

Abstract

The application of solar thermal systems to preserve and process the agriculture products like fruits and vegetables has found a prominent scope in recent years. In the present research paper, the performance analysis of solar dryer is investigated on the basis of temperature, moisture content (%) and relative humidity. The experiments were performed on onion and garlic. For the complete drying of 1 kg of onion took around 36 h, while it took 188 h for complete drying of 300gm of garlic in an indirect solar dryer. The results were compared with the conventional open sun drying (OSD) method. In the solar dryer, the maximum temperature recorded was 47.6℃. In the open sun drying (OSD) method, the onion and garlic were exposed to direct sun light that diminished the sensory properties (aroma, colour, taste and nutrients). While in case of indirect solar dryer, products were not exposed to direct sunlight and hence retained sensory properties. It is found that within a span of 24 h of experimentation on onion and garlic, the moisture content reduced to 25 % and 60 % while in case of OSD it was recorded 67 % and 63 % respectively. It envisaged that solar dryer is efficient than the conventional OSD method.