Assessment of Solar Thermal Energy Potential as a Source of Energy for Drying Applications
Abstract
Solar energy can be tapped to produce directly the two widely sought forms of energy- heat and electricity. Solar energy is routinely used in the developing countries to dry up food crops and medicinal plants by spreading them in the open sun but this practice leads to severe losses, both in quality and quantity, of the products and requires long periods to dry up. Further, in Kenya there is a general trend where people are now reverting back to what nutritionists call Africa Indigenous Vegetables (AIV) and value addition through drying is necessary for longer storage or exportation without spoilage. Solar air heaters (SAHs) are technologies that can be used to heat up ambient air to produce hot air for drying or heating applications and there is still scope to improve on them. The performance of a SAH system of the convectional type with airflow above the absorber plate in the tropics is reported. The plane-of-array (POA) solar radiation on the collector varies between 800-1200 Wm2 on clear sky days with ambient temperature range of 20-30 oC. The thermal efficiency under natural airflow operation was evaluated to be about 38%.
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