Design, Fabrication and Evaluation of Solar and Biomass Hybrid Dryer with Trackable Solar Collector

Abstract

Newly constructed solar and biomass hybrid dryer consists of solar collector with solar tracking option, biomass backup heater and a drying chamber. The absorber of the trackable solar collector was made of black painted corrugated GI sheet and clear glass for the top. Saw dust was used as the fuel for the biomass burner. The drying chamber was built of plywood and insulated by aluminium foil. The performance was evaluated using five drying treatments with three replicates; namely, only with solar power (T1), solar power with tracking (T2), only with biomass (T3), with hybrid mode (T4), and direct sun drying (T5; Control). Invented hybrid dryer reduced the initial moisture content of Musa spp. (banana), Artocarpus heterophyllus (jackfruit) and Pleurotus ostreatus (oyster mushroom) from 80%, 74% and 90% to 12%, 12% and 10%, respectively. Under no-load condition, the average temperature of drying chamber reached to 45.04 0C with solar drying and 55.65 0C with solar tracking option, while the ambient temperature was 33.52 0C. The solar collector efficiency obtained from the no-load test was 34.07%. Results revealed that the dryer can reduce the high initial moisture contents up to a safe storage moisture content within a day. With the support of the backup heater, the dryer can be used even under the inadequate solar radiation. Improper drying chamber insulation was observed as a limitation.