Solar, Biomass and Hybrid Dryers - BioEnergy Discussion Lists

Package 10: Transpired Collector Solar-Biomass HybridCabinet DryerUPSL/UPD developed a hybrid solar-biomass dryer that incorporated severalinnovative features. . This drying system is distinct from the traditional solar dryerdesigns due to use of an Unglazed Transpired Solar Collector (UTC) for harnessingsolar energy. The major use envisaged for this dryer was fish drying. The dryer,which can accommodate 10 kg of fish, consists of a drying chamber, a solar collectorand a biomass stove/furnace.Design detailsThe hybrid dryer was designed to operate with the UTC and the biomass gasifierstove as the primary heat sources. This ensures continuous operation of the hybriddryer even during periods of inadequate solar radiation, as at night. For the UTCoperation, the solar radiation incident on the UTC heats the perforated absorberplate. Convection transfers the heat absorbed by the collector to the ambient airbeing drawn into the UTC plenum through the perforations. The heated air from thecollector is ducted into the heat exchanger shell. The heated air inside the dryingchamber passes through the drying trays while picking up the moisture from theproducts being dried. The moist air exits the drying chamber through the exhaustvent located on top of the drying chamber. The continuous flow of air in the dryingchamber has been ascertained through the use of the vent mounted exhaust fan.Varying the size of the opening of the exhaust vent through the use of dampersregulates the airflow rate.Table 10.1: Technical specifications of the transpired collector hybrid cabinet dryerSl. No. Parameter Specification1. Capacity per batch 10 kg (~40 fishes)2. Drying air temperature 50°C (maximum)3. Air velocity 0.03 m/s4. Dimensions 0.914 m×1.829 m×0.465 m5. No. of trays 36. Total tray area 2.9 m 27. Solar collector type Unglazed transpired solar collector (UTC)8. Solar collector area 2.33 m 2 (1.83 m×1.22 m)9. UTC air gap (plenum) 10 cm10. UTC perforation pitch 14.5 cm11. UTC porosity 1.1%12. Biomass stove type Natural draft cross-flow gasifier stove13. Fuel for stove Fuelwood50