Solar, Biomass and Hybrid Dryers - BioEnergy Discussion Lists

Package 3: Solar-Biomass Hybrid Tunnel DryerConsidering the low land-holding of marginalized rural farmers in developingcountries, a solar tunnel dryer has been designed for drying small quantities ofagricultural products that are harvested by the farmers in the region.This dryer is an adaptation of the tunnel dryer developed at the University ofHohenheim, Germany. The prototype described here is suitable for drying 115 kg offruits (banana) and has been designed and fabricated at AIT.Design DetailsThe dryer (Figure 3.1) consists of a flat plate air-heating solar collector, integratedwith a drying chamber. A common glazing, provided for both the collector and thedrying chamber, forms a tunnel. A biomass stove-heat exchanger assembly is fittedat one end of the tunnel, at the collector side. The biomass stove is used as analternate heat source for the dryer when solar energy is not available.The integrated collector-dryer unit rests on footings made of brick and mortar. Theexact size of the brick column depends on the size of locally available bricks andmay vary from place to place.Several trays are provided inside the drying chamber, on which the products areloaded in a thin layer. During day time, the dryer is operated as a solar dryer. Incloudy weather conditions or at night, the biomass stove may be used.Figure 3.1: The solar-biomass hybrid tunnel dryer19