Solar, Biomass and Hybrid Dryers - BioEnergy Discussion Lists

Chapter 1PACKAGES DEVELOPED AT AIT, ThailandPackage 1: Direct Solar Box DryerA direct-solar box-type dryer has been developed at AIT after optimizing the designparameters through a detailed study. The dryer, which operates on the natural draftprinciple, has two trays kept inside an insulated box. The trays are made ofaluminum angle frames and stainless steel wire mesh. A cover glazing, hinged atone side to the box, is fixed at the top. The glazing can be opened for loading andunloading of the dryer. The dryer is fixed on an inclined stand, facing the south. Themain parameters which determine the drying air temperature are the distances ofthe cover glass and the dryer bottom surface from the tray surface. These parametershave been optimized, to adjust airflow both above and below the trays to enhancethe air contact with the product. Figure 1.1 shows the assembled drier. The physicalparameters of the dryer are presented in Table 1.1.Products to be dried are spread on a thin layer over the two trays kept inside thebox. During operation, the hot and humid air escapes through an opening at the top,while fresh ambient air enters through a bottom opening.Figure 1.1: A fully assembled direct-solar box dryer2