Solar, Biomass and Hybrid Dryers - BioEnergy Discussion Lists

Table 11.1: Technical specifications of the solar box dryerType of dryerDirect solarOverall size - length × width x height 152 × 70 x 15.5 cmAperture area 0.91 m 2Air inlet/outlet areas472 cm 2 each (59 cm × 8 cm)Box materialGI sheet, 22 SWGTray materials Aluminum frame; SS wiremeshGlazing3 mm window glassGap: Tray surface - Cover glass 10.0 cmGap: Tray surface - Dryer bottom 2.5 cmDimensions are in mmFigure 11.2: Isometric view of the box type solar dryerThe dryer operated in natural draft principle. While the hot and humid air escapesthrough the opening at the top, fresh ambient air enters through the bottom opening.The dryer has two trays kept inside the box for loading the products to be dried. Thetrays are made of aluminium angle frames and stainless steel wire mesh. Thedistance between the tray surface, cover glass and dryer bottom surface is kept suchthat air flows both above and below the tray for maximum drying effect.The dryer box is fixed on a mild steel stand with a tilt of 20°, and placed facingsouth, to maximize the incident solar radiation (Figure 11.3).55