Solar, Biomass and Hybrid Dryers - BioEnergy Discussion Lists

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Chapter 2PACKAGES DEVELOPED AT RECAST, NEPALSolar dryers of various capacities and designs are being used in Nepal for dryingvarious agricultural, horticultural and medicinal products. The most popular dryersare box dryers, cabinet dryers, and tunnel dryers. These are being used forhousehold and small-scale commercial drying. Except for tunnel dryers and largecabinet dryers, most dryers are based on natural convection.Based on research carried out within the RETs in Asia programme, the ResearchCentre for Applied Science and Technology (RECAST) improved existing dryerdesigns with the following objectives: (i) to improve the thermalperformance/efficiency, (ii) to reduce the capital cost, (iii) to reduce weatherdependency, and (iv) to enhance the ease of operation and maintenance. Thefollowing solar dryer packages were developed: improved solar box dryer, cabinetdryer, tunnel dryer and solar/biomass hybrid cabinet dryer. The details of eachpackage are presented in the following sections.Package 4: Improved Solar Box DryerRECAST redesigned the classical solar box dryer to minimize heat losses and tofacilitate easy handling. The improved box dryer consists of an insulated dryingchamber and a chimney attached at the top. Window glass is used a glazing at thetop of the box. The dryer, shown in Figure 4.1, has three trays on which the productsto be dried are loaded. The products are spread in thin layers on the drying trays forbetter contact of drying air with the product. The trays are designed as drawers thatcan be pulled out individually for loading and unloading.Figure 4.1: Improved Box Dryer24
Design DetailsThe technical specifications of the improved solar box dryer are presented in Table4.1, while its dimensional details are given in Figure 4.2.Table 4.1: Technical specifications of the improved box dryerSl. No. Parameter Specifications1. Mode of drying Direct2. No. of glazing Single3. Loading Pulling the drawer from backside4. Air outlet Chimney at the top5. Air circulation Natural6. Drying area 0.8 m 27. Glazing slope 30 degrees8. Collector area 1m 29. Drying capacity 4 kg-fresh per batch10. Construction materialsWood, steel section, aluminum sheets, glasssheet and glass wool11. Approximate cost NRs. 8,000**1 US$ = 74 NRs (Nepalese Rupees), March 2004Dimensions are in mmBottominsulationFigure 4.2: Dimensional details of the improved box dryerThe drying chamber, which is made of wood, is 0.7m x 1.84m in cross-section andhas a height of 0.315 m. Figure 4.3 illustrates the dimensional details of the improved25
Page 1: Technology Packages:Solar, Biomass
Page 4 and 5: Technology Packages: Solar, Biomass
Page 6 and 7: PrefaceIt is increasingly becoming
Page 8 and 9: NepalEr. Rishi K. B. ShahVice Presi
Page 10 and 11: viii
Page 12 and 13: Chapter 1PACKAGES DEVELOPED AT AIT,
Page 14 and 15: Glass cover40A - A10535Glass woolin
Page 16 and 17: The main advantage of using the gas
Page 18 and 19: LidWater sealFuel chamberGas burner
Page 20 and 21: 15Ø cylinderStud. 5/16" dia.A101"
Page 22 and 23: The ash scraper slides through a cy
Page 24 and 25: welded at the top with the water se
Page 26 and 27: Other fuels such as saw dust brique
Page 28 and 29: Figure 2.19: Thermostat used in the
Page 30 and 31: The dimensions and other design par
Page 32 and 33: stove at one end and a chimney at t
Page 36 and 37: ox dryer. The drawer type tray desi
Page 38 and 39: Figure 5.1: Improved solar cabinet
Page 40 and 41: Dimensions are in mm1.1.1.1.1Figure
Page 42 and 43: Package 6: Improved Solar Tunnel Dr
Page 44 and 45: Dimensions are in mmFigure 6.3: Det
Page 46 and 47: Package 7: Solar-Biomass Hybrid Cab
Page 48 and 49: Dimensions are in mmFigure 7.2: Bac
Page 50 and 51: Telescopic chimney110 cmTop cover88
Page 52 and 53: chimney is removed and the drum is
Page 54 and 55: Chapter 3PACKAGES DEVELOPED AT UP,
Page 56 and 57: Dimensions are in mmFigure 8.2: Dim
Page 58 and 59: ChimneyDryingChamber1DryingChamber2
Page 60 and 61: Package 10: Transpired Collector So
Page 62 and 63: Table 10.2: Technical specification
Page 64 and 65: Chapter 4PACKAGES DEVELOPED AT ITC,
Page 66 and 67: Figure 11.3: Fully assembled box ty
Page 68 and 69: total drying area of 2 m 2 . The dr
Page 70 and 71: The drying chamber is built with ha
Page 72: Renewable Energy Technologies in As

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