Best-Ever Solar Food Dehydrator Plans. Mother Earth News article detailing the construction and performance of an indirect solar dryer at Appalachian State University. As I understand it, this was used to guide one of the dryer's at the ECHO East Africa Impact Center. With an Al foil layer on the collector floor and several layers of metal lath (expanded metal) for an absorber, the article reports two day drying times for apples and temperatures above 60° C.
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Chimney Solar Dryer Manual. University of California Davis publication outlining the design, construction, and operation of a direct solar dryer (sun shines on the drying food) with a chimney. Construction is done with polyethylene plastic. Included are claims about the chimney dimensions required for good draft. Also has some temperature guidelines for drying different foods.
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Understanding Solar Food Dryers. A Volunteers in Technical Assistance (VITA) document outlining solar dryer construction. The basic direct model is based on Fig. 4. Includes some technical data on moisture content of dried food and moisture levels for mold growth. The nomenclature for solar food dryer types used in the website comes from Fig. 2.
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Solar Bruecke. This has some generally useful references to solar use for cooking and drying. It includes, as noted on the direct drying page, information about solar tunnel dryers that are a type of direct dryer. These resources are also noted on the direct dryer page.
Document on tunnel dryers from this website
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Solar Dehydrator. ECHO Technical Note 41 from 2001. Design shown has some of the technical characteristics other indirict dryer opened up to make the drying chamber have direct solar radiation. Includes drying instructions for various fruits and vegetables from a University of Georgia extension bulletin.
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How to make a solar food dryer. An InnoFoodAfrica manual for building both direct and indirect dryers. Also available in Amharic and Oromo language versions..
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DryCard. Information about indicators cards that can be placed in containers with dried food to determine if they are sufficiently dry for storage.
Greenhouse Covering Systems. U of Arizona publication on greenhouse cover materials. Includes data relevant so solar dryer glazing. Also has IR blockage info for fiberglass panels.
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Using solar air heating for fruit drying: Thermo-economic and environmental studies. Paper showing an indirect, active fruit dryer with accompanying computer model.
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Solar transmittance of greenhouse covering materials. Relevant data on glazing materials.
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Does light transmission through greenhouse glassing matter? More data on transmission.
Spectral transmission of solar radiation by plastic and glass materials. UV transmission data but not complete article. Full article is behind a paywall.
Greenhouse Glazing Effects on Heat Transfer for Winter Heating and Summer Cooling. This one has IR transmission information about polyethylene film. Says IR is transmitted unless it is coated for this purpose or has water film.
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The Solar Spectrum. Give technical background and shows what elements block with parts of spectrum.
Transmission curves for polymer optics. Shows IR blocking by polycarbonate.
Large area, low cost anti-reflective coating for solar glasses. Shows IR spectrum for low iron glass.
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Broadband antireflective coating stack based on mesoporous silica by acid-catalyzed sol-gel method for concentrated photovoltaic application. Includes figures showing affects of coatings on low iron glass transmissions spectrum.
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Evaluation of Optical Transmissivity of Transparent Materials on the Performance of Solar Flat Plate Collectors.
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