the hitch in the processing of the cassava was the drying before milling into flour. traditionally it's laid in the sun and left until dry. to increase drying capacity they had built a greenhouse and elevated drying racks out of poly tarps with a poly cover for rain protection. unfortunately they didn't understand that air circulation was as important as heat (sun), so i fiddled with an improved design that used old woven poly sacks, which was a bust. then i built a prototype scaled solar dryer designed by dennis scanlin, a professor at app state. it works by allowing radiant solar heat to penetrate a transparent cover (in this case old corrugated fiberglass that was lying around) and heating a black metal surface that absorbs the heat. cool air is drawn in through the bottom and is convectively heated by the metal as it rises through the mesh shelves that hold the cassava, thus decreasing the drying time (in theory).
work in the developing world faces inherent problems, one of which is the language barrier. just showing up at a impromptu carpentry shop with a set of plans and a dumb look wasn't enough. after endless explanation and drawings i decided i would have to show them by demonstration. next, acquiring materials is an ordeal. this hardware store has only two sheets of plywood and half a can of paint. this store has 20 nails and a two metres of hardware cloth. after a day and a half of squabbling over "m'zungu" (whiteman) prices i began to build, often with a crowd.
the crowd gathers
frame coming together
fiberglass cover and flat black painted absorber bottom.
mesh drying racks
still skeptical huh?!
my best helper and i after a job well done
taking pre and post weights
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