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re: solar still problem -- please help
2 apr 1997
william a. rhodes, ph.d. wrote:
> as calcium buildup progresses, rivulets increase, and
>distilled delivery drops off in proportion to the curtain color,
>gradually turning gray. upon dryout, the curtain is white and
>stiff like cardboard. when clear it is a silky glistening black.
>i have failed to discover another method of decalcification and
>must turn to you for advice.
i suppose you have tried increasing the flow of water over the cloth, ie
evaporating a smaller percentage of it so the calcium concentration is lower,
along with preheating the incoming water with the outgoing water to avoid
losing much heat with the increased water flow.
perhaps this problem can be avoided by putting the water to be distilled in a
shallow dark pool on the bottom, or in a trench along the north edge, with a
reflective parabolic surface above, allowing some solar concentration as well.
it's nice you are working on solar stills. i've been thinking lately about the
possibility of storing solar heat by concentrating a lithium chloride solution
by heating it to about 130 f, minimum, and recovering heat by letting the licl
absorb water from house air, evaporated by people, showers, cooking or heat
from the ground, as people water an indoor lawn or garden or basement floor.
if the still were in the sunspace of a house with significant thermal mass, the
condensing water might heat the air in the sunspace, which would in turn keep
the house warm, so this heat wouldn't be lost. this still might have a similar
"salt problem," or moreso.
licl can absorb 12x its weight in water. cyprus foote-mineral at (800) 523-7116
sells it for $4/lb. osha classifies it as fairly harmless to humans. can we
store a week's worth of heat for a house in 2 55 gallon drums full of licl
solution, at 1000 btu/lb of water, vs 50 btu or so for sensible heat storage?
nick
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