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re: evaporative cooling
20 may 2002
cm wrote:
>a "dessicant" is a substance like lithium chloride, calcium chloride,
>or silica gel that absorbs moisture from the atmosphere. the dry air can
>then be cooled by water evaporation. when the dessicant gets saturated,
>it can be heated using solar heat to drive off the contained moisture,
>then reused.
>this process can be done either open cycle (loosing water to outdoors)
>or closed cycle (recycling the water).
one closed form is a greenhouse on the roof containing a licl pond and
a water pond, with licl and water tanks in the room below.
during the day, the greenhouse acts as a still, filling the water tank,
with the water pond empty. to air condition, pump water up into the pond
at night, when the licl solution is cool. for dehumidification, turn on
a fan to move room air through the still when its rh drops to, say 20%,
with the water pond empty.
the thermal mass of the water and licl tanks keep the room cool during
the day, with the licl tank plumbed as a cool cell (tm), thermosyphoning
warm weak licl solution up through the pond. the water tank also works
as a cool cell at night.
nick
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