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re: information wanted on solar ac for boat
14 jul 1997
caspopub wrote:
>...i have a 26 foot cabin cruiser docked in southwest florida where the
>humidity and temperature this time of year are running neck & neck...
>can anyone point me towards a source of information about solar powered air
>conditioning units that would cool the interior of the boat while not
>draining her battery system?
how about a dehumidifier that also provides fresh water? the paper "unglazed
collector/regenerator performance for a solar assisted open cycle absorption
cooling system." by m. n. a. hawlader et al in solar energy, vol. 50, pp 59-73,
1993 describes an ordinary black shingled roof used as a collector/regenerator
for the evaporation of water to obtain a strong solution of lithium chloride
absorbent. results [with a 36' x 36' roof] showed a regeneration efficiency
varying between 38 and 67%, corresponding to cooling capacities from 31 to 72
kw (8.8 to 20 tons), ie up to 240k btu/h, like 48 window air conditioners, or
185 btu/ft^2/hr.
the collector might be covered with 1 or 2 sheets of polycarbonate plastic to
recover fresh water and latent heat, and avoid problems with rain. it takes
about 1000 btu to evaporate a pound of water, so a still making 10 gallons of
fresh water per 8 hour day might require 10gx8lb/gx1000btu/lb/8h/185btu/ft^2
= 54 ft^2 of solar aperture. licl costs about $4/lb from cyprus foote mineral,
and it can hold up to 11 times its weight in water. ingesting more than 1 gram
per day can be harmful to health.
the cycle might go something like this:
1. absorb water vapor from air, diluting the concentrated licl solution.
2. remove sensible heat from the air with a seawater heat exchanger.
3. rehumidify the air to cool it, using a fresh water fountain.
4. concentrate the licl solution in the still.
5. return to step 1.
step 3 might be omitted, with people on board. the water recovered in
step 4 might be charcoal-filtered to eliminate odors...
nick
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