Posted by nicksanspam on March 24, 2007, 5:44 am
A pond-type solar water heater might have a plastic bag full of distilled
water in the pond, open at the top. It might distill water on sunny days
and reabsorb water vapor on cloudy days.
It can be more efficient (by 1000 Btu/lb) if the water is condensed.
It was once used as a table salt substitute, but ingesting 1 gram a day
is teratogenic (bad for fetuses.)
Stacked transparent trays might do multiple-effect distillation. Evaporate
water from a lower tray and condense it on the bottom of the tray above.
Hawlader's 1993 experiment had no glazing, just a dark asphalt roof.
They saved the first flush after a rain.
Posted by Jeff on March 26, 2007, 4:37 am
I have a thought about using the attic as a solar collector.
The attic I have here is unventilated except for a gable mounted
exhaust fan. What if I duct the the intake of the fan (inside the attic)
to a liquid desiccant regenerator:
to exhaust fan and out of attic
|********| brine sprayer
| |air enters through louvers here
__________ sump which returns to brine sprayer
So, when the attic reaches 110, the hot attic exhaust is used to
regenerate the desiccant. That is heat that would otherwise be thrown
away. With 4 million BTUs falling on my 2000 SF roof on a June day that
would give about 4 therms of desiccant regeneration if the efficiency
What do you think?
Posted by nicksanspam on March 27, 2007, 12:42 pm
Glazing the south roof could help.
IIRC from Hawlader's paper, we need 130-140 F for this to work well.
After you glaze the south roof, you might add a reflective north wall
to concentrate sun through a few layers of glazing onto a desiccant pond.