[Greenbuilding] Pond cooling and clay dehumidification

[nick pine]

John Canivan <canivan at ...> wrote:

> Are you saying you could fill an attic with kitty litter and circulate 
> household humid air through a dry cold attic at night and allow the wet 
> kitty litter to dry out during a sunny day?

Maybe. The clay has to be heated to about 113 F during the day, and the 
water vapor needs to leave the attic during the day, so the attic needs to 
be vented during the day. And the clay needs to be about 80 F at night, 
hence the car radiator inside the house and the outdoor shaded pond.

In my house, the small pond and clay bed would go on a flat roof, and the 
radiator might take the form of water in poly film ducts on some shallow 
trays under the ceiling in the room below the roof, as in a Zomeworks 
architectural Cool Cell 
zomeworks.com/files/cool-cell-files/ArchitecturalCoolCell.pdf

Bentonite has a specific heat of about 0.24 Btu/lb-F, so 334 pounds with C = 
80 Btu/F under a 4'x8' R1 cover and RC = R1/4'/8'x80 = 2.5 hours would cool 
from 113 to 80 F with 72 F outdoor air in -2.5/ln(80-72)/(113-72)) = 1.5 
hours.

That's not too long to wait, in a 12 hour night, but if the clay adsorbs 
30.6 pounds of water vapor in the next 10.5 hours making 30.6K/10.5 = 2914 
Btu/h of heatflow, it will warm to 72+2914xR1/4'x8' = 163 F, with a very low 
moisture content capacity. Hence the need for cooling the clay.

Nick