A cloudy-day and DHW heat store?
nick pine
inside a larger duct that's filled with air during the day and soap
bubbles at night...
Start by putting 48' of 2"x4'x8' Styrofoam over a $66 12'x50' piece of
4-year 6-mil polyethylene film on flat ground, then place a $43 24"
diameter x 48' long polyethylene film duct
from http://www.greenhousemegastore.com/product/power-tube-tubing/fan-jets-power-tubes
on the Styrofoam, then raise the film edges and seal them together
with 2" horizontal plastic conduit at the top to make a 4'x4'x4'x50'
equilateral Tablerone bar with supports for the conduit every 8' or
so.
Then fill the duct with about 9400 pounds of water and make an opening
for soap bubble foam near the bottom of one triangular endwall and
another opening for an air return near the top of the opposite
endwall, like this, viewed in a fixed font:
conduit conduitconduitconduitconduitconduit
f f e e air -->
f film n n
4' f f 4' d d
f f w w
f duct f a ductductductductductductduct a
f foamboard f foam -->l foamboardfoamboardfoamboard l
fffffffffffff lfffffffffffffffffffffffffffffffffl
4' 50'
On an average January day in Phila, with the envelope filled with air,
it would transmit about 0.9x50'(1000x3.46'+620x4')
= 267K Btu. Over 6 hours with water temp T, it would lose about
6h(T-34)50'x4'/R1 Btu. With no useful heat output, T = 257 F :-)
At 140 F, it could supply about (140-80)9400 = 564K Btu to a house
with sufficient air heaters and thermal mass for an average day.
Nick