re: ultrasound for bubble breaking?
18 mar 2003
sherwood botsford wrote:
>> >one of the ag permaculture groups has a discussion going on about
>> >insulating poly greenhouses with soap bubbles.
>> which one?
>solaroof (note only 1 r)
>i'm in central alberta. the chilly-bugs grow big here.
perhaps you can quantify this :-) calgary's cold as well.
>ideally i want a photocell pointing at winter dawn, and
>when insolation passes a threshhold, insulation vanishes.
you might build a bubblewall and see what happens. one thing that can
happen is freezing, unless the bubble solution contains antifreeze...
frozen bubbles can be good solar reflectors.
>> you might just turn off the bubble generator and turn on the static
>> inflation fan at dawn.
>this is the current practice with richard nelson's unit in ottawa.
>he uses about 1/3 kwhr of power/day for the inflation and bubble
>generation in his 1200 sqft house. (1 kw x 20 minutes/day)...
>having a quick way to destroy bubbles makes bubble windows more
>attractive. it doesn't take 2 hours to "open the drapes"
you might store some warm bubble solution in an insulated tank or a tank
in the ground, with a heater, and pump it up to the peak of the greenhouse
and let it dribble down through the foam to more quickly destroy or thaw
>people quote r1/inch for bubbles...
you might find that with a 1500:1 expansion ratio. it also depends on
the temp. tiny cold bubbles (eg 1/16" at 50 f mean temp) are almost as good
as fiberglass insulation, on the order of us r3 per inch, which decreases
with increasing size and temperature, altho solar transmission increases.