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re: prevent horse watering trough from freezing
27 oct 2000
george estep wrote:
>...i particularly like the idea of the floating containers. i wonder if
>blocks of parafin would work?
perhaps, if they were thin, but then they would tend to break. maybe some
transparent swimming pool or bathtub toy... a round transparent pillow?
i can imagine a bored or curious horse eating a pillow or paraffin wax.
ziploc makes a nice inexpensive "disposable" 2.5 cup polypropylene food
container with a translucent bottom and a light blue lid. it's 2" thick,
5.5" square at the top, and 5" square at the bottom. it floats most stably
in my sink with the heavier lid down, despite the unstable upward bouyancy
taper in that position (this taper direction would also allow it to be
more easily pushed down through an icy surface with water beneath.)
you might encourage it to float with the lid down and keep it from blowing
away and seal it better by pouring some hot wax into the container, then
attaching the lid and holding it flat, upside down, and tilting it slightly
from side to side until the wax hardens. silicone caulk could help too.
it might be nice for energy storage if the sun melted the wax, but that's
probably too much to hope for in winter with water underneath.
or you might cover the tank with some large sealed translucent baggies with
a little water inside to keep them from blowing away and a few drops of oil
to reduce condensation. these "coverites" (us patent no. 4,467,786, issued
8/28/84) would allow the horses to drink (and give them something to play
with and choke on) and allow rainwater to fill the tank. if a few broke or
leaked and sank, the remainder would close up ranks so the surface stayed
insulated. if there were enough of them, and the water surface only froze
in a sparse lacy pattern between them, a horse might easily break that ice
to get to the water.
richmond isn't that cold or unsunny, an average of 35.7 f in january, with
a 55.7 f deep ground temp and 710 btu/ft^2 of sun per day that falls on
a horizontal surface. you could cut the top off a 3' tall 55 gallon dark
plastic drum, bury the bottom in an 18" hole in the ground, surround it
with a 1' tall x 2' diameter dirt donut, and float the containers on top.
hard to clean, but some horses drink out of puddles and ponds...
ignoring the ground heat and the open water between 80% transmissive r1
containers, a square foot of water might gain 0.8(710) = 560 btu/day and
lose 24h(t-35.7)1ft^2/r1, making t = 59.4 f, if the gain equals the loss.
nrel says richmond's record low is -12 f in january. with no sun, and
an r1 cover, the water would lose (32-(-12))1ft^2/r1 = 44 btu/h-ft^2
on a day like that, and freeze at about 44/(144x64) = 0.005 ft^3/h or
1.4" per day.
nick
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