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re: fridge
20 aug 1998
marc archambaut - northshore developments wrote:
>in north bay, ontario, canada in winter i unplug my freezer in my shed
>and let mother nature take over the next 5 month of cold weather. no
>hydro costs and since the shed is insulated and so is the freezer, i
>don't get much in temperature fluctuations on warmer days...it works
>great.
sounds great. i keep my "summer kitchen" at about 36 f in the winter.
it's off the north side of my 1820 stone farmhouse with exterior foam
insulation, so the temperature changes slowly, and the fridge seldom
turns on. food on shelves lasts longer too. and if i leave the milk
on the counter overnight, no problem.
>but how about this idea. keep your fridge in your shed or porch in
>winter... and let the outside cold work for you. the only problem is
>that your food will freeze. but what if you put a 40 or 60 watt bulb
>inside the fridge, hooked up to a thermostat. when the temperature
>drops too low, the light comes on and heats the inside.
sounds cool. let's see: a 4x4x8' tall box with us r10 (2" styrofoam)
insulation has a thermal conductance of 160 ft^2/r10 = 16 btu/h-f, and
a 60 watt bulb makes about 200 btu/h, so it could keep that fridge
from freezing until the surrounding air temp drops to 32-200/16 = 19 f.
if the fridge were in an insulated room surrounded by sealed containers
of water, that would keep the air in the room from dropping much below
32 f until the water freezes: an 8' r10 cube with 24 55 gallon water drums
inside and 0 f air outside would collect (32-0)6x64ft^2/r10 = 1229 btu/h
of coolth, and require 24x55x8x144 = 1.5 million btu to freeze solid,
after 1.5 million/1229 = 1237 hours or 52 days at 0 f.
>am i missing something or would that not save alot of energy...
that could save lots of energy, but that light bulb power is bothersome.
maybe there's a way to keep the air surrounding the fridge warmer, say
with an earth tube?
>my well water is 8 degrees celsius, in farenheit that's about 46 degrees.
>would it make sense to flow well water through a water baseboard radiator
>located inside a freezer to cool it's inside to use as a fridge?
i think 46 f is a little warm for a fridge, and the food will be even
warmer than that if the radiator/heat exchanger is not 100% efficient.
otoh, you might flow a little well water through an outdoor fridge to
keep it from freezing...
>one last one, get an old fridge and drill a couple of holes in it, keep
>it inside but connect the holes to the outside with insulated pipes
>(caulked). one hole higher than the other for convection to occur. have
>some sort of thermostat connected to a baffel to allow or stop air
>flowing. in winter, would that not work?
sounds good to me, altho i think this would be easier to do with a
small fan. let's see: our fridge gains about (70f-40f)16 = 480 btu/h,
and 1 cfm of airflow with a 1 f temp difference moves about 1 btu/h, so
if the outdoor air is say, 20 f, the fan needs to supply an average of
480/(40-20) = 24 cfm. grainger's $20 4c548 fan moves 55 cfm with 6.5 w,
so in the winter, this fridge might use less power than an alarm clock.
nick
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