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re: modifying chest freezer
12 mar 1999
vernon lecount wrote:
>...his idea was then to fill several one gallon (about 4 liter ea.)
>plastic water containers (sold for water & milk containers in some
>parts of the world) and place them in the area where the freezer was.
>then, when we have the sun shining... we run the refrigerator until
>the water freezes. once the power is off the ice keeps the rest of
>the refrigerator cold for a 24 hour period.
or longer...
>obviously this is dependent on the amount of times the door is opened,
>the room temperature, the insulation and the amount of water frozen.
say it's a 4' cube with r20 insulation (4" of styrofoam or a 1" foam
panel over 2 or 3 pieces of foil in foam picture frames), and the back
half away from the door contains 128 6" square x 10" tall 1 gallon jugs
stacked up horizontally behind a piece of foamboard so they can be frozen
without freezing the food in the fridge. melting the ice stores about
144x128x8 = 147k btu, and the fridge thermal conductance is 6x4'x4'/r20
= 4.8 btu/h-f, so it needs (70f-32f)4.8 = 182 btu/h to stay cold in a
70 f room, so it can do so for 147k/182 = 808 hours or 34 cloudy days
in a row if the door is closed and it has no air leaks.
>my smarter friend says that water is a better storage medium than a
>battery bank.
well, it's certainly cheaper. new milk jugs cost about 10 cents each,
and store 338 wh of ice melting energy. a trojan 350 ah 6v l-16 battery
costing $200 stores 350x6x0.6 = 1260 wh at a 60% discharge depth, so it
costs about 500 times more per kwh, not counting shipping (126 pounds),
the charger, inverter, and so on, and it may not last as long, and
it contains lead.
>might also help to use outside air to help keep the frig cold in cooler
>climates by mounting the refrigerator through a north facing exterior wall
>(in the northern hemisphere) to the outside.
sure. or just keep your whole kitchen at 36 f in the winter, like me.
i left a topless insulated mug with some ice in it on the counter a
few days ago, and the ice still hasn't melted.
nick
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