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Freezer air conditioning? - Page 3

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Posted by Solar Flare on May 26, 2008, 10:28 pm
 
If the outside temperature never goes below your comfort level the "over the
top" insulation level won't matter. Some cooloing will still be required,
just much less. A combo technique is required.




Posted by AmyJFriedland on May 23, 2008, 11:22 pm
 
I don't think you could have a small PV panel or small battery to
power a freezer.

Posted by Solar Flare on May 26, 2008, 10:29 pm
 Evaporator coil in your water bed mattress?



Posted by Jeff on May 27, 2008, 12:48 am
 Solar Flare wrote:

   Or maybe put the ice in the mattress!

   Jeff


Posted by j.soar.aero on May 27, 2008, 2:26 pm
 Then you have that little issue of capacity.


" Lets say you have a small 6000 BTU/hr window AC. By definition 6000
BTUs is 1/2 ton of air conditioning, that is how much cooling you
would
get by melting 1000 pounds of ice.

How many pounds of ice will your freezer make in a day? "



Some simple calcs:

After a hot day my ac runs full time for about 4 hours to cool the
room in the evening. My ac unit is rated at about 5000 btu/h. At 5000
btu/h, it would produce 20000 btu of cooling in that time. Melting a
pound of ice at 32 F requires 143 BTU. It would take about 140 pounds
of melting ice (not 1000 pounds) to equal what the ac unit does. That
would be about 18 gallons of water. One cubic foot of water is 7.5
gallons. That would be  2.4 cubic feet of water, no capacity problem
for even a very small freezer.

However that is still a lot of freezing to do in just a few hours of
sun per day and would take a lot of PV panel area and a very powerful
freezer to do it (and a lot of money to purchase all of it). So
probably not practical for around here.

Now I'm thinking of doing something like just running the window ac
when it can thru a battery-buffered inverter powered by a  wind
generator. There is a lot of wind around here, but of course with
erratic timing. Plug the ac into the wall/grid when there is no wind.
Also I could use the power from the wind-gen for electric heat in the
winter.

BTW I just got my solar hot water system going, and it looks good so
far. And I'm now on "real time pricing" for my electric power and it
is much cheaper from midnight to about 6am, so I'm trying to move some
loads to that time period, like crock pot cooking, etc. The rates are
highest in the evening, another good reason to not use the ac in the
evening.

JRB in central Illinois

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