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a pv fridge with an ice battery?
7 jul 1997
steve spence wrote:
>you don't need batteries if you don't mind your food getting warm after 2
>days of no sun.
this might work well if the "battery" were some ice that melted over 2 days.
>david wells wrote:
>>the 12 cubic foot sun frost rf-12... draws about 336 watt-hours per day
>>at 70 f ambient... the cooler can be run by two 48 watt solar pv panels.
anyone know the cop of a typical fridge? that 336 wh might move about 1.1 kwh
per day or 48 btu/hour of heat, with a cop of 3, so the fridge might stay cool
for 2 days if it began with 2x1100/144 btu/lb = 16 pounds of ice above it, eg
4 1/2 gallon plastic milk jugs. losing 48 btu/hr from ice containers with a
10 f delta t and a still air film thermal conductance of 1.5 btu/h-f-ft^2
requires a total surface of 48/10/1.5 = 3.2 ft^2.
nick
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