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re: heat storage "portable heater" ??
9 nov 2000
mr. toby wrote of:
>> >...an r20 floor with 3 btu/h-f room-to-ground conductance
>> >borders the 54f ground.
>> is seems unreasonable to assume that the ground under this outside
>> room would be so warm in the winter.
>no it's not.
i disagree.
>have you ever studied ground temperatures in different parts of the usa?
sure. the ground near the edge of the house and near the surface would be
closer to the monthly than the yearly average air temperature, unless
you choose to invent further unplausible assumptions :-)
>at any rate, it's alot better estimate than your 34f which you assumed.
au contraire, i went with your very own dubious assumptions...
>>and what's the floor area of this odd 5-sided room?
>8'x8'. the roof is 8'x8'. the north,south,east,and west walls are all
>8'x8' too. it has 6 sides counting the floor.
would they include the 3 outdoor walls and 2 interior walls that you
mentioned in your posting? :-)
>> >the heat flowing out of the 74f room, would be:
>> >outside: (74-34)10=400btu/hr
>> >woodstove room: (74-74)6=0 btu/hr
>> >floor: (74-54)3=60 btu/hr
>> >total: 460 btu/hr
>> ok...
>you finally get it eh?
i agreed with your heat loss discussion's sake, but your subsequent
calculations were still incorrect, based on your very own assumptions.
>> so this "10 or 15 pound heater" has now grown to
>> 21 pounds plus the weight of the container...
>
>ok, so i added a few pounds....
and walls, and wall insulation, and bodies and light bulbs,
and incorrect arithmetic, inter alia.
>> >the thermal time constant: 21 btu/f / [13 btu/h-f] = 1.6 hours
no, it's 2.72 hours. get real, nitwit.
>> with a thevenin equivalent circuit like this:
>>
>> 74 f
>> |
>> 1/13 | 1/19
>> t ---www---*---www--- 49.8 f
>>
>> the series resistance is 0.1296, with rc = 2.72 hours...
you might consider a different hobby, toby, something requiring
less practice and education. for instance, surgery... :-)
nick
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