[Gasification] [Stoves] Heat transfer and in-line water heater
Thomas Reed
tombreed at comcast.net
Sun Dec 9 19:48:01 EST 2007
Dear Steve, Andrew and All:
Radiation goes as
W = seA (T2^4 -T1^4 )
where s is the Stefan-Boltzmann constant, (5.670 400(40)×10^-8 W
<http://en.wikipedia.org/wiki/Watt>·m^-2 ·K^-4 [I prefer to remember is
at 5.67 Watts/cm2 (K * .001), thinking in thousands of Kelvins] e is the
effective emissivity, (1 for carbon and .01 for silver); A is the area
of the emitter and T2 is the emitter and T1 the receiver.
Because of the fourth power dependency you can usually ignore T2 if it
is less than 3/4 of T1.
Let's all be grateful to Stefan and Boltzmann.
TOM REED BEF
Since
Steve Taylor wrote:
> andrew wrote:
>
>>>>>
>>>>>
>>>>>
>>> Temperature DIFFERENCE.
>>>
>>>
>> I don't think so Steve, that's true of conduction (where adjacent
>> atoms jostle each other to exchange energy) but radiation is
>> absolute and is related to the 4th power of the absolute
>> temperature.
>>
>>
> So do two objects at identical temperature radiate to each other ?
> I thought thats why a black body radiator works, and why you can't see
> the inside of a fire very well
>
> Steve
>
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