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Offline Absalom

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« on: 09/08/2010 03:04:30 »
Can an insulated box reach a higher temperature than than the heat source? Or relatedly, given a constant energy input, will a heat source like propane combustion with constant fuel gas pressure  and oxy ratio,  remain at some temperature, or increase in temperature with insulation?


 

Offline flr

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« Reply #1 on: 09/08/2010 04:15:18 »
 As long as you have a heat transfer from the heat source to the box, then the box will heat up to the temperature of the heat source. The 2nd principle of thermodynamics will prevent the box to became hotter than the source.   
 

Offline Absalom

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« Reply #2 on: 09/08/2010 22:51:50 »
Thanks. That's pretty much what I thought, and even why, but in a discussion with a friend we accidentally hypothesized an impossibility and I got all turned around.
 

Offline Geezer

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« Reply #3 on: 10/08/2010 19:46:06 »
But you could make it hotter if you did work on it too.
 

Offline flr

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« Reply #4 on: 11/08/2010 23:03:41 »

 From the 1st principle of thermodynamics, there should be no limit on how hot it could get by giving it work.

 However, in practice, the thermal transfer between the source of work and the box is unavoidable, and that should limit how hot the box gets for a certain power/intensity of the 'work source'.
 

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physics/thermodynamics
« Reply #4 on: 11/08/2010 23:03:41 »

 

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