# Heat to power

Discussion in 'General Science' started by MusicTech, Apr 12, 2008.

1. ### MusicTech Thread Starter Active Member

Apr 4, 2008
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is there any equation for a formula that converts dissipateing energy over a given volume into heat in degrees?

2. ### beenthere Retired Moderator

Apr 20, 2004
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You might want to look up the topic "specific heat" and "calorimetry".

3. ### Dave Retired Moderator

Nov 17, 2003
6,960
144
Heat transfer is a hugely complex field, and you must consider everything from specific heat, mass density thermal diffusivity, energy velocity, energy accumulation, conductive/convective energy flow, evaporation, all as a function of position, time and initial temperature conditions.

For example in dielectric heating, the 1-dimensional heat equation which equates energy from EM sources, Q, as a function of temperature, T, is given by the attached equation.

Dave

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4. ### MusicTech Thread Starter Active Member

Apr 4, 2008
144
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Ok, specific heat, I have a general idea of what that is. It's why water can cool anything (generally not a common liquid) down real quick without getting warmer and why you can leave a cup of hot tea out for an hour and it will still be very hot. haha, calorimetry... When we learned about that in biology... the bomb calorimeter... my very curious friend almost went running throughout school screaming we have a bomb in the school!!!!

I uuhhh... I think I stick to 1D for now thanks. Although I do have this nifty book on thermal physics so I will try to understand some of the words you just said. Even though I do not really understand some of that, thank you for exposing me to it. I would never have learned otherwise. by the way what is the upside down greek e, is that permittivity of free space?

5. ### thingmaker3 Retired Moderator

May 16, 2005
5,072
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The "upside down Greek e" is actually a right-side up Greek d. It means "derivative." The Greek letter is a type of derivative distinctive from the one for which a modern "d" is used. "Partial derivative," if memory serves. I don't have my copy of Calculus for Dummies at hand now, so I'll have to let someone else fill in the details.

6. ### Dave Retired Moderator

Nov 17, 2003
6,960
144
Yes the upside down "e" is a partial derivative symbol.

As a pointer in the above equation, the terms (each group of symbols between the + and = signs) are as follows:

The First term is the rate of energy accumulation.

The Second Term is the convective energy flow.

The Third Term is the diffusive energy.

The Fourth Term is energy deposited, in this case the Dielectric Heating Equation as a function of time and position, although this could be any energy term.

The Final Term is the energy used in the process of internal evaporation.

Note that the specific heat, mass density and thermal diffusivity are implicit in the general heating equation.

Dave