# Thread: Thermodynamics, from gas to solid

1. Hi Guys

What equation can I use to calculate how much thermal energy has been transferred from a very hot gas to a metal (pipe for example, of known thickness)?

2.

3. Unless I've misunderstood what you mean this is not a simple problem (I have to admit the maths in the theory is beyond me! although the empirical equations on p530 of the first link seem simple enough) but you may find these links useful:

http://users.ugent.be/~mvbelleg/lite...Properties.pdf

http://www.ipta.demokritos.gr/CHousi...MTSlipFlow.pdf

4. Thanks for the great material, let me elaborate a bit more.

I know the specific heat capacity of the gas (which, of course, changes with T, but for now I am assuming a constant heat capacity to help make the problem more manageable),
I know the coefficient of heat transfer of the metal,
I know the specific heat capacity of the metal,
I know the density of the Gas
The gas happens to be 8 parts CO2 and 4 parts N2 (so a 2:1 ratio)
I know initial Temperature of the gas
I know the Area of the metal that the gas will be in contact with,

So I wan't to know (based on the known properties of the materials in question, and basic thermodynamic principles) what the temperature (T) left in the gas is after a time (t).

Unfortunately I don't have any experimental data that I can use, I have to somehow make an expression from basic principles (built from bottom up), I don't know how many of the things above I would have to use to work this out. Does that clarify the problem enough?

Oh btw, I'm finally in Uni now, studying Physics at Nottingham, but the profs. said they don't specialise in thermodynamic research here, and that he couldn't (off the top of his head) think of a module that goes into enough detail on thermal exchange between mediums, so hopefully you guys can help. Again thanks for the material, I'm gonna have a read through it.

5. This page from MIT may help.

If you want to find the temperature of the gas (or metal) after a certain time, you'll need to use the heat conduction equation, which you can find online. It involves solving a differential equation with a convective boundary condition.

6. @Chaos, OK, it's not really my area (the thermodynamics I know most about is the chemical stuff, enthalpy, entropy and Gibbs free energy changes of reactions and solution thermo - activity coefficients etc.) but this page might be useful: Heat equation - Wikipedia, the free encyclopedia

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