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-   -   Inverted Janaf formula (http://www.cfd-online.com/Forums/cfx/24601-inverted-janaf-formula.html)

gianpaolo September 27, 2007 10:01

Inverted Janaf formula
 
Hi all,

Could Somebody help me? I'm looking for the inverted Janaf Formula to calculate T from enthalphy.

Thanks

bye

opaque September 27, 2007 11:48

Re: Inverted Janaf formula
 
Dear gianpaolo,

I have never heard of a inverted Janaf Formula?

To get T from enthalpy, you must find the solution of the problem

"Your value of H" - JANAF @(T) = 0

since JANAF formula is nonlinear (positive and negative powers of T), you will use something like a Newton's root finder, or secant method, or plain bisection. Hopefully, there is only one positive root.

Opaque


gianpaolo October 1, 2007 05:13

Re: Inverted Janaf formula
 
I had thought about this kind of solution, using secant method, and in this way the solver is ok, but I wish I make my solver faster.

So I wonder if someone implemented any approximated formulas for the H -T since this formula is monotone.

Anyway I thank you very much for the answer.

Gianpaolo


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