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Induction Heating Equation

Induction Heating Equation

Induction Heating Equation

I found this simple but useful equation on a website for induction heating,

P = k.I^2.(u.p.f)^-0.5


P is the heating power to the workpiece
k is a constant
I is the current in the pick-up coil
u is the relative permeability
p is the resistivity (ohms mm^2/m)
f is the frequency

From this equation I want to work out the current in the pick up coil. I have values for all the parameters except the constant k.
Has anyone seen this equation before and know the value for the constant? Or does anyone know of other simple equations using similar parameters??

Does anybody know the value of this constant

RE: Induction Heating Equation

k depends on the coil and object and their geometries --
measure it using medium power -- defined by temp. increase rate -- and extrapolate.


RE: Induction Heating Equation

k is most likely the coupling coefficient, which is configuration and material dependent.

This site has a spreadsheet for inductive heating calculations, might be of some use:




RE: Induction Heating Equation


The thing is I am investigating the use of induction heating and I wouldn't know what the coupling coefficient would be.

Is the equation used a standard equation?

If so does anyone know where I can find it?       

RE: Induction Heating Equation

It's probably an empirical relationship... Oddly enough, my websearch for "induction heating equation" pulled up your equation on the 2nd hit:


although most of the remaining hits give something like this:


If you do the same websearch on Google, you'll pull up some interesting material,  not sure how relevant to your specific needs, but there were some good hits, particularly one comparing inductive range tops with gas and electric.


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