Melting with a cartridge heater ANSYS

[AliceEng]

Has anyone simulated transient thermal models with a cartridge heater?
I am simulating a melting process of a paraffin-like material. The heat source is a small heating cartridge (omega). During the simulation I apply the same amount of heat flux as in the laboratory test (simply as W/m^2). However I get too high values of the temperature in my model. All other BCs as convection and so on seem to be correct. Maybe it is something about the structure of the heating cartridge (it has a spring inside) and I consider it as a cylinder.
What can cause such a big difference in temperatures? Thank you.

 

[IRstuff]

How high is too high? 1.5x, 10x, 100x? Is your paraffin actually melting in the model?

TTFN
faq731-376

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[AliceEng]

Thank you for your reply!
The model is solving a phase change problem, that is why I use a thermal transient
analysis. I did it analogously to the ANSYS tutorial about a solidification of an aluminum flywheel casting contained
in a sand mold.
I get a max value of the 70C during the lab test and in the model around 120C (so 1.7x). The cartridge is pretty small, the sizes DxL are 4x40 mm.

 

[IRstuff]

There could be a number of reasons for the mismatch

> unmodeled heat loss mechanisms
> convection model mismatch
> conduction model mismatch

TTFN
faq731-376

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