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convective heat transfer on a sphere

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Hey guys,

I'm writing a simulation of freeze drying for my bachelor thesis.

In my bachelor-thesis, i’m looking at a system with a particle of pure ice (T=230 K), which is exposed to a ingoing water vapor mass flow (T=240 K, mass flow=const.) under reduced pressure (10 Pa). I’m studying the change of the outgoing mass flow, which is caused by the presence of the particle, and I’m also looking at the time dependent temperature distribution inside the particle. The steam shall heat the particle, the supplied energy of the steam leads to sublimation of the ice.

I orientated myself on the simulation from the model library:
www.comsol.com/model/a-transie...analysis-of-freeze-drying-3924

I use the physics "conjugate heat transfer" for the heat transfer in the particle and the mass flow, "transport of diluted species" for the concentration distribution inside the system, and "deformed geometry" for the moving of the sublimation front of the particle. The simulation works, but the whole particle stays at a constant temperature and won't shrink. I use the ideal gas equation for defining the BC of temperature on the particle surface. I think something is wrong with my combination of the physics. If somebody could help me, I would be very thankful. I already tried everyting... I uploaded the simulation:

www.file-upload.net/download-8787063/05.04-convective-heat-transfer-sphere.rar.html


Best regards,

Andreas Schäfer

0 Replies Last Post 5 avr. 2014, 15:08 UTC−4
COMSOL Moderator

Hello Andreas Schäfer

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