Discussion Forum

Hi guys,
I’m writing my bachelor thesis and want to do a simulation of freeze-drying of coffee with comsol 4.4, but I have not much experience with it. I made some tutorials and simulated examples like:

www.comsol.com/model/phase-change-474
www.comsol.com/model/a-transient-analysis-of-freeze-drying-3924

In my bachelor-thesis, i’m looking at a system with a particle of pure ice(T=-80°C), which is exposed to a ingoing water vapor mass flow (T=const, mass flow=const.) under reduced pressure (0.1 mbar, app.1). 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. At first, the steam resublimates to ice at the surface of the particle and releases latent heat, the mass and energy inside the particle increase to a certain point. When the particle is “warm enough”, the supplied energy of the steam leads to sublimation of the ice(app.2).

So, I need a model, where I have a laminar steam flow around a sphere with convective heat transfer and phase change. Has anybody ideas which physics I can use for this problem?
I think that I can use the “deformed geometry” to simulate the geometry change, but how can I handle the convective heat transfer with Sublimation/Resublimation? I’m very thankful for any ideas.

greetings