Hello!

I'm a postgraduate student and curently having problems with damp-air condensation treatment.

Problem description: the bulk flow is consisted of damp air which should be cooled and heated in some areas. The main objective is to simulate the condensate flow where the bulk flow is cooled (heat exchanger with plates almost parallel to the main stream). Second problem is to simulate the motion of hard particles, which are washed off the plates by the condensate.

I would very much appreciate any help or input (which literature, which CFD code is capaible of treating that, ...).

With best regards Gregor Kotnik

The motion of hard particle in the flow has to be treated with a two phase flow modeling. I am not sure what software you are using (commercial or 'private'), but in your case you can treat the particles by solving for the equation of motion, when the forces that act on them are drag due to the gas flow, gravity and any other things you might have there in your problem. So you might want to look in the litterature for two phase flow, where the 'second' flow is treated as particles. You can also treat the particles as a flow itself, that's another option. So the first step is to look into two phase flow.

Concerning your first point, it should not be a problem to add the needed thermodynamic terms into the energy equation as a source or sink term on the right hand side.

Patrick

The condensation is very tricky because you have to solve for a thin liquid film which might form in the case of condensation and which also might disappear in the case of evaporation. This film completely changes the condition of heat transfer.

Have a look at the paper "Two-Phase Structure of the Condensation Boundary Layer with a Non-Condensing Gas and Liquid Droplets", Int. J. Multiphase Flow Vol. 17, No. 2, pp. 213-225, 1991.

Andrzej

thanks a lot for that info!

Gregor