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-   -   Simulating condensation using evaporation-condensation model (http://www.cfd-online.com/Forums/fluent/117203-simulating-condensation-using-evaporation-condensation-model.html)

athonyburk May 4, 2013 10:10

Simulating condensation using evaporation-condensation model
 
Hi,

I'm modeling a wall-bounded flow with boundary conditions of a velocity inlet and no outflow. I enabled evaporation-condensation model to account for the mass transfer along with the phase change. Since the working fluid is user-defined and I didn't input its latent heat values, I was wondering how is energy transfer considered in the model? (I didn't find a place where I can manully define the energy source term.)

And according to FLUENT theory guide, the evaporation-condensation model is only available with mixture or Eulerian multiphase models, probably because of the smaller-than-grid scale of the interface length. I actually used VOF model and discovered the condensation. Is my result valid? And what's the specific length scale of the droplets FLUENT used in its model?

Thank you very much!

athonyburk May 17, 2013 06:18

Nobody knows?

I read in other post that the latent heat is given in the enthalpy of reacting phase. But how? In my case, where condensation is of the most interest, should I define a negative value of enthalpy for the vapor phase, or a positive value for the liquid phase?

Still, since condensation is only calculated in FLUENT when temperature is below saturation, how could this model be accurate anyway? Shouldn't it be full of liquid below saturation temperature?

Felja May 17, 2013 15:17

latent heat
 
Latent heat can only have liquid phase. You can always read from thermodynamic tables as: latent heat = vaporization heat - p (v''-v ')!
Felja,


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