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 SSAA August 26, 2013 14:01

Evaporation and Condensation

Hi,
I really need help to simulate evaporation and condensation.
My model has inlet which produces liquid from a top of a cylinder The cylinder is under heat flux from bottom then the vapor moves through a vapor channel in the bottom side of the cylinder and condense in a condenser which is under constant temperature 289 K then the liquid return back to cylinder by a liquid channel.
I am using mixture model but i am not able to see volume fraction of vapor

Thanks a lot.

 yangbinsunshine November 14, 2013 08:31

hi, i am very intrested ijn your problem

i am working on a problem which is like yours. is your problem sloved?

 SSAA November 18, 2013 12:57

Not yet :( what about yours?

 moftah November 19, 2013 06:02

Hi,
if you are using a mixture model then you have to use pressure-inlet as a boundary conditions then you will be easy define the second phase with either its volume fraction or a slipe velocity.

Regards,
moftah

 SSAA November 20, 2013 12:36

Hi Moftah,
I have sent you an email.
Thank you

 Zaktatir November 21, 2013 17:15

Some Questions:
1/Evaportion and Condensation:This start to happen on the wall (subcool boiling) and then in the volume. The one way is quite validated there you have to acount for wall boiling and then bulk boiling whereas for the condensation if you have a cold wall this may lead to problem since you have to account for source terms in your mass & energy transfer
3/How big are the vapor bubbles or do you expect that bubbles undergo colascence and then getting a vapor continiumm
4/ In general the mixture mode is based on one fluid formulation assuming a local equalibrium between the phase and therefore you may assume an algebraic formulation of the relative speed. This is only limited to particle relaxation time smaller than 0.1 and not appropriate if fluids are not flowing in the same direction. Eulerian-Approach is here quite superior but somewhat difficult
5/Start with simple case and trying to consider one phenomena by means of two-resistance modelling or tomiyama heat transfer.

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