Evaporation and Condensation

SSAA · August 26, 2013, 14:01

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

Please help me.
Thanks a lot.

yangbinsunshine · November 14, 2013, 07:31

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

SSAA · November 18, 2013, 11:57

Not yet

what about yours?

moftah · November 19, 2013, 05:02

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, 11:36

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

Zaktatir · November 21, 2013, 16:15

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
2/Please give more input
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.

August 26, 2013, 14:01	Evaporation and Condensation	#1
SSAA New Member SA Join Date: Apr 2013 Posts: 6 Rep Power: 13	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 Please help me. Thanks a lot.

November 14, 2013, 07:31	hi, i am very intrested ijn your problem	#2
yangbinsunshine New Member yangbin Join Date: Nov 2013 Location: haerbin Posts: 4 Rep Power: 12	i am working on a problem which is like yours. is your problem sloved?

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November 18, 2013, 11:57		#3
SSAA New Member SA Join Date: Apr 2013 Posts: 6 Rep Power: 13	Not yet what about yours?

November 19, 2013, 05:02		#4
moftah New Member abo salsabil Join Date: Nov 2013 Posts: 1 Rep Power: 0	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

November 20, 2013, 11:36		#5
SSAA New Member SA Join Date: Apr 2013 Posts: 6 Rep Power: 13	Hi Moftah, I have sent you an email. Thank you

November 21, 2013, 16:15		#6
Zaktatir Senior Member Join Date: Jan 2010 Location: Germany Posts: 268 Rep Power: 17	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 2/Please give more input 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.