CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Main CFD Forum

Modeling Condensation in water vapour-air mixture

Register Blogs Members List Search Today's Posts Mark Forums Read

Like Tree2Likes
  • 1 Post By Jing
  • 1 Post By salam

Reply
 
LinkBack Thread Tools Display Modes
Old   March 5, 2002, 09:10
Default Modeling Condensation in water vapour-air mixture
  #1
Amol
Guest
 
Posts: n/a
Can any one throw some light on "Modeling Condensation in vapour-air mixture".. to be precise... Is their any commercial code that will solve these kind of problems ???

I would appreciate your responses

Thanks

Amol
  Reply With Quote

Old   March 5, 2002, 17:03
Default Re: Modeling Condensation in water vapour-air mixt
  #2
Peter Rozovski
Guest
 
Posts: n/a
I can reccomend this book about numerical simulation of condensation

Nonequilibrium Condensation in High Speed Gas Flows by Yu A. Ryzhov, U.G. Pirumov, V.N. Gorbunov http://www.amazon.com/exec/obidos/AS...159262-3232920

If you have some commercial CFD product like FLUENT or CFD-ACE you can add condensation model by yourself by UDF - the simplest model consists from 4 ODE along streamline. Condensation of water wapor in mixture with air is pretty well been studied, but the main question - what you are interesting in ? Temperature levels or location of Wilson's line can be predicted by simple model, with droplets size distribution function situation is worse.
  Reply With Quote

Old   March 7, 2002, 05:15
Default Re: Modeling Condensation in water vapour-air mixt
  #3
Herve
Guest
 
Posts: n/a
Amol,

If I'm not mistaken this has been looked at by some CFX people. Get in touch with their indian office for info: Mr Hari Doss AEA Technology Engineering Software 16 Jayamahal Main Road, Bangalore 560-046 India

Tel:+91 (80) 226 7272 Fax: +91 (80) 225 1133 Email: haridoss@vsnl.com

  Reply With Quote

Old   March 7, 2002, 10:15
Default Re: Modeling Condensation in water vapour-air mixt
  #4
Jing
Guest
 
Posts: n/a
In StarCD, I have simulated the condensation by programming the nucleation and droplet growth model. The Young's nucleation model and Gyarmathy's droplet growth model are all very popular in the region of condensation. You can try them.
TinyBlack likes this.
  Reply With Quote

Old   March 8, 2002, 09:42
Default Re: Modeling Condensation in water vapour-air mixt
  #5
Amol
Guest
 
Posts: n/a
Thanks Peter

I would really appreciate if you can give some more insight about how I should model this through udf.. and you guess is correct .. I want to know "droplets size distribution"

Thanks again

waiting for you response.

Amol
  Reply With Quote

Old   March 8, 2002, 09:47
Default Re: Modeling Condensation in water vapour-air mixt
  #6
Amol
Guest
 
Posts: n/a
Thanks Herve !
  Reply With Quote

Old   March 8, 2002, 09:52
Default Re: Modeling Condensation in water vapour-air mixt
  #7
Amol
Guest
 
Posts: n/a
Jing

I would appreciate if you can give some more info about it,,

Thanks in advance..

Anant
  Reply With Quote

Old   March 8, 2002, 14:39
Default Re: Modeling Condensation in water vapour-air mixt
  #8
Peter Rozovski
Guest
 
Posts: n/a
The simple model of condensation is based on dividing the whole process into two separate steps - nucleation and droplet growth. It is dishonest - but in some situations it works. After it the nucleation rate is calculated by Frenkel-Zeldovich expression, and droplet growth - by some other expression (there are a lot of variants). In this case one has no need to calculate cluster size distribution function itself but can calculate only first 4 moments for it. So one has system from 4 ODE. This was usual approach for a long time and a lot of simulations of condensation of water vapors in turbines were done by such method, which was described in many books, but I prefer the one which I reccomended to you. The good agreement with experimental data is achived by fitting parameters. For some substances such approach works good, for other - not (Lothe-Pound paradox, etc.). For water it works. I think, 99.999% of all calculations of condensation were done for condensation of water vapors. But it also depends from two other main factors : average cooling rate between saturation point and Wilson's point and mass fraction of monomers. If cooling rate (the temperature gradient) is less than 1000-10000 K/sec - Frenkel's formula works. There a lot of details here. But the great disadvantage of such approach is that you don't have cluster size distribution function. If you really(!) need it - there are two approaches. If you are working with small clusters - honestly solve the system of ODE for nucleation process (I was using such approach to simulate metal cluster formation and growth for metal clusters beam generators). If you are working with large droplets - solve the system of equations for different fractions of droplets. It is hard to make more detail advise without knowledge of your problem.

About UDF. It again depends from your problem, but in many cases you can put selected model into your own code and call this code from commercial solver after each time step to recalculate heat source (result of condensation) and mixture molecular weight and enthalpy (function of P,T and cluster size distribution function). In CFD-ACE such approach can be realized. I have no hand-on-experience with FLUENT, but it is clear that situation is the same. If you have more questions - you can use my e-mail.

  Reply With Quote

Old   March 11, 2002, 05:55
Default Re: Modeling Condensation in water vapour-air mixt
  #9
Jing
Guest
 
Posts: n/a
Hi, Amol

Peter has described the nucleation and droplet growth process in detail. I just add something.

For the homogeneous condesation, the classical nucleation theory is good enough. You can get the droplet size and number distribution at the nucleation line with the nucleation equation. Please check the following paper:

Young, J. B., 1992. Two dimensional, nonequilibrium, wet-steam calculation for nozzles and turbine cascade. J. of Turbomachinery, Vol. 114, 569-579.

In the following flow passage, the droplet growth process could be simulated by the Gyarmathy's equation. Please check:

Gyarmathy, G. et.al.1973. Spontaneous condenstion of steam at high pressure : First experimental results. Instn Mech. Engrs. Wet Steam 4. Paper C66/73 Conference, Univ. of Warwick.

Hopefully they are helpful!

Jing
  Reply With Quote

Old   March 13, 2002, 05:14
Default Re: Modeling Condensation in water vapour-air mixt
  #10
Amol
Guest
 
Posts: n/a
Thanks Peter

I will definately get back to you on this.

  Reply With Quote

Old   March 13, 2002, 05:16
Default Re: Modeling Condensation in water vapour-air mixt
  #11
Amol
Guest
 
Posts: n/a
Jing

Thanks a lot for those references.
  Reply With Quote

Old   January 28, 2010, 10:09
Default
  #12
Senior Member
 
Join Date: Nov 2009
Posts: 125
Rep Power: 7
mactech001 is on a distinguished road
would anyone have any tutorial/procedure to help me kick start on modeling heat transfer using spray liquid please?
__________________
Thank you for your kind attention.

Kind regards,
mactech001
Currently using: ANSYS v13
mactech001 is offline   Reply With Quote

Old   August 12, 2010, 05:23
Default wet steam model
  #13
New Member
 
maryam
Join Date: Jul 2010
Location: Iran
Posts: 8
Rep Power: 7
salam is on a distinguished road
hello every one.
I have a high pressure real gas that contains water vapor.and in my model condensation of water and growth of the droplet size is occurred.can I use the wet steam model and if yes can i use the srk eos as the udf in my work?
thanks a lot
Rasoul likes this.
salam is offline   Reply With Quote

Old   April 25, 2011, 10:20
Default modeling dust particles in air flowing through a pipe FLUENT
  #14
New Member
 
zino
Join Date: Mar 2010
Posts: 23
Rep Power: 7
zino is on a distinguished road
hey!
Can any one tell me how can i model multiphase flow silicon/any metal particles flowing through a pipe in Fluents by using eluer-euler approach?
say volume fraction of metal is 0.2
zino is offline   Reply With Quote

Old   April 10, 2012, 00:28
Default
  #15
New Member
 
Join Date: May 2011
Posts: 22
Rep Power: 6
Spring.s is on a distinguished road
Quote:
Originally Posted by salam View Post
hello every one.
I have a high pressure real gas that contains water vapor.and in my model condensation of water and growth of the droplet size is occurred.can I use the wet steam model and if yes can i use the srk eos as the udf in my work?
thanks a lot
Hi
Can you use the wet steam model for high pressure steam flow?
I can't achieve to convergence in solution for high pressure flow. Can you help me?
Thanks
Spring.s is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
problem with two phase flow (air injected in water) miles_davis OpenFOAM 14 October 11, 2011 17:53
Turbulent Jets in Water and Air haze_1986 FLUENT 2 October 3, 2011 21:08
Multiphase model, water disperses in air bugra Main CFD Forum 1 January 30, 2010 11:57
Problem of air bubbles in water. Please help !!! xc FLUENT 4 February 6, 2008 06:05
Mixture model - water droplet + air - EVAPORATION bohis FLUENT 4 January 25, 2008 12:04


All times are GMT -4. The time now is 01:17.