CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > FLUENT

gas/liquid reburning combustion

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   January 8, 2001, 22:03
Default gas/liquid reburning combustion
  #1
Jong Que Kim
Guest
 
Posts: n/a
Hi.

Currently I solving gas/oil reburning problem using finite rate/eddy dissipation model in Fluent 5.4. (oil is main fuel and methane is reburning fuel.)

In that case, what kind of methane reaction mechanism is modeled include CH, CH2, CH3 radicals?

Waiting for your help.

Kind regards.

  Reply With Quote

Old   January 9, 2001, 00:14
Default Re: gas/liquid reburning combustion
  #2
Jin-Wook LEE
Guest
 
Posts: n/a
Dear Jong-Que Kim

If you include many species and/or radicals, maximum flame temperature might be slightly(or fairly) lower compared to the case of neglecting them. Consequently, some result, for example NOx prediction, might be more accurate. However, the computational cost(CPU and convergency) would be more expensive if you use finite rate / eddy dissipation model. And one more difficult aspect is, how to judge which reaction, among couple of tens(or hundreds) reactions, can be neglected without affecting much accuracy to the result.

So, if you really want to include more species and/or radicals, rather than only considering major species(CH4, O2, N2, CO2, H2O, CO and evaporating species), I recommend PDF combustion model. This model can treat many species without much increase of computational effort. Its non-benificial effects are, as you might know, to over-predict CO, and it should be applied to the high temperature combustion system because of its limitation of fast chemistry.

My 'personal' opinion is, the reaction of minor species(whose residence time is very short) can be neglected if your main purpose is not related to the NOx prediction and if your purpose is engineering design(not advanced research). Many engineers, including CFD specialists, are doing so.

Sincerely, Jinwook
  Reply With Quote

Old   January 9, 2001, 00:39
Default Re: gas/liquid reburning combustion
  #3
Jong Que Kim
Guest
 
Posts: n/a
Dear Jin-Wook LEE

Thanks for your response.

The main purpose of this calculation is NOx, so I have to include the CH radicals to postprocess of NOx module.

And in my experinece, the calculation of 3D problem with two mixture fraction pdf model(liquid/gas) takes more time than using the finite rate/dissipation model of 10 steps of reactions.

Therefore I think that it's better to use finite rate/dissipation model include simplified methane reactions in high temperature and fuel rich conditions.

Sincerely, Jong Que Kim
  Reply With Quote

Old   January 9, 2001, 21:53
Default Re: gas/liquid reburning combustion
  #4
Jin-Wook LEE
Guest
 
Posts: n/a
Dear Jong-Que Kim

O.K., Now, I understand your meaning and your purpose. I agree that you should include CH, CH2, and CH3 to model the NOx reburning.

However, I do not agree that finite rate / eddy dissipation model with many species(eg, 10 species : CH4, evap. species, O2, N2, CO2, H2O, CO, CH, CH2, CH3) takes less time than two mixture fraction pdf model. As you know, two mixture fraction pdf model requires 4 transport equations, whereas 10 species finite rate / eddy dissipation model requires 9 transport equations. Of course, two mixture fraction pdf model requires some auxiliary calculation such as interpolation of look-up table and some numerical integration. But I do not think that these auxiliary equations take more time than five transport equations. One possible way is, I think, the difference of total iteration number for convergence.

O.K., let me consider the above mentioned opinion as my personal one. And I think that it's very important to select which combustion model you are going to use, by yourself, based on your experience. I fully appreciate your experience.

Hoping good luck with you for your future research.

Sincerely, Jinwook
  Reply With Quote

Old   February 3, 2001, 15:48
Default Re: gas/liquid reburning combustion
  #5
aouissi mokhtar
Guest
 
Posts: n/a
Iam looking for basic software simulate nitrogeneous emissions in internal combustion engine -diesel engines so that to reduce NOx emissions by reburning exhauts gases.

  Reply With Quote

Old   February 3, 2001, 15:57
Default Re: gas/liquid reburning combustion
  #6
aouissi mokhtar
Guest
 
Posts: n/a
Hi.

Currently I try to solve gas/oil reburning problem (in internal combustion diesel engine) using psr software ,( methane is reburning fuel.) Waiting for your help.

or yor probleme I think that you must use chemkin software package

Kind regards.

  Reply With Quote

Old   February 28, 2001, 04:34
Default Re: gas/liquid reburning combustion
  #7
Jong Que Kim
Guest
 
Posts: n/a
Hi.

I'm sorry for very late replay.

Until now, I trying to solve the reburning problem.

You said, I have to chemkin software. How to use the chemkin software with FLUENT or chemkin only for boiler problem.

And what is the psr?

Waiting for your response.

Best regards.

  Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Modelling Combustion in Porous Zone tanjinjack FLUENT 2 September 26, 2016 05:10
hydrocarbon gases + Boron particle combustion nileshjrane OpenFOAM 1 December 13, 2010 07:20
Hydrogen Air combustion in a combustion chamber popi CFX 7 July 11, 2007 19:40
A role of combustion modeling in flow solver? Yoon Main CFD Forum 0 November 26, 2006 13:00
Need Similar Combustion Tutorial as my model Arnab Siemens 0 May 24, 2005 19:23


All times are GMT -4. The time now is 04:53.