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-   -   How can I calculate equivalence ratio? (http://www.cfd-online.com/Forums/cd-adapco/56596-how-can-i-calculate-equivalence-ratio.html)

 Duan J Q April 27, 2008 21:10

How can I calculate equivalence ratio?

When simulate diesel engine, equivalence ratio is an important parameter. But how can I calculate it?

Can anybody tell me?

Thanks for any help you can give me.

 Mac April 29, 2008 04:09

Re: How can I calculate equivalence ratio?

Equivalance ratio is the ratio of Air-fuel mixture (stoic) to the Air-fuel mixture (actual). Hope this helps - Mac.

 Andrea April 29, 2008 17:50

Re: How can I calculate equivalence ratio?

As Mac said the equiv. ratio is air-to-fuel stoich / air-to-fuel actual...depending on the combustion model that you use you have different way to get the correct mass concentration to calculate the air-to-fuel ratio.

 Duan J Q May 6, 2008 02:51

Re: How can I calculate equivalence ratio?

The model what I use are:

1 Turbulent flow model: standard К-&epsilon;

2 Droplet Break-Up Model: Reitz/Diwakar

3 Spray impingement model: Bai's

4 Ignition model: shell

I want to know only steam or liquid and steam reckon in fuel?

And when I calculate air, air is equal to subtract fuel from cell mass or O2+N2+CO2+H2O or O2/0.233 or some way else?

 Andrea May 15, 2008 18:23

Re: How can I calculate equivalence ratio?

Use only the mass of fuel vapor and the mass of air...calculated by means of m_02/0.233

 sankar May 21, 2008 02:44

Re: How can I calculate equivalence ratio?

Hi i too need to calclulate Equivalence ratio..The pecentage of exhaust gases and composition are given..The Stoichiometric A/F ratio is known but i dunno actual A/F ratio..Can i find out the equivalence ratio from chemical equations..could anyone help me

 sankar May 21, 2008 02:44

Re: How can I calculate equivalence ratio?

Hi.. i too need to calclulate Equivalence ratio..The pecentage of exhaust gases and composition are given..The Stoichiometric A/F ratio is known but i dunno actual A/F ratio..Can i find out the equivalence ratio from chemical equations..could anyone help me

 Andrea June 7, 2008 12:40

Re: How can I calculate equivalence ratio?

You must calculate the actual A/F ratio from the output of your simulation...?!
Use command getc to load the mass of fuel vapour in each cell and to load the mass of oxygen in the same cells. Then you can calculate the locale A/F ratio and the local equiv. ratio.
Bye

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