EGR composition
 

Hi..
what does it mean when we give EGR composition 1?

Hi,
composition 1 means that the O2 is fully burnt (equi. ratio=1) and only CO2, H2O and N2 inside the domain is initialised.

With composition 1.1 you would have unburnt fuel because the "combustion before" is rich (equi=1.1). Composition 0.8 would mean that you would have also unburned O2 (equi=0.8, lean combustion) inside the domain.

br

thanks for your response
but EGR composition cannot be more than 1

It can be more than 1 because it is not the mass fraction! This is defined with "EGR mass fraction".
Composition is related to the species which are initalised (or at the boundary condition), as already mentioned the initalised EGR can have unburnt O2 or unburnet fuel or all is burnt (composition=1, equi ratio of the mixture which the EGR is based on is 1).

Dear kschi,
You are correct about kschi. But I remember seeing somewhere in the FIRE manual, that we cannot model rich EGR ( that is EGR with unburned fuel). FIRE always assumes that EGR doesn't contain fuel. IF we have to model Rich EGR we should use general transport model. Have you tried to simulate rich EGR with standard transport model.