If one go literally to what you wrote, one can think that you mean fuel blending. But, as one know, the rate at which such mixtures are formed does not affect their properties. So you probably mean something else, e.g. the mechanism of the combustion process of fuel mixtures in the engine. You should be clear about this. As for the composition, it is best to use mass fractions here.

Dear professor Mirosław Grzesik

I appreciate your clarifications,

First of all, my mixture is comprised of diesel, biodiesel, and gasoline, and the matter I am dealing with is that I have developed a reduced mechanism entailing diesel-biodiesel-gasoline surrogates, but Chemkin software (as utilized for combining each individual fuel surrogate) does not offer an option to specify the fraction of each fuel in the finalized combined kinetic mechanism.

One of my colleagues has told me I must combine the mechanisms manually, that way I get to choose the proportion of each fuel in the merged mechanism, but I am afraid I am not familiar with manual combining approaches.

So, the concern is how can I define a particular fraction for each surrogate existing in my mixture when combining the mechanisms.

Also, I believe you mentioned the mass fraction throughout the 0-D simulations, but I want to give fractions in the combining process, not in the simulation stage.

This matter has been raised by one of my supervisors, but I am afraid it is impossible to do so because the kinetic mechanisms combinig section of Chemkin has nothing to do with defining fractions.

Please kindly give me an update whenever you have the time,

Thanks

Hello,

I am not familiar with the Chemkin software and don't know what kind of kinetics it supports; therefore my answer is a bit abstract. In any way the main assumption is that every component of your mixture reacts independently.

In this case the kinetic parameters of the combined model (activation energies, preexponents, reaction orders, etc.) remain the same as in the individual models.

If your kinetics is based on concentrations then the only thing required is to define the initial composition of the mixture (in mass fractions as suggested by Prof. Grzesik, or in mole fractions). Then your combined kinetics will work for any mixture because concentration-based models are informed about mixture composition.

If your model is of a formal kind (such models are typical for studies that involve thermal analysis methods)

then you will have to adjust the values of reactions' effects - heat effects, specific gas generation and so forth. If, for example, mixture contains 2 components with mass fractions 0.2 and 0.8 respectively, heat effect for the component 1 is Q1= 100 J/g and for component 2 is Q2=300 J/g, then the effective heat effects of the combined model will be Q1,eff=0.2Q1; Q2,eff=0.8Q2.

dear Dr. Arcady Kossoy

I appreciate your concern and thorough insight into this matter,

However, we are on the same page I believe.

With one difference, your explanation mainly concerns defining either mole fractions or mass fractions for each of my individual fuels. But, I am thinking about a way to do this. To be more precise:

As shown in the picture attached, the chemkin software does allow you to merge the kinetic mechanisms of each fuel, but it does not come with an option to specify the effective fraction of each fuel. Please do note, I am not simulating via Chemkin, I am done with simulations, now I just want to combine the tested kinetic mechanisms for my mixture using the combining module of Chemkin.

As stated earlier, I have been told to merge the mechanisms manually, so I can get to define a fraction for each fuel, but I am afraid I am not familiar with how to do this.

I hope you have an idea of how to resolve this matter.

appreciate your time