[DeoVader]

Hello,
I have a small doubt regarding fuel properties, but since I am using Converge, I thought it was a good place to ask.
When defining your fuel with mechanism files, is it essential to enter LHV of the fuel sample?
Also, what is the difference in a combustion simulation when the fuel's LHV is mentioned and is not mentioned in the other one, keeping the rest of the simulation parameters exactly the same?

[alenp07]

Originally Posted by DeoVader

Hello,
I have a small doubt regarding fuel properties, but since I am using Converge, I thought it was a good place to ask.
When defining your fuel with mechanism files, is it essential to enter LHV of the fuel sample?
Also, what is the difference in a combustion simulation when the fuel's LHV is mentioned and is not mentioned in the other one, keeping the rest of the simulation parameters exactly the same?

It is not essential to provide the LHV of the fuel sample as it is calculated using therm.dat in Converge. I suppose you are asking about LHV option under gas simulation. I am not sure if manually entering the LHV will override the values predicted by therm.dat.

It is always better to keep the LHV value close to what you have with your reference fuel so that your heat release is in check.

A good old post by MFGT has all details on the same topic here. There are methods to correct the LHV value as well which is mentioned in the link. You can explore the same as well if you want. But again I am not sure if you need to do the same in the newer versions of Converge.

[DeoVader]

Thanks for the reply.

I also have a question regarding the plotting feature.
Actually, I have been trying LTC for Syngas + diesel in RCCI. I get pressure curves accurately. But the temperature seems too high, to define as LTC.
1. I have reduced the intake temperature of the syngas-air mix, as less as i could.
2. And also tried reducing the equivalence ratio of the fuel mix.

the pressure curves seem reasonable, but the temperature plots Do Not change AT ALL.
We also tried reducing the 'quantity' of the fuel mix, while mainataining the same equivalence ratio, but still I do not see any changes in the temperature plots.
This was the reason behind adding maybe LHV values (although we knew it won't matter much, cuz it comes form therm.dat file inserted). But can you give us any insights for the same?

[alenp07]

Originally Posted by DeoVader

Thanks for the reply.

I also have a question regarding the plotting feature.
Actually, I have been trying LTC for Syngas + diesel in RCCI. I get pressure curves accurately. But the temperature seems too high, to define as LTC.
1. I have reduced the intake temperature of the syngas-air mix, as less as i could.
2. And also tried reducing the equivalence ratio of the fuel mix.

the pressure curves seem reasonable, but the temperature plots Do Not change AT ALL.
We also tried reducing the 'quantity' of the fuel mix, while mainataining the same equivalence ratio, but still I do not see any changes in the temperature plots.
This was the reason behind adding maybe LHV values (although we knew it won't matter much, cuz it comes form therm.dat file inserted). But can you give us any insights for the same?

I am not the right person to comment on the same since I have absolutely no idea about your case setup or the considerations made. If you have test data please try validating the same with simulation. Also, the term " pressure curves seem reasonable" is very vague and unclear. There are many reasons for the issues you are facing and with the above information it is not possible to arrive at some suggestions.

[angela.wu]

Hello,

Have you tried different heat transfer models in your setup to see if that affects your temperature predictions at all? Did you verify that your compression ratio is accurate and you're obtaining the right amount of trapped mass? How close are you getting in terms of pressure predictions?

Thank you,

Angela