Learning Forum

[Usman]

Dear Sir,

I hope this message finds you well. 

Can you please let me know how the IVC mixture in tutorial 2 (Dual fuel combustion modelling using a 60% sector mesh) of Forte was calculated? I followed the reference paper (Referenced at the end of tutorial 2) and used the given values in the IVC calculator:



mass of gasoline = 104.96mg

mass of diesel = 23.04mg

Phi = 0.77

EGR = 0.455

However, I did not get the same values which are provided in the dual fuel tutorial. Can you please let me know how we can use the IVC calculator to find the mass fractions of species in a homogenous mixture of gases at IVC when gaseous fuel is premixed with the air and liquid fuel is injected directly into the cylinder?



Many thanks!

[SVV]

Hi Usman,

The initial gas composition used in this tutorial is not based on the IVC calculator with the data from the reference attached along with the tutorial. For explanation of discrepancy (oxygen mass fraction of 0.147 vs. 0.137), the reference uses 5 component gasoline and it was subsequently simplified to a 1-component gasoline for this tutorial to run faster. I hope this explains the discrepancy. 

[Usman]

Thank you for letting me know. Could you please let me know what is 1-component and 5-component gasoline?

 

For dual fuel, hydrogen is premixed with the air at IVC. We normally make a mixture using IVC Calculator. There are many options to calculate each specie mass fraction like at IVC before injections, exhaust, premixed after injection and dual fuel injections. Do I need to go with premixed after injection? I am confused with the values. Is it like we need to put the mass fraction of gaseous fuel as 90mg (which will be the 90% if the total mass of both fuels is 100mg)? After it, we write the values of phi and EGR and will get the values in the bottom right section. Also, do I need to put the value of diesel mass in IVC calculator in dual fuel case?

 

There is another option I.e., dual fuel between injections. Which one is right to select?

[SVV]

Hi Usma,

You can check the composition of gasoline in the reference and in the tutorial to compare. For example, table 1 in reference gives the composition of gasoline used in the journal. When we have dual-fuel cases, in terms of the IVC Calculator one fuel can be specified as main fuel, and the other as Secondary fuel. In this case, gasoline (ic8h18) can be specified under Fuel, and diesel (nc7h16) can be specified as Secondary Fuel. ‘Dual fuel between injections’ is what we want for IVC specification, since the gasoline should be accounted in IVC but diesel injection is specified under Spray model.  

 

[Usman]

Thank you for letting me know. I appreciate it. 

For instance, if I am using hydrogen as a main fuel and diesel as a secondary fuel, how can I provide the equivalence ratio of hydrogen with air (phi)? I am aware there is an option for Phi in the IVC calculator. However, is it for the main fuel?

Many thanks!