Learning Forum

[vorgiazic]

I am trying to simulate a dual fuel DI/DI engine (methanol + diesel direct injection) using the Chemkin DI Diesel Engine simulator. I would like to know if it is possible to define two separate injectors with different fuel species (one for diesel, one for methanol). Is it possible? If yes, is it supported natively in the model, or does it require any workaround?

[Richie Mathew]

 

Hello,

You can simulate a dual fuel DI/DI engine in DI Diesel Engine simulator. To do so, you will have to add another injector (Inlet_source) to the existing model. You can set your injector charateristics for this new injector. For the addition of methanol, your chemical mechanism file needs to have mechanisms for both diesel and methanol combustion (under one file). Also, your thermodynamic file should have all the needed liquid properties. You can refer to the existing Diesel thermo file for properties and format needed by Chemkin to recognise it as a liquid. 

 

 

[vorgiazic]

Thank you for the confirmation. I have indeed set up the model with two injectors using different fuel species and the mechanism file covers both fuels. The thermo file also has the liquid properties for both fuels in the correct format, taken from the official fuel_library.inp.

However I am running into two issues. The first is that even when following the official DI Engine tutorial precisely, the simulation completes without errors but the cylinder pressure trace shows motoring behavior with no heat release visible, suggesting that no combustion is taking place. The second is that in my dual fuel setup the simulation terminates early with repeated DIE Error 31 messages followed by the DASPK error "THE NONLINEAR SYSTEM SOLVER CANNOT CONVERGE BECAUSE THERE ARE ILLEGAL INPUT VALUES", and again the pressure trace from the results CSV shows no combustion for either fuel.

Could you advise on what might be causing the motoring behavior even in the tutorial case, and what DIE Error 31 and the ILLEGAL INPUT VALUES condition typically indicate in this context? Any help would be greatly appreciated.