Summary of Current Diesel Combustion Issues

Engines designed for lower NOX have lower in cylinder combustion temperatures which leads to:

  • Carbon Build Up

    This is caused by incomplete in-cylinder combustion. The more complex the Hydrocarbon Chain in the fuel (Diesel is complex) the more difficult the combustion process is to completely combust the Hydro Carbon to CO2.
  • Time for Combustion:

    Low Timing Advance (S.O.I. near T.D.C.) leaving less time for the combustion process. Diesel is a comparatively slow burning fuel, so the reduction in injection timing as resulted in lower net efficiency from the combustion process.

Advantages of Hydrogen Inclusion

The addition of free H2 atoms into the combustion process combines to help remove carbon build-up in 2 ways:

  • Additional Hydrogen helps the combustion process in terms of providing more Hydrogen > Carbon thus allowing for a better, more complete combustion, thus eliminating residual carbon. This is evident in University studies regarding Particulate Matter dropping significantly with the inclusion of H2.
  • The free H2 molecules can actually bond with the residual carbon within the engine frame turning the Carbon into a low-energy hydrocarbon and thus allowing it to simply ‘burn off’ back into H2O + CO2.

Flame front speed for Hydrogen and Oxygen is nearly 10 times faster than normal Diesel Combustion. This means that we can minimize or reverse the negative impact of the reduced Start of Injection timing on MEP (Mean Effective Pressure) of the combustion process.

You can see from the heat release rate shown that the time to burn the fuel is significantly decreased and the phenomenon can be utilised to reverse the negative effects of NOX tuning methods.