The importance of endothermic pyrolysis reactions in the understanding of diesel spray combustion

The addition of 1% of the cetane booster, 2-ethylhexylnitrate (2-EHN), to the fuel was found to shorten the measured ignition delay time, as expected. However the presence of 2-EHN can also increase the magnitude of the initial pressure decrease compared to conventional diesel fuel. Detailed chemical kinetic modeling shows that the effects observed in the constant volume vessel can plausibly be attributed to pyrolysis reactions, and that the addition of 2-EHN to the base fuel enhances their influence. The modelling results also imply that the influence of these pyrolysis reactions increases with increasing temperature, pressure, the alkyl chain length of the base fuel, and the amount of any radical initiator in the fuel.