Real Gas Effects in High-Pressure Ignition of n-Dodecane/Air Mixtures

This work studies the real gas effects on the autoignition of hydrocarbon fuels under high pressures, using normal dodecane (n-dodecane) as the representative fuel and the Redlich-Kwong equation of state (EoS) as the real gas description. It is demonstrated that the real gas description yields a shorter ignition delay time (IDT) compared with the ideal gas description, especially in low-temperature regimes which could encompass the negative temperature coefficient (NTC) phenomena and has a stronger dependence on the molecular volume than the attractive potential. The study further shows that high pressure facilitates low-temperature reaction pathways, where the compressibility factors of key reactants contribute to real gas effects. Moreover, the results suggest that accounting for real gas behavior leads to an increase in the formation of polycyclic aromatic hydrocarbons (PAHs), which, in turn, promotes soot generation.