Evaluation and application of real gas effect models in ignition delay of hydrogen/n-decane blends

Accurate prediction of ignition behavior is essential for designing advanced combustion systems. Previous studies have demonstrated that real-gas effects significantly influence the evaporation and mixing of alkanes. However, the applicability of existing real-gas models to hydrogen-containing fuels has not yet been evaluated. Moreover, how the thermophysical transients induced by real-gas effects affect ignition delay time (IDT) is still unclear. In this work, four representative equations of state (EoS) were evaluated and applied to model the thermophysical properties of hydrogen/ n -decane blends under engine-relevant conditions. The resulting real-gas corrections were incorporated into detailed chemical kinetic simulations to quantify their influence on IDT. The PC-SAFT model exhibits the highest accuracy for density and isobaric heat capacity, with larger variations in thermophysical properties enhancing molecular interactions that promote QOOH isomerization and chain-branching reactions. Higher densities at low-temperature increase intermolecular interactions and accelerate chain-initiation reactions. Enhanced specific heat and residual enthalpy/entropy modify the thermal response and effective activation energy, promoting earlier formation of key intermediates. Consequently, the chain-branching sequence proceeds faster in the low-temperature and negative temperature coefficient regimes, leading to a pronounced shortening of IDT. This work emphasizes the necessity of employing real-gas models that incorporate intermolecular interactions in the investigation of ignition kinetics.