Real gas effect on ignition in ideal and non-ideal reactors

We studied the real gas effect on the ignition characteristics in chemical reactors with one-step irreversible reaction. The real gas effects were characterized by the inter-molecular attraction term ( α ) and the finite molecular volume term ( β ). The Noble-Abel and van der Waals equations of state were employed to derive non-dimensional reactor models. In addition to ideal reactors, i.e., constant volume and constant pressure, non-ideal reactors that account for the non-ideal pressure variation in shock tube and rapid compression machine were also considered. For all reactors, low value of α /β and high value of β (approximately α /β <1.0 and β >0.1 ) induce a decrease of the ignition delay-time, while high value of both α /β and β (approximately α /β >2.0 and β >0.1 ) induces an increase of the ignition delay-time. The variations of the ignition delay-time induced by real gas effects are mainly related to the change of the fugacity coefficient with α and β . Additional contributions are due to the real gas heat capacity at constant pressure when considering a constant pressure reactor and to non-ideal volume variation when considering non-ideal reactors. The impact of various parameters was also investigated, including the heat capacity ratio of perfect gas, the reduced activation energy of the one-step reaction, and the heat content of the mixtures. Comparison with simulation performed with detailed reaction mechanisms and considering real gas models demonstrates that the present approach constitutes a rapid and simple, yet qualitatively or even quantitatively accurate method to assess the need of accounting for real gas effects to model chemical kinetics under high-pressure conditions.