An Analytical Study of the Shock Tube Ignition of Mixtures of Methane and Ethane

Abstract

An analytical study of the ignition of mixtures of methane and ethane has been carried out, using a numerical model consisting of 25 chemical species and 75 elementary chemical reactions. Computed ignition delay times and effective activation energies are compared with published experimental shock tube results. Initial conditions studied include temperatures from 1300-1900 K. and mixtures ranging from pure methane to pure ethane, with stoichiometric amounts of oxygen, diluted in argon. The analytical model reproduces experimental results for the effective activation energy and ignition delay time for both pure methane and pure ethane. Ignition delay times computed for mixtures of methane and ethane are found to lie between the pure methane and the pure ethane results. Addition of relatively small quantities of ethane to methane rapidly reduces the ignition delay time of the methane-ethane mixtures to values close to those of pure ethane. The chemical kinetic factors involved in the ignition of fuel mixtures are discussed in detail. The implications of these results for safety studies of liquified natural gas are also examined.