Effects of equivalence ratio and blending ratio on the ignition delays of n-pentane/hydrogen mixtures under engine relevant pressure

Abstract

In this work, new ignition delay times of n-pentane/hydrogen binary mixtures were measured at a pressure of 20 atm, equivalence ratios of 0.5, 1.0, and 2.0 using a shock tube. Literature Pentane Isomer model is found to well capture the ignition delay times of n-pentane/hydrogen mixtures under the current condition. Kinetic analyses are performed to interpret the equivalence ratio dependence for n-pentane/hydrogen blends and to understand the interplay chemistry between the two fuels. It is found that the ignition delay times of all the n-pentane/hydrogen mixtures in this study show the equivalence ratio dependence similar to pure n-pentane. The reaction pathway indicates that n-pentane reacts independently from the hydrogen after blending. Hydrogen addition only gives the moderate promotion on n-pentane ignition for small hydrogen proportions since the H radicals in the dual-fuel system were mostly supplied to the n-pentane H-abstractions and the oxidation chemistry hydrogen is inhibited after blending.