Experimental and chemical kinetic behaviors at the explosion reaction of typical C6 hydrocarbons

Abstract

This research is aimed at exploring the influence of the vapor molecular structure of hydrocarbons on vapor explosion. To achieve this aim, the overpressure and flame propagation images of typical C6 hydrocarbons (benzene, cyclohexane and n-hexane) at equivalence ratios (φ = 0.6, 0.8, 1, 1.2 and 1.4) were studied in a closed visual explosion experimental pipeline (initial temperature 22–25 °C and initial pressure 1 atm), and the chemical kinetic behaviors were analyzed through the JetSurF2.0 mechanism. The results reveal that different molecular structures of fuels lead to great differences in the activities of their reaction intermediates. Many stable resonance groups such as C5H5 and C3H3 are generated in the reaction system of benzene vapor as a result of the special benzene ring structure. Cyclohexane decomposes into more highly active intermediates, i.e., 1,3-butadiene (SAXC4H7), and fewer chain terminators, i.e., propylene, due to its ring structure. N-hexane decomposes into more small-molecule substances as a result of its linear structure. The difference in the activity of the intermediates greatly affects the production of the key free radical OH, and further influences the intensity of the branched chain reaction. Hence, the explosion intensities of the three kinds of hydrocarbon vapors follow the order: cyclohexane > n-hexane ≈ benzene. In addition, as their C/H ratios differ, the equivalence ratio variation exerts varying influences on the reaction H+O2=O+OH. This study is of theoretical significance for the prevention and control of hydrocarbon vapor explosion.