Experimental and kinetic study of hydrocarbon fuel pyrolysis in a shock tube

Abstract A pyrolysis study of hydrocarbon fuels (n-heptane and iso-octane) in a shock tube was conducted at temperatures range of 1200–2100 K and pressures range of 0.22–0.28 MPa. Several pyrolytic products were detected and quantified using gas chromatography. Different kinetic models were selected to simulate the fuel pyrolytic processes under the same experimental conditions. The results show that CH4, C2H2, C2H4, and C3H6 are the main products in the pyrolysis of n-heptane and iso-octane. The sensitivity and rate of production analysis indicate that olefins are the most important products in the pyrolysis, with the main decomposition pathways of n-heptane and iso-octane being hydrogen abstraction and C-C bonds scissions, respectively. In the pyrolysis of n-heptane, the main decomposition pathway is the hydrogen abstraction reaction by H/CH3 radicals, with ethylene as the main olefin product. In the pyrolysis of iso-octane, the main decomposition pathways are the direct cleavage reactions of the C-C bonds and isobutylene is the main olefin product. The difference in the pyrolysis characteristics between n-heptane and iso-octane is mainly caused by their different molecular structures.