Reduced Kinetic Mechanisms for Propane Diffusion Flames

Abstract

Propane is an important practical fuel and its high temperature combustion is characterised by the rapid decomposition into smaller C₁–C₃ intermediates [15.1]. This behaviour is similar to the combustion of more complex hydrocarbon fuels. From a modelling perspective, a propane combustion mechanism, compared to that of other higher hydrocarbons, requires the smallest number of species and reactions that are necessary for a thorough kinetic study of the C₁–C₃ species. Previous modelling studies of propane combustion with detailed [15.1,15.2] and simplified [15.3] chemistry have mainly focused on premixed flames with little attention given to non-premixed conditions [15.4]–[15.5]. There is also a lack of simplified mechanisms based on the systematic reduction of complex chemical mechanisms for non-premixed propane flames. The purpose of the present study is to formulate reduced reaction mechanisms based on the systematic theoretical investigation of propane-air diffusion flames using a planar counterflow geometry and the detailed chemistry defined in Chap. 1. Propane flames are here computed using rates of strain from 10/s to extinction at pressures ranging from 1 to 10 bar. The deduced mechanisms are also validated against the experimental results obtained by Tsuji and Yamaoka [15.6] for counterflow propane-air flames at strain rates of 150/s and 350/s. Using the results of the above computations the behaviour of non-premixed propane flames is analysed and the most important reaction paths indentified as functions of rate of strain and pressure.