Assessment of Chemical Markers for Heat-Release Rate Correlations in Laminar Premixed Flames

There is considerable interest in formulating practical correlations for the quantification of heat-release rate in flames via appropriate chemical markers, mainly due to difficulties in obtaining a direct estimation of the former. Experimental and numerical studies performed in methane-air flames have identified corrections between suitable kinetic information and heat-release rate. The present work investigates the validity of corrections developed for methane to the combustion of other fuel classes (e.g., alcohols, unsaturated hydrocarbons, and aromatics), and proposes a methodological approach for the development of generic correlations. Numerical assessment of such correlations and their underlying methodology is performed on the basis of experimental data from 24 laminar premixed flames, utilizing a single, in-house, recently published C1–C6 detailed chemical kinetic model. It is shown that the proposed correlations are valid for methane-based fuels but they are largely inadequate for unsaturated fuels under rich conditions and for oxygenated fuels under most conditions. It is shown that heat-release rate is correlated with the dominant carbon path and that the oxidation chemistry of the parent alkyl radical is of pronounced importance. Alternatives to the proposed heat-release rate correlations are also proposed and assessed.