Rich methane premixed laminar flames doped by light unsaturated hydrocarbons - Part I : allene and propyne

TL;DR

This study investigates the structure and species profiles of three rich laminar premixed flames, including pure methane and methane doped with allene and propyne, providing detailed experimental data and improved reaction mechanisms.

Contribution

It provides new experimental measurements and an enhanced reaction mechanism for flames doped with allene and propyne, focusing on C3-C4 unsaturated hydrocarbons.

Findings

Species concentration profiles measured for key hydrocarbons and intermediates

Temperature profiles ranged from 700 K to 1850 K

Improved reaction pathways for allene and propyne consumption

Abstract

The structure of three laminar premixed rich flames has been investigated: a pure methane flame and two methane flames doped by allene and propyne, respectively. The gases of the three flames contain 20.9% (molar) of methane and 33.4% of oxygen, corresponding to an equivalence ratio of 1.25 for the pure methane flame. In both doped flames, 2.49% of C3H4 was added, corresponding to a ratio C3H4/CH4 of 12% and an equivalence ratio of 1.55. The three flames have been stabilized on a burner at a pressure of 6.7 kPa using argon as dilutant, with a gas velocity at the burner of 36 cm/s at 333 K. The concentration profiles of stable species were measured by gas chromatography after sampling with a quartz microprobe. Quantified species included carbon monoxide and dioxide, methane, oxygen, hydrogen, ethane, ethylene, acetylene, propyne, allene, propene, propane, 1,2-butadiene, 1,3-butadiene, 1-butene, isobutene, 1-butyne, vinylacetylene, and benzene. The temperature was measured using a PtRh (6%)-PtRh (30%) thermocouple settled inside the enclosure and ranged from 700 K close to the burner up to 1850 K. In order to model these new results, some improvements have been made to a mechanism previously developed in our laboratory for the reactions of C3-C4 unsaturated hydrocarbons. The main reaction pathways of consumption of allene and propyne and of formation of C6 aromatic species have been derived from flow rate analyses.