Simultaneous measurement of the adiabatic flame velocity and overall activation energy using a flat flame burner and a flame asymptotic model

Abstract

This work presents a method for the simultaneous measurement of the adiabatic flame velocity and the overall apparent activation energy from measurements taken at a single unburned gas temperature. This is achieved using a McKenna flat flame burner and measuring the heat loss from the flame region for different mixture flow velocities. Then, the measurements of laminar flame velocity in the presence of heat loss are curve-fitted to a flame asymptotic model assuming one-step reaction, providing the estimated adiabatic flame velocity and the corresponding overall activation energy. Care is taken to establish clear cut conditions to reduce the effect of flame instabilities in the measurements. Then, an orthogonal regression method is used for the curve fitting and to precisely assess the uncertainties in the adiabatic flame velocity and overall activation energy. The method was tested with mixtures of methane and air, for equivalence ratio between 0.75 and 1.05, 298K, 1bar. The values of adiabatic flame velocity and apparent overall activation energy obtained at stoichiometric mixture were 37.8±0.4cm/s and 271±4kJ/mol, respectively, which are in good agreement with values from the literature, including estimates using GRIMech 3.0.