The effect of initial conditions on the laminar burning characteristics of natural gas diluted by CO₂

The initial conditions such as temperature, pressure and dilution rate can have an effect on the laminar burning velocity of natural gas. It is acknowledged that there is an equivalent effect on the laminar burning velocity between any two initial conditions. The effects of initial temperatures (323 K–423 K), initial pressures (0.1 MPa–0.3 MPa) and dilution rate (0–16%, CO₂ as diluent gas) on the laminar burning velocity and the flame instability were investigated at a series of equivalence ratios (0.7–1.2) in a constant volume chamber. A chemical kinetic simulation was also conducted to calculate the laminar burning velocity and essential radicals’ concentrations under the same initial conditions. The results show that the laminar burning velocity of natural gas increases with initial temperature but decreases with initial pressure and dilution rate. The maximum concentrations of H, O and OH increase with initial temperature but decrease with initial pressure and dilution rate. Laminar burning velocity is highly correlated with the sum of the maximum concentration of H and OH.