Experimental investigation of laminar flame speeds of propane in O2/CO2 atmosphere and kinetic simulation

In this paper, the laminar flame speeds of C3H8 in O-2/CO2 atmosphere were investigated experimentally and numerically. The laminar flame speeds of C3H8/O-2/CO2 were measured using a Bunsen flame under the condition of different equivalent ratios and O-2 concentrations at ordinary pressure and temperature. It was found that the laminar flame speed gradually increased with the increase of O-2 concentration. The equivalent ratio of the highest laminar flame speed is between 1.0 and 1.1 under each fixed oxygen concentration. The high concentration CO2 reduces the laminar flame propagation velocity of C3H8, which is due to thermal, radiative and chemical properties of CO2. The calculations were performed to investigate the effects of CO2 on the laminar flame speed. Results show that the thermal effect of CO2 is the determining factor, the chemical effect is the second factor and radiative effect is the last one. Reaction H + O-2 = O + OH is the most important chain reaction for the oxidation of C3H8. In addition to this, the third body effect in reaction H + O-2+ M = HO2 + M changed the laminar flame speed significantly in the condition of very low equivalent ratio and O-2 concentration.