Experimental and modeling study on effects of N2 and CO2 on ignition characteristics of methane/air mixture.
The ignition delay times of methane/air mixture diluted by N2 and CO2 were experimentally measured in a chemical shock tube. The experiments were performed over the temperature range of 1300-2100 K, pressure range of 0.1-1.0 MPa, equivalence ratio range of 0.5-2.0 and for the dilution coefficients of 0%, 20% and 50%. The results suggest that a linear relationship exists between the reciprocal of temperature and the logarithm of the ignition delay times. Meanwhile, with ignition temperature and pressure increasing, the measured ignition delay times of methane/air mixture are decreasing. Furthermore, an increase in the dilution coefficient of N2 or CO2 results in increasing ignition delays and the inhibition effect of CO2 on methane/air mixture ignition is stronger than that of N2. Simulated ignition delays of methane/air mixture using three kinetic models were compared to the experimental data. Results show that GRI_3.0 mechanism gives the best prediction on ignition delays of methane/air mixture and it was selected to identify the effects of N2 and CO2 on ignition delays and the key elementary reactions in the ignition chemistry of methane/air mixture. Comparisons of the calculated ignition delays with the experimental data of methane/air mixture diluted by N2 and CO2 show excellent agreement, and sensitivity coefficients of chain branching reactions which promote mixture ignition decrease with increasing dilution coefficient of N2 or CO2.
School of Aerospace Engineering, Shenyang Aerospace University, Liaoning, Shenyang 110136, PR China.
Wen
W
Zeng
School of Aerospace Engineering, Shenyang Aerospace University, Liaoning, Shenyang 110136, PR China.
Hongan
H
Ma
State Key Laboratory of Coal Mine Safety Technology, Shenyang Branch of China Coal Research Institute, Liaoning, Shenyang 110016, PR China.
Yuntao
Y
Liang
State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Shanxi, Xi'an 710049, PR China.
Erjiang
E
Hu
Chemical shock tube; Gas explosion; Ignition delay; Sensitivity analysis; Simulation