O_2/CO_2气氛下火焰传播速度影响因素分析

Analysis of Influence Factors on Flame Speed Under O_2/CO_2 Atmosphere

O2/CO2气氛下高浓度CO2的存在对碳氢化合物的火焰传播特性有重要影响。基于化学动力学分析软件CHEMKIN对初始压力为105 Pa,初始温度为298 K,当量比为0.6～1.4的C1～C7直链烷烃在O2/CO2、O2/N2、O2/CO2/AR气氛下的层流火焰传播速度进行模拟计算,探讨气氛、当量比、O2浓度、CO2浓度对火焰传播速度的影响规律。结果表明,火焰传播速度随当量比的增大而先增大后减小,火焰传播速度的最大值出现在当量比1.0或1.1处;在相同O2浓度下,O2/CO2气氛下火焰传播速度要比O2/N2气氛下明显减小,表明CO2的存在对火焰传播有阻碍作用;在O2/CO2/AR气氛下,在O2浓度不变情况下,火焰传播速度随CO2浓度的增大而减小;在O2/CO2气氛下,随O2浓度的提高,火焰传播速度逐渐增大,说明提高O2浓度可改善烷烃的燃烧特性。

The flame propagation characteristic of hydrocarbons has a significant relationship with high CO2 concentrarion in an Oe/CO2 atmosphere. Laminar flame speed of C1-C7 n-alkanes were studied by detailed chemical kinetic models for O2/CO2 atmosphere, O2/N2 atmosphere and O2/ CO2/AR atmosphere respectively. The equivalence ratios were varied from 0.6 to 1.4 for initial pressure p=105 Pa, initial temperature T=298 K. The effects of equivalence ratio, O2 concentration, CO2 concentration and atmospheres on flame speed were explored. Results show that flame speed increases with equivalence ratio in fuel lean region, then decreases in the fuel rich region, and the maximum flame speed ap, pears at equivalence ratio 1.0 or 1.1. For the same O2 concentration, flame speed in an O2/CO2 atmosphere is markedly lower than that in O2/N2, which reveals that CO2 has a negative effect on flame propagation. Under O2/CO2/AR atmophere, flame speed decreases with increasing CO2 concentration, when O2 concentration remains unchanged. Besides, improving the O2 concentration in O2/CO2 atmosphere can increase flame speed, having a positive effect on n-alkanes combution process.