通道火灾CO输运过程中体积分数随时间的变化特征

Time-Variation Characteristics of Carbon Monoxide Concentration During Transport in Channel Fires

根据理论分析,将通道内的火灾烟气层划分为若干个区段,对每一区段建立了组分守恒方程;通过求解,得到各区段内CO体积分数在稳定燃烧阶段随时间呈幂指数增长关系.通过开展小尺寸模拟实验,测得了各区段内的CO体积分数和温度数据,并对CO体积分数随时间的变化进行了分析.结果表明,理论方程能够很好地对实验测量结果进行逼近;近火源位置相比于远离火源位置的CO体积分数增长速度快,稳态体积分数值高;随着与火源距离的增大,CO体积分数的增长速度以及稳态值都会减小.

The temporal CO concentration in horizontal layer zones arbitrarily divided under a channel fire was theoretically analyzed by solving the conservation equations built for CO species. An exponential growth of CO concentration with time was observed during the steady burning phase. Experiments were conducted in a model channel. CO concentration and smoke temperature were then measured in each smoke layer zone. The results show that the measured values can be well approached by the theoretical equations, that CO concentration in the near-fire field undergoes a faster growth rate and achieves a larger constant value during the steady sate than that in the far-fire field, and that both the growth rate and constant value decrease with the increase of the distance away from the fire.