细水雾中雾滴和高温环境的热质交换研究

由雾滴的表面的组分方程和能量方程入手,探讨雾滴在静止的高温环境中的热质交换及生存时间。应用折算薄膜理论,通过特征时间的比较,提出雾滴与高温环境主要通过沸腾机制实现热质交换;考虑滴径与速度变化的耦合作用,应用数值方法研究雾滴在强迫对流环境中与高温环境的热质交换情况。结果表明:对于滴径较小的雾滴不可能达到火焰区或可燃物表面实施火焰冷却和表面冷却,其灭火作用主要依赖于汽化吸热。

Heat and Mass Transfer between Water Droplets and High Temperature Environment

From species equation and energy equation of droplet surface,heat and mass transfer and lifetime of droplet in still high temperature environment are researched.With converting film theory,it is put forward that heat and mass transfer are achieved by boiling mechanism via the comparison of characteristics time.Taking into account the coupling effect of variation of droplet diameter and velocity,heat and mass transfer of droplet in forced convection high temperature environment are studied by using numerical method.The results show that it is impossible to carry out fire suppression by flame cooling and surface cooling for smaller droplet.The extinguishing mechanism for them depends primarily upon decalescence via gasification.