O_2/CO_2气氛下考虑斯蒂芬流的碳粒燃烧模型

Combustion Model of a Char Particle Considering Stefan Flow Effects in O_2/CO_2 Atmosphere

针对富氧燃烧中的O2/CO2气氛,考虑表面氧化反应、表面还原反应和斯蒂芬流,建立了新的碳粒燃烧理论模型.实验表明,与未考虑斯蒂芬流的模型相比,该模型的预报结果与实验值符合得更好.对斯蒂芬流影响的分析计算显示,无论斯蒂芬流存在与否,燃烧速率均随氧体积分数(20%和30%)、粒径(100～240,μm)、表面温度(1,750～1,900,K)、环境气体温度(1,200～1,400,K)的增大而增大,但由于斯蒂芬流阻碍了反应气体向颗粒表面的扩散,减缓了反应进程,因此在本文计算条件下,新模型计算得到的燃烧速率比未考虑斯蒂芬流的情况低1/4～1/3.

Considering oxidation reaction, reduction reaction and Stefan flow, a novel combustion model for a char particle burning in the O2/CO2 mixture was developed. Compared with the model neglecting Stefan flow, the new model can make predictions which are in better agreement with the data measured in the drop tube furnace. The numerical simulations showed that the combustion rate of char increases with the increase of O2 concentration （20% and 30%）, particle size （100-240 p.m）, surface temperature （1 750-1900K）, and ambient temperature （1 200- 1 400 K） regardless of Stefan flow. However, as Stefan flow can hinder the diffusion of reactive gases to particle surface and hence slow down surface reactions, the combustion rate predicted by the new model is about 1/4 to 1/3 lower than that calculated by the model neglecting Stefan flow under the present calculation conditions.