Burning and Extinction of a Laser‐Ignited Carbon Particle in Quiescent Mixtures of Oxygen and Nitrogen
Burning and Extinction of a Laser‐Ignited Carbon Particle in Quiescent Mixtures of Oxygen and Nitrogen
复制标题
激光点燃碳颗粒在氧气和氮气的静态混合物中的燃烧和熄灭
DOI：
10.1149/1.2132920
复制
发表时间：
1976
影响因子：
3.9
通讯作者：
F. Williams
中科院分区：
文献类型：
--
作者：
S. Ubhayakar;F. Williams
给出了激光点燃的电极碳颗粒（50 ~ 200~）在室温下在氧和氮的静态混合物中燃烧模式和寿命、表面温度和自发熄灭的实验数据。试验变量为混合物的氧质量分数（0.5-1）和压力（0.5-3 atm）。燃烧颗粒的高速电影显微摄影显示，可见的燃烧区域仅限于表面。为了解释消光现象，提出了两种理论模型，一种忽略了氧的解离，另一种近似地包含了氧的解离。将这些模型计算的消光结果与实际数据进行比较，表明忽略解离的模型是较好的消光模型。该模型表明，在2000~温度范围内，电极碳的氧化动力学可以用有效的Arrhenius表面氧化反应来表示，生成CO，活化能为18 kcal/mol，级数在0.5 ~ 1范围内。碳的氧化一直是燃烧领域研究最广泛的课题之一，然而，关于亚毫米颗粒在静止氧化气氛中燃烧的数据仍然缺乏。大约20年前，Spalding（1,2）提出了两种球形碳颗粒燃烧的模型，其中一种假设CO- o2气相反应产生CO2，而CO2又在其表面非均相氧化碳，而另一种假设o2与碳的非均相表面反应产生CO和/或CO，，。到目前为止，还没有实验数据来证实这两种模型对小碳颗粒的有效性。此外，关于大碳球通常通过一种涉及孔内扩散和反应的机制燃烧的事实也有很多讨论（3,4）。因此，本研究的最初目的是确定亚毫米颗粒是否发生气相燃烧机制或表面燃烧机制，可能伴有孔隙扩散。另一个目标是获得精度更高的燃烧持续时间数据。
Experimental data on the burning mode and lifetime, on the surface temperature, and on the spontaneous extinction of a laser-ignited particle of electrode carbon (50-200~) in quiescent mixtures of oxygen and nitrogen at room temperature are presented. The test variables were the oxygen mass fraction (0.5-1) and the pressure (0.5-3 atm) of the mixture. High speed cinemicrography of the burning particle showed that the visible combustion zone was restricted to the surface. Two theoretical models, one neglecting the dissociation of oxygen and the other including it approximately, are developed in order to explain the extinction phenomenon. Comparison of the extinction results computed from these models with the data indicates that the model neglecting dissociation is the preferred one. Based on this model it is shown that the kinetics of oxidation of electrode carbon in the temperature range 2000~ can be represented by an effective Arrhenius surface oxidation reaction producing CO and having an activation energy of 18 kcal/mole and an order in the range 0.5-1.The oxidation of carbon has been one of the most widely studied topics in the field of combustion, and yet there remains a paucity of data on the burning of submillimeter particles in quiescent oxidizing atmospheres. About two decades ago Spalding (1, 2) proposed two models for the burning of spherical carbon particles, one of which assumed a CO-O2 gas-phase reaction producing CO2 which in turn oxidizes carbon heterogeneously at its surface, while the other assumed a heterogeneous surface reaction of 02 with carbon producing CO and/or CO,,. To date, there exist no experimental data to confirm the validity of either of these two models for small carbon particles. Furthermore, there has been much discussion of the fact that large carbon spheres often burn by a mechanism that involves diffusion and reaction within the pores (3, 4). Therefore, an initial objective of the present study was to ascertain whether a gas phase burning mechanism or a surface burning mechanism, possibly accompanied by pore diffusion, occurs for submillimeter particles. An additional objective was to obtain burning duration data of improved accuracy.