锆,铝颗粒活化能尺寸效应的理论模型

Analytical Model for Size Effect of Activation Energy of Zirconium and Aluminum Particles

摘要:

提出了一个通过金属颗粒着火温度计算活化能的理论模型,着火温度的临界条件为燃烧反应产热率与对周围环境放热率达到热平衡。放热率由Knudsen数控制,铝颗粒燃烧产热率通过Arrhenius形式的模型计算,锆颗粒燃烧产热率由扩散模型计算,通过迭代计算,得到金属颗粒着火温度对应的活化能。结果表明,铝颗粒、锆颗粒的活化能随粒径增大而增大,与粒径的对数呈线性关系。在纳米至微米的更大尺寸范围内,单一理论模型不足以描述金属颗粒活化能的尺寸效应,而基于数据拟合的多项式模型更具有普适性。

Abstract:

A theoretical model of calculating activation energy by ignition temperature of metal particles is proposed. The critical condition of ignition temperature is that the heat generation rate of combustion reaction and the heat loss rate to the surrounding reach a heat balance. The heat loss rate is controlled by Knudsen number. The heat generation rate of aluminum particle combustion is calculated using the simplest Arrhenius-type model. The heat generation rate of zirconium particle combustion is calculated by diffusion model. And the activation energy corresponding to the ignition temperature of metal particle is obtained by iterative calculation. The results show that the activation energy of aluminum particles and zirconium particles increases with the increase of particle size, which is linear with the logarithm of particle size. In the larger size range of nanometer to micron, a single theoretical model is not enough to describe the size effect of activation energy of metal particles. The polynomial model based on data fitting is more universal.