多分散结构团聚体烧结的数值模拟

高温环境下团聚体颗粒的烧结现象决定了颗粒表面积、内部非均匀结构等。现有数值模拟方法中一般认为团聚体由若干尺度相同的一次粒子组成,不符合实验测量结果。该文考虑团聚体内一次粒子的多分散性,建立一次粒子质量平衡和数目平衡关系,描述烧结过程团聚体内一次粒子尺度分布函数的演变。对气相法制备TiO2纳米颗粒的烧结定制过程进行数值模拟,模拟结果与实验结果吻合较好,且考虑团聚体内一次粒子多分散分布的模型结果比考虑团聚体内一次粒子单分散分布的模型结果更精确。所建立的描述团聚体烧结过程的多分散模型可适用于多尺度模拟、颗粒群平衡模拟–Monte Carlo方法、多相流模拟的欧拉–拉氏模型等。

Numerical Simulation for Sintering of Agglomerates Consisting of Polydisperse Primary Particles

The sintering of agglomerates under high temperature determines their surface area and internal inhomogeneous structure.These available models for numerical simulation of sintering phenomenon generally assume that agglomerate consists of equally-sized primary particles(PP),which conflicts with experimental measurements.In this paper,it was considered primary particles within agglomerates satisfy polydisperse distribution.The population balance equations for the mass and number of primary particles were constructed to obtain the evolution of size distribution of primary particles within agglomerates.The polydisperse PP model was then used to simulate the sintering process that was used to tailor TiO2 nanoparticles from the gas phase.It is found that the agreement between experimental measurements and numerical results is well in general,and the polydisperse PP model has advantage in numerical precision with respect to the monodisperse PP model(that considers monodisperse PP within agglomerates).The polydisperse PP model for agglomerate sintering presented in this paper is capable of applying to multiscale modeling,population balance-Monte Carlo simulation,and Eulerian-Lagrangian model for multi-phase flows.