Madras Giridhar, McCoy Benjamin J
Department of Chemical Engineering, Indian Institute of Science, Bangalore 560012, India.
J Colloid Interface Sci. 2003 May 15;261(2):423-33. doi: 10.1016/S0021-9797(03)00129-2.
Condensation phase transitions from metastable fluids occur by nucleation with accompanying particle growth and eventual Ostwald ripening. During ripening the subcritical particles dissolve spontaneously while larger particles grow and possibly coalesce if their volume fraction is large enough. The classical diffusion-influenced rates are also affected by large particle concentrations and are here described by mass-dependent rates. We represent the kinetics of ripening through growth, dissolution, and biparticle coalescence by a new population dynamics equation for the particle size distribution (PSD). Numerical solutions of the scaled governing equations show that coalescence plays a major role in influencing the PSD when the scaled mass concentration (volume fraction) or number concentration is relatively large. The solution describes the time range from initial conditions to the final narrowing of polydispersity. We show that the time dependence of the average particle mass in the asymptotic period of ripening has a power-law increase dependent on rate expressions for particle growth and coalescence at large values of volume fraction.
亚稳态流体的凝聚相变通过成核以及伴随的颗粒生长和最终的奥斯特瓦尔德熟化过程发生。在熟化过程中，亚临界颗粒会自发溶解，而较大的颗粒则会生长，如果它们的体积分数足够大，还可能合并。经典的受扩散影响的速率也会受到大颗粒浓度的影响，这里用质量依赖速率来描述。我们通过一个新的颗粒尺寸分布（PSD）群体动力学方程来表示通过生长、溶解和双颗粒合并实现熟化的动力学过程。缩放后的控制方程的数值解表明，当缩放后的质量浓度（体积分数）或数量浓度相对较大时，合并在影响PSD方面起着主要作用。该解描述了从初始条件到多分散性最终变窄的时间范围。我们表明，在熟化的渐近期，平均颗粒质量的时间依赖性具有幂律增长，这取决于在大体积分数值下颗粒生长和合并的速率表达式。
