Dimensionless spray flux in wet granulation: Monte-Carlo simulations and experimental validation
Dimensionless spray flux in wet granulation: Monte-Carlo simulations and experimental validation
复制标题
湿法制粒中的无量纲喷雾通量：蒙特卡罗模拟和实验验证
DOI：
10.1016/j.powtec.2004.02.005
复制
发表时间：
2004
影响因子：
5.2
通讯作者：
Damina G Jones
中科院分区：
文献类型：
--
作者：
K. Hapgood;J. Litster;E. T. White;P. Mort;Damina G Jones
无因次喷雾流量ΨA是一个无量纲组，它表征了液体分散中的三个最重要的变量：流量、液滴大小和通过喷雾区的粉末流量。本文用泊松分布给出了单液滴成核比例(FSingle)和被液滴覆盖粉末表面的比例(Fovered)随Ψa变化的解析解，并用蒙特卡罗方法模拟了喷雾区，研究了Ψa、fSingle和fovered之间的关系。蒙特卡罗方法的计算结果与Ψα的解析解符合得很好。在低Ψa时，液滴覆盖表面的比例等于Ψa。随着Ψ的增加，液滴重叠变得更加明显，粉料表面覆盖率趋于稳定。由单个液滴形成的核的比例(FSingle)随着Ψa的增加而指数下降。在所覆盖的范围内，这些结果与液滴尺寸、液滴数量、液滴尺寸分布(单尺寸、双峰和三峰分布)以及喷雾的均匀性无关。通过定义单个液滴核的切割尺寸，将核尺寸分布随喷雾通量变化的实验数据与FSingle的解析解进行了拟合。拟合的切割尺寸遵循喷雾液滴尺寸，这表明该方法是稳健的，切割尺寸确实表明了单个液滴和团聚核之间的过渡尺寸。这说明原子核的分布是由无因次喷雾通量决定的，液滴控制的原子核的比例可以预先解析计算。
Dimensionless spray flux Ψais a dimensionless group that characterises the three most important variables in liquid dispersion: flowrate, drop size and powder flux through the spray zone. In this paper, the Poisson distribution was used to generate analytical solutions for the proportion of nuclei formed from single drops (fsingle) and the fraction of the powder surface covered by drops (fcovered) as a function of Ψa. Monte-Carlo simulations were performed to simulate the spray zone and investigate how Ψa, fsingleand fcoveredare related. The Monte-Carlo data was an excellent match with analytical solutions of fcoveredand fsingleas a function of Ψa. At low Ψa, the proportion of the surface covered by drops (fcovered) was equal to Ψa. As Ψaincreases, drop overlap becomes more dominant and the powder surface coverage levels off. The proportion of nuclei formed from single drops (fsingle) falls exponentially with increasing Ψa. In the ranges covered, these results were independent of drop size, number of drops, drop size distribution (mono-sized, bimodal and trimodal distributions), and the uniformity of the spray. Experimental data of nuclei size distributions as a function of spray flux were fitted to the analytical solution for fsingleby defining a cutsize for single drop nuclei. The fitted cutsizes followed the spray drop sizes suggesting that the method is robust and that the cutsize does indicate the transition size between single drop and agglomerate nuclei. This demonstrates that the nuclei distribution is determined by the dimensionless spray flux and the fraction of drop controlled nuclei can be calculated analytically in advance.