Dickenson Joshua A, Sansalone John J
Environmental Engineering and Sciences, University of Florida, Gainesville, Florida 32611, USA.
Environ Sci Technol. 2009 Nov 1;43(21):8220-6. doi: 10.1021/es901527r.
Modeling the separation of dilute particulate matter (PM) has been a topic of interest since the introduction of unit operations for clarification of rainfall-runoff. One consistent yet controversial issue is the representation of PM and PM separation mechanisms for treatment. While Newton's Law and surface overflow rate were utilized, many historical models represented PM as a lumped gravimetric index largely out of economy and lack of particle analysis methods. As a result such models did not provide information about particle fate in or through a unit operation. In this study, PM discrete phase modeling (DPM) and computational fluid dynamics (CFD) are applied to model PM fate as a function of particle size and flow rate in two common types of hydrodynamic separator (HS) units. The study examines the discretization requirements (as a discretization number, DN) and errors for particle size distributions (PSDs) that range from the common heterodisperse to a monodisperse PSD. PSDs are categorized based on granulometric indices. Results focus on ensuring modeling accuracy while examining the role of size dispersivity and overall PM fineness on DN requirements. The fate of common heterodisperse PSDs is accurately predicted for a DN of 16, whereas a single particle size index, commonly the d(50m), is limited to monodisperse PSDs in order to achieve similar accuracy.
自从引入用于澄清降雨径流的单元操作以来，对稀颗粒物（PM）分离进行建模一直是一个备受关注的话题。一个持续存在但有争议的问题是用于处理的PM及其分离机制的表征。虽然使用了牛顿定律和表面溢流率，但许多历史模型将PM表示为一个总的重量指数，这主要是出于经济性和缺乏颗粒分析方法的考虑。因此，这类模型没有提供关于颗粒在单元操作中或通过单元操作时的归宿信息。在本研究中，应用PM离散相建模（DPM）和计算流体动力学（CFD）来模拟两种常见类型的水力分离器（HS）单元中PM的归宿，该归宿是颗粒尺寸和流速的函数。该研究考察了从常见的多分散到单分散粒度分布（PSD）的离散化要求（作为离散化数，DN）和误差。PSD根据粒度指数进行分类。结果聚焦于确保建模准确性，同时考察尺寸分散性和整体PM细度对DN要求的作用。对于DN为16的情况，可以准确预测常见多分散PSD的归宿，而单个粒径指数（通常是d(50m)）仅限于单分散PSD才能达到类似的准确性。
