Validation study on a scaling law model of the DEM in industrial gas-solid flows
Validation study on a scaling law model of the DEM in industrial gas-solid flows
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DOI：
10.1016/j.powtec.2018.11.015
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发表时间：
2019-02-01
影响因子：
5.2
通讯作者：
Sakai, Mikio
中科院分区：
文献类型：
--
作者：
Mori, Yuki;Wu, Chuan-Yu;Sakai, Mikio
大型气固流动系统，例如，流化床、旋风分离器和气动输送机在化学工程中经常遇到。数值模拟技术被广泛应用于设计和理解这些气固流动系统中的复杂现象，通常采用离散元法（DEM）和计算流体力学（CFD）的耦合模型。然而，这些系统的数值模拟的应用仍然是有限的，因为可以建模的颗粒的数量（约几十万）是相当小的相比，在工业过程中使用的不可估量的颗粒的数量，并不足以充分理解这些过程中的复杂行为。粗粒化DEM的开发，然后提供了一种替代的方法来模拟真实的工业过程。到目前为止，粗粒化DEM的精度已经被证明是简单系统的精度。在本研究中，粗粒化DEM的适用性复杂形状的域进行了探索，其中被认为是典型的工业过程，如流化与插入管，粉末流到一个有限的空间。在这些计算中，符号距离函数（SDF）和浸没边界法（IBM）被用来模拟气固流动中的任意形状的壁边界。采用粗粒化离散元进行数值模拟和实验研究，并将实验结果与数值模拟结果进行了比较。结果表明，粗粒化离散元模型能够准确模拟工业气固两相体系。此外，这种数值方法被证明是提供有价值的信息，如粉末注射过程中的压力分布和气泡和流化床中的结构之间的相互作用。(C)2018 Elsevier B.V.版权所有。
Large-scale gas-solid flow systems, e.g., fluidized beds, cyclone separators and pneumatic conveyors, are often encountered in chemical engineering. Numerical modeling technologies are widely applied for design and understanding of complex phenomena in these gas-solid flow systems, for which the coupled model of the discrete element method (DEM) and computational fluid dynamics is generally employed. However, application of the numerical simulations for these systems is still limited because the number of the particles that can be modeled (about several hundreds of thousand) is quite small comparing with the immeasurable number of particles used in the industrial processes, and not sufficient to fully understand the complex behavior in these processes. The coarse graining DEM is then developed to provide an alternative approach for modeling the real industrial processes. Accuracy of the coarse graining DEM has been proven for simple systems so far. In the present study, applicability of the coarse graining DEM for complex shaped domains is explored, for which typical industrial processes, such as fluidization with inserted tubes, and powder flow into a confined space, are considered. In these calculations, signed distance functions (SDF) and immersed boundary method (IBM) are used to model an arbitrary shape wall boundary in a gas-solid flow. Both numerical modeling using the coarse graining DEM and experimental investigation are performed with a thorough comparison between the experimental and numerical results. It is demonstrated that the coarse graining DEM is capable of accurately modeling of industrial gas-solid two-phase systems. Besides, this numerical approach is shown to provide valuable information such as pressure profile during powder injection and interaction between bubbles and structures in a fluidized bed. (C) 2018 Elsevier B.V. All rights reserved.