Development and verification of a resolved 3D inner particle heat transfer model for the Discrete Element Method (DEM)
Development and verification of a resolved 3D inner particle heat transfer model for the Discrete Element Method (DEM)
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DOI：
10.1016/j.powtec.2015.12.008
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发表时间：
2016-04
影响因子：
5.2
通讯作者：
T. Oschmann;M. Schiemann;H. Kruggel-Emden
中科院分区：
文献类型：
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作者：
T. Oschmann;M. Schiemann;H. Kruggel-Emden
隐式三维传热模型推导出代表解决的球形和非球形颗粒在周围流体的存在下的热传导。所提出的方法，基于有限差分解，被集成到离散元法（DEM）适用于多粒子系统占以下传热机制：粒子-粒子，粒子-壁，粒子-流体-粒子热传导，粒子-粒子辐射和粒子-流体对流。为此，制定了第二和第三类边界条件。基于进行的各种验证，基本的子方法的传热模型进行了验证，对解决FVM模拟与商业CFD软件包ANSYS Fluent。这首先包括恒定的热通量和传热系数规定为一个单一的颗粒，允许一个基本的系统验证的实施模型的情况下。其次研究了粒子间的辐射和粒子间的热传导。这些情况是更大的复杂性，因为所使用的热传递模型的分辨率和局部热传递本身变得重要。除了在小规模上进行彻底的模型验证外，填充床内的传热也作为大规模情况进行处理。为了比较实施解决内部颗粒传热模型与文献数据，有效导热系数（ETC）计算热薄颗粒填料与各种颗粒导热系数。为了强调一个解决的三维传热模型的DEM的上下文中的重要性，材料参数被认为是归因于热厚颗粒，此后。在这里，解析的热传递模型与更常用的未解析模型方法进行比较，其中一个恒定的温度值与颗粒相关联。在评估填料内的热通量、达到稳定状态的时间和获得的ETC值时，会出现明显的差异。所进行的调查奠定了基础，包括派生解决DEM内部颗粒传热模型的一部分，耦合DEM-CFD框架。
An implicit 3D heat transfer model is derived to represent resolved heat conduction within spherical and non-spherical particles in the presence of a surrounding fluid. The proposed method, based on a finite difference solution, is integrated into the Discrete Element Method (DEM) applicable to multi-particle systems accounting for the following heat transfer mechanisms: particle–particle, particle–wall, particle–fluid–particle heat conduction, particle–particle radiation and particle–fluid convection. For this purpose, boundary conditions of the second and third kind are formulated. Based on various verifications performed, the underlying sub-approaches of the heat transfer model are validated against resolved FVM simulations performed with the commercial CFD-package ANSYS Fluent. This firstly includes cases with constant heat flux and heat transfer coefficient prescribed for a single particle which allows a basic systematic verification of the implemented model. Secondly particle–particle radiation and particle–particle heat conduction are investigated. These cases are of greater complexity as the resolution of the used heat transfer model and the local heat transfer itself become important. In addition to the thorough model validation on the small scale, heat transfer within packed beds is addressed as large scale cases. To compare the implemented resolved inner particle heat transfer model with literature data, the effective thermal conductivity (ETC) is calculated for packings of thermally thin particles with various particle thermal conductivities. To underline the importance of a resolved 3D heat transfer model in the context of the DEM, material parameters are considered which are attributed to thermally thick particles, thereafter. Here the resolved heat transfer model is compared against the more commonly used unresolved model approach with one constant temperature value associated to a particle. Noticeable differences occur when evaluating heat fluxes within the packing, the time to reach the steady state and for ETC-values obtained. The performed investigations lay the foundation to include the derived resolved DEM inner particle heat transfer model as part of a coupled DEM–CFD framework.