Purpose

This paper aims to present a novel approach for computing particle temperatures in simulations coupling computational fluid dynamics (CFD) and discrete element method (DEM) to predict flow and heat transfer in fluidized beds of thermally thick spherical particles.

Design/methodology/approach

An improved lumped formulation based on Hermite-type approximations for integrals to relate surface temperature to average temperature and surface heat flux is used to overcome the limitations of classical lumped models. The model is validated through comparisons with analytical solutions for a convectively cooled sphere and experimental data for a fixed particle bed. The coupled CFD-DEM model is then applied to simulate a Geldart D bubbling fluidized bed, comparing the results to those obtained using the classical lumped model.

Findings

The validation cases demonstrate that ignoring internal thermal resistance can significantly impact the temperature in cases where the Biot number is greater than 0.1. The results for the fixed bed case clearly demonstrate that the proposed method yields significantly improved outcomes compared to the classical model. The fluidized bed results show that surface temperature can deviate considerably from the average temperature, underscoring the importance of accurately accounting for surface temperature in convective heat transfer predictions and surface processes.

Originality/value

The proposed approach offers a physically more consistent simulation without imposing a significant increase in computational cost. The improved lumped formulation can be easily and inexpensively integrated into a typical DEM solver workflow to predict heat transfer for spherical particles, with important implications for various industrial applications.

中文翻译：

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采用改进的传热集总公式对流化床进行 CFD-DEM 耦合模拟

目的

本文旨在提出一种在模拟中计算颗粒温度的新方法，结合计算流体动力学（CFD）和离散元方法（DEM）来预测热厚球形颗粒流化床中的流动和传热。

设计/方法论/途径

基于厄米特型积分近似的改进集总公式将表面温度与平均温度和表面热通量相关联，用于克服经典集总模型的局限性。通过与对流冷却球体的解析解和固定颗粒床的实验数据进行比较，对该模型进行了验证。然后应用耦合的 CFD-DEM 模型来模拟 Geldart D 鼓泡流化床，并将结果与​​使用经典集总模型获得的结果进行比较。

发现

验证案例表明，在毕奥数大于 0.1 的情况下，忽略内部热阻会显着影响温度。固定床案例的结果清楚地表明，与经典模型相比，所提出的方法产生了显着改善的结果。流化床结果表明，表面温度可能与平均温度有很大偏差，这强调了在对流传热预测和表面过程中准确考虑表面温度的重要性。

原创性/价值

所提出的方法提供了物理上更加一致的模拟，而不会显着增加计算成本。改进的集总公式可以轻松且经济地集成到典型的 DEM 求解器工作流程中，以预测球形颗粒的传热，这对各种工业应用具有重要意义。