基于颗粒尺度的离散颗粒传热模型

Heat transfer model for particles with discrete element method

颗粒间传热在诸多工业过程中有着十分重要的作用。详细考虑颗粒间传热机理,对颗粒间各传热途径建模,包括颗粒内部导热、颗粒粗糙表面传热、颗粒表面气膜及接触颗粒间隙气膜传热,并与离散颗粒模型(DEM)耦合,建立颗粒尺度下离散颗粒传热模型。以固定床为对象,考察颗粒粒径、颗粒比热容、颗粒热导率及压缩负载对固定床有效传热系数的影响,并将本文计算值和文献的实验值及模型预测值对比,结果表明,该模型可定量预测固定床有效传热系数。本文建立的离散颗粒传热模型为合理预测颗粒体系内的传热提供了一种有效方法。

Heat conduction in granular assemblies plays an important role in industrial applications.In this paper,the details of heat transfer mechanism are considered in particle scale.The conduction resistances of solid interior,rough surface,gas film between solids,and gas-gap between contacted surfaces are modeled and coupled with discrete element method to deduce a heat transfer model.Numerical simulations are performed to investigate the effects of particle diameter,specific thermal capacity,thermal conductivity of particles and compressive load on effective thermal conductivity（ETC） in fixed beds.The predicted ETC is compared with experimental and simulated data in literature,indicating that the presented model can predict ETC satisfactorily,which provides a useful tool for studying heat transfer in particle assemblies.