扁椭球体填充床传热性能研究

Heat transfer characteristics of packed bed comprising oblate ellipsoids

在结构化填充床应用中,经常会遇到扁椭球体颗粒,其形状以及颗粒取向会对填充床的传热效率产生较大影响。因此,使用商业CFD(计算流体力学)软件Fluent,在Re∈[10,200]范围内对均匀流动中不同形状扁椭球体颗粒的阻力系数和努塞尔数进行计算,以对传热效率进行表征。研究表明:扁椭球体颗粒阻力系数近似呈sin 2θ变化且颗粒取向对阻力系数影响较大,而对颗粒Nu(努塞尔数)影响很小。Nu与阻力系数的比值随着颗粒取向的增加而增加,这意味着流体流过颗粒取向为90°的扁椭球体时有较低的压降和较高的传热率,可以为结构化填充床的设计以及相关工业应用提供参考。

In the applications of structured packed bed,oblate ellipsoidal particles with different shapes and incident angles are often encountered,which have a significant influence on the heat transfer efficiency of structured packed beds.Therefore,the commercial CFD(Computational Fluid Dynamics)software Fluent was used to calculate the drag coefficient and Nusselt number of oblate ellipsoids with different aspect ratios in uniform flow within Re∈[10,200].The result shows that the particle drag coefficient evolves as sin 2θ.In addition,the incident angle has a great influence on the drag coefficient,but has little effect on the Nusselt number.The ratio of Nusselt number to drag coefficient increases with the increase of incident angle,which means that the fluid has a lower pressure drop and higher heat transfer rate when flowing through oblate ellipsoids withθ=90°.Thus,a reference can be provided for the design of structured packed bed and industrial applications.