Abstract

The study investigates experimentally and numerically the problem of turbulent convective heat transfer and pressure drop in a packed bed with internal heat generation. The main objective is to develop correlations for the heat transfer between the bed and coolant as well as the pressure drop in the system using detailed experimental and 3-dimensional pore-scale numerical simulation. The system analyzed is a horizontal circular channel filled with different stainless steel spheres with diameters of 5.5 mm, 6.5 mm, and 7.5 mm. Dry air is used as working fluid. The study is performed for turbulent flow regimes with different Reynolds number (based on the spheres diameter) in the range of 900–2600. The spheres are heated using an electromagnetic induction heating method. Based on the experimental data, empirical correlations for turbulent pressure drop and convective heat transfer coefficient are developed. Results of pore-scale analysis show the complexity of the flow domain, which the velocity experiences a considerable increase compared to inlet velocity and is more evident in narrow gaps between spheres. Moreover, numerical results indicate the coupling of temperature and velocity fields, which a nonuniform velocity filed leads to nonuniform temperature distributions of air and solid spheres in the packed bed.

摘要

该研究通过实验和数值研究了具有内部发热的填充床中的湍流对流传热和压降问题。主要目标是使用详细的实验和 3 维孔隙尺度数值模拟来建立床和冷却剂之间的热传递以及系统中的压降的相关性。所分析的系统是一个水平圆形通道，其中填充有直径为 5.5 mm、6.5 mm 和 7.5 mm 的不同不锈钢球体。干燥空气用作工作流体。该研究针对具有不同雷诺数（基于球体直径）在 900-2600 范围内的湍流状态进行。使用电磁感应加热方法加热球体。根据实验数据，建立了湍流压降和对流传热系数的经验关系式。孔隙尺度分析结果表明流动域的复杂性，与入口速度相比，速度经历了相当大的增加，并且在球体之间的狭窄间隙中更为明显。此外，数值结果表明温度和速度场的耦合，不均匀的速度场导致填充床中空气和固体球的温度分布不均匀。