管内螺旋液固两相流的流动行为及传热

Flow Behavior and Heat Transfer of Liquid-Solid Flow in Tubes with Spiral Insert

利用Fluent–EDEM耦合方法对管内插螺旋线的液固两相流动与传热进行数值模拟,分析了螺旋线对固相颗粒的诱导碰撞作用和液固两相流传热性能的影响.通过实验验证,模拟值与实验值的偏差为6.3%～13.8%.模拟结果表明,与管内未插螺旋线对比,管内插螺旋线对液固两相流体具有诱导作用,使流体呈螺旋流状态;在流体离心力和螺旋线共同作用下,贴近管内壁运动的固体颗粒体积分数由0.44%提高到3.27%;相同雷诺数Re条件下,内插螺旋线液固两相流传热方法的努赛尔数Nu最大.在Re≤60000范围内,内插螺旋线液固两相流的综合评价指标值均高于内插螺旋线和液固两相流单独作用方式.因此,该技术适用于低Re下管内防垢除垢及强化传热的工况.

Numerical simulation on flow and heat transfer of liquid-solid flow in the tubes with spiral insert was carried out with the Fluent–EDEM coupling method. The particles collision on heat transfer surface and the heat transfer enhancement were analyzed, which was induced by spiral insert. The experiments show that the deviation between the simulation and experimental data is small in the range of 6.3%～13.8%. The fluid flows spirally, and the volume fraction of particles close to wall is increased from 0.44% to 3.27%, induced by the spiral insert. The results indicate that Nu of the combination is greater than that of only two-phase flow without insert under the same Re. When Re is below 60 000, the two-phase tube flow with spiral insert has greater comprehensive evaluation index PEC than liquid-solid flow without insert and spiral insert without particles, respectively. Therefore, this combination technology can be applied in prevention of fouling and enhancement of heat transfer under the condition of low Re condition.