板间颗粒流动换热特性实验与数值分析研究

Experimental and Numerical Analysis of Particle Flow and Heat Transfer Characteristics Between Flat Plates

本文基于垂直结构的板壳式移动填料床太阳能颗粒换热器,实验研究了颗粒与不同板型壁面间的换热特性,并采用离散单元模型对颗粒在板内的流动轨迹和流动状态进行了三维模拟,分析了不同壁面形状对换热过程的影响机理。研究结果表明,与普通光滑铜板相比,波浪板对整体换热产生明显削弱,而粗糙板在高流量下(25~54 g·s^(-1))也是削弱换热的。波纹板虽在低流量下(6~25 g·s^(-1))削弱换热,但在高流量下(26~54 g·s^(-1))可实现换热强化。进一步的数值分析表明,虽然波浪板、波纹板和粗糙板都会增强颗粒的波动,但也会延长颗粒的下落时间,当增强波动所引起的换热强化程度大于增长下落时间所引起的换热削弱程度时,整体换热过程便呈现强化效果,反之则出现削弱效果。

Based on a vertical structure of a plate shell moving packed bed solar particle heat exchanger,the heat transfer characteristics between particles and different plate wall surfaces were experimentally studied in this paper.The discrete element model was used to simulate the flow trajectory and state of particles inside the plate in three-dimensional,and the influence mechanism of different wall shapes on the heat transfer process was analyzed.The results indicate that compared with ordinary smooth copper plates,wavy plates significantly weaken overall heat transfer,rough plates also weaken heat transfer at high flow rates(25~54 g·s^(-1)).Although the corrugated plate weakens heat transfer at low flow rates(6~25 g·s^(-1)),it can achieve heat transfer enhancement at high flow rates(26~54 g·s^(-1)).Further numerical analysis shows that although wave plates,corrugated plates,and rough plates all enhance particle disturbance,they also extend the falling time of particles.When the degree of heat transfer enhancement caused by enhanced disturbance is greater than the degree of heat transfer weakening caused by increased falling time,the overall heat transfer process exhibits a strengthening effect,and conversely,a weakening effect occurs.