颗粒流移动床换热器单元研究

Study on Flow in Moving Bed Heat Exchanger Element

本文采用双欧拉方法模拟管壁间细粒径颗粒流流动换热,分析颗粒密度、比热容、入口流速、导热系数与颗粒直径对换热的影响。主要结论如下:颗粒与管壁间平均换热系数随颗粒密度,比热容及入口流速增大升高,但热回收效率随之下降。增大导热系数则使换热系数与效率同时增加,但对换热系数的强化效果不如前者。当颗粒直径增大时,气膜热阻会迅速增大,而中央核心区热阻有减少的趋势。故强化换热时,对细粒径颗粒需减少核心区热阻;对大粒径颗粒则需减少气膜热阻。

Granular flow with heat transfer in moving bed heat exchanger element is numerically simulated by Euler-Euler method in current work. The influence of particles density, special heat capacity, velocity, conductivity and diameter on heat transfer is analyzed. The results show that,average heat transfer coefficient between particles and tube would increase with the increasing of density, special heat capacity, velocity, while the efficiency would decrease. The increasing of conductivity would make heat transfer coefficient and efficiency all increase, but the positive effect on heat transfer coefficient is less. Contact heat resistance would rapidly increase with increasing of diameter, while penetration heat resistance would decrease. In order to enhance heat transfer,penetration heat resistance should be weaken for smaller particles, while contact heat resistance should be weaken for larger particles.