纵向涡发生器在管翅式换热器中的应用及优化

Application and optimization of fin-and-tube heat exchangers with longitudinal vortex generators

纵向涡发生器能够在较大幅度提升换热器换热能力的同时,较小幅度地增加其流动阻力。利用三维数值模拟的方法,详细分析和研究了纵向涡发生器对管翅式换热器传热流动的影响;并对纵向涡发生器的关键参数(攻角,数目,摆放位置)进行了优化。结果表明:纵向涡发生器的攻角为15°,采用3对矩形小翼时,管翅式换热器的空气侧换热能力的提升幅度超过了其流动阻力增加的幅度,与未采用强化措施的换热器相比,其空气侧传热系数提升了71.3%～87.6%,相应的流动阻力增加了54.4%～72%;空气侧的换热能力随着纵向涡发生器数目的增加而逐渐变大,但空气侧的局部换热能力在第5根换热管之后几乎不受涡发生器数目的影响;与纵向涡发生器的顺排布置相比,纵向涡发生器以交错叉排的方式布置时,可以在保证强化换热水平的同时,进一步减小换热器流道内的流动阻力。

The longitudinal vortex generator（LVG）can significantly enhance the heat transfer in fin-and-tube heat exchangers with a moderate pressure loss penalty.A 3-D numerical simulation was employed to investigate the flow and heat transfer characteristics of fin-and-tube heat exchangers.The optimizations for critical parameters of vortex generator,i.e.,the attack angle,number and position of LVG,were performed.The results show that the enhancement of heat transfer on the airside can surpass the increase of the pressure drop in a fin-and-tube exchanger with three pairs of rectangular winglets and an attack angle of 15°.Compared with the conventional configuration,the heat transfer coefficient of the enhanced configuration is improved by 71.3%—87.6% while the pressure loss is increased by 54.4%—72%.The average heat transfer coefficient on the airside increases with the number of vortex generator,but the local heat transfer is affected little by the number of vortex generator after the fifth tube.Compared with the inline arrangement of vortex generators,the staggered arrangement of vortex generators can further reduce the pressure loss penalty while maintain the enhanced heat transfer.