涡发生器强化环形翅片管束管外传热的数值研究

Numerical Simulation of Enhanced Heat Transfer Outside of Annular Finned Tube Bundle in Vortex Generator

针对大型商用厨房排烟温度高、能源利用率低等问题,提出了一种大型商用厨房余热回收再利用系统,该系统以分离式热管换热器作为主要的换热元件。对热管换热器蒸发段环形翅片管束管外进行强化传热数值模拟,通过增添涡发生器来提升环形翅片管外的综合换热性能。研究表明:内八型摆放形式的矩形涡发生器,其综合评价因子相较于其他涡发生器和摆放形式更优,能更好地压缩管后低速回流区的涡旋,产生纵向涡,加剧冷热流体掺混,努塞尔数比环形光翅片提升了42%~58%,综合评价因子提升了16.2%~35.6%;涡发生器在环形光翅片上相对位置为极径14 mm,极角60°和75°时,管束的综合换热性能更好。

Aiming at the high exhaust gas temperature and low energy utilization rate in large commercial kitchens,a waste heat recycling and reusing system for large commercial kitchens was proposed,in which,a separated-type heat pipe heat exchanger was employed as the main heat exchange element.In this paper,numerically simulating heat transfer enhancement outside of the annular finned pipe bundle at evaporation section of the heat pipe heat exchanger was implemented,including adding a vortex generator to improve comprehensive heat transfer performance outside of the annular finned tube.The research results show that,the comprehensive evaluation factor of the rectangular vortex generator with the inner eight type arrangement outperforms that of other vortex generators and arrangements,which can better compress the vortex in the low-speed reflux area behind the tube,generate longitudinal vortex and intensify the mixing of cold and hot fluids.The Nusselt number can be increased by 42%to 58%higher than that of the annular smooth fin,and the comprehensive evaluation factor is raised by 16.2%to 35.6%;when the relative position of the vortex generator on the annular light fin is 14 mm in polar diameter and 60°and 75°in polar angle,the overall heat transfer performance of the tube bundle becomes better.