为了探讨涡流发生器间距对矩形吸收器换热性能的影响。研究采用了TiO2-Cu水基纳米流体作为传热流体,在矩形吸收器内部布置了穿孔挡板涡流发生器。利用FLUENT软件进行数值模拟,分析了不同穿孔挡板安装间距以及穿孔直径对吸收管内部流体流动和传热性能的影响,结合涡结构、边界层理论以及场协同原理对强化传热机理进行解释,并给出强化传热效果最佳的涡流发生器结构参数。研究表明：涡流发生器间距的改变对流动结构影响较大,较小的间距拥有强度较大的回流区纵向涡,主流被限制在吸收管中心。对于较大的间距,回流区形成横向涡并裹挟主流冲击受热壁,充分促进吸收管内的流体混合和能量交换。综合换热性能随着间距的增加表现出先增大后减小的趋势,当挡板间距为0.75H,穿孔直径2.5 mm时,吸收器内部具有最好的强化传热效果。

The present study aims to investigate the influence of vortex generator pitch on the heat transfer performance of a rectangular absorber. TiO2-Cu water-based nanofluid was employed as the heat transfer fluid, and perforated baffle vortex generators were installed within the rectangular absorber. Numerical simulations were conducted using FLUENT software to analyze the effects of different perforated baffle installation pitch and perforation diameters on the internal fluid flow and heat transfer performance within the absorption tube. The enhanced heat transfer mechanism was elucidated by considering vortex structures, boundary layer theory, and the principle of field synergy, and the optimal structural parameters of the vortex generators for enhanced heat transfer were provided. It is shown that the change of the pitch of the vortex generator has a large influence on the flow structure, and a smaller pitch possesses a stronger longitudinal vortex in the reflux zone, with the main flow being confined to the center of the absorber tube. For a larger pitch, the reflux zone forms transverse vortices and wraps the main flow to impact the heated wall, which fully promotes the fluid mixing and energy exchange in the absorber tube. The comprehensive heat transfer performance shows a tendency of increasing and then decreasing with the increase of pitch, and when the perforation baffle is installed with a pitch of 0.75H and a perforation diameter of 2.5 mm, the absorber has the best reinforced heat transfer effect inside the absorber.

TK124

宁夏回族自治区重点研发计划项目(2023BDE020134)