Heat transfer and energy performance of Al₂O₃/water nanofluid in a 90° bend with circular cross-section are investigated in the range of Reynolds number (Re) from 5 000 to 30 000, particle volume concentration (Φ) from 0.005% to 4%, Schmidt number (Sc) from 9 870 to 296 100, Dean number (De) from 6 636 to 14 847. The momentum and energy equations of nanofluid together with the dynamic equation for nanoparticles are solved numerically with the particle convection, diffusion, coagulation and breakage taken into consideration. Some results are validated by comparing with the available experimental or numerical results. The effect of Re, Φ, Sc and De on the friction factor and heat transfer of Al₂O₃/water nanofluidis discussed. The results showed that the particle number decreases along the pipeline. Increasing De, Sc leads to a decrease and increase of Φ, respectively. The mean particle diameter and particle polydispersity increase with increasing Debut with decreasing Sc. The friction factor increases with increasing Φ, Sc De and Pr but with decreasing Sc. The ratio of energy performance evaluation criterion (PEC) for the Al₂O₃/water nanofluid to the base fluid increases with increasing Re, Φ and De, but with decreasing Sc. Finally, the expression of ratio of energy PEC for the nanofluid to the base fluid as a function of Re, Φ, Sc and De is derived.

在雷诺数（ Re）为5 000至30 000，颗粒体积浓度（Φ）为0.005%的范围内，研究了Al ₂ O ₃ /水纳米流体在90°弯曲圆形截面中的传热和能量性能至 4%，施密特数 ( Sc ) 从 9 870 到 296 100，迪恩数 ( De ) 从 6 636 到 14 847。纳米流体的动量和能量方程以及纳米粒子的动力学方程通过粒子对流进行数值求解，考虑到扩散、凝结和破损。通过与可用的实验或数值结果进行比较来验证一些结果。Re , Φ的影响，Sc和De对Al ₂ O ₃ /水纳米流体的摩擦系数和传热进行了讨论。结果表明，沿管道的粒子数减少。增加De和Sc分别导致Φ减小和增加。平均粒径和颗粒多分散性随着 Debut 的增加而随着Sc的降低而增加。摩擦因数随着Φ、Sc De和Pr的增加而增加，但随着Sc的减少而增加。_{Al 2}的能源性能评价标准 (PEC) 的比率O ₃ /water 纳米流体对基础流体的影响随着Re、Φ和De的增加而增加，但随着Sc的减少而增加。最后，导出了作为Re、Φ、Sc和De函数的纳米流体与基础流体的能量 PEC 比的表达式。