Abstract Experiments were conducted to study the turbulent heat transfer growth of single pot sonochemically assisted new Al2O3@TiO2-ZnO/DW based ternary composite nanofluids in a closed circular heat exchanger under constant heat flux boundary conditions. The two-step facile nanofluid preparation approach was used to prepare the new ternary hybrid nanofluids. The UV–Vis and FESEM analysis were performed to confirm the absorbance and uniform dispersion of all nanoparticles. Under uniform heat flux conditions, Al2O3@TiO2-ZnO/DW based ternary composite nanofluids at 0.1, 0.075, 0.05, and 0.025 wt% reveals positive growth in heat transfer coefficient (h) and Nusselt numbers (Nu) with an increase in Reynolds (Re) number from 5849 to 24,544 without using any surfactant. The maximum increase in effective thermal conductivity was recorded up to 1.14 W/m.K for Al2O3@TiO2-ZnO/DW ternary composite nanofluids with 0.1 wt% at 45 °C, which increases by 69% compared to the base fluid. The overall average and local heat transfer/Nusselt numbers were noticed to improve with an increase in wt% of all metal oxide nanoparticles and Reynolds numbers (Re) under constant heat flux conditions in the circular heat exchanger. The highest heat transfer coefficient was recorded for Al2O3@TiO2-ZnO/DW ternary composite nanofluids at 0.1 wt% up to 3200 W/m2K for the highest Reynold (Re) numbers, which increases by 79% compared to the base fluid (DW). At 0.075 wt% the heat transfer enhancement was 2272 W/m2K, similarly, at 0.05 wt% the heat transfer was 2150 W/m2K while at 0.025 wt% the enhancement was 1950 W/m2K which is more than base fluid (DW). This enhancement is credited to the composite of nanoparticles with different shapes and particle sizes. The experimental results showed that the metal oxide-based new ternary composites nanofluids enhanced the thermophysical and heat transfer properties, hence, it is a suitable choice for enhanced energy transportation.

中文翻译：

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超声辅助新型 Al2O3@TiO2-ZnO/DW 三元复合纳米流体增强封闭水平圆形流道中的能量传输

摘要 通过实验研究了单锅声化学辅助新型Al2O3@TiO2-ZnO/DW基三元复合纳米流体在恒定热通量边界条件下在封闭圆形换热器中的湍流传热生长。两步简便的纳米流体制备方法用于制备新的三元混合纳米流体。进行 UV-Vis 和 FESEM 分析以确认所有纳米粒子的吸光度和均匀分散。在均匀热通量条件下，Al2O3@TiO2-ZnO/DW 基三元复合纳米流体在 0.1、0.075、0.05 和 0.025 wt% 时显示传热系数 (h) 和努塞尔数 (Nu) 随雷诺数的增加呈正增长（ Re) 编号从 5849 到 24,544，不使用任何表面活性剂。记录的有效热导率的最大增加高达 1.14 W/m。Al2O3@TiO2-ZnO/DW 三元复合纳米流体的 K 在 45°C 下为 0.1 wt%，与基液相比增加了 69%。注意到整体平均和局部传热/努塞尔数随着所有金属氧化物纳米粒子的 wt% 和雷诺数 (Re) 的增加而改善，在循环换热器中的恒定热通量条件下。Al2O3@TiO2-ZnO/DW 三元复合纳米流体的最高传热系数记录为 0.1 wt% 至 3200 W/m2K，最高雷诺 (Re) 数，与基础流体 (DW) 相比增加了 79% . 在 0.075 wt% 时，传热增强为 2272 W/m2K，类似地，在 0.05 wt% 时，传热为 2150 W/m2K，而在 0.025 wt% 时，传热增强为 1950 W/m2K，高于基础流体 (DW)。这种增强归功于具有不同形状和粒径的纳米粒子的复合材料。实验结果表明，基于金属氧化物的新型三元复合纳米流体增强了热物理和传热性能，是增强能量传输的合适选择。