Abstract The heat transfer coefficients and friction factor for SiO2 – ethylene glycol/water (50 wt%) nanofluids, with the SiO2 particle diameter ranging from 100 to 1000 nm, and particle weight concentration ranging up to 10%, were measured for flow in a circular tube under constant temperature boundary conditions. The measurements were performed under turbulent flow conditions, wherein the temperature at the entrance of the test section was 353.15 K. Both the heat transfer coefficient and friction factor of the SiO2 nanofluids are higher than those of the ethylene glycol/water system. The heat transfer coefficient of the SiO2 nanofluids increases with particle concentration up to 7 wt% and saturates thereafter. Interestingly, the heat transfer coefficient of the SiO2 nanofluids depends on the particle diameter and it attains maximum value at the diameter of 300 nm and solid fraction of 7 wt%. The heat transfer coefficient of SiO2 nanofluids increases by up to 25% as compared with that of the ethylene glycol/water solution. Additionally, a new correlation formula is proposed to correlate the Nusselt numbers and the Reynolds numbers for the SiO2 nanofluids.

中文翻译：

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乙二醇/水纳米流体中分散的SiO2颗粒异常增强对流传热

摘要 测量了 SiO2-乙二醇/水 (50 wt%) 纳米流体的传热系数和摩擦系数，SiO2 粒径范围为 100 至 1000 nm，颗粒重量浓度范围为 10%，在恒温边界条件下的圆管。测量在湍流条件下进行，其中测试段入口处的温度为353.15 K。SiO2纳米流体的传热系数和摩擦系数均高于乙二醇/水系统。SiO2 纳米流体的传热系数随颗粒浓度增加至 7 wt% 并在此后饱和。有趣的是，SiO2 纳米流体的传热系数取决于粒径，在直径为 300 nm 和固体分数为 7 wt% 时达到最大值。与乙二醇/水溶液相比，SiO2 纳米流体的传热系数提高了 25%。此外，提出了一个新的相关公式来关联 SiO2 纳米流体的努塞尔数和雷诺数。