Abstract The enhancement mechanism on the heat transfer coefficient of SiO2 nanofluid compared to the ethylene glycol/water solvent was investigated by means of synchrotron x–ray radiographic imaging at 300.15 K. The experimental results showed a low concentration of local particles near the wall in the channel cross–section. This anomalous particle distribution alters the flow velocity distribution. Based on the law of conservation of momentum, the thickness of the thermal boundary layer becomes thin in the nanofluid, consequently enhancing the convective heat transfer. The thickness of the thermal boundary layer in the nanofluid based on the particle distribution visualized from x–ray imaging depends on the particle diameter, and its dependency is consistent with the magnitude relation of the heat transfer coefficient.

中文翻译：

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纳米流体增强对流传热机理——基于同步辐射成像的分析

摘要 通过 300.15 K 同步辐射 X 射线成像研究了 SiO2 纳米流体与乙二醇/水溶剂相比传热系数的增强机制。通道横截面。这种异常的粒子分布改变了流速分布。根据动量守恒定律，纳米流体中的热边界层厚度变薄，从而增强了对流传热。基于 X 射线成像可视化的粒子分布，纳米流体中热边界层的厚度取决于粒径，其依赖性与传热系数的大小关系一致。