Abstract In view of the heat transfer deterioration of supercritical CO2 under the condition of low mass flow rate and high heat flux, the influence of Body-Centred Cubic (BCC) lattice, Kagome lattice and Pin-fin structure on the heat transfer of supercritical CO2 in rectangular channels were investigated in this article. The results showed that all the three structures can generate arch-shaped vortices near the wall, which increases the wall shear stress and the fluid turbulence intensity, promotes the full mixing of the mainstream and the near-wall fluid, and weakens the heat transfer deterioration. In addition, there was obvious longitudinal vortices distributed between adjacent lattices, which increases the turbulence intensity of the mainstream, facilitates the mixing of high and low speed fluids, so as to improve the heat transfer rate of supercritical CO2 channel and reduce the heat transfer deterioration. In the vertical upward channel, the buoyancy reduces the turbulence intensity of the near-wall fluid and the shear stress of wall, and results in the heat transfer deterioration. In the horizontal channel, the buoyancy leads high-density fluid to settle, thus enhances the turbulence intensity of the fluid near the down-wall surface, and intensifies the heat transfer of the down-wall surface.

中文翻译：

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晶格结构对矩形通道超临界CO2传热劣化的影响

摘要 针对超临​​界 CO2 在低质量流量和高热通量条件下的传热劣化，体心立方 (BCC) 晶格、Kagome 晶格和 Pin-fin 结构对超临界 CO2 传热的影响在这篇文章中研究了矩形通道。结果表明，三种结构均能在壁面附近产生拱形涡流，增加壁面剪应力和流体湍流强度，促进主流与近壁面流体充分混合，减弱传热劣化. 此外，相邻晶格之间分布着明显的纵向涡流，增加了主流的湍流强度，有利于高低速流体的混合，从而提高超临界CO2通道的传热速率，减少传热劣化。在垂直向上的通道中，浮力降低了近壁流体的湍流强度和壁面的剪应力，导致传热恶化。在水平通道中，浮力导致高密度流体沉降，从而增强了下壁面附近流体的湍流强度，加强了下壁面的传热。