微通道扁管H型金字塔翅片通道内层流流动与强化传热特性

Laminar Flow and Enhanced Heat Transfer Characteristics in a Microchannel Flat Tube Channel with H-Shaped Pyramid Fins

摘要: 本文提出一种新型H型金字塔翅片，以平行流扁管微通道换热器为研究对象，系统分析金字塔翅片与传统平直翅片的空气侧层流流动及传热特性差异。结果表明，金字塔翅片通过周期性凸起结构在流道内诱导出强烈的二次流与局部涡旋，有效破坏热边界层，显著提升局部对流换热系数。在所研究的雷诺数范围内，金字塔翅片的平均努塞尔数较平直翅片提高明显，综合热性能评价因子JF始终大于1，表明其传热强化收益超过阻力增加代价。二次流强度分布与局部换热系数分布高度一致，揭示了涡旋结构对强化传热的本质作用。本研究为微通道换热器翅片结构的优化设计及CO₂热泵系统的高效运行提供了理论依据与技术支撑。

Abstract: The paper proposes a novel H-shaped pyramid fin. Taking a parallel-flow flat-tube microchannel heat exchanger as the research object, a systematic analysis is conducted on the differences in air-side laminar flow and heat transfer characteristics between the pyramid fin and the traditional plain fin. The results show that the periodic protrusion structure of the pyramid fin induces strong secondary flows and local vortices within the flow channel, effectively disrupting the thermal boundary layer and significantly enhancing the local convective heat transfer coefficient. Within the investigated Reynolds number range, the average Nusselt number of the pyramid fin is considerably higher than that of the plain fin, and the comprehensive thermal performance evaluation factor JF consistently exceeds 1, indicating that the benefits of heat transfer enhancement outweigh the penalty of increased flow resistance. The distribution of secondary flow intensity is highly consistent with that of the local heat transfer coefficient, revealing the essential mechanism by which vortex structures enhance heat transfer. This study provides a theoretical basis and technical support for the structural optimization of microchannel heat exchanger fins and the efficient operation of CO₂ heat pump systems.