Abstract The present study investigates the thermo-fluid characteristics of a double pipe heat exchanger (DPHX) with split longitudinal fins (SLF) on the annulus side. The studied tubes with SLF are a modification of the conventional longitudinal finned tubes (LF) that allows for consecutive surface interruptions to break the boundary layer and provide an interrupted fluid passage along the flow length. The study is conducted using a high Prandtl number fluid (engine oil) with variable thermo-physical properties. Three-dimensional computational fluid dynamics (CFD) simulations are carried out under laminar flow conditions for configurations with a fin split interval between 0.333 and 0.166 m. A comparative analysis of the SLF configurations against the reference LF configuration is conducted based on fluid flow, heat transfer rate, and required pumping power. Furthermore, by evaluating integrated quantities such as the axially local heat transfer coefficient, total pressure, and bulk fluid temperature, it is noted that the main advantage of SLF is to repeat an entrance region-like effect along the flow length. The results demonstrate that the heat transfer rates in annulus equipped with SLF are higher than those with conventional LF by 31%–48% for the same pumping power and unit weight.

中文翻译：

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在双管换热器中使用表面中断增强翅片环的性能

摘要 本研究研究了在环空侧具有分裂纵向翅片 (SLF) 的双管换热器 (DPHX) 的热流体特性。所研究的具有 SLF 的管是对传统纵向翅片管 (LF) 的改进，它允许连续的表面中断以破坏边界层并沿流动长度提供中断的流体通道。该研究使用具有可变热物理特性的高普朗特数流体（发动机油）进行。三维计算流体动力学 (CFD) 模拟在层流条件下进行，用于翅片分裂间隔在 0.333 和 0.166 m 之间的配置。SLF 配置与参考 LF 配置的比较分析是基于流体流量、传热率、和所需的泵送功率。此外，通过评估轴向局部传热系数、总压力和整体流体温度等积分量，注意到 SLF 的主要优点是沿流动长度重复入口区域效应。结果表明，在相同的泵送功率和单位重量下，配备 SLF 的环空的传热率比配备传统 LF 的环空高 31%–48%。