In this paper, the enhanced heat transfer performance and mechanism of a multi-tube heat exchanger (MTHX) with outward helically corrugated tubes (HCTs) are investigated by a numerical approach. Three types of tube arrangement (circle, square and triangle, indicated as CTA, STA and TSA, respectively) and four different tube spacings (1.25, 1.375, 1.5 and 1.625) are compared for Reynolds (Re) number ranging from 8900 to 89,400. Details of the coupled relationship among the multiple spiral detached vortices and turbulent pulsations are presented to explore the complex flow features. In addition, the variation trends of the average Nusselt number, friction factor, and performance index (PEC) are compared to obtain the optimum geometry parameter of the MTHX with HCTs. The results show that the rotational flow with opposite direction presents a strong overlay effect, and the circumferential velocity can reach up to 20% of the mean velocity. The non-directional turbulent pulsation only presents an overlap and strengthening effect. Besides, the secondary flow causes better heat transfer in the sub-layers, the turbulent pulsation has better heat transfer between the sub-layer and main flow region, while the rotational flow has a minor inhibiting effect on heat transfer performance. The TTA presents better interaction at the intervals of the tubes, and the Nu, f and PEC index of the TTA are all outstanding compared to the CTA and STA. The SL/Φ_t = 1.375–1.5 of the MTHX-TTA are suggested from the findings, and the Re should not exceed 40, 000.

本文通过数值方法研究了带有向外螺旋波纹管（HCT）的多管热交换器（MTHX）的增强的传热性能和机理。比较了三种类型的试管布置（圆形，正方形和三角形，分别表示为CTA，STA和TSA）和四种不同的试管间距（1.25、1.375、1.5和1.625），雷诺数（Re）为8900至89,400。提出了多个螺旋分离涡与湍流脉动之间耦合关系的详细信息，以探索复杂的流动特征。此外，比较了平均努塞尔数，摩擦系数和性能指数（PEC）的变化趋势，从而获得了带有HCT的MTHX的最佳几何参数。结果表明，相反方向的旋转流具有较强的叠加效果，圆周速度可达平均速度的20％。无方向性湍流脉动仅表现出重叠和强化作用。此外，二次流在子层中引起更好的传热，湍流脉动在子层和主流区域之间具有更好的传热，而旋转流对传热性能的抑制作用较小。TTA在管子的间隔处表现出更好的相互作用，并且 湍流脉动在子层和主流区域之间具有更好的热传递，而旋转流对热传递性能的抑制作用较小。TTA在管子的间隔处表现出更好的相互作用，并且 湍流脉动在子层和主流区域之间具有更好的热传递，而旋转流对热传递性能的抑制作用较小。TTA在管子的间隔处表现出更好的相互作用，并且与CTA和STA相比，TTA的Nu，f和PEC指数都非常出色。的SL / Φ_吨 的MTHX-TTA的= 1.375-1.5从发现表明，与RE不应超过40，000。