Flow in curved pipes have been considered as a well-known technique of passive enhancement of heat transfer rate. However, there exists a lack of research considering the impact of geometrical modifications on heat transfer properties of spiral coils. In the present study, thermal and hydrodynamic behavior of the flow in spirally coiled tubes equipped with longitudinal internal fins are numerically studied. Steady three dimensional flow of water is simulated. The geometrical parameters in the present study include fin number, fin height, and fin width. Results reveal that for the spirals with a pair of horizontal fins, the increase in fin protrusion leads to PEC as high as 2.99. However, inappropriate orientation of longitudinal fins severely deteriorates the heat absorption capability of the spiral while imposing excessive pressure drop. This inefficiency is attributed to the disruption in formation of Dean vortices due to the presence of radial bumps. Thus, four-fin and three-fin configurations are generally inefficient. Changing the fin orientation in the two-fin geometries from horizontal to vertical lead to a similar inefficiency with the PEC falling as low as 0.24. Finally, the effect of local curvature on the thermal behavior of the spiral tube is investigated.

弯管中的流动已被认为是被动提高传热速率的一种众所周知的技术。然而，缺乏考虑几何形状修改对螺旋线圈的传热特性的影响的研究。在本研究中，对装有纵向内部翅片的螺旋盘管内流动的热和流体动力学行为进行了数值研究。稳定的三维水流被模拟。本研究中的几何参数包括鳍片数量，鳍片高度和鳍片宽度。结果表明，对于带有一对水平鳍片的螺旋而言，鳍片突出的增加导致PEC高达2.99。然而，纵向翅片的不适当取向严重地恶化了螺旋的吸热能力，同时施加了过多的压降。这种低效率归因于由于径向隆起的存在而破坏了迪安涡旋的形成。因此，四鳍和三鳍配置通常效率低下。将两翅片几何形状中的翅片方向从水平更改为垂直会导致效率低下，PEC降至0.24。最后，研究了局部曲率对螺旋管热性能的影响。