Evaluation of hydraulic thermal flow and heat performance augmentation in a 3D tube fitted with varying concavity dimple turbulator configurations

Abstract

AbstractEnhanced pipe surfaces offer greater heat transfer enhancement due to increased turbulence levels, leading to improved heat exchange performance. This study combines numerical simulations and experimental work to identify the best geometric design of enhanced tubes for thermal–hydraulic performance, flow structure, and pressure drop, and the simulations are validated with experimental data. Water is a working fluid with Reynolds numbers ranging from 4000 to 15,000, q = 25,500 W/m2, and an inlet temperature of 298 K with constant fluid property, steady state, and no‐slip condition. The three‐dimensional steady incompressible turbulent flow in the concavity dimpled shape‐enhanced tubes is numerically studied. This research found that pipes with a concave shape transfer heat most effectively. The overall heat transfer is significantly influenced by the shape of the dimples, their arrangement in rings, the size of these rings, and the number of rings. However, the number of cylindrical dimples does not seem to impact heat transfer much. The increase in heat transfer performance was by 9.8%–61% for dimple rings = 2ring performed best compared with a smooth pipe and by 8.21%–38.49% at the effect of ring numbers as grouping, also the dimple ring diameters by 5%–38% and by 7%–39% at dimple numbers. The performance evaluation factor (PEF) assesses overall performance by considering both the pressure drop penalty and improved heat transfer. The optimal configuration achieving the highest performance (PEF = 1.295) at a flow rate (Re) of 4000 involves a single dimple ring with a 2‐mm diameter, spaced 10‐mm apart, containing four dimples. Furthermore, discussing the different parameters of thermal and hydraulic performances to obtain the best thermal performance, and increasing the number and size of dimples gives a better guide for engineering to obtain better thermohydraulic performances for heat exchangers.