Investigate the influence of dimple distribution around the circumference of a pipe on the hydrothermal performance of dimpled tubes

Abstract The current study aims to investigate the impact of the dimple distribution around the circumference of a pipe on the hydrothermal performance of dimpled tubes under turbulent flow conditions. This study focused on examining the effect of the dimple distribution around the diameter of the pipe for three angles, namely, 45°, 60°, and 90°, as well as develop two correlation equations to predict Nu number and friction factor to make calculating the hydrothermal response easier for such systems. To accomplish this, we conducted a comprehensive numerical investigation using the ANSYS Fluent 2022 R1 software. The range of Re numbers from 2300 to 10,000 was considered, and water was employed as the cooling fluid. The study found that tubes with dimples offer an increased surface area for heat transfer, resulting in improved heat transfer performance. All the proposed models showed superior heat transfer compared with traditional models. The model with a 45° angle showed the most significant enhancement in the Nu number, approximately twice the value of the traditional model. The average friction factor for the 45° angle was 0.0713 K/W, compared with the traditional model's 0.0418 K/W. Additionally, the average performance criteria for Model 45°, 60°, and 90° are 1.1, 1.21, and 1.28, respectively. In addition, two equations were developed that can be utilized to predict the friction factor and Nu number. These equations are functions of the Reynolds number, Prandtl number, and the angle between dimples encircling the tube. Notably, these equations exhibited exceptional accuracy, achieving a remarkable prediction accuracy of 98.96% and 96.17% for the Nu number and the friction factor, respectively.