Evaluation of Vortex Generators in the Heat Transfer Improvement of Airflow through an In-Line Heated Tube Arrangement

Abstract

Improving heat transfer from surface to airflow is a current research concern for enhancing energy efficiency. The use of vortex generators for improving heat transfer from the surface to the airflow is very effective. Therefore, this study focuses on applying flat and concave vortex generators with and without holes in order to improve heat transfer. In this study, the number of pairs of vortex generators was varied from one to three pairs at a certain angle of attack for various forms of vortex generators. The airflow velocity through the duct was varied in the range of 0.4 to 2.0 m/s at 0.2 m/s intervals. From the investigation results, we observed that the highest thermal performance was found with the use of concave delta winglets without holes for various pairs of vortex generators in terms of the overall Reynolds number. The highest thermal enhancement factor was found to be around 1.42 at a Reynolds number of approximately 9000. From this study, it was also shown that the lowest cost–benefit ratio was about 1.75 at a Reynolds number of approximately 3500 for three pairs of vortex generators.

Numerical Investigation of Heat Transfer Enhancement in Circular Channel with Variation in Angle of Delta-Winglet Vortex Generator

“…The 90° DW VG appears to have the highest pressure drop. This reflects the temperature contour shown in Figure 11 (a), as an increase in heat transfer can lead to a high pressure drop along the flow [26,27]. This confirms that the LV produced by the DW VGs is highest at an angle of 90°, which is corroborated by the velocity vectors shown in Figure 9 (a) which have the highest velocity.…”