CFD analysis on the spatial effect of vortex generators in concentric tube heat exchangers – A comparative study. (November 2022) - Aridi, Rima
Highlights: Heat transfer enhancement using a trapezoidal vortex generator in a Concentric Tube Heat Exchanger. Computational Fluid Dynamics (CFD) code ANSYS Fluent is used. Heat transfer and fluid flow analysis are conducted for various Reynolds numbers inside the tube and annular. Results show that Vortex generators are effective in all locations and cases. Enhancement of heat transfer ratios up to 97% and thermal enhancement factor up to 210% are obtained. Abstract: The present article is discussing the performance of heat transfer enhancement (HTE) using a trapezoidal vortex generator in a Concentric Tube Heat Exchanger (CTHE) through Computational Fluid Dynamics (CFD) code ANSYS Fluent. Heat transfer and fluid flow analysis are conducted for various Reynolds numbers inside the tube and annular. The effects of Vortex Generators (VGs) are studied as well, and the turbulence flow is simulated using the k-ꞷ model. The analysis was made on four designs, where the VGs are placed in three different locations as follows: (case 0) no VGs, (case 1) VGs inside the tube, (case 2) VGs on the interface between annular and tube, and (case 3) VGs on the outer wall of the annular part. Accordingly, the overall heat transfer, heat transfer ratio, and heat transfer/power of each of the three cases with VGs are normalized to case 0 to study the effect of VGs on the flow and heat transfer enhancement. Results show that VGs are effective in all locations and cases, however, the highest improvement was spotted in case 1 at Reynolds number of 8000 for the cold fluid and Reynolds number of 2000 for the hot water, where the enhancement of heat transfer ratio was 97% for case 1, 92% for case 2 and 56% for case 3, whereas the thermal enhancement factor was 210% for case 1, 180% for case 2 and 142% for case 3.