International Journal of Thermofluids (Nov 2023)
Performance enhancement of fin and tube heat exchanger employing curved delta winglet vortex generator with circular punched holes
Abstract
The generation of vortices has recently gained attention as a potential passive technique for improving air-side heat transfer in a fin and tube heat exchanger. This study proposes novel configurations of a curved delta winglet vortex generator (CDWVG) with and without circular holes to improve heat transfer in FTHEs. The present study utilizes a three-dimensional numerical analysis to investigate the thermal-hydraulic performance analysis of fin and tube heat exchanger (FTHE) with curved delta winglet vortex generators (CDWVG) with or without circular holes, operating across a wide Reynolds number range (i.e., from 400 to 2000). In addition to being arranged in vertical and horizontal configurations, the CDWVGs are oriented in the same way as the flow direction. Therefore, the pressure distribution, temperature distribution, and flow structure distribution of an FTHE with a four-in-line circular tube configuration are analyzed and compared between FTHE without vortex generator (VG) and five different configurations of CDWVG (i.e., CDWVG without hole, CDWVG with 1 hole, CDWVG with 2 holes, CDWVG with 3 holes and CDWVG with 6 holes). The pressure drop (ΔP), London area goodness factor (LAGF) (j/f), Nusselt number (Nu), and Colburn factor (j) are also used to evaluate the thermo-hydraulic performance of FTHE. The FHTE performance with CDWVGs can be affected by the number of punched holes, which is evaluated using a dimensionless number including Performance Evaluation Criteria (PEC), Colburn factor, etc. The thermo-hydraulic efficiency of the FTHE is improved significantly by using CDWVGs with circular punched holes. Nusselt number decreases across all the VG configurations (i.e., CDWVG without hole, CDWVG with 1 hole, CDWVG with 2 holes, CDWVG with 3 holes, and CDWVG with 6 holes) due to the lower flow resistance. Compared to other CDWVG configurations, the 6-hole configuration of CDWVG is the most effective. The Nusselt number of CDWVG with 6 holes increases by 77.25% and 42.51% at Reynolds numbers of 400 and 2000, with respect to fin and tube heat exchangers without vortex generator, respectively. On the other hand, friction is decreased by 5.11%. Therefore, when considering the London area goodness factor, CDWVG with six holes is found to be superior to other CDWVG configurations.
