Heat Transfer in Circular Pipe Fitted with Perforated Trapezoidal Vortex Generators

Abstract

Numerical simulations are carried out to infer the heat transfer performances of perforated trapezoidal vortex generators (PTVG) in a turbulent regime, for Reynolds numbers ranging from 7500 to 15000. The flow geometry consists of a circular pipe fitted with seven arrays of perforated tabs, similarly, arranged as in the high efficiency vortex static mixer (HEV™) used in the industry. Four configurations using the PTVG are studied, differing by the flow direction, direct or inverse, and the arrangement of the tab arrays, aligned or alternate. The flow pattern shows the presence of primary pair of counter-rotating streamwise vortices at the tip of the tabs, as well as smaller secondary vortices near the wall region, well-known as the main transfer intensification mechanism. The perforation in the tab generates a jet-like flow structure which penetrates the dead zone behind the tabs and therefore, locally enhances the heat transfer and the global performance of the device. It is found that the heat transfer relative to empty pipe is enhanced from 40 to 80%, for the same pumping power. The new proposed PTVG exhibits better performance than classical HEV™, especially for Reynolds numbers greater than 10,000. This study is fundamental for highlighting the effect of perforating the vortex generators on heat transfer performance. Moreover, the novel PTVG would be of great benefit to enhance commercial multifunctional heat exchangers/reactors.

Additional information

Notes on contributors

Charbel Habchi

Charbel Habchi is an Assistant Professor of Mechanical Engineering at Notre Dame University-Louaize (NDU). He is member of the Thermofluids Research Group at NDU since 2015. He obtained his Mechanical Engineering Degree in 2007 from the Lebanese University (Lebanon). In 2010, he earned his PhD in thermal and fluid sciences from the University of Nantes (France). His current research activities focus on heat transfer and mixing enhancement, flow instabilities, magneto-hydrodynamic flows, bioheat modeling and machine learning for optimization problems. He has published more than 50 papers in peer-reviewed journals and more than 50 papers in international conferences and has served as a reviewer for more than 15 international journals.

Thierry Lemenand

Thierry Lemenand obtained a Master’s Degree in Engineering from the Ecole Normale Supérieure (ENS, France) in 1999 and a PhD in Fluid Mechanics and Energy from the University of Nantes, France in 2002. He was an Assistant Professor since 2002 and became an Associate Professor in 2012 at Polytech Angers of the University of Angers (France). Currently, he is a researcher at LARIS laboratory. He has been involved in fundamental and applied research in mixing and heat transfer intensification, complex turbulent and laminar flows, two-phase flows, vorticity generator in static mixers, chemical probe to characterize mixing, laminar chaotic advection, pulsating flows, and multifunctional heat exchangers/reactors. He has published more than 50 papers in peer-reviewed journals and more than 60 papers in international conferences and has served as a reviewer for more than 15 international journals.

Dominique Della Valle

Dominique Della Valle is an Associate Professor at the Food Process Engineering Department of ONIRIS, Nantes (France), with expertise in fluid mechanics and rheology. Her research focuses on transfers phenomena in complex flows, mixing, heat transfer intensification, energetic efficiency, and multiphasic food systems, with applications on baking and foams manufacturing. She is coauthor of 60 papers in peer-reviewed journals.

Hassan Peerhossaini

Hassan Peerhossaini is Distinguished Professor of Fluid Mechanics and Heat Transfer at the University of Paris (France) where he has founded and chaired the Paris Interdisciplinary Energy Research Institute (PIERI). He is also Western Research Chair in Urban Resilience and Sustainability, and the director of Mechanics of Active Fluids and Bacterial Physics Lab in the University of Western Ontario, London, (Canada). His research focuses on the physics of active matter, physics of turbulence in reactive flows, hydrodynamic stability and transition to turbulence, convective heat transfer, heat transfer and process intensification, energy efficiency, bio-resourced energy, and on chaotic advection and its technological applications. His research interests lie also in interdisciplinary approach to energy and urban climate change adaptation and its social and economic impacts. He is the author of more than 500 publications.