Can Natural Convection on Smooth Vertical Plates in the Laminar Regime be Improved by Adding Forward Facing Triangular Roughness Elements?

Research output: Contribution to book/anthology/report/conference proceedingArticle in proceedingResearchpeer-review

Abstract

Vertical smooth surfaces are commonly used for transferring heat by natural convection. Many studies have tried altering smooth surfaces in various ways to increase heat transfer. Many of these studies fail to increase global heat transfer. The problem commonly reported is dead zones appearing just upstream and downstream obstructions that effectively decrease wall temperature gradients normal to the surface. In this study, we simulate how changes geometry of forward facing triangular roughness elements affect local and global heat transfer for isothermal plates. We change the aspect ratio of the triangular elements from L/h = 5 to L/h = 40 at Grashof numbers of Gr L = 8.0 · 10 4 and Gr L = 6.4 · 10 5. In all cases the flow remains laminar. Even when accounting for the increase in surface area, we keep observing a decrease in global heat transfer compared to the smooth vertical plate. However, the results show by carefully selecting the aspect ratio and pitch distance of the triangular elements based on the Grashof number, the dead zone behind the horizontal part can be eliminated thereby significantly increasing local heat transfer. This observation could help to improve cooling of electronics with high localised heat fluxes.

Original languageEnglish
Title of host publicationProceedings of the ASME - JSME - KSME Joint Fluids Engineering Conference 2019 : Fluid Mechanics
Number of pages7
Volume1
PublisherAmerican Society of Mechanical Engineers
Publication dateJul 2019
Pages1-7
ISBN (Electronic)978-0-7918-5902-5
DOIs
Publication statusPublished - Jul 2019
EventASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference - San Francisco, United States
Duration: 28 Jul 20191 Aug 2019

Conference

ConferenceASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference
CountryUnited States
CitySan Francisco
Period28/07/201901/08/2019

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  • Cite this

    Hærvig, J., Jensen, A. L., & Sørensen, H. (2019). Can Natural Convection on Smooth Vertical Plates in the Laminar Regime be Improved by Adding Forward Facing Triangular Roughness Elements? In Proceedings of the ASME - JSME - KSME Joint Fluids Engineering Conference 2019: Fluid Mechanics (Vol. 1, pp. 1-7). American Society of Mechanical Engineers. https://doi.org/10.1115/AJKFluids2019-5441