Influence of inlet contraction ratios on the heat transfer and pressure drop characteristics of single-phase flow in smooth circular tubes in the transitional flow regime

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dc.contributor.author Bashir, Abubakar Idris
dc.contributor.author Everts, Marilize
dc.contributor.author Meyer, Josua P.
dc.date.accessioned 2019-11-07T07:08:36Z
dc.date.issued 2019-12
dc.description.abstract An experimental investigation of the single-phase heat transfer and pressure drop characteristics in the transitional flow regime has been performed using flow-calming sections with different inlet geometries and section-to-tube inlet contraction ratios. Four different types of inlets were investigated namely a square-edged, re-entrant, a hydrodynamically fully developed inlet, and a 90° bend inlet. The contraction ratios for the squared-edged and re-entrant inlets were 5, 11, 15 and 33. For the hydrodynamically fully developed inlet and the 90° bend inlet, a contraction ratio of one was used. Experiments were conducted using a circular test section with an inner diameter of 5.1 mm, at a Reynolds number range of 1000–6000 to ensure that the laminar, transitional, quasi-turbulent and turbulent flow regimes were covered. Water was used as the working fluid and the test section was heated at constant wall heat fluxes of 4, 6 and 8 kW/m2. It was found that for a square-edged inlet geometry, the transition from the laminar to the turbulent flow regimes occurred earlier as the inlet contraction ratio increased, while for the re-entrant inlet, transition was delayed. The transitional flow regime was significantly affected by smaller contraction ratios and this effect increased with increasing heat flux. However, it was found that the critical Reynolds numbers were independent of inlet geometry for contraction ratios larger than 33. For the 90° bend inlet, transition occurred earlier than all the other inlet geometries and contraction ratios. en_ZA
dc.description.department Mechanical and Aeronautical Engineering en_ZA
dc.description.embargo 2020-12-01
dc.description.librarian hj2019 en_ZA
dc.description.sponsorship The Department of Science and Technology (DST) in South Africa and Bayero University Kano in Nigeria. en_ZA
dc.description.uri http://www.elsevier.com/locate/etfs en_ZA
dc.identifier.citation Bashir, A.I., Everts, M. & Meyer, J.P. 2019, 'Influence of inlet contraction ratios on the heat transfer and pressure drop characteristics of single-phase flow in smooth circular tubes in the transitional flow regime', Experimental Thermal and Fluid Science, vol. 109, art. 109892, pp. 1-16. en_ZA
dc.identifier.issn 0894-1777
dc.identifier.other 10.1016/j.expthermflusci.2019.109892
dc.identifier.uri http://hdl.handle.net/2263/72159
dc.language.iso en en_ZA
dc.publisher Elsevier en_ZA
dc.rights © 2019 Elsevier Inc. All rights reserved. Notice : this is the author’s version of a work that was accepted for publication in Experimental Thermal and Fluid Science. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. A definitive version was subsequently published in Experimental Thermal and Fluid Science, vol. 109, art. 109892, pp. 1-16, 2019. doi : 10.1016/j.expthermflusci.2019.109892. en_ZA
dc.subject Square-edged inlet en_ZA
dc.subject Re-entrant inlet en_ZA
dc.subject Flow-calming section en_ZA
dc.subject Contraction ratio en_ZA
dc.subject Pressure drop en_ZA
dc.subject Heat transfer en_ZA
dc.subject Transitional flow regime en_ZA
dc.subject Elbow en_ZA
dc.title Influence of inlet contraction ratios on the heat transfer and pressure drop characteristics of single-phase flow in smooth circular tubes in the transitional flow regime en_ZA
dc.type Postprint Article en_ZA


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