Numerical study on mechanisms underlying the heat transfer enhancement of upward supercritical CO2 flow at low Reynolds numbers near the pseudo-critical region through a microtube

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dc.contributor.authorBayrak, Ergin
dc.contributor.authorAhn, Hojin
dc.date.accessioned2026-01-24T12:31:10Z
dc.date.available2026-01-24T12:31:10Z
dc.date.issued2025
dc.departmentAlanya Alaaddin Keykubat Üniversitesi
dc.description.abstractThe buoyancy and thermal acceleration effects of supercritical CO2 flow near the pseudo-critical region have been widely mentioned as the mechanism of heat transfer enhancement in the literature. However, most publications deal with turbulent flows and do not discuss the details of how these effects alter flow structure and enhance heat transfer. The present study numerically investigated mechanisms underlying the heat transfer enhancement of upward supercritical CO2 flow through a microtube, 0.5 mm in diameter, at low Reynolds numbers. The heat transfer enhancement was closely associated with the appearance and disappearance of the M-shaped velocity profile. When the M-shaped profile started forming by the buoyancy effect, the first local maximum of the heat transfer coefficient appeared as the thermal acceleration of the boundary layer entrained fluid from the wall region. The fluid entrainment carried thermal energy from the wall toward the core, thus enhancing the heat transfer. When the M-shaped profile started disappearing due to the thermal acceleration in the core region, the second maximum appeared in some cases due to abrupt turbulence developed by two forces in the opposite direction: one force dragging the local maximum velocity in the M-shaped profile and the other force accelerating the core region.
dc.description.sponsorshipScientific and Technological Research Council of Turkey (TUBITAK) [122M862]
dc.description.sponsorshipThis work was supported by The Scientific and Technological Research Council of Turkey (TUBITAK) [grant number 122M862] . The work has been conducted in partial fulfillment of the Ph.D. degree requirements at the Mechanical Engineering Department of Yeditepe University in Istanbul, Turkey, by the first author under the supervision of the second author.
dc.identifier.doi10.1016/j.icheatmasstransfer.2025.108995
dc.identifier.issn0735-1933
dc.identifier.issn1879-0178
dc.identifier.scopus2-s2.0-105003754078
dc.identifier.scopusqualityQ1
dc.identifier.urihttps://doi.org/10.1016/j.icheatmasstransfer.2025.108995
dc.identifier.urihttps://hdl.handle.net/20.500.12868/5703
dc.identifier.volume165
dc.identifier.wosWOS:001494302000001
dc.identifier.wosqualityQ1
dc.indekslendigikaynakWeb of Science
dc.indekslendigikaynakScopus
dc.language.isoen
dc.publisherPergamon-Elsevier Science Ltd
dc.relation.ispartofInternational Communications in Heat and Mass Transfer
dc.relation.publicationcategoryMakale - Uluslararası Hakemli Dergi - Kurum Öğretim Elemanı
dc.rightsinfo:eu-repo/semantics/closedAccess
dc.snmzKA_WoS_20260121
dc.subjectSupercritical CO2
dc.subjectLaminar
dc.subjectUpward flow
dc.subjectThermal acceleration
dc.subjectBuoyancy
dc.subjectMicrotube
dc.titleNumerical study on mechanisms underlying the heat transfer enhancement of upward supercritical CO2 flow at low Reynolds numbers near the pseudo-critical region through a microtube
dc.typeArticle

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