Natural convective heat transfer characteristics of Al2O3-water nanofluids in a vertical cylindrical enclosure
The present numerical investigation deals with the natural convection in a vertical cylindrical enclosure with a water-based Al2O3 nanofluids. The enclosure with an aspect ratio of 1 (= diameter / height) is filled with Al2O3-water nanofluids or pure water. These fluids are isothermally heated from...
| Main Authors: | , , |
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| Format: | Article |
| Language: | Japanese |
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The Japan Society of Mechanical Engineers
2020-03-01
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| Series: | Nihon Kikai Gakkai ronbunshu |
| Subjects: | |
| Online Access: | https://www.jstage.jst.go.jp/article/transjsme/86/883/86_19-00358/_pdf/-char/en |
| _version_ | 1797989015162454016 |
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| author | Masato AKAMATSU Kanji SUZUKI Mitsuo IWAMOTO |
| author_facet | Masato AKAMATSU Kanji SUZUKI Mitsuo IWAMOTO |
| author_sort | Masato AKAMATSU |
| collection | DOAJ |
| description | The present numerical investigation deals with the natural convection in a vertical cylindrical enclosure with a water-based Al2O3 nanofluids. The enclosure with an aspect ratio of 1 (= diameter / height) is filled with Al2O3-water nanofluids or pure water. These fluids are isothermally heated from below and cooled from above, while the sidewall is thermally insulated. Both fluids are assumed to be Newtonian and incompressible, with laminar flows. In addition, Al2O3-water nanofluids are assumed to be a single-phase (homogeneous) fluid, due to the extremely tiny particles and very low volume fraction of the suspended nanoparticles, even though nanofluids are a mixture in which nanoparticles are dispersed in a base fluid. Thermophysical properties of Al2O3-water nanofluids are estimated by the experimental correlation equations reported by Khanafer and Vafai. The main objective of this numerical investigation is to clarify the influences of the reference temperature, the nanoparticle diameter, the volume fraction of Al2O3 nanoparticles, and the Rayleigh number on the convective heat transfer of the one-sided natural convection of Al2O3-water nanofluids induced in the enclosure. Transient three-dimensional numerical results are presented over a wide range of reference temperatures (θ0 = 293.15, 303.15, 313.15 K), nanoparticle diameters (dp = 25, 50, 100 nm) , volume fractions of Al2O3 nanoparticles ( φp = 0 - 0.04), and Rayleigh numbers (Ra = 104, 105). Furthermore, the convective heat transfer characteristics of the unique one-sided natural convections of Al2O3-water nanofluids and water are presented by the average Nusselt number, isotherms, and particle paths. Comparison between the one-sided natural convection of Al2O3-water nanofluids and that of water shows that the deterioration of the natural convective heat transfer of Al2O3-water nanofluids is observed with the decrease of the nanoparticle diameter and with the increase of the volume fraction of Al2O3 nanoparticles under three different reference temperatures and two different Rayleigh numbers. However, the degree of deterioration depends on the reference temperature and the Rayleigh number. |
| first_indexed | 2024-04-11T08:12:15Z |
| format | Article |
| id | doaj.art-38909497f27749e1b8a420f9adc28ebb |
| institution | Directory Open Access Journal |
| issn | 2187-9761 |
| language | Japanese |
| last_indexed | 2024-04-11T08:12:15Z |
| publishDate | 2020-03-01 |
| publisher | The Japan Society of Mechanical Engineers |
| record_format | Article |
| series | Nihon Kikai Gakkai ronbunshu |
| spelling | doaj.art-38909497f27749e1b8a420f9adc28ebb2022-12-22T04:35:16ZjpnThe Japan Society of Mechanical EngineersNihon Kikai Gakkai ronbunshu2187-97612020-03-018688319-0035819-0035810.1299/transjsme.19-00358transjsmeNatural convective heat transfer characteristics of Al2O3-water nanofluids in a vertical cylindrical enclosureMasato AKAMATSU0Kanji SUZUKI1Mitsuo IWAMOTO2Graduate School of Science and Engineering, Yamagata UniversityDepartment of Mechanical Systems Engineering, Yamagata UniversityDepartment of Mechanical and Energy Systems Engineering, Oita UniversityThe present numerical investigation deals with the natural convection in a vertical cylindrical enclosure with a water-based Al2O3 nanofluids. The enclosure with an aspect ratio of 1 (= diameter / height) is filled with Al2O3-water nanofluids or pure water. These fluids are isothermally heated from below and cooled from above, while the sidewall is thermally insulated. Both fluids are assumed to be Newtonian and incompressible, with laminar flows. In addition, Al2O3-water nanofluids are assumed to be a single-phase (homogeneous) fluid, due to the extremely tiny particles and very low volume fraction of the suspended nanoparticles, even though nanofluids are a mixture in which nanoparticles are dispersed in a base fluid. Thermophysical properties of Al2O3-water nanofluids are estimated by the experimental correlation equations reported by Khanafer and Vafai. The main objective of this numerical investigation is to clarify the influences of the reference temperature, the nanoparticle diameter, the volume fraction of Al2O3 nanoparticles, and the Rayleigh number on the convective heat transfer of the one-sided natural convection of Al2O3-water nanofluids induced in the enclosure. Transient three-dimensional numerical results are presented over a wide range of reference temperatures (θ0 = 293.15, 303.15, 313.15 K), nanoparticle diameters (dp = 25, 50, 100 nm) , volume fractions of Al2O3 nanoparticles ( φp = 0 - 0.04), and Rayleigh numbers (Ra = 104, 105). Furthermore, the convective heat transfer characteristics of the unique one-sided natural convections of Al2O3-water nanofluids and water are presented by the average Nusselt number, isotherms, and particle paths. Comparison between the one-sided natural convection of Al2O3-water nanofluids and that of water shows that the deterioration of the natural convective heat transfer of Al2O3-water nanofluids is observed with the decrease of the nanoparticle diameter and with the increase of the volume fraction of Al2O3 nanoparticles under three different reference temperatures and two different Rayleigh numbers. However, the degree of deterioration depends on the reference temperature and the Rayleigh number.https://www.jstage.jst.go.jp/article/transjsme/86/883/86_19-00358/_pdf/-char/ennanofluidsal2o3waternatural convectionthermophysical properties3d simulation |
| spellingShingle | Masato AKAMATSU Kanji SUZUKI Mitsuo IWAMOTO Natural convective heat transfer characteristics of Al2O3-water nanofluids in a vertical cylindrical enclosure Nihon Kikai Gakkai ronbunshu nanofluids al2o3 water natural convection thermophysical properties 3d simulation |
| title | Natural convective heat transfer characteristics of Al2O3-water nanofluids in a vertical cylindrical enclosure |
| title_full | Natural convective heat transfer characteristics of Al2O3-water nanofluids in a vertical cylindrical enclosure |
| title_fullStr | Natural convective heat transfer characteristics of Al2O3-water nanofluids in a vertical cylindrical enclosure |
| title_full_unstemmed | Natural convective heat transfer characteristics of Al2O3-water nanofluids in a vertical cylindrical enclosure |
| title_short | Natural convective heat transfer characteristics of Al2O3-water nanofluids in a vertical cylindrical enclosure |
| title_sort | natural convective heat transfer characteristics of al2o3 water nanofluids in a vertical cylindrical enclosure |
| topic | nanofluids al2o3 water natural convection thermophysical properties 3d simulation |
| url | https://www.jstage.jst.go.jp/article/transjsme/86/883/86_19-00358/_pdf/-char/en |
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