On the Numerical Investigation of Natural-Convection Heat Sinks Across a Wide Range of Flow and Operating Conditions
Many designs for natural-convection heat sinks and semi-empirical correlations have been proposed in the recent years, but they are only valid in a limited range of Elenbaas numbers <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><...
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| author | Louis Dewilde Syed Mughees Ali Rajesh Nimmagadda Tim Persoons |
| author_facet | Louis Dewilde Syed Mughees Ali Rajesh Nimmagadda Tim Persoons |
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| description | Many designs for natural-convection heat sinks and semi-empirical correlations have been proposed in the recent years, but they are only valid in a limited range of Elenbaas numbers <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>E</mi><mi>l</mi></mrow></semantics></math></inline-formula> and were mostly tested for laminar flows. To alleviate those limits, parametric studies with 2D and quasi-3D models were carried out, in ranges of Grashof numbers up to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1.55</mn><mo>×</mo><msup><mn>10</mn><mn>11</mn></msup></mrow></semantics></math></inline-formula> and Elenbaas numbers up to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>3.42</mn><mo>×</mo><msup><mn>10</mn><mn>7</mn></msup></mrow></semantics></math></inline-formula>. Ansys Fluent’s laminar, transition-SST, SST k-<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>ω</mi></semantics></math></inline-formula> and k-<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>ϵ</mi></semantics></math></inline-formula> models were applied. In addition, when used in this valid range, i.e., mean Elenbaas numbers, with the simplified quasi-3D model, the transition-SST model could predict better results, overestimating the heat flux by 10 to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>15</mn><mo>%</mo></mrow></semantics></math></inline-formula> compared to semi-empirical correlations. The 2D model was not deemed satisfying, regarding turbulence models. Consequently, a quasi-3D model was developed: it appeared to be an efficient trade-off between computational time and prediction accuracy, in particular for turbulence models. New grouping factors were also found, to ensure proper dimensioning of natural-convection heat sinks. They corresponded to non-dimensional parameters that dictated the physical behaviour of the heat sink with respect to the semi-empirical correlations. Typically, the ratio of the spacing to the optimal spacing predicted by Bar-Cohen’s correlation turned out to be an appropriate grouping factor with a threshold of 1, above which the fins could safely be considered as isolated, thus greatly simplifying all further calculations. |
| format | Article |
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| spelling | doaj-art-89dce064f0cc45bf95c596ae2ff3ced12025-08-20T01:53:44ZengMDPI AGFluids2311-55212024-10-0191125210.3390/fluids9110252On the Numerical Investigation of Natural-Convection Heat Sinks Across a Wide Range of Flow and Operating ConditionsLouis Dewilde0Syed Mughees Ali1Rajesh Nimmagadda2Tim Persoons3Department of Mechanical, Manufacturing & Biomedical Engineering, Trinity College, University of Dublin, D02 PN40 Dublin, IrelandDepartment of Mechanical, Manufacturing & Biomedical Engineering, Trinity College, University of Dublin, D02 PN40 Dublin, IrelandDepartment of Mechanical, Manufacturing & Biomedical Engineering, Trinity College, University of Dublin, D02 PN40 Dublin, IrelandDepartment of Mechanical, Manufacturing & Biomedical Engineering, Trinity College, University of Dublin, D02 PN40 Dublin, IrelandMany designs for natural-convection heat sinks and semi-empirical correlations have been proposed in the recent years, but they are only valid in a limited range of Elenbaas numbers <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>E</mi><mi>l</mi></mrow></semantics></math></inline-formula> and were mostly tested for laminar flows. To alleviate those limits, parametric studies with 2D and quasi-3D models were carried out, in ranges of Grashof numbers up to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1.55</mn><mo>×</mo><msup><mn>10</mn><mn>11</mn></msup></mrow></semantics></math></inline-formula> and Elenbaas numbers up to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>3.42</mn><mo>×</mo><msup><mn>10</mn><mn>7</mn></msup></mrow></semantics></math></inline-formula>. Ansys Fluent’s laminar, transition-SST, SST k-<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>ω</mi></semantics></math></inline-formula> and k-<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>ϵ</mi></semantics></math></inline-formula> models were applied. In addition, when used in this valid range, i.e., mean Elenbaas numbers, with the simplified quasi-3D model, the transition-SST model could predict better results, overestimating the heat flux by 10 to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>15</mn><mo>%</mo></mrow></semantics></math></inline-formula> compared to semi-empirical correlations. The 2D model was not deemed satisfying, regarding turbulence models. Consequently, a quasi-3D model was developed: it appeared to be an efficient trade-off between computational time and prediction accuracy, in particular for turbulence models. New grouping factors were also found, to ensure proper dimensioning of natural-convection heat sinks. They corresponded to non-dimensional parameters that dictated the physical behaviour of the heat sink with respect to the semi-empirical correlations. Typically, the ratio of the spacing to the optimal spacing predicted by Bar-Cohen’s correlation turned out to be an appropriate grouping factor with a threshold of 1, above which the fins could safely be considered as isolated, thus greatly simplifying all further calculations.https://www.mdpi.com/2311-5521/9/11/252natural convectionheat sinkturbulence modellingcomputational fluid dynamicselectronics cooling |
| spellingShingle | Louis Dewilde Syed Mughees Ali Rajesh Nimmagadda Tim Persoons On the Numerical Investigation of Natural-Convection Heat Sinks Across a Wide Range of Flow and Operating Conditions Fluids natural convection heat sink turbulence modelling computational fluid dynamics electronics cooling |
| title | On the Numerical Investigation of Natural-Convection Heat Sinks Across a Wide Range of Flow and Operating Conditions |
| title_full | On the Numerical Investigation of Natural-Convection Heat Sinks Across a Wide Range of Flow and Operating Conditions |
| title_fullStr | On the Numerical Investigation of Natural-Convection Heat Sinks Across a Wide Range of Flow and Operating Conditions |
| title_full_unstemmed | On the Numerical Investigation of Natural-Convection Heat Sinks Across a Wide Range of Flow and Operating Conditions |
| title_short | On the Numerical Investigation of Natural-Convection Heat Sinks Across a Wide Range of Flow and Operating Conditions |
| title_sort | on the numerical investigation of natural convection heat sinks across a wide range of flow and operating conditions |
| topic | natural convection heat sink turbulence modelling computational fluid dynamics electronics cooling |
| url | https://www.mdpi.com/2311-5521/9/11/252 |
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