Natural Convection Heat Transfer from an Isothermal Plate
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thermo-03-00010-v2.pdf
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568.67 KB
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93d014a290d60e71983b0789f69a70fa
Author(s)
Jaffer, Aubrey
Date Issued
February 3, 2023
Publisher
Multidisciplinary Digital Publishing Institute
Citation
Thermo 3 (1): 148-175 (2023)
Version
Final published version
Abstract
Using boundary-layer theory, natural convection heat transfer formulas that are accurate over a wide range of Rayleigh numbers (Ra) were developed in the 1970s and 1980s for vertical and downward-facing plates. A comprehensive formula for upward-facing plates remained unsolved because they do not form conventional boundary-layers. From the thermodynamic constraints on heat-engine efficiency, the novel approach presented here derives formulas for natural convection heat transfer from isothermal plates. The union of four peer-reviewed data-sets spanning 1<Ra<1012 has 5.4% root-mean-squared relative error (RMSRE) from the new upward-facing heat transfer formula. Applied to downward-facing plates, this novel approach outperforms the Schulenberg (1985) formula’s 4.6% RMSRE with 3.8% on four peer-reviewed data-sets spanning 106<Ra<1012. The introduction of the harmonic mean as the characteristic length metric for vertical and downward-facing plates extends those rectangular plate formulas to other convex shapes, achieving 3.8% RMSRE on vertical disk convection from Hassani and Hollands (1987) and 3.2% from Kobus and Wedekind (1995).
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Creative Commons Attribution
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DOI of Published Version
https://doi.org/10.3390/thermo3010010
