Mechanika
86 (1/14), DOI: 10.7862/rm.2014.12
Determining heat transfer correlations for transition and turbulent flow in ducts
Dawid Taler, Jan Taler
DOI: 10.7862/rm.2014.12
Abstract
The objective of the paper is to develop correlations for the Nusselt number Nu in terms of the friction factor ξ (Re) and also Reynolds number Re and Prandtl number Re, which is valid for transitional and fully developed turbulent flow. After solving the equations of conservation of momentum and the energy for turbulent flow in a circular tube subject to a uniform heat flux, the Nusselt number values were calculated for different values of Reynolds and Prandtl numbers. Then, the form of the correlation Nu = f (Re, Pr) was selected which approximates the results obtained in the following ranges of Reynolds and Prandtl numbers: 2300 ≤ Re ≤ 1000000, 0.1 ≤ Pr ≤ 1000. The form of the correlation was selected in such a way that for the Reynolds number equals to Re=2300, i.e. at the point of transition from laminar to transitional flow the Nusselt number should change continuously. Unknown coefficients x1, …, xn appearing in the heat transfer correlation expressing the Nusselt number as a function of the Reynolds number and Prandtl number were determined by the method of least squares. To determine the values of the coefficients at which the sum of the difference squares is a minimum, the Levenberg-Marquardt method is used.
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About this Article
TITLE:
Determining heat transfer correlations for transition and turbulent flow in ducts
AUTHORS:
Dawid Taler (1)
Jan Taler (2)
AUTHORS AFFILIATIONS:
(1) Cracow University of Technology, ul. Warszawska 24, 31-155 Kraków
(2) Cracow University of Technology, ul. Warszawska 24, 31-155 Kraków
JOURNAL:
Mechanika
86 (1/14)
KEY WORDS AND PHRASES:
tube flow, heat transfer, coefficient of friction, correlation for the Nusselt number, transition and turbulent flow
FULL TEXT:
http://doi.prz.edu.pl/pl/pdf/mechanika/73
DOI:
10.7862/rm.2014.12
URL:
http://dx.doi.org/10.7862/rm.2014.12
RECEIVED:
2014-05-15
COPYRIGHT:
Publishing House of Rzeszow University of Technology Powstańców Warszawy 12, 35-959 Rzeszow