Thermally Developing Forced Convection of Non-Newtonian Fluids Inside Elliptical Ducts

Maia, Cássio Roberto Macedo; Aparecido, J. B.; Milanez, Luiz Fernando

doi:10.1080/01457630490495805

Cited by 11 publications

(2 citation statements)

References 9 publications

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“…The results confirmed the Nusselt number enhancement, predicted before theoretically by Javeri (1976). Maia et al (2004, 2006) investigated the thermal development of laminar power-law fluid flow in elliptical duct subjected to a constant wall heat flux (Maia et al , 2004) and constant wall temperature (Maia et al , 2006).…”

Section: Introductionsupporting

confidence: 82%

“…To verify the validity of the proposed numerical solution and the selected mesh, comparisons with literature were made in terms of local Nusselt number for different geometrical configurations and working conditions (Shah and London, 1978b; Cotta and Özişik, 1986; Maia et al , 2004; Pozzi and Lupo, 1990). Table IV presents the numerical values of the local Nusselt number at different axial locations.…”

Section: Resultsmentioning

confidence: 99%

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Numerical investigation of laminar forced convection for a non-Newtonian nanofluids flowing inside an elliptical duct under convective boundary condition

Ragueb

Mansouri

2019

HFF

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Purpose The purpose of this study is to investigate the thermal response of the laminar non-Newtonian fluid flow in elliptical duct subjected to a third-kind boundary condition with a particular interest to a non-Newtonian nanofluid case. The effects of Biot number, aspect ratio and fluid flow behavior index on the heat transfer have been examined carefully. Design/methodology/approach First, the mathematical problem has been formulated in dimensionless form, and then the curvilinear elliptical coordinates transform is applied to transform the original elliptical shape of the duct to an equivalent rectangular numerical domain. This transformation has been adopted to overcome the inherent mathematical deficiency due to the dependence of the ellipsis contour on the variables x and y. The yielded problem has been successfully solved using the dynamic alternating direction implicit method. With the available temperature field, several parameters have been computed for the analysis purpose such as bulk temperature, Nusselt number and heat transfer coefficient. Findings The results showed that the use of elliptical duct enhances significantly the heat transfer coefficient and reduces the duct’s length needed to achieve the thermal equilibrium. For some cases, the reduction in the duct’s length can reach almost 50 per cent compared to the circular pipe. In addition, the analysis of the non-Newtonian nanofluid case showed that the addition of nanoparticles to the base fluid improves the heat transfer coefficient up to 25 per cent. The combination of using an elliptical duct and the addition of nanoparticles has a spectacular effect on the overall heat transfer coefficient with an enhancement of 50-70 per cent. From the engineering applications view, the results demonstrate the potential of elliptical duct in building light-weighted compact shell-and-tube heat exchangers. Originality/value A complete investigation of the heat transfer of a fully developed laminar flow of power law fluids in elliptical ducts subject to the convective boundary condition with application to non-Newtonian nanofluids is addressed.

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