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标题：Heat transfer enhancement of free surface MHD-flow by the wall with non-uniform electrical conductivity
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作者：H. L. Huang ; B. Li
期刊名称：International Journal of Energy and Environment
印刷版ISSN：2076-2895
电子版ISSN：2076-2909
出版年度：2010
卷号：1
期号：6
页码：1027-1038
出版社：International Energy and Environment Foundation (IEEF)
摘要：Due to the Magnetohydrodynamic (MHD) effect, which degrades heat transfer coefficients by pulsation suppression of external magnetic field, on the electrically conducting flow, the wall with non-uniform electrical conductivity is employed in a free surface MHD-flow system for heat transfer enhancement. The non-uniform electrical conductivity distribution of the channel wall may create alternate Lorentz forces along spanwise direction, which can effectively produce flow disturbance, promote mixture, reduce the thickness of boundary layer, and enhance heat transfer. So the heat transfer performances enhanced by some conducting strips aligned with the mean flow direction on the insulating wall of free surface MHD-flow are simulated numerically in this paper. The flow behaviors, heat transfer coefficients, friction factors and pressure drops are presented under different Hartmann numbers. Results show that, in the range of Hartmann numbers 30≤Ha≤100, the wall with non-uniform conductivity can achieve heat transfer enhancements (Nu/Nu0) of about 1.2 to 1.6 relative to the insulating wall, with negligible friction augmentation. This research indicates that the modules with three or five conducting strips can obtain better enhancement effect in our research. Particularly, the heat transfer augmentation increases monotonically with increasing Hartmann numbers. Therefore, the enhancement purpose for high Hartman number MHD-flow is marked, which may remedy the depressing heat transfer coefficients by MHD effect.