Natural Convection over a Non-Isothermal Vertical Flat Plate in Supercritical Fluids

Authors

1 Department of Mechanical Engineering,Ferdowsi University of Mashhad

2 Department of Engineering,Ferdowsi University of Mashhad

Abstract

In many applications, convection heat transfer is coupled with conduction and radiation
heat transfer, which generate temperature gradients along the walls and may greatly a ect natural
convection heat transfer. The main objective of this study is to calculate the heat-transfer characteristics
for natural convection from a non-isothermal vertical
at plate into a supercritical
uid. The in
uence
of the non-uniformity of wall temperature on the heat transfer by natural convection along a vertical
plate, having a linearly distributed temperature (characterized by the slope S) is also investigated.
The thermal expansion coecient is considered as a function of the temperature, the pressure, the
van der Waals constants and the compressibility factor. The trends of the curves obtained with this
equation and with values from tables of thermodynamic properties were similar and diverged at a critical
point. These features con rmed the validity of this equation. Then, the governing systems of partial
di erential equations are solved numerically using the nite di erence method. The local Nusselt number
was then calculated and plotted as a function of the local Rayleigh number. It was observed that a
positive slope of temperature distribution increases the heat transfer rate and a negative slope decreases
it.

Keywords

Scientia Iranica
Volume 16, Issue 6 - Serial Number 6
Transactions on Mechanical Engineering (B)
December 2009

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