COMPUTATIONAL ANALYSIS OF INSERTED POROUS BLOCKS INTO HORIZONTAL CONCENTRIC ANNULI IN MIXED CONVECTION MODE

Year 2018, , 1692 - 1701, 12.12.2017

Yacine Ould-amer

https://doi.org/10.18186/journal-of-thermal-engineering.364958

Abstract

This study numerically investigates
the effect of porous blocks thickness on laminar mixed convection in a horizontal
annulus. With attached four porous blocks on the inner cylinder, steady 3D
laminar mixed convection is presented for the fully developed region of
horizontal concentric annuli.

Results are presented for two values
of porous blocks thickness and a range of the values of the Grashoff number,
Darcy number and the conductivity ratio between the porous medium and the fluid.
Results are presented in the form of contours plots of the streamlines and for
the temperature isotherms, and in terms of the overall heat transfer
coefficients and friction factor.

The average Nusselt number increases
significantly with an increase of the thickness of porous blocks. With the use
of the four porous blocks, the friction factor is consequently increased
compared with the situation without porous blocks. The decrease of the Darcy
number leads to an increase of the friction factor. 

If the fully fluid case is taken as
a reference, the use of porous blocks is justified only when the ratio of the
average Nusselt number to the friction factor is enhanced.

Keywords

Renewable Mixed Convection, Concentric Annuli, Porous, Thickness

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