Entropy generation of viscous dissipative flow in thermal non-equilibrium porous media with thermal asymmetries

Chee YS, Ting TW, Hung YM, Energy 89 (2015) 382e401, 2015

The effect of thermal asymmetrical boundaries on entropy generation of viscous dissipative flow of
forced convection in thermal non-equilibrium porous media is analytically studied. The two-dimensional
temperature, Nusselt number and entropy generation contours are analysed comprehensively to provide
insights into the underlying physical significance of the effect on entropy generation. By incorporating
the effects of viscous dissipation and thermal non-equilibrium, the first-law and second-law characteristics
of porous-medium flow are investigated via various pertinent parameters, i.e. heat flux ratio,
effective thermal conductivity ratio, Darcy number, Biot number and averaged fluid velocity. For the case
of symmetrical wall heat flux, an optimum condition with a high Nusselt number and a low entropy
generation is identified at a Darcy number of 104, providing an ideal operating condition from the
second-law aspect. This type of heat and fluid transport in porous media covers a wide range of engineering
applications, involving porous insulation, packed-bed catalytic process in nuclear reactors,
filtration transpiration cooling, and modelling of transport phenomena of microchannel heat sinks.

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