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The current study summarizes previous studies carried out on heat convection, fluid flow, and entropy generation of porous enclosures filled with hybrid/nanofluid. Newtonian and non-Newtonian base fluids and

The conjugate natural convection heat transfer in a partially heated square porous enclosure had been studied numerically. The governing dimensionless equations are solved using COMSOL Multiphysics and Darcy model assumed to be used. The considering dimensionless parameters are modified Rayleigh number, finite wall thickness, thermal conductivity ratio and the heat source length. The results are presented in terms of streamlines, isotherms and local and average Nusselt number. The results indicate that; the heat transfer can be enhanced by increasing the modified Rayleigh number. When the heat source length increases, the local Nusselt number of fluid phase increases, while, a reverse behavior of the local Nusselt number along the heat source is found. As the Rayleigh number increase, the local Nusselt number for both fluid and solid phase increases, therefore, the heat transfer rate will be enhanced. On the other hand, when the thermal conductivity ratio increase, the local Nusselt number for the fluid phase increases, and the local Nusselt number along the heated wall decreases.

The mixed convective heat transfer has many multiple engineering applications, such as solar collectors, electronic equipment cooling and heat exchanger, and geothermal engineering. This work presents comprehensive coverage of a wide range of published studies in terms of convection heat transfer inside the enclosure in recent years. The convective heat transfer in porous media with/without nanofluid, and the effect of stationary/rotating cylinder inside cavities, as well as the position of the cylinder, had been addressed and discuss to draw the main conclusions and recommendations. It is worthy to mention that the mixed convective with the effect of entropy generation with inner bodies in enclosure has been investigated less than the other simple enclosure shapes due to its complexity. The researchers can be extended their future studies by adding the MHD effects with mixed conviction in simple/complex shapes of enclosure. This study gives an important and useful summary for provides researchers of heat transfer in academic and industrial. At the end of this investigation, the governing equations of the 2-D mixed convection in an enclosure filled with porous medium, and nanofluid addressed.

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The conjugate natural convection heat transfer in a partially heated porous enclosure had been studied numerically. The governing dimensionless equations are solved using finite element method. Classical Darcy model have been used and the considering dimensionless parameters are modified Rayleigh number (10 ≤ Ra ≤ 10 3), finite wall thickness (0.02 ≤ D ≤ 0.5), thermal conductivity ratio (0.1 ≤ Kr ≤ 10), and the aspect ratio (0.5 ≤ A≤ 10). The results are presented in terms of streamlines, isotherms and local and average Nusselt number. The results indicate that heat transfer can be enhanced by increasing the modified Rayleigh number, and thermal conductivity ratio. Wall thickness effects on the heat transfer mechanism had been studied and it is found that; as the Wall thickness increases, the conduction heat transfer mechanism will be dominated. Also, increasing aspect ratio will increase the stream function and reduced the heat transfer rate.