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This study deals with a numerical investigation of conjugate heat transfer phenomena in a porous enclosure subjected to magnetic field with internal heat generation/absorption. The physical domain of the numerical model encompasses a vertical annulus with a thick inner cylinder wall, where the porous annular region is saturated with an aqueous-MWCNT nanofluid. In this model, the momentum equation includes the non-Darcy viscous terms and additional body term to accurately represent the influence of porous media and magnetic fields on the flow behavior. To estimate conjugate heat transfer phenomena, the energy conservation equations for the solid wall and the fluid-saturated porous region are solved simultaneously. The finite difference technique is used to solve the non-dimensionalized governing equations, and validated against existing studies. Using the proposed model, a series of numerical calculations is performed for various parameters including Hartmann number (Ha = 0 ∼ 50) , Darcy number (Da = 10 - 5 ∼ 10 - 1) , thermal conductivity ratio (Kr = 0.1 ∼ 10) , dimensionless solid wall thickness (ε = 0.1 ∼ 0.5) , nanoparticle concentration (ϕ = 0 ∼ 0.05) , and dimensionless internal heat generation/absorption rate (Q = - 10 ∼ 10) . The numerical results reveal that a significant improvement in thermal transport can be achieved by increasing either Da or Kr: An increment in Da from 10 - 5 to 10 - 1 , for example, results in 95.6% increase in the flow circulation rate. Either a decrease in Q or an increase in ϕ also contributes to enhancing the heat dissipation rate. For instance, there is a 16.6% reduction in heat dissipation rate for internal heat generation (Q = 10) case compared to internal heat absorption (Q = - 10) case. On the other hand, an increase in either Ha or ε results in a suppression in flow and heat transport. Among the considered range of parameters, greater heat dissipation could be obtained for Da = 10 - 1 , Kr = 10, ε = 0.1 , and Ha < 10 . These findings can expand our understanding of natural circulation and heat transfer within the fluid-filled enclosures and serve as building block for efficient thermal design guidelines in diverse applications. [ABSTRACT FROM AUTHOR]

The primary challenge in the majority of heat transfer applications, in view of design perspective, is to maximize the thermal transport with the minimum generation of entropy. This paper addresses the numerical investigation of buoyant convection and entropy generation processes of Al2O3–water nanofluid inside a vertical annular configuration having two coaxial cylinders. The vertical cylindrical surfaces are imposed with sinusoidal thermal distribution having different phase deviation and amplitude, while the horizontal surfaces are retained adiabatic. In this analysis, the numerical computations of conservation equations governing the physical process are performed using the time‐splitting technique and line overrelaxation methods. Detailed numerical simulations are performed for broad ranges of critical parameters, such as Rayleigh number, phase deviation, amplitude ratio, and nanoparticle volume fraction. From the vast numerical experiments, we systematically identified the suitable parameter regimes at which enhanced thermal transport has been produced with minimum entropy generation. Furthermore, the critical quantities, such as thermal dissipation and entropy generation, could be effectively monitored by a particular selection of phase deviation (γ) and amplitude ratio (ε). It has been identified that these parameters have more influence on thermal transport as well as entropy production as compared to other parameters of the analysis. [ABSTRACT FROM AUTHOR]