Entropy Generation Analysis and Optimization of Cooling Strategies Using Nano-Encapsulated Phase Change Materials in an Oblique-Vented Porous Chamber for Renewable Energy Applications: A Response Surface Methodology Approach

Normalization of entropy generation provides a dimensionless and physically consistent framework for comparing irreversibility mechanisms under different operating conditions, while log-space third-order polynomial regression enables accurate representation of nonlinear coupled transport behavior over wide parameter ranges. Accordingly, this study investigates entropy generation associated with double-diffusive mixed convection in an oblique vented chamber filled with a nano-encapsulated phase change material suspension under local thermal non-equilibrium (LTNE) conditions in a porous medium. The governing equations are formulated by incorporating the effects of inlet and outlet sizes through the Reynolds number to provide a more realistic representation of the physical configuration. The dimensionless governing equations are discretized using the finite volume method based on the control-volume approach. The resulting entropy generation, heat transfer, and mass transfer characteristics, including the average fluid Nusselt and Sherwood numbers, are normalized and correlated using log-space third-order polynomial regression models. An effective RSM approach is employed to perform a sensitivity analysis of the key operating parameters. The results reveal that, for all inlet and outlet configurations, the normalized average fluid Nusselt number increases with increasing nanoparticle volume fraction. Moreover, both the normalized average Sherwood number and normalized fluid entropy generation increase with the Soret coefficient, demonstrating its pronounced influence on double-diffusive transport and irreversibility within the LTNE porous chamber.