Optimized entropy analysis of unsteady electromagnetic Powell–Eyring hybrid nanofluid flow over an inclined surface for solar water heating applications

Abstract Enhancing thermal and mass transport in solar water heating systems is critical for improving their operational efficiency and sustainability. This study presents a comprehensive numerical and statistical analysis of unsteady magnetohydrodynamic Powell–Eyring hybrid nanofluid flow over an inclined stretching sheet, targeting its application in solar thermal energy systems. The hybrid nanofluid consists of multiwall carbon nanotubes and silicon dioxide nanoparticles dispersed in a water base fluid, selected for their superior thermal conductivity and stability. The flow is modelled as two‐dimensional, incompressible, and subjected to electromagnetic effects, incorporating Soret and Dufour phenomena to capture coupled heat and mass transfer mechanisms. The governing nonlinear partial differential equations are solved using the finite element method, while multiple linear regression analysis is employed to quantify the sensitivity of unsteadiness, porosity, and magnetic field strength on system performance indicators. The results reveal that skin friction increases with higher unsteadiness but decreases with increasing porosity and magnetic field intensity. Heat transfer, characterized by the Nusselt number, is significantly enhanced in the presence of unsteadiness, Dufour number, and thermal radiation. Similarly, mass transfer, represented by the Sherwood number, is predominantly influenced by the Schmidt number, Soret number, and solutal Biot number. Quantitatively, the proposed hybrid nanofluid model demonstrates a 23.26% enhancement in heat transfer and a 17.64% improvement in mass transfer compared to the conventional single‐phase nanofluid. These findings establish the hybrid model as a promising candidate for optimizing solar water heating applications through improved thermofluidic performance.