Magnetohydrodynamic thermal analysis of Cu-Fe ₃ O ₄ /engine-oil hybrid nanofluid for thermal management in hydrogen energy systems

Thermal management remains a critical challenge in contemporary energy and hydrogen-based energy systems, especially when considering fuel cells, hydrogen compressors, and compact heat exchangers in which high temperatures decrease efficiency and reliability. Motivated by the combined effects of thermophysical properties, non-Newtonian rheology, particulate contamination, porous resistance, and magnetic control, this study investigates MHD flow of an engine-oil-based Cu-Fe ₃ O ₄ hybrid nanofluid through an inclined porous channel. Cu enhances thermal transport, while Fe ₃ O ₄ enables magnetic control of the flow. The study considers an unsteady two-phase dusty Casson fluid model between inclined parallel plates under the influence of a relative magnetic field, taken to be fixed either with respect to the fluid (MFFRF) or with respect to the plate (MFFRP). Additionally, porous medium resistance, thermal radiation, and internal heat generation are incorporated to represent practical thermal systems. The governing momentum and energy equations are solved analytically using the Poincaré-Lighthill perturbation technique (PLPT). Thermal and flow characteristics are evaluated using engineering performance indicators, namely the skin-friction coefficient and the Nusselt number. From the results, it is observed that the heat transfer rate of the hybrid nanofluids is higher than that of the mono-nanofluids and conventional engine oil. When the volume fraction of the nanoparticles varies from 0.01 to 0.04, the value of the Nusselt number varies from 2.10 to 2.80 for the conventional oil, from 2.18 to 3.11 for the Cu nanofluid, and from 2.64 to 3.94 for the Cu-Fe ₃ O ₄ hybrid nanofluid, showing a growth of 25.71%–40.71%. Lorentz braking and Darcy resistance suppress momentum transport, whereas buoyancy and channel inclination enhance convective heat transfer. The results can prove useful for designing magnetically controlled cooling passages and heat-exchanging devices for use in hydrogen fuel cell cooling, hydrogen compressors, and other hydrogen energy systems.