Experimental study on the thermal performance of hybrid nanofluid in a compact plate heat exchanger under the influence of a magnetic field

This study presents an experimental investigation into the thermal and hydrodynamic performance of a compact plate heat exchanger utilizing Fe 3 O 4 /water and Fe 3 O 4 –Cu/water hybrid nanofluids under the influence of an externally applied magnetic field (0.46 T). The effects of nanoparticle concentration, hybrid nanoparticle composition, and flow conditions on heat exchanger effectiveness and convective heat transfer were analyzed under laminar flow conditions (172 ≤ Re ≤ 400). The results indicate that while nanofluids enhance overall heat exchanger effectiveness compared to water, the effectiveness increased by up to 20 % for hybrid nanofluids in the absence of a magnetic field. However, the application of a magnetic field reduced effectiveness by up to 15 %. Similarly, the Nusselt number decreased by up to 12 % and the convective heat transfer coefficient declined by up to 10 % with increasing nanoparticle concentration, with higher concentrations (1.0 %) causing greater reductions due to elevated viscosity and suppressed flow mixing. The application of a magnetic field further reduces convective heat transfer performance by approximately 6–8 % for hybrid nanofluids, likely due to nanoparticle retention and local velocity reduction caused by the Lorentz force. These findings provide insights into optimizing nanofluid-based heat exchanger systems, emphasizing the need for careful selection of nanoparticle composition and magnetic field parameters to balance heat transfer performance and flow efficiency.