Comparative performance study of active magnetic regenerative system using mono/hybrid nanofluids

This study presents a comparative numerical analysis of an active magnetic regenerative (AMR) system using Al₂O₃ nanofluids, multi-walled carbon nanotube (MWCNT) nanofluids, and hybrid nanofluids composed of a 50–50 % mixture of Al₂O₃ and MWCNT, with volume concentrations ranging from 0–1 %. In the hybrid nanofluid, the concentration of each component (Al₂O₃ and MWCNT) is equal and ranges from 0–0.5 % to make up the total concentration. Results indicate that nanofluid density increases with nanoparticle concentration, enhancing mass and fluid dynamics, while specific heat capacity decreases, impacting heat storage. Thermal conductivity improves with higher nanoparticle concentration, benefiting heat transfer, but viscosity increases, affecting fluid resistance and pumping power. MWCNT nanofluids, particularly at 1.0 %, exhibit superior cooling performance, achieving the lowest temperatures and enhancing cooling efficiency by about 42.4 % compared to water. They also show the best improvement in temperature span (5.2 %) and the highest increase in cooling capacity (51.3 %) and COP (37.0 %). Hybrid Al₂O₃+MWCNT nanofluids also show considerable improvements, highlighting their potential for advanced thermal management. These findings underscore the potential of MWCNT nanofluids to significantly enhance AMR system performance.