Effects of using nanofluid, applying a magnetic field, and placing turbulators in channels on the convective heat transfer: A comprehensive review

Recent studies in the field of thermal engineering revealed that employing nanofluid as a working fluid in a specific channel, considering both turbulators and magnetic field effect is scarce. Studies on the convective heat transfer performance of the thermal systems focus mostly on the effect of using either nanofluid as a new fluid, magnetic field, or turbulators. This review highlights the single and combined effects of these parameters on the heat transfer enhancement of such systems. Nanofluid type, its volume fraction, channel and turbulator geometry, magnetic field type, and flow regime were considered as the base parameters while the enhancement in heat transfer is evaluated. From a state-of-the-art review, it was noticed that most studies reveal that increasing the volume fraction of nanofluid, magnetic field strength, and Reynolds number can attain an upsurge in the heat transfer in a specific channel. Nevertheless, drawbacks are poorly discussed in the open literature. Regarding the turbulator geometry, which actually limits the magnetohydrodynamic and thermal boundary layer development, its complexity boosts also the convective heat transfer. The maximum heat transfer enhancement was noticed for higher nanoparticle volume fractions, higher magnetic field strengths, and complex geometries in channel flow. The highest heat transfer improvement was obtained for the MWCNT/H2O nanofluid (i.e., between 70% and 190%). With the effect of magnetic field intensity of Ha = 30 applied to the Cu/H2O nanofluid flow, a thermal recovery of 76% was achieved. Concluding, this comprehensive review can be beneficial to researchers working in the field of flow and heat transfer applications with the use of nanofluid, turbulator, and magnetic field together.