Thermophysical properties of magnetic nanofluids under effects of magnetic field-a review on mechanisms and studies

Magnetic nanofluids play a crucial role in enhancing thermal properties, providing a promising pathway for optimizing energy supply systems and improving heat transfer efficiency. Beyond advanced thermal management, these innovative fluids showcase potential applications in the medical field, underscoring their versatility in addressing challenges across various industries. In this review, emphasis is placed on the nature and philosophy of magnetic field effects on the thermophysical properties, explaining basic mechanisms and investigating implications across applications. Under magnetic influence, particles align, forming clusters and chains, influencing thermal conductivity, viscosity, and specific heat capacity. Temperature variations serve a vital function, impacting the fluid’s response to magnetic fields. Brownian motion, affected by these fields, contributes to controlled particle motion, while agglomeration tendencies under magnetic conditions further shape thermal properties. In this review, several key findings about the behavior of magnetic nanofluids are revealed. For example, it is found that by increasing the magnetic field intensity at a constant shear rate, the viscosity first reaches a plateau and then decreases with further increases in field intensity. Furthermore, below/above the Curie temperature, the alignment of magnetic nanoparticles increases/decreases, influencing thermal expansion coefficient. This review presents two novel aspects that have not yet been compiled coherently elsewhere: firstly, an in-depth description of the nature and mechanisms of the magnetic field’s effect on thermophysical properties, and secondly, an examination of the rarely investigated properties of thermal expansion coefficient and specific heat capacity.