Heat exchange enhancement of ferrofluid flow into rectangular channel in the presence of a magnetic field

•The heat exchange enhances up to 20% by suspending ferromagnetic naoparticles in the pure water.•The only action of the magnetic field can enhances the heat exchange up to 60%.•The combined effect of both ferromagnetic nanoparticles and magnetic field can gives up to 86% heat exchange enhancement. Heat exchange and Fe3O4/water nanofluid flow behaviors into horizontal channel subjected to the effect of a magnetic field was studied numerically. The basic equations were solved using the finite volume method with the time-splitting algorithm. The results were represented by temperature field, streamlines, velocity field, averaged and normalized Nusselt numbers, for various nanoparticles volume fractions, Reynolds numbers and magnetic numbers. Results show that the isotherms, the streamlines and the heat exchange rate are strongly changed by applying a magnetic field. A recirculation region is created near the magnetic source where the thermal boundary layer is removed enhancing so the local heat exchange. The overall heat exchange is enhanced by suspending nanoparticles and/or by increasing magnetic field strength. In the absence of a magnetic field, suspending nanoparticles can enhance heat exchange rate up to 20%. Under the only action of magnetic field a maximum 60% heat exchange enhancement is obtained. It can reach up to 86% as the combined effects of both nanoparticles and magnetic field are considered.