The effect of a magnetic field on heat and fluid flow of ferrofluid in a helical tube is studied numerically. The helical tube is under constant wall temperature boundary condition. Parametric studies are done to investigate the effects of different factors such as the magnetic field gradient value and Reynolds number on heat transfer rate and pressure drop. Results indicate that the magnetic field increases the Nusselt number by about 40%. At high magnetic gradient value, Nusselt number and friction factor rise slightly, while at low magnetic gradient value, the increment of Nusselt number is considerable. Furthermore, the growth of wall shear stress on tube wall results in lower thermal–hydraulic performance at the high magnetic gradient value. There is an optimum case for thermal–hydraulic performance which results in most top performance of helical tube in the presence of the magnetic field.
