Evaporation of ferrofluid drop in magnetic field in Leidenfrost mode

When a droplet evaporates in the Leidenfrost mode, the intensity of heat transfer is significantly reduced compared to the boiling mode, which is highly undesirable for a number of applications. Here we demonstrate a method for intensifying heat transfer during droplet evaporation in the Leidenfrost mode. The essence of this method is that if a magnetic nanofluid is used as a cooling liquid, then with the help of an inhomogeneous magnetic field it is possible to forcibly press a levitating drop to a superheated surface, which contributes to the intensification of the drop evaporation. An aqueous suspension of Fe3O4 is used here as a ferrofluid. The experimental results show that this method can reduce the drop evaporation time by several times. When the magnetic field gradient increases, the drop evaporation time decreases according to the power law. A simple phenomenological model is proposed to substantiate the observed effects.