Flow boiling critical heat flux characteristics of magnetic nanofluid at atmospheric pressure and low mass flux conditions

Abstract

In this study, we suggest a new working fluid: magnetic nanofluid, or magnetite-water nanofluid, which is a colloidal suspension of magnetite nanoparticles in the pure water. By using the nanofluid, we can expect the critical heat flux (CHF) enhancement, and also for the magnetic nanofluid. Since the magnetite nanoparticles can be controlled by magnetic field, the magnetic nanofluid is regarded as a controllable nanofluid, and thus, we expect the advantages of magnetic nanofluid: (1) the nanofluid concentration can be localized by applying the magnetic field for the region of interest and (2) the magnetite nanopartides can be removed from the magnetic nanofluid easily. A series of experiments were performed at the atmospheric pressure and low mass flux conditions. Based on the experimental data, we conclude that the use of magnetic nanofluid improves the flow boiling CHF characteristics: the flow boiling CHF enhanced for the magnetic nanofluid. This is mainly due to the deposition of magnetite nanoparticles on the heat transfer surface, which results in the improvement of wettability and re-wetting characteristics. And we need enough time to ensure the nanoparticle deposition and the flow boiling CHF enhancement, when a nanofluid is used as a working fluid. Also, the effects of magnetic field on the enhancement of flow boiling CHF for the magnetic nanofluid were investigated experimentally. (C) 2012 Elsevier Ltd. All rights reserved.