Degraded boiling heat transfer from hotwire in ferrofluid due to particle deposition

Transient boiling heat transfer from an electrically-heated microwire in Fe₃O₄/water nanofluid (ferrofluid) was investigated for the first time. The transient temperature rise of the wire for different electrical currents was measured and compared with results for deionized water to highlight the effect of the magnetic particles on the heat transfer. It was observed that below the normal boiling point of water, the ferrofluid enhances the heat transfer. However, above the boiling point, the heat transfer ability of the ferrofluid significantly decays due to deposition of particles on wire. Scanning electron microscope (SEM) images of the wire showed that the ferromagnetic particles form a coating layer on the wire of various morphologies depending on electric current and duration of heating. Parameters affecting both heat transfer and particle deposition such as current, time and concentration of ferrofluid were investigated. It was observed that the rate of particle deposition on wire and the thickness of the coating layer increases by increasing current, time and concentration of ferrofluid.