LAUSR

Abstract High-performance cooling is of vital importance for the cutting-edge technology of today, from micro-electronic devices to nuclear reactors. Boiling heat transfer is expected to play a critical role for the safe and efficient operation of components exposed to high heat flux in future nuclear fusion reactors. Recent advances in nanotechnology have allowed the development of a new category of coolants, termed nanofluids, which exhibit superior thermophysical characteristics over traditional heat transfer fluids. Qualitative experimental results of Al2O3-H2O nanofluids under subcooled pool boiling conditions are reported and compared to deionised water that served as a benchmark in the current work. A visual evaluation of the impact of nanoparticles on bubble dynamics and nucleation site activity at the heated surface of a bare NiCr wire is performed with the use of a Guppy F-080 FireWire camera. It was observed that the presence of nanoparticles significantly modifies the nucleation site density, bubble size at departure and frequency of bubble generation from the surface of the heating wire. Intense nanoparticle deposition on the heating wire surface was identified as a key mechanism for the observed differences via scanning electron microscopy. The deposited nanolayer reported to alter the surface texture of the wire. The outcome of this work is a step forward towards the evaluation of the applicability of nanofluids in cooling applications via boiling heat transfer.