In our efforts to improve the pool boiling heat transfer of water, three sets of experiments are carried out to investigate the best coolant for heat removal among alumina, silica, and zinc oxide as nanoparticles and water as base fluid: (a) pool boiling heat transfer of γ-alumina/water nanofluid with and without surfactant in both distilled water and treated water as base fluids, (b) pool boiling heat transfer of silica/water nanofluid with two different nanoparticle sizes, and (c) pool boiling heat transfer of zinc oxide/water nanofluid with surfactant. In all the above experiments, the effect of heater surface on boiling heat transfer coefficient has been investigated by repeating the experiment using pure water on the coated surface before cleaning it. Moreover, two effective thermophysical properties of fluids, dynamic viscosity and surface tension, are measured to explain the boiling behavior of the nanofluids. The experimental results indicate that (a) the presence of γ-alumina in the base fluid enhances the pool boiling heat transfer coefficient, but sodium dodecyl sulphate (SDS) as surfactant deteriorates the performance of pool boiling heat transfer of γ-alumina/water nanofluid and (b) silica nanoparticles reduce the boiling performance of pure water. Moreover, the larger particle size of silica nanoparticles shows less reduction in heat transfer coefficient, (c) zinc oxide/water nanofluid is the best coolant among all the above-mentioned nanoparticles for heat removal.

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