The quenching curves (temperature vs time) of small metallic spheres and rodlets were acquired experimentally in pure water and water-based nanofluids with alumina and silica nanoparticles at low concentrations (<=0.1 vol(percent)). The experiments were performed at both saturated and subcooled conditions at atmospheric pressure. The results show that the quenching behavior in nanofluids is nearly identical to that in pure water, that is, the nanoparticles present in the nanofluids have no major effect on the quenching process. However, it was found that some nanoparticles accumulate and form a porous layer on the surface of the test specimens, which results in both destabilization of the vapor film at a higher temperature and increase of the quench front velocity in subsequent tests with the same specimen. The possible mechanisms by which the nanoparticles affect the quenching process were analyzed. It appears that surface roughness increase and wettability enhancement due to the nanoparticle deposition may be responsible for the premature disruption of film boiling and acceleration of quenching.
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