Prediction of extremely high minimum heat flux point during quenching in nanofluid

In nanofluid that is a liquid containing colloidal dispersion of nanometer-sized particles, it is known that the quenching heat transfer characteristics such as TMHF (minimum heat flux temperature) is improved mainly due to modification of the surface properties caused by nanoparticle deposition during boiling. In this study, the water-based silica (SiO2) nanofluid was used to clarify the mechanisms of the quenching characteristics variation in nanofluid. The Inconel 718 rodlet (φ16×30mm) and SUS304 rodlet (φ15×30mm) were used as the test pieces. The four properties of the nanoparticle layer were measured: Roughness, wettability, wickability, and thickness. Then, the temperature transient in the nanoparticle layer was calculated using the one-dimensional heat conduction equation. It was shown that the surface temperature of the nanoparticle layer should be maintained low enough for a sufficiently long time after immersing the high-temperature test piece in the nanofluid for remarkable increase in TMHF to occur.