PREDICTION OF EXTREMELY HIGH MINIMUM HEAT FLUX POINT DURING QUENCHING IN NANOFLUID

摘要

In nanofluid that is a liquid containing colloidal dispersion of nanometer-sized particles, it is known that the quenching heat transfer characteristics such as T_(MHF) (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 (SiO_2) 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 nanofluidd for remarkable increase in T_(MHF) to occur.