2013 年 12 巻 1 号 p. 43-49
The critical heat flux (CHF) enhancement effect by nanofluid is widely known, and it is expected that nanofluid can be applied to in-vessel retention (IVR) under severe accident. The purpose of this study is to investigate the mechanism of CHF enhancement by nanofluid. In this study, an atmospheric saturated pool boiling test was performed. TiO2 nanoparticles were used. To observe the boiling phenomenon in nanofluid, a Pt wire was boiled in nanofluid and coated with TiO2 nanoparticles, and the coated wire was tested in pure water. The following conclusions can be obtained from test results: (1) Nucleation site density was decreased using the Pt wire coated with TiO2 nanoparticles. (2) CHF enhancement in this study was about 200%. (3) CHF asymptotically increased with an increase in boiling time in nanofluid. (4) Nucleation site density had a strong effect on CHF enhancement.