ナノ流体による限界熱流束増大効果の実験的研究ナノ粒子によリ表面処理した細線による限界熱流束試験

摘要

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. TiO_2 nanoparticles were used. To observe the boiling phenomenon in nanofluid, a Pt wire was boiled in nanofluid and coated with TiO_2 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 TiO_2 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.%ナノ流体によって限界熱流束（以下,CHF=Critical Heat Flux)が増大することは多くの研究者により確認されており,原子炉の苛酷事故対策や熱流体機器への適用が検討されている。例えば,苛酷事故発生時,溶融炉心が原子炉圧力容器（RPV=Reactor Pressure Vessel)底面に堆積した際,溶融炉心をRPV内に留めるためには,RPV底部の除熱限界,つまりCHFを高める必要がある。そこで,RPVを水没させて冷却する際,冷却水にナノ流体を用いる案が検討されている。