Experimental Research On The Enhancement Of Critical Heat Flux Using Nanofluids On Downward Facing Surface

As one of severe accidents management strategies,In-Vessel Retention (IVR) strategy has been implemented in AP1000, APR1400 and HL1000 et al. However, with the improvement of reactor power,the effectiveness of In-Vessel Retention strategy will be limited to the local Critical Heat Flux (CHF). Therefore, it is necessary to enhance the Reactor Pressure Vessel (RPV) downward facing surface CHF for the success of IVR strategy.In this article, nanofluid experiments have been done to explore the characteristics of CHF enhanced by nanofluid. Four kinds of prepared nanofluids,including Al2O3, TiO2, Al,CNT are checked with Scanning Electron Microscope (SEM) and Nano Particle Analyzer(NPA) for particle size distribution. An electrical heating 316-stainless steel plate section is used to simulate the RPV downward surface situation for pooling boiling and flowing boiling experimental investigation at atmosphere pressure. Pooling boiling experiments are conducted for the influence research of variety, concentration and surface roughness on the enhancement of CHF. While the flowing experiments are done for the CHF enhancement effect of different orientation conditions. Moreover, the mechanism of CHF enhancement is discussed in the end.The results of pool boiling experiments show that compared to Al2O3, CNT nanofluids,the 10-3 vol.% TiO2 nanofluid gets the best enhancement of CHF about 60.6%; for different volume concentration TiO2 nanofluids, it gets best enhancement with 10-3 vol.% TiO2 nanofluid; besides, the CHF enhancement effect falls with Ra ranging from 0.086?m to 1.765?m while it goes up with Ra at 2.287?m. The results of flowing experiments show that the CHF is enhanced by nano-coating plate for orientation angle changing from 0° to 50°while it deteriorates at 79°.