Critical Heat Flux Experiments for IVR-ERVC Strategy Under the Pool Boiling Condition

Heat transfer limit is one of the main concerns of IVR-ERVC strategy. When the liquid level in the system is so low that natural circulation cannot be formed, the coolant near the outer surface of the reactor pressure vessel lower head is in the pool boiling state. In this research a one-dimensional full-height experimental facility was established to research the heat transfer limit (CHF) of ERVC under the pool boiling condition with a one-dimensional heating block, which is used to simulate the lower head of reactor pressure vessel. The experiment was carried out at different liquid levels and the results are compared with those of natural circulation experiment at the same liquid level. Experimental results show that CHF increases with the increase of the inclination angle of heating block. Meanwhile, the increase of liquid level is beneficial to the improvement of CHF. In addition, it can be found that the influence of flow path size on CHF is complex, and CHF does not change monotonically with the increase of flow path size. On the other hand, compared with the results of natural circulation at the same liquid level, the CHF values under pool boiling are relatively low. These results are expected to improve the understanding of IVR-ERVC strategy.