核动力装置中两相相间换热边界限制对于换热计算的影响分析

Analysis of the influence of boundary restriction of two-phase heat transfer on heat transfer calculation in nuclear power plant

在开发系统程序时,经常发现相间换热系数过大导致程序计算两相流动时出现物性错误,从而导致计算失败。因此采用RELAP5使用的相间换热系数限制关系式对相间换热系数进行限制,采用水平环形雾状流、垂直环形雾状流2种工况进行计算,计算结果表明,单纯的采用RELAP5使用的相间换热系数限制关系式并不能使计算稳定,必须减小该相间换热系数限制关系式的最大值才能使得计算稳定。同时,不同空泡份额下能够稳定计算两相流动的相间换热系数最大值限制不相同,且相间换热系数值的大小对空泡份额的计算有很大影响。

When the in-house two-phase system analysis code is developed, it is usually found that the fluid property error occurs during the computation of two-phase flow due to the too large interfacial heat transfer coefficient, and the computation fails. Therefore, the interfacial heat transfer coefficient limit correlation used in RELAP5 is applied in our in-house code, and the horizontal and vertical annular mist flow are computed, the computation results show that the only application of interfacial heat transfer coefficient limit correlation used in RELAP5 can′t stabilize the computation and decreasing the maximum limitation of the interfacial heat transfer coefficient limit correlation can stabilize the computation. Meanwhile, the maximum limitation of the interfacial heat transfer coefficient is different for two-phase flow computation with different void fraction, and the effect of the value of interfacial heat transfer coefficient on the void fraction is great.