单相-两相自然循环过渡点的实验研究

Experimental research on transition point from single-phase to two-phase natural circulation

针对闭合回路自然循环单相—两相流动的过渡特性进行实验研究.结果表明自然循环流动由单相向两相过渡过程中,流量随入口温度的变化曲线存在明显的拐点,经理论分析,运用Levy模型和Saha_Zuber模型验证,证实拐点为自然循环过冷沸腾净蒸汽产生点,即单相和两相的过渡点;过渡点两侧自然循环流动的流量与入口温度呈不同的线性关系,体现了单相和两相流动的差异,净蒸汽的产生大幅度提高自然循环能力.

<Abstrcat>The transition from single_phase to two_phase natural circulation in an enclosed loop was researched.The results show that an obvious inflexion exists over the varied curve of the flow_rate with the increasing of inlet temperature in the transition from single_phase to two_phase natural circulation. Analysis shows that this inflexion is just the point of net vapor generation in subcooled boiling, i.e. the transition point from single_phase to two_phase. The experimental data compare reasonably well with Levy correlation and Saha_Zuber correlation. The flow_rate curve varies linearly with the inlet temperature but with different slopes at the two sides of the inflexion. This shows the different characteristics of the single_phase and two_phase flow. The generation of net vapor increases natural circulation ability.