自然循环过冷沸腾流动和CHF的实验研究

为了研究自然循环过冷沸腾条件下流动不稳定性和临界热流密度 ( CHF)的影响因素及其规律 ,以氟里昂作工质 ,在系统压力为 0 .9～ 2 .4MPa,入口过冷度为 -0 .61～-0 .0 8K,加热功率为 1.2～ 13 k W实验条件下 ,对自然循环过冷沸腾流动不稳定性和 CHF进行了实验研究。实验结果证实 ,自然循环系统内可能发生两类流动不稳定性 :高频声波型脉动和低频密度波型脉动。流动不稳定性的发生与整个系统的几何结构及总加热功率有关 ,而 CHF则主要取决于局部的流动参数和加热热流密度。得到了判断系统流动不稳定性的发生界限。修正的 Bowring关系式可以可靠地用于预测自然循环过冷沸腾条件下的临界热流密度

Experimental study of flow instability and CHF in a natural circulation system with subcooled boiling

Flow instability, critical heat flux (CHF) and the relationship between flow instability and CHF have been investigated experimentally in a natural circulation system with subcooled boiling. Freon 12 was used as the working medium. The experiment showed two kinds of flow instabilities, both high frequency and low frequency flow instabilities. The high frequency flow instability is due to acoustic oscillation and the low frequency flow instability is due to density wave instabilities. The experiments show that the heat input power to the heated section and the working medium properties greatly influence the onset of the two kinds of flow instabilities while the CHF mainly depends on the heat flux to the heated section. The stability boundaries were determined experimentally. The CHF data obtained experimentally was compared with the Bowring correlation to develop a modified Bowring correlation which accurately predict the experimental CHF data.