低流速过冷沸腾压降实验与计算方法研究

Experimental and Predictive Study of Pressure Drop in Low-flow Sub-cooled Boiling

在中压强迫循环工况下开展了低流速过冷沸腾压降实验,实验中同时对过冷沸腾空泡率进行了测量。基于得到的实验数据,对低流速过冷沸腾压降计算方法进行了研究。研究表明,过冷沸腾工况下的流动压降与重力压降亦即空泡率密切相关,选用合理的空泡率计算模型对于低流速过冷沸腾压降的准确计算极为重要。由于目前普遍采用的Saha模型、Levy模型难以得出准确的低流速过冷沸腾真实含汽率与空泡率预测结果,应用于低流速过冷沸腾压降计算时会产生较大偏差。笔者提出的真实含汽率模型和净蒸汽产生点(NVG)空泡率模型可用于蒸汽-水强迫循环低流速过冷沸腾压降计算。通过本文研究,最终得出蒸汽-水强迫循环低流速过冷沸腾压降的推荐计算方法。

This paper presents the experimental study of the pressure drop for low-flow forced circulation in medium pressure sub-cooled boiling. The average void fraction is also measured in this experiment.Based on the experimental results, predictive investigation on pressure drop in low-flow sub-cooled boiling is carded out in this paper. The investigation shows that the pressure drops in low-flow sub-cooled boiling are dominated by pressure drop due to static head. Since the pressure drop due to static head are strongly affected by void fraction, it is very important to select the calculation model for void fraction. The Saha model and Levy model cannot be used to determine the void fraction for the calculation of pressure drop reliably. The NVG model and the true mass quality model proposed by the authors can be used to calculate the void fraction for the calculation of pressure drop in low-flow sub-cooled boiling correctly. Through the investigation,the proper method for the calculation of pressure drop in steam-water low-flow sub-cooled boiling with forced circulation is suggested in this paper.