汽泡边界层模型在矩形管道下的适用性分析  

Accuracy Analysis of Bubble-layer-based Model Applied on Rectangular Channel

作　　者：何雯 赵陈儒[1] 韩晋玉 薄涵亮[1] HE Wen;ZHAO Chenru;HAN Jinyu;BO Hanliang(Institute of Nuclear and New Energy Technology,Tsinghua University,Beijing 100084,China)

机构地区：[1]清华大学核能与新能源技术研究院,北京100084

出　　处：《原子能科学技术》2024年第4期751-760,共10页Atomic Energy Science and Technology

基　　金：中核集团“青年英才”项目;中核集团领创科研项目。

摘　　要：过冷流动沸腾中的流动和传热特性对反应堆的安全运行和经济性都具有重要意义。汽泡边界层模型是预测流动沸腾的一种新理论模型,它将流场沿径向划分为主流和汽泡边界层两个区域,能同时获得两个区域多个两相参数的变化规律,为空泡份额的预测提供了一种新的方法。然而,过冷沸腾段汽泡边界层模型目前仅在常规圆管中开展了验证,当管道类型和尺寸发生变化后,模型的准确度还有待进一步分析。基于此,本文将汽泡边界层模型进一步推广到长宽比较大的矩形管道中。为验证模型的准确性,将模型获得的空泡份额与现有实验数据进行对比,并同时与现有空泡份额预测模型进行了对比。结果显示,汽泡边界层模型不仅较现有模型的准确度更高,还能同时应用于矩形常规管道和窄缝通道,受管道结构和尺寸的影响较小。模型还描述了矩形窄缝通道内空泡份额、压力、流速、温度、滑速比等的变化情况,这些结果能为反应堆矩形燃料元件内的热工物理耦合分析提供基础数据。Subcooled flow boiling contains complex bubble behaviors and interactions.Accurate prediction and analysis of the subcooled flow boiling are of great significance for the safe operation and economy of the nuclear reactors.The bubble-layer-based model is a new theoretical model in predicting the flow boiling,which divides the flow filed into two regions in the radial direction,which are the bubble layer region and the core region.Bubble behaviors in each region,mass and energy exchanges between different regions,and variations of parameters in the axial direction are analyzed and reflected through a set of two-dimensional steady-state conservation equations of mass,momentum and energy.Therefore,this model can provide more detailed information of the flow field than current one-dimensional models.However,this bubble-layer-based model for the subcooled flow boiling has only been verified in conventional tubes.When the channel type and sizes change,the accuracy of the model is still uncertain.Considering that rectangular channels are widely encountered in multiphase flow equipment,this paper aims to further extend this model to the prediction of the subcooled flow boiling in rectangular channels.Firstly,several flow boiling experiments in both conventional rectangular channels and narrow rectangular channels were selected.The working conditions are 0.1-8 MPa for pressure,211-1700 kW/m^(2) for heat flux,240-2200 kg/(m^(2)·s)for mass flux,4.42×103-3.72×105 for liquid Reynold number and 0.83-1.76 for Prandtl number.Then,variations of void fraction obtained by this model were compared with these experimental data.The results show that this bubble-layer-based model shows high accuracy when it is applied to both conventional rectangular channels and narrow rectangular channels,which reflects that the channel size and shapes have limited impact on the accuracy of this model.In addition,to further verify the accuracy of this model,one of the existing models(Cai model)in predicting the void fraction in subcooled flow boili

关 键 词：过冷流动沸腾 汽泡边界层模型 矩形管道 空泡份额 两相参数 

分 类 号：TL36[核科学技术—核技术及应用] TB126[理学—工程力学]