摘要
分析了液氮流动沸腾过程中气液两相间动量、能量以及质量的传输规律,建立了相应的理论模型,新模型重点修正了界面面积浓度和气泡挣脱直径的计算式;采用新建立的理论模型作为封闭方程对CFX-4.3中内建的双流体模型进行了修正,并采用修正后的双流体模型模拟了液氮在垂直圆管内的流动沸腾过程.数值模拟的结果与文献中的实验数据吻合较好,证明了本文所建模型的合理性.通过数值模拟发现,两相流参数分布的不均匀性对液氮流动沸腾过程中的热质传输特性有重要影响.
The closure equations of the two-fluid model for heat and mass transfers between liquid phase and vapor phase during boiling flow of liquid nitrogen were developed. The formulas of the interfacial area concentration and the bubble departure diameter were modified for accurate prediction. The equations were incorporated into the two-fluid model and the commercial CFD code CFX-4.3. Two dimensional numerical simulations of subcooled boiling flow of nitrogen in a vertical tube were performed by using the modified CFD code. The numerical results showed encouraging agreement with the experimental data available in the literature. Detailed distributions of the void fraction, heat transfer coefficient and liquid temperature difference were obtained, leading to better understanding of the basic mechanisms of boiling flow and related cooling systems.
出处
《化工学报》
EI
CAS
CSCD
北大核心
2006年第3期491-497,共7页
CIESC Journal
关键词
液氮
流动沸腾
双流体模型
相间传输
传热
空泡份额
liquid nitrogen
boiling flow
two-fluid model
inter phase transfers
heat transfer
void fraction
