机构地区: 西安交通大学能源与动力工程学院动力工程多相流国家重点实验室
出 处: 《核动力工程》 2004年第5期408-412,共5页
摘 要: 建立了垂直管内流动沸腾换热与阻力特性的数值计算模型。该模型以环状流为研究对象,认为强制对流与核态沸腾两种换热方式同时存在。通过求解质量守恒、动量守恒、能量守恒方程,获得液膜厚度、速度与温度等参数。由汽泡脱离频率、脱离直径、汽化核心密度及抑制因子等参数计算核态沸腾换热。换热系数根据热流密度叠加原理确定。对一种有机工质在垂直管内向上流动时的沸腾换热进行了数值预测,计算值与实验结果符合良好。随着干度的增加,核态沸腾在总换热系数中的比例由约20%下降至1%。 A new model is proposed for the prediction of saturated flow boiling heat transfer inside vertical tubes. The model assumes the forced convection and nucleate boiling coexist in the annular flow regime. Conservation of mass, momentum, and energy are used to solve for the liquid film thickness, velocity, and temperature. The heat transfer due to nucleate boiling is determined from the frequency and diameter of bubble departure, the density of active nucleation sites, and suppression factor. The overall heat transfer coefficients are calculated from the total heat flux partitioned into the two components of forced convection and nucleate boiling. Predictions of the model agree with the experimental data within the error of ±20%. The numerical results indicate that the nucleate boiling contribution to the overall heat transfer coefficients decreases from 20% to 1% with quality increasing.
领 域: [核科学技术]