摘要
本文基于不同流速下变传质强度因子的Lee模型,对低热通量下上升管内流动沸腾进行了数值模拟。通过分析气相分布、局部气泡行为解释了沸腾换热特性和局部传热恶化。结果表明:低热通量下,不同流速的平均气体体积分数沿管长线性分布,沿径向呈双峰状分布,峰值在壁面附近;高流速时,近壁处气体体积分数的增长速率最大。换热性能受流速影响显著,流速越大,换热系数越大;三种流速下换热系数最小值对应的气体体积分数相同,气相分布不同是换热特性产生差异的直接原因。低中流速下,壁温局部升高位置与换热系数骤降位置是一致的,表明壁面附近局部气泡附着会造成壁温的局部升高,导致传热恶化。
Based on the Lee model of variable mass transfer intensity factor at different flow velocities,the numerical simula⁃tion of flow boiling in riser tubes at low heat flux was carried out.By analyzing the vapor phase distribution and local bubble be⁃havior,the boiling heat transfer characteristics and local heat transfer deterioratio were explained.The results show that under low heat flux,the mean vapor volume fraction at different flow velocities is linearly distributed along the length of the tube,and the radial variation is bimodal,with the peak value near the wall.At high flow velocity,the growth rate of vapor volume fraction near the wall is the largest.The heat transfer performance is significantly affected by the flow velocity.The higher the flow velocity is,the higher the heat transfer coefficient is.The vapor volume fraction corresponding to the minimum value of heat transfer coeffi⁃cient at the three flow velocities is the same.The different vapor phase distribution is the direct cause of the difference in heat transfer characteristics.At low and middle flow velocities,the local increase of wall temperature is consistent with the drop of heat transfer coefficient,indicating that the local bubble adhesion near the wall will cause the local increase of wall temperature and lead to the deterioration of heat transfer.
作者
贾敏
张曙昌
耿佃桥
袁双
Jia Min;Zhang Shuchang;Geng Dianqiao;Yuan Shuang(Key Laboratory of Electromagnetic Processing of Materials,Ministry of Education,Northeastern University,Shenyang 110819,China;School of Metallurgy,Northeastern University,Shenyang 110819,China)
出处
《低温与超导》
CAS
北大核心
2023年第7期41-48,共8页
Cryogenics and Superconductivity
基金
中央高校基本科研业务费专项资金(N180904007)资助。
关键词
低热通量
上升流
Lee模型
流动沸腾
数值模拟
Low heat flux
Vertical upflow
Lee model
Flow boiling
Numerical simulation
