摘要
在压力为23-28 MPa、质量流速为600-1 200 kg/（m2.s）、热流密度为200~400 kW/m2的试验条件下,对内径为26 mm、倾角为22°的倾斜上升管内高温高压水的传热特性进行了试验研究.倾斜管壁温沿管壁周向非均匀分布,顶部壁温最高,底部壁温最低,两者温差随压力和质量流速的升高而减小,随热流密度升高而增大.浮升力引起的自然对流使低密度的热流体聚集在倾斜管顶部,导致顶部传热条件恶化,壁温高于底部.Petukhov准则给出了浮升力与顶部和底部温差的关系,Jackson准则计算值与试验值符合较好,二者均可判定倾斜管内浮升力效应.根据试验结果拟合得出了超临界水强制对流传热的关联式,由此可预测倾斜上升管的对流换热系数.
Experiments were conducted to investigate the forced convection heat transfer of water with high temperature and pressure in an inclined upward tube with an inclination angle of 22° and an inner diameter of 26 mm at pressure of 23-28 MPa,mass velocity of 600-1 500 kg/（m2·s）,and heat flux at inside wall of 200-600 kW/m2.The results show that the circumferential wall temperatures of the inclined tube were not uniform,and the wall temperature at the top was the highest while the lowest temperature occurred at the bottom.The top-bottom temperature difference decreased with an increase in pressure and mass velocity but increased with the heat flux.Moreover,the low-density hot water gathered at the top of the inclined tube because of natural convection caused by buoyancy effect,leading to the deterioration of the heat transfer condition,and thus the temperature at the top was higher than that at the bottom.The relationship between buoyancy and top-bottom wall temperature difference was obtained by Petukhov＇s criterion,and the predictions with Jackson＇s criterion agree well with the experimental data,indicating that both of the two criteria can be used to judge the buoyancy effect in an incline tube.The heat transfer correlations of the forced convection heat transfer of supercritical water were achieved from the experimental data,which can be used to predict heat transfer coefficients of inclined upward flow in tubes.
出处
《西安交通大学学报》
EI
CAS
CSCD
北大核心
2011年第5期6-11,共6页
Journal of Xi'an Jiaotong University
基金
国家重点基础研究发展规划资助项目(2009CB219805)
关键词
超临界水
强制对流
传热特性
倾斜管
浮升力
supercritical water
forced convection
heat transfer characteristics
inclined tube
buoyancy
