水平管内蒸汽冷凝局部换热特性实验研究

Experimental Investigation on Steam Condensation Local Heat Transfer Characteristics Inside Horizontal Tube

以水蒸气为工质,实验研究了水平管内纯蒸汽冷凝的局部换热特性。实验选取换热管内径为25mm、换热管进口压力为0.15~0.4MPa、局部蒸汽的Re=5 756~92 289,分析了蒸汽压力及流速、壁面过冷度对冷凝传热系数的影响,并将采用现有关系式计算的冷凝传热系数与实验结果进行了对比。结果表明：冷凝传热系数随壁面过冷度的增大而减小,随压力的升高和流速的增大而增大;采用现有关系式计算的冷凝传热系数与实验值的偏差较大,关系式有待进一步改进;在实验范围内,由拟合换热关系式计算所得冷凝传热系数与实验结果的相对偏差在15%左右。

An experimental investigation on the steam condensation local heat transfer characteristics inside horizontal tube was presented.The experiments were conducted in the following conditions：Tube internal diameter 25 mm,inlet steam pressure 0.15-0.4 MPa,and steam Re=5 756-92 289.The influences of inlet steam pressure and velocity,and wall sub-cooling on condensation heat transfer coefficient were analyzed.The experimental condensation heat transfer coefficient was compared with the calculated values of currently known correlations.It is shown that the condensation heat transfer coefficient decreases with the increase of wall sub-cooling,while increases with the steam pressure and the steam velocity.The deviation between calculated values and experimental data is large and the current correlations need further improving.A correlation of steam condensation heat transfer coefficient was developed,and the new correlation shows a good agreement with experimental results with 15%relative deviation.