横置圆筒内壁蒸汽冷凝换热分析

摘要

为了对横置圆筒内壁进行蒸汽冷凝换热分析,从Nusselt经典冷凝换热模型导出横置圆筒内壁的冷凝换热模型,考虑到不可凝气体对计算结果的影响,用GDLM模型对其进行了修正.然后,通过冷凝壁面热流量的计算,对比分析了文中计算模型与GDLM模型和Uchida模型优缺点,并计算了不同圆筒半径下冷凝液膜厚度和换热量随流动距离的变化.结果表明:冷凝液膜厚度只在上下两端变化剧烈,总的冷凝换热量随圆筒半径的增大而增大,但单位面积换热量随圆筒半径的增大而减小.%In order to analyze the heat transfer of steam condensation on the wall of inner horizontal cylinder,based on the Nusselt classical condensation model,a modified condensation model on the horizontal cylinder wall is developed.With the consideration of great influence of non-condensable gas,this model is modified by GDLM(generalized diffusion layer model).By calculating heat transfer rate on condensation wall,the merits and demerits between GDLM,Uchida model and the proposed model are compared.On this basis,variations of condensation liquid film thickness and heat transfer rate with flow distance are calculated.The result shows that liquid film thickness changes obviously only at upper and lower ends.With an increase in cylinder radius,the total heat transfer rate grows w hile the heat transfer in unit area declines.