水平管内含空气蒸汽流动冷凝局部换热特性

通过进行含空气蒸汽在水平管内强制对流冷凝换热实验,结合流型判断结果,详细分析了空气质量分数、混合气流速和压力以及换热管内壁面过冷度对局部冷凝传热系数的影响。结果表明:局部冷凝传热系数始终随空气质量分数的增加而减小,随混合气总压的增加而增大;在环状流下,局部传热系数主要受混合气流速影响;在波状流下,局部传热系数大小由局部空气含量和波状流的发展程度决定;在分层流下,局部传热系数受壁面过冷度影响。

Local heat transfer characteristics for forced convection condensation of steam/air in horizontal tube

An experimental investigation on forced convection condensation of steam with air in a horizontal tube was presented. Based on the results of flow regime prediction, influences of air mass fraction, velocity and pressure of the mixture gases and inner wall sub-cooling on local condensation heat transfer were analyzed. According to the experiment results, local heat transfer coefficient always decreased with the increase of air mass fraction and increased with the increase of total mixture gases pressure. For annual flow, the local heat transfer coefficient was affected by the mixture velocity, and for wavy flow, the ability of local heat transfer was influenced greatly by the air mass fraction and development of wavy flow, while for stratified flow, the effect of wall sub-cooling on heat transfer was dominated.