不凝气体存在时水平单管外膜状凝结换热的数值研究

为查明不凝气体对水平管外膜状凝结换热特性的影响规律，建立了水平单管的气、液双边界层模型，该模型考虑了气、液膜之间的质量连续及能量连续特征，对于不同的壁面过冷度，用数值方法首次求解并分析了边界层内局部不凝气体质量分数、温度和速度的分布规律，计算结果表明，从主流蒸汽到气流界面，不凝气体含量和气膜速度逐渐增加而气膜温度降低，平均凝结换热系数值解与实验解符合较好 。

Film Condensation Heat Transfer in the Presence of a Non-Condensable Gas

Film condensation heat transfer characteristics are studied by numerical simulation for a single horizontal tube in the presence of a non condensable gas. The vapor liquid two boundary layer model is applied to predict local mass concentration of the non condensable gas, temperature profiles and velocity profiles in the boundary layer. It is shown that mass concentration and velocity of the non condensable gas increase while temperature decreases from the bulk of the vapor to the interface. The numerical predictions agree well with condensation heat transfer measurements for steam with air as the non condensable gas.