水平管内含空气蒸汽强制对流冷凝换热模型研究

为研究含空气蒸汽在水平管内强制对流冷凝换热特性，基于对传热传质过程的分析，建立了管内为环状流与波状流条件下的流动冷凝换热模型。从潜热、显热和液膜3个环节对整个换热过程进行建模，最终得到计算局部冷凝换热系数的理论关系式。模型预测结果与实验数据的对比表明，二者相对偏差在±20%以内，验证了该换热模型的准确性与适用性。通过进一步的研究发现：从换热管入口至出口，随着冷凝的进行，管内换热主要热阻由液膜热阻向气液界面的凝结热阻转变；主流气体对流换热过程基本可忽略。

Study on Heat Transfer Model for Forced Convection Condensation of Steam-air Mixture in Horizontal Tube

For the purpose of analyzing the heat transfer characteristics of forced convection condensation for steam-air mixtures in a horizontal tube, based on the heat and mass transfer analogy (HMTA) formulation, a theoretical model was established. By dividing the whole process of heat transfer into the sensible heat, latent heat and liquid film, a correlation for local heat transfer coefficient was obtained. The calculated heat transfer coefficients show good agreement with the experiment data with a relative deviation within ±20%. According to the further research, with the steam condensing inside the tube, the major heat resistance changes from the film heat resistance to the condensation heat resistance on the interface between gas and liquid. Compared with the other heat transfer process, the convective heat transfer between the bulk gases and the interface can be neglectable.