非共沸混合工质管内流动凝结换热系数的分析与计算

摘要

对非共沸混合工质R32/R134a的管内流动凝结局部换热系数进行了理论分析和计算.计算表明，非共沸混合工质的管内流动凝结换热系数总是低于具有等同物性的纯工质的换热系数，其换热系数下降的程度不仅受浓度的影响，还受干度的影响.对混合工质R32/R134a而言，换热系数的极小值出现在R32质量分数为10%～30%的区域内.%A theoretical approach to forced convective condensation heattransfer coefficient of nonazeotropic mixtures inside smooth tubes was developed. Calculations were performed for R32/R134a mixtures with the R32 mass fraction ranged from 0 to 60.1%. The results revealed that there was a reduction of heat transfer coefficient for a nonazeotropic mixture when compared with that of a single component substance with the same thermophysical properties. The reduction of the heat transfer coefficient depended not only on the mass fraction of the mixture,but also on the vapor quality of fluid. Besides,minimum heat transfer coefficients were observed at mass fractions ranging from 10% to 30% for R32/R134a mixtures.