竖直低温星形翅片管表面结霜及传热传质理论模型

摘要

An instantaneous theoretical model for heat and mass transfer during frosting on a vertical cryogenic star-shaped fin-tube is proposed in this paper. In the model, mechanisms including natural convection, sublimation as well as radiation are taken into account. Then the theoretical model is resolved numerically. The numerical results illustrate that the increasing rates of both frost mass and the frost temperature slows down with the increasing frost thickness. Due to the increase in frost thickness, the power partitions of the three mechanisms vary and the length by which the subcooled and saturated fluids occupy shrinks.%文中采用维元法建立了竖直星形翅片管表面的非稳态结霜及传热传质模型,重点考虑了霜层表面存在的对流、凝华以及辐射三种传热机理.理论模型的计算结果表明,霜层的生长速度以及霜层表面的温度升高都是一个逐渐变缓的过程.在这个过程中,三种机理的传热分量也随之变化.同时,随着霜层厚度的增加,翅片管整体传热效率降低,管内过冷区和饱和区的长度都被拉长.