翅片管式换热器表面结霜特性的数值分析和实验研究

Numerical analysis and experimental study on frosting quality of finned-tube heat exchanger

换热器表面结霜会增加传热热阻和流动阻力 ,为合理确定融霜周期 ,必须对其结霜特性作深入的了解。文中采用了数值求解方法预测了平翅翅片管式换热器的结霜量和霜层密度的变化过程。翅片管结霜是一个瞬变问题 ,为了计算方便 ,将其简化为准稳态过程 ,即在时间步长内 ,认为该过程是稳定的 ,然后把所得的霜层厚度以及霜层的表面温度作为下一时间步长内传热传质的边界条件。在研究中考虑了霜层阻力引起风量下降这一因素 。

This paper adopts numerical method to predict the frost accumulation quantity and frost density of the plate fin and tube heat exchanger.The course of frosting on fins is simplified to a quasi stable problem for convenience.In every time step the process is considered to be stable and the obtained data,the frost thickness and the temperature of the frost surface are used the boundary conditions in the next time step.In the study,the disease of airflow rate caused by frost layer is taken into account.The calculated results are conformed to the experimental results very well.