平直翅片管换热器结霜是湿空气、霜层和换热器结构多物理场交互作用的结果。基于流固热耦合计算方法，考虑结霜过程中霜层密度和导热系数的变化，定义更真实求解域边界，对三维平直翅片管换热器的结霜过程进行数值模拟研究。模拟计算得到的结霜量与实验值之间的平均误差为4.67%，较以往数值模拟方法得到的结果精度有所提升。计算对比了湿空气进口流速分别为1.0, 2.0, 3.0, 3.7 m/s，相对湿度分别为60%, 70%, 80%时霜层的生长情况。结果表明，霜层厚度沿气流方向不断降低，随着来流速度和相对湿度增加，生长速率增大。对空气侧换热系数的研究表明，在结霜初期，空气相对湿度越大，换热系数越大；在结霜后期，空气相对湿度越大，换热系数越小。

Plane finned tube heat exchanger was widely used in household air conditioner, environmental testing chamber, closed heat source tower, and other heat pump refrigeration systems because of its high heat transfer efficiency, low air resistance, and stable mechanical properties. It was easy to form a frost layer on the surface of flat finned tube heat exchanger working in low temperature and high humidity environment, which greatly reduced heat transfer efficiency and caused waste of energy. The study on the frosting growth on the surface of straight finned tube can provide guidance for the design of plane finned tube heat exchanger. The frosting process of plane finned tube heat exchanger is the result of the interaction of wet air, frosting layer, and heat exchanger structure. In this work, based on the fluid-solid thermal coupling calculation method, considering the changes in frost density and thermal conductivity during the frosting process, a more realistic solution domain boundary was defined, and the frosting process of 3D plane finned tube heat exchanger was numerically simulated. The average error between the simulated frost amount and the experimental value is 4.67%, which is better than the results obtained by previous numerical simulation methods. The frost growth was calculated and compared when the wet air inlet velocity was 1.0, 2.0, 3.0, and 3.7 m/s, and the relative humidity was 60%, 70%, and 80%, respectively. The results showed that the frost thickness decreased along the airflow direction, and the growth rate increased with the increase of velocity and relative humidity. The study on the heat transfer coefficient of air side showed that the higher the relative humidity of air was, the higher the heat transfer coefficient was at the beginning of frosting. In the late frosting period, the greater the relative humidity of the air was, the smaller the heat transfer coefficient was.