Temporal and spatial frost growth prediction of a tube-finned heat exchanger considering frost distribution characteristics

•The novel frosting model improves the prediction accuracy of frost mass by 2.0%.•Frost on edge of windward fin impacts more on heat and mass transfer as frosting.•Frost density on edge of windward fin is 30.8% lower than that on finned surface.•The change rule of temperature is opposite to frost density inside the frost layer. To better understand the frost growth characteristics of a tube-finned heat exchanger, a novel frosting model was developed based on its frosting distribution characteristics. The frosting model considered both the frost growth on the edge of windward fins and the uneven frost distribution on the surfaces of tube-finned segments. Compared to a conventional frosting model, the novel one can improve the prediction accuracy on frost thickness on the surfaces of fins and tubes, and total frost mass of the tube-finned heat exchanger by 5.1%, and 2.0%, respectively. The temporal and spatial frost growth characteristics of the tube-finned heat exchanger were numerically investigated based on the novel frosting model. The results showed that the frost growth on the edge of windward fins impacted more on the entire frost growth of tube-finned heat exchanger as frosting progressed. After a 3,600-s frosting period, the heat transfer rate and frosting rate on the edge of windward fins accounted for 10.4% and 10.3% of the entire heat transfer rate and frosting rate of the tube-finned heat exchanger, respectively. Besides, the relative differences between the frost density at the frost surface and wall surface on the surfaces of fins and tubes, and the edge of windward fins were 68.0%, and 71.7%, respectively. This study is meaningful for the accurate control of defrosting and thus energy saving.