In this study

the surface temperature of the frost layer was measured using an infrared thermal imager and calibrated using direct measurements from a micrometer and thermocouple device. The growth characteristics of the frost layer on the surface of the finned-tube heat exchanger were experimentally studied. The effects of fin type and fin pitch on the frost thickness

frost mass

and heat transfer capacity were analyzed. The frost growth characteristics were analyzed by considering the condition at the frost wet air interface as the driving force of heat and mass transfer. The experimental results indicated that the driving force of heat and mass transfer at the interface of the wavy fin and the split fin heat exchangers is higher than that of the flat fin

resulting in higher growth rates of the frost layer on the wavy and split fins than that on the flat fin. In the late frosting period

the growth rate of the frost layer on the split fin was significantly accelerated. Among the three types of fins

the frosting duration on the split fin was the shortest and the longest on the flat fin. The average heat transfer capacity of the wavy fin heat exchanger during the frosting and defrosting periods was the largest

which was 0.61% and 2.67% higher than that of the split and flat fin heat exchangers

respectively. Meanwhile

the influence of the fin pitch on the driving force of heat and mass transfer at the interface is weak

and the larger the fin pitch is

the faster the frost layer thickness increases

and the longer the frosting duration is. Considering the average heat transfer capacity during the frosting defrosting period and the air flow resistance of the heat exchanger

the optimal fin pitch is approximately 2.2 mm under the frosting condition.