Frosting is one of the main factors restricting the application of microchannel heat exchangers in refrigeration and air conditioning systems. Aiming at the frosting problem of a microchannel heat exchanger

the frosting mechanism was analyzed based on the phase transformation driving force

and the growth morphology of the frost layer on the cold surface under different environmental factors was observed in this study. The effects of wet air temperature

humidity ratio

air velocity

and coolant temperature on the frosting characteristics

and the heat transfer performance of the microchannel heat exchanger were experimentally studied. The results show that the humidity ratio and air velocity of the wet air are the main factors affecting the frosting of the microchannel heat exchanger. At 15 min of frosting

the amount of frost on the heat exchanger surface under a humidity ratio of 5.75 g/(kg dry air) increased by 63.87% compared with a humidity ratio of 3.58 g/(kg dry air); the amount of frost on the heat exchanger surface under an air velocity of 2.5 m/s increased by 55.4% compared to the air velocity of 1 m/s. With the increase in frosting time

the lower the temperatures of the humid air and coolant

the greater the humidity ratio and air velocity are

and the more obvious the downward trend of the heat exchange capacity is.