Frosting Surface of Finned Tube Evaporator under Strong Convection
Frosting on the surface of finned tube evaporator was one of the main adverse factors that hindered the efficient operation of refrigeration system.A visual experimental platform for frosting on the surface of finned tube of evaporator under forced convection was built by using constant temperature and humidity chamber.The dynamic growth process of frost layer was recorded in real time with air temperature 0～8 ℃,relative humidity 55％～75％and head wind speed 0.8～2.4 m/s.The effects of ambient temperature,relative humidity and head-on wind speed on frost growth characteristics and heat transfer performance of evaporator were studied.The results show that ambient temperature and head-on wind speed are the main factors affecting frosting of evaporator.When frosting for 50 min,the frost thickness under the ambient temperature of 0 ℃ is 12.78％higher than that under the ambient temperature of 8 ℃,and the frost thickness under the wind speed of 2.4 m/s is 14.66％higher than that under the wind speed of 0.8 m/s.The frost amount and heat transfer increase the same trend.In the early stage of frosting,the greater the relative humidity,the greater the heat transfer.In the later stage of frosting,the lower the relative humidity,the greater the heat transfer.The correlation between the environmental parameters and the time of heat transfer is obtained.
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