强制对流下翅片管蒸发器表面结霜实验

Frosting Surface of Finned Tube Evaporator under Strong Convection

翅片管蒸发器表面结霜是阻碍制冷系统高效运行的主要不利因素之一。利用恒温恒湿箱搭建强制对流下蒸发器翅片管表面结霜可视化实验平台,在环境温度0~8℃、相对湿度55%~75%及迎面风速0.8~2.4 m/s时,实时记录霜层动态生长过程,研究了环境温度、相对湿度和迎面风速对霜层生长特性及蒸发器换热性能的影响规律。结果表明:环境温度和迎面风速是影响蒸发器结霜的主要因素,结霜50 min,环境温度为0℃的霜层厚度比环境温度为8℃的提高了12.78%,迎面风速为2.4 m/s的霜层厚度比迎面风速为0.8 m/s的提高了14.66%,结霜量与换热量提高趋势相同。在结霜初期,相对湿度越大,换热量越大;结霜后期,相对湿度越小,换热量越大,并得到了换热量关于环境参数与时间的相关关系。

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 a constant temperature and humidity box.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 m/s~2.4 m/s.The effects of ambient temperature,relative humidity and head wind speed on frost growth characteristics and heat transfer performance of evaporator were studied.The results show that ambient temperature and head 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.The lower the air temperature and the greater the frontal wind speed,the smaller the evaporation pressure,the greater the frost thickness and frost amount,and the greater the heat exchange.The higher the relative humidity is,the larger the frost amount is.The frost layer thickness,evaporation pressure and heat transfer trend change,and the correlation between heat transfer and environmental parameters and time is obtained.