空气源热泵用开圆孔翅片管式换热器结霜特性实验研究

Experimental Study on Frosting Characteristics of Perforated Finned-tube Heat Exchangers of Air Source Heat Pump

利用吸收式风洞实验台对空气源热泵用开圆孔翅片换热器表面霜层生长特性进行了实验研究,计算了换热器的阻力、换热量、当量对流换热系数和结霜量,通过录像观察了换热器表面霜层生长过程,并与平直翅片管式换热器的实验结果进行了比较。结果表明:结霜初始阶段,2种片型换热器表面霜层生长速度基本一致;霜层快速生长阶段,圆孔翅片管式换热器表面霜层生长速度明显慢于平直翅片管式换热器。相比于平直翅片管式换热器,圆孔翅片管式换热器的换热量、当量对流换热系数分别提升了11.7%、35.1%,但是结霜量也增加了11.7%。其主要原因是,圆孔对翅片表面的湿空气产生强烈的扰流作用,除了强化换热之外,还促进换热器表面的霜层均匀分布,延缓了结霜周期。

Experiments on frosting characteristics of perforated finned-tube heat exchangers of air source heat pump were made using the absorption of wind tunnel test rig.The resistance,heat exchange amount,equivalent coefficient of convective heat transfer,frost accumulation of perforated finned-tube heat exchangers were calculated and the growth process of frost on the surface of heat exchangers was observed by video,and all the above parameters were then compared with the results of plain finned-tube heat exchangers.The experimental results show that the growth rates of the frost on the two types of finned-tube heat exchangers were similar in the initial frosting,but that of the frost on the perforated finned-tube heat exchangers was slower than the plain finned-tube heat exchangers in the rapid frosting growth stage.Compared with plain finned-tube heat exchangers,the heat exchange amount and equivalent coefficient of convective heat transfer of perforated finned-tube heat exchangers were increased by 11.7% and 35.1%,but the frost accumulation was also increased by 11.7%.The main reason is that the circular hole of the perforated fin can make an intense disturbance to moist air when that washed the surface of the fin,by which the frost layer was uniform distribution on the surface of heat exchangers and the frost period was extended,except for heat transfer enhancement.