空气源热泵机组结霜问题的实验分析

基于空气源热泵在低温寒冷地区运行中遇到的结霜问题,对不同风速工况下,结霜过程中设备性能的变化进行分析,以换热量、换热系数为指标对不同翅型换热器的换热特性进行研究。实验结果显示:换热器结霜过程中,换热过程主要分为初始增加段、换热平稳段、缓慢衰减段、后期平稳等四段,结晶体在增加空气湍流度强化换热的同时,也增加了换热热阻使换热效果变差,因此换热效果本质而言是两种换热效果的综合体现;空气阻力随风速的增大、结霜量的增加而增大,而蒸发压力随着风速的增加而升高、随结霜量的增大而减小;百叶窗翅片表面结霜量大于平翅片,因此平翅片翅型当量换热系数更大,翅片结霜量、当量换热系数随风速的增加而增大,风速由1 m/s增至4 m/s时,结霜量、当量换热系数增加约三倍。

Experimental analysis on the frost formation problem of air source heat pump unit

Based on the frost formation problem which happens when air source heat pump is operating in cold regions, equipment performance during frosting was analyzed under different wind speed conditions, and the heat transfer characteristics of different finned heat exchangers were also studied with Indexes of the heat exchange capacity and the equivalent heat transfer coefficient in the paper. The experimental results show that the heat transfer process during frosting is mainly divided into four steps: the initial increase section, the heat transfer stable section, the slow decay section and the later stable section, crystal not only can increase air turbulence enhancing the heat transfer, but also can increase the heat transfer resistance worsing the heat transfer effect.Therefore, the heat transfer effect is essentially a comprehensive reflection of two factors.In addition, air resistance increases with the increase of air speed and frost quantity, while evaporation pressure increases with the increase of air speed and decreases with the increase of frost quantity.The equivalent heat transfer coefficient of flat fin heat exchanger is larger due to frost quantity on the surface of louvered fin;the frost quantity and equivalent heat transfer coefficient all increase with the increase of air speed, the frost quantity and equivalent heat transfer coefficient increase by about 3 times when air speed increases from 1 m/s to 4 m/s.