Experimental study on frost growth and dynamic performance of air source heat pump system
Experimental study on frost growth and dynamic performance of air source heat pump system
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DOI：
10.1016/j.applthermaleng.2008.01.007
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发表时间：
2008-12
影响因子：
6.4
通讯作者：
Xian-min Guo;Yi-guang Chen;Wen Wang;Chunzheng Chen
中科院分区：
文献类型：
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作者：
Xian-min Guo;Yi-guang Chen;Wen Wang;Chunzheng Chen
通过实验研究了霜层生长和霜层形态对空气源热泵性能的影响。测试了霜层厚度、霜层累积量和热泵的动态性能。结果表明，根据霜层的形态，霜层的生长可分为三个阶段。在初始阶段，冷凝水首先在翅片和管上冻结形成透明的薄冰层，然后在冰层上出现颗粒状冰并逐渐长大，最后形成柱状冰晶。随着结霜时间的延长，霜层厚度的增长速率、热泵制热量和性能系数均显著增大，直至形成柱状霜层。在第二阶段，柱状冰晶沿半径方向生长，而不是沿长度方向生长，霜层厚度增长速率减小或保持不变。而室外盘管结霜对热泵的制热量和COP影响较小。第三阶段，冰晶主要沿长度方向生长，并逐渐形成冰锥状冰晶，最后形成蓬松的霜层。霜层厚度增长速率约为第二阶段的2-4倍。加热能力和COP的每分钟下降量增加到第二阶段的数倍。此外，还发现在室外空气温度为0°C左右，不同相对湿度条件下，霜层生长速率和热泵性能的下降幅度最大。除第三结霜阶段外，实验结果与相应的模拟数据基本一致。
The effect of the frost growth and frost morphology on the performance of an air source heat pump was investigated experimentally. The frost thickness, frost accumulation and the dynamic performance of the heat pump were measured. It is found that the frost growth can be divided into three stages according to the frost morphology. In the initial stage, condensed water freezes and forms a transparent thin ice layer on the fins and tubes firstly, then the granular ices appear and grow gradually on the ice layer, and the column-shaped ice crystals are formed at last. The growth rate of the frost thickness, the heating capacity and COP of the heat pump increase with the frosting time significantly until the column-shaped frost layer is formed. In the second stage, the column-shaped ice crystals grow in its radius rather than in its length, and the frost thickness growth rate decreases or remains to be constant. However, the heating capacity and COP of the heat pump are only slightly affected by frosting on the outdoor coils. In the third stage, the ice crystals mainly grow in its length, and become gradually of an acerose-shaped one, finally a fluffy frost layer is formed. The frost thickness growth rate is about 2–4 times of that in the second stage. The drops per minute in the heating capacity and COP are increased by several times of those in the second stage. In addition, it is found that the frost growth rate and the drop in the performance of the heat pump are highest when the outdoor air temperature is about 0°C with various relative humidity. The experimental results are in agreement with the corresponding simulation data except in the third frosting stage.