文档介绍：Available online at
Applied Thermal Engineering 28 (2008) 2267–2278
ate/apthermeng
Experimental study on frost growth and dynamic performance
of air source heat pump system
Xian-Min Guo a,b,*, Yi-Guang Chen b, Wei-Hua Wang b, Chun-Zheng Chen a
a Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, PR China
b School of Mechanical Engineering, Tianjin University merce, Tianjin 300134, PR China
Received 11 April 2007; accepted 6 January 2008
Available online 18 January 2008
Abstract
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 e 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