Frosting and refrigerant distribution uneven easily are two key problems restricting the wide application of micro-channel heat exchanger in the field of air source heat pump (ASHP). In this paper, frosting experiments were carried out on two kinds of micro-channel heat exchanger in three cases that with different refrigerant distribution characteristics. Frost and temperature distribution characteristics and their influence on the heat pump’s COP and heating capacity was studied. The results show distribution of refrigerant in heat exchanger directly affects the frost and temperature distribution on the surface of micro-channel heat exchanger, and affects the heating capacity and COP of ASHP greatly. Vertical placement of flat tubes and horizontal placement of the headers can be beneficial to the refrigerant distribution compared with that with the headers vertically placed. Flow direction of refrigerant in the heat exchanger must be from bottom to top to avoid deteriorated heat transfer performance and instability of ASHP. Difference between the lowest temperature and largest temperature on heat exchanger surface can be used as an index to judge whether ASHP works in high performance state.

结霜和制冷剂分布不均匀容易成为限制微通道热交换器在空气源热泵（ASHP）领域中广泛应用的两个关键问题。本文在三种制冷剂分布特性不同的情况下，对两种微通道换热器进行了结霜实验。研究了霜冻和温度分布特性及其对热泵COP和热容量的影响。结果表明，制冷剂在换热器中的分布直接影响微通道换热器表面的霜冻和温度分布，极大地影响了ASHP的热容量和COP。与竖直放置集管相比，扁平管的垂直放置和集管的水平放置可有利于制冷剂分配。热交换器中制冷剂的流动方向必须是从下到上，以避免传热性能下降和ASHP不稳定。热交换器表面的最低温度和最高温度之间的差异可以用作判断ASHP是否在高性能状态下工作的指标。