An experimental study on defrosting performance for an air source heat pump unit with a horizontally installed multi-circuit outdoor coil
An experimental study on defrosting performance for an air source heat pump unit with a horizontally installed multi-circuit outdoor coil
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DOI：
10.1016/j.apenergy.2015.12.107
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发表时间：
2016-03
期刊：
影响因子：
11.2
通讯作者：
Mengjie Song;S. Deng;N. Mao;X. Ye
中科院分区：
文献类型：
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作者：
Mengjie Song;S. Deng;N. Mao;X. Ye
空气源热泵（ASHP）机组室外盘管表面结霜会严重影响系统的运行性能。逆循环法是应用最广泛的标准循环法。先前的相关研究报告称，由于重力作用，融化的霜在垂直多回路室外盘管上向下流动，会降低反向循环制冷性能。若室外盘管改为水平安装，可缩短融霜在盘管表面的流动路径，使制冷剂与融霜的流动方向由相反变为正交。因此，预期会有更好的抗干扰性能。为此，本文对多回路室外盘管水平安装的空气源热泵机组的制冷性能进行了试验研究。实验结果表明，当室外盘管由垂直安装改为水平安装时，在相同的制冷持续时间为186 s的情况下，制冷效率提高了9.8%。此外，当室外风扇在除湿期间反向吹送融化的霜时，收集的保留水的总质量减少222g。但是，由于热盘管与冷空气之间的传热增强，冷却效率并没有增加，反而下降了6.6%。
When frost forms and accumulates over the outdoor coil’s surface in an air source heat pump (ASHP) unit, system operating performance will be dramatically deteriorated. Reverse cycle defrosting is the most widely used standard defrosting method. A previous related study reported that downwards flowing of melted frost due to gravity over a vertical multi-circuit outdoor coil would decrease the reverse cycle defrosting performance. If the outdoor coil can be changed to horizontally installed, the flow path of melted frost over coil surface can be shortened, and the flow directions of refrigerant and melted frost changed from opposite to orthogonal. Consequently, a better defrosting performance is expected. In this paper, therefore, an experimental study on defrosting performance for an ASHP unit with a horizontally installed multi-circuit outdoor coil was conducted. Experimental results show that, when a vertical outdoor coil was changed to horizontally installed, the defrosting efficiency increased 9.8%, however, with the same defrosting duration at 186 s. Furthermore, when the outdoor air fan was reversed to blowing the melted frost during defrosting, the total mass of the retained water collected decreased 222 g. However, the defrosting efficiency was not increased, but decreased 6.6% because of the heat transfer enhanced between hot coil and cold ambient air.