准二级压缩空气源热泵补气加速除霜实验

Experimental Investigation on the Effects of Vapor Injection on Defrosting Performance Improvement of Quasi-two Stage Compression Air-source Heat Pumps

准二级压缩空气源热泵在除霜过程中,由于室外换热器面积大和室外环境温度低的原因,通过室外盘管表面的散热量更大,导致其除霜时间长的问题更加突出。为提升准二级压缩空气源热泵的除霜性能,本文利用其既有的循环结构,提出补气除霜技术,并设计了5组实验对其性能进行研究。结果表明,补气可有效缩短除霜时间,降低除霜能耗并提升除霜效率。电子膨胀阀在最佳开度时,除霜时间缩短20.61%,从水中的吸热量和压缩机输入功分别降低8.74%和17.98%,除霜效率提升6.22%。

During reverse-cycle defrosting of an air-source heat pump,the defrosting time is always long owing to insufficient heat sources.For the quasi-two stage compression air-source heat pump(QTASHP),owing to its larger outdoor coil operated at lower ambient temperatures,a considerable amount of heat is dissipated from the surface of the outdoor coil during defrosting,such that the long defrosting time problem becomes more severe.To improve the defrosting performance of the QTASHP,defrosting with vapor injection was proposed based on the existing cycle structure.Five groups of experiments were designed to investigate the defrosting performance.The results showed that vapor injection was beneficial for shortening the defrosting duration,decreasing power consumption,and increasing defrosting efficiency.At the optimal opening of the injection electronic expansion valve,the defrosting duration was shortened by 20.61%;the heat absorbed from water and power consumption decreased by 8.74%and 17.98%,respectively;whereas the defrosting efficiency increased by 6.22%.