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通过实验研究了室外换热器采用平直、波纹、波纹/开缝翅片对热泵空调器动态结霜性能的影响。结果表明,在结霜工况下,平直、波纹、波纹/开缝三种翅片类型的系统制热量、COP和压缩机功率的峰值、平均值依次增大,其中,波纹/开缝翅片的各项平均值比平直翅片分别减小了14.57%、8.26%和7.11%。波纹/开缝翅片的性能参数最早开始衰减且衰减幅度也最大,其次是波纹翅片,平直翅片最晚开始衰减且幅度最小。结霜时,水蒸气变为霜的相变过程对传热具有强化作用,同时霜层减小了翅片间隙使风阻增大、室外风机流量减小,这对传热具有恶化作用。结霜时性能参数的曲线存在上升段和衰减段,与霜层微观成长特性一致:结霜初期,冰晶由粒状变为柱状,尚未显著阻塞翅片间隙,对传热的强化作用较显著,曲线处于上升段;结霜中后期,冰晶先沿半径成长,后又在柱状晶间隙堆垛,对传热的恶化作用较显著,曲线处于衰减段。
The effects of flat, corrugated, corrugated / slotted fins on the dynamic frosting performance of heat pump air conditioners were studied experimentally. The results show that in the frosting condition, the system heating capacity, the peak value and the average value of COP and compressor power of flat, corrugated, corrugated / slitted three fin type systems increase in turn, of which the ripple / open fin The mean values of the films were reduced by 14.57%, 8.26% and 7.11% respectively compared with the straight fins. The performance parameters of corrugated / slotted fins start to decay and have the largest attenuation at the earliest, followed by the corrugated fins, which start to decay and have the smallest amplitude at the latest. During frosting, the phase change process of water vapor into frost has an enhancement effect on the heat transfer, meanwhile the frost layer reduces the fin air gap to increase the air resistance and the flow rate of the outdoor fan decreases, which has a deteriorated effect on heat transfer. Frosting performance parameters of the curve there are ascending section and attenuation section, consistent with the microscopic growth characteristics of frost layer: the initial frost, ice crystals from the column into a column, has not significantly blocked fin gap, heat transfer enhancement is more significant curve In the middle and late stages of frost formation, the first ice crystals grew along the radius, and then they were stacked in the columnar crystal interspaces. The deterioration of heat transfer was more pronounced, and the curve was in the attenuation section.