不均风速场对中大型热泵结霜工况性能的影响

针对一台名义制冷量为50 kW的风冷热泵冷热水机组,研究了风速不均匀分布对机组结霜工况性能的影响.实验结果表明:风速的不均匀分布是系统反馈控制支路产生振荡的主导因素;随着风速不均匀度增加,结霜速度加快,致使系统的稳定工作时间缩短,系统的换热性能降低;风速分布不均匀度为0.93与0.18时相比,系统的稳定工作时间缩短了34 min,系统的制热量降低约14.2%;结霜振荡阶段,霜层的阻塞作用成为影响系统性能的主要因素,随着风速分布不均匀度的增加,系统参数衰减加剧.

Influence of Airflow Maldistribution on Performance of Air-to-Water Heat Pump System under Frosting Conditions

The experiments for different airflow maldistribution degree(AMD) were conducted on a 50 kW unitary air-to-water heat pump.The results indicate that the airflow maldistribution at the face of finned tube heat exchanger is the dominant factor which results in the hunting of the thermostatic expansion valve.With AMD increasing,the process of frosting quickens and the stable work time of the heat pump shortens.The heating capacity decreases accordingly.When AMD was 0.93 and 0.18,the stable work time of heat pump reduced 34 minutes and the heating capacity decreased by 14.2 % accordingly.For the hunting stage,the frost block effect became the main factor degrading the refrigeration system performance.