医用冷藏箱热气旁通化霜性能的试验研究

Experimental study on defrosting performance with hot gas pass for medical freezer

结霜现象普遍存在于冷冻冷藏装置中,并会降低系统传热性能、增加能耗。为了代替传统的电加热除霜,本文利用一台医用冷藏箱研究了热气旁通化霜的效果,它的原理是利用压缩机排出的高温气态制冷剂融化蒸发器表面的霜层。通过结霜、化霜试验分析得到热气旁通的化霜效率可以达到80%以上;并进一步分析了结霜时间和微调阀开度对化霜性能的影响,得到结论:1)结霜时间越长,化霜效率越高,但霜层较厚时,系统制冷性能严重下降;2)阀门开度越大,旁通流量越大,化霜效率越高。此外,综合考虑系统性能和化霜效率,本文提出了适用于医药冷藏箱的除霜控制策略。

Defrosting is common in refrigeration devices and will degrade the heat transfer performance and increase energy consumption.With a medical freezer,this paper investigated the effectiveness of defrosting with hot gas bypass instead of conventional electric heater,and its principle is to utilize the high temperature gaseous refrigerant from compressor to melt frost on the evaporator.Through the frosting and defrosting experiments,the defrosting efficiency of hot gas bypass was measured to be more than 80%.In addition,this paper investigated the effect of the defrosting period and the valve opening on defrosting performance.It was found that a longer defrosting period was helpful to improve defrosting efficiency,but impaired the heat transfer performance of system,and a larger opening valve resulted in higher efficiency because of more gaseous refrigerant to melt frost.After considering the heat transfer performance of the refrigeration system and the defrosting efficiency,this paper presented defrosting tactics for medical freezer.