用于冷库冻结间液体冷媒除霜能效分析

Energy Efficiency Analysis of Liquid Refrigerant Defrosting Applied in Freezing Room

液体冷媒除霜具有在除霜期间制冷过程连续,库温波动小,无需附加能耗的优势。本文通过采用6 mm翅片间距的双联冷风机进行实验,探究冷媒除霜的除霜规律。在库温为-20℃工况下,进行了不同结霜质量下的除霜实验,得到不同结霜质量下的除霜时间、库温升高值、制冷量和压缩机进出口温度的变化值;得出系统制冷和除霜过程的能效比与除霜周期(除霜时间与结霜时间之和)之间的关系。实验研究表明:除霜过程中,除霜时间短,库温波动小,食品冷冻时可以进行多次除霜,因此可以将翅片间距从12 mm减小为6 mm,减小冷风机体积,减小制冷剂的充注量。结霜质量在5 kg以内,相对湿度为70%、80%、90%的情况下,冷媒除霜系统的最佳除霜周期分别为16.4 h、10.9 h、7.5 h,最大能效比分别为1.51、1.48、1.45。

The liquid refrigerant defrosting has many advantages： the refrigeration process is continuous during the defrosting period; the temperature fluctuation of the cold storage is small; and there is no additional energy consumption. The defrosting rule of the liquid refrigerant defrosting system was studied by using the duplex air cooler with 6 mm fin spacing basing on the liquid refrigerant defrosting system applied in the freezer. The defrosting experiments with different frosting mass were carried out under the condition of the cold storage temperature of-20 ~C.The experiments obtained the defrosting time, the increased value of the cold storage temperature and cooling capacity in different frosting mass and the temperature variation of inlet and outlet of the compressor. The relationship between COP and defrosting cycle （sum of defrosting time and frosting time） was obtained in the process of refrigerating and defrosting. The experiments research shows that in the process of defrosting, defrosting time is short, and the temperature fluctuation is small. Cold storage can carried out several times defrosting. Therefore, the fin spacing can be reduced from 12 mm to 6 mm, the volume of the air cooler can be reduced, and the charge of refrigerant can be reduced. In the case of relative humidity of 70%, 80%, 90%, the optimum defrosting cycle of the experiment system is 16.4 h, 10.9 h, 7.5 h and the maximum COP is 1.51, 1.48, 1,45.