制冷系统二次冷凝除霜循环理论分析

Theoretical Analysis of Secondary Condensation Defrost Cycle of Refrigeration System

为降低制冷系统低温运行时因冷风机除霜产生的能耗,提出制冷剂二次冷凝除霜方式。建立制冷和除霜模型,探究适宜的二次冷凝除霜制冷剂旁通比,比较不同蒸发温度以及单次除霜时长对二次冷凝除霜理论循环性能的影响。分析结果表明,二次冷凝除霜制冷剂旁通比宜取值0.15,除霜过程实现了对制冷环境净吸热,并且在蒸发温度为-35、-25、-15、-5℃时,二次冷凝除霜周期COP相比制冷周期COP提高了13%~16%,有效降低了制冷系统低温运行时的除霜能耗。

In order to reduce the energy consumption caused by defrosting of cooling fan during low temperature operation of refrigeration system,the method of refrigerant secondary condensation defrosting was proposed.The frosting and defrosting models were established to explore the appropriate refrigerant bypass ratio for secondary condensation defrosting,and the effects of different evaporation temperatures and single defrosting duration on theoretical cycle performance of secondary condensation defrosting were compared.The analysis results show that the refrigerant bypass ratio of secondary condensation defrosting should be 0.15,the defrosting process can absorb heat completely to the refrigeration environment.When the evaporation temperature is-35、-25、-15、-5℃,the COP of secondary condensation defrosting cycle increases by 13%-16%compared with that of refrigeration cycle,and effectively reduces the defrosting energy consumption of refrigeration system under low temperature operation.