自复叠双温冰箱的流程改进和性能分析

Improvement on the Flow of Two-Stage Temperatures Refrigerator Using Auto Cascade Cycle and Analysis of the Performance

针对传统双温冰箱制冷循环存在的不足,提出了自复叠双温冰箱循环,在以前设计流程的基础上研究了4种流程改进方案,并分析了换热器不同布置方式、不同换热效果和分凝分离级数对冰箱性能的影响．模拟计算结果表明:在冷藏室蒸发器前增加逆流换热器只能降低冷藏室蒸发器的温度而不能提高系统性能系数(C=_(COP));在冷冻室蒸发器前增加逆流换热器可以提高系统C_(COP);在气液分离器前增加逆流换热器可以通过提高气液分离效率来改善系统性能,但C_(COP)提高不大;采用两级分凝分离方式可以较好地提高气液分离效率,降低压缩机的压力比,提高系统C_(COP),也达到了改进系统性能的目的,但流程较复杂．这4种改进流程从不同方面改善了循环工作参数,为改善实际装置的系统性能提供了理论基础．

The auto-cascade refrigeration cycle for two-stage temperature refrigerator was proposed and four kinds of modified flow paths were studied. The influence of different locations and efficiency of a heat exchanger and different separating steps on performance of the refrigerator was also analyzed. The results of simulating calculation show that the evaporating temperature of fridge chamber is reduced but the coefficient of performance （COP） is not increased when a counterflow heat exchanger is set ahead of the evaporator of fridge chamber; the COP is improved when the heat exchanger is set ahead of the evaporator of freezer chamber; the vapor-liquid separating efficiency is improved but the COP is not increased significantly when the heat exchanger is set ahead of the vapor-liquid separator. Moreover, the vapor-liquid separating efficiency can be improved by using two steps dephlegmation and separation, and thus the pressure ratio of the compressor is decreased and the COP is increased, but the flow path of the refrigerator is more complex.