非共沸混合天然工质泄漏对自复叠循环制冷机性能的影响

Influence of leakage of natural non-azeotropic mixture refrigerants on performance of auto-cascade refrigeration cycle

以非共沸混合工质两相区的等温泄漏模型为基础,分析自复叠循环装置中各部件的泄漏对工质组分的影响,以天然工质R600a/CO2自复叠低温冷冻箱为例,研究不同泄漏点和不同泄漏率的泄漏特性。结果表明:当工质泄漏时,混合工质组分和循环性能均发生变化,在蒸发器出口处的泄漏对循环性能影响最大;当泄漏引起循环工质组分发生较大变化时,压缩机变容量和变压力比调节能力明显降低,此时系统不能满足设计工况的要求,工作性能变差。

Analyzes the influence of leakage in different parts which leads to the composition change of refrigerant based on the isothermal leakage of non-azeotropic refrigerant in two-phase area. Studies the leakage characteristics of different leakage points with different leakage ratio using natural refrigerants R600a/CO2. The results show that the refrigerant composition and performance of cycle both change when refrigerant leaks out. In particularly, the leakage at the outlet of evaporator plays the most important role in system performance. The adjusting ability in capacity and pressure ratio of compressor reduces obviously if the composition of refrigerant changes a lot due to the leakage,which also results to the unsatisfied requirement of working condition and worse system performance.