N_2O跨临界二级蒸气压缩制冷循环及回热特性

N_2O transcritical two-stage vapor compression refrigeration cycle and internal heat exchange characteristics

为解决CO2跨临界循环能效低、排气压力高的问题,将天然工质N2O用于跨临界循环,建立了相应的理论模型,比较了CO2和N2O用于二级蒸气压缩跨临界循环的性能,并分析了回热效率对于CO2和N2O系统能效Ccop和最优高压侧排气压力的影响。结果表明:N2O用于二级蒸气压缩跨临界制冷循环中的综合性能要优于CO2,在所选定的工况范围内,N2O的Ccop值比CO2最多提高13.3%,最优高压侧排气压力最多降低17.7%。回热效率对于CO2和N2O系统的最优高压侧排气压力几乎没有影响,回热循环对于CO2二级压缩跨临界系统的能效提升更为有利。

The recommended natural refrigerant N2O was supposed to be applied to a transcritical refrigeration cycle in order to solve the disadvantages of low energy efficiency and high discharge pressure in conventional CO2 transcritical cycle.A corresponding theoretical model was set up,in which the performance was compared between CO2 and N2O in the transcritical two-stage vapor compression refrigeration cycle.The influences of thermal efficiency on the energy efficiency Ccop of CO2 and N2O and the optimal high discharge pressure were analyzed.The results show that N2O plays a better performance than CO2 in the two-stage vapor compression refrigeration cycle under certain operating conditions.The Ccop of N2O is higher than that of CO2 by 13.3% at most,and the optimal high-side discharge pressure reduces by 17.7% at most.The optimal high side discharge pressure is hardly affected by the thermal efficiency of CO2 and N2O.However,the internal heat exchange cycle is more advantageous for the CO2 system.