回热器与制冷工质对复叠制冷系统性能的影响

建立了复叠制冷系统的热力学模型,对比分析了低温级冷凝温度、高温级冷凝温度以及回热器位置对R449A/CO₂、NH₃/CO₂、R404A/CO₂3种复叠制冷系统性能的影响。结果表明,相同低温级蒸发温度下,NH₃/CO₂系统的最佳低温级冷凝温度低于R449A/CO₂和R404A/CO₂系统的,NH₃/CO₂系统的最佳性能系数COP与R449A/CO₂的相差约2%,大幅高于R404A/CO₂系统的;复叠系统的CO2低温级设置回热器会使系统性能降低,而高温级设置回热器,R449A/CO2和NH₃/CO₂系统的性能下降,R404A/CO₂系统的性能提高。R449A在复叠制冷系统中性能优良,可作为低GWP冷媒推广使用。

Effects of regenerator and refrigerant on performance of cascade refrigeration system

In order to optimize the cascade refrigeration system, the thermodynamic models of cascade refrigeration systems were established in this study, and the effects of low and high temperature stage condensation temperature, and regenerator position on the performance of R449A/CO₂, NH₃/CO₂, R404A/CO₂ cascade refrigeration systems were compared and analyzed. The results show that: at the same low temperature stage evaporation temperature, the optimal low temperature stage condensation temperature of the NH₃/CO₂ system is lower than that of the R449A/CO₂ and R404A/CO₂ systems, and the best COP of the NH₃/CO₂ system differs from R449A/CO₂ by about 2%, which is much higher than that of the R404A/CO₂ system. Adding the regenerator to the CO₂ low temperature stage of the cascade system will reduce performance of system. However, Adding the regenerator to the high temperature stage will reduce the performance of the R449A/CO₂ and NH₃/CO₂ systems and increase the performance of the R404A/CO₂ system. R449A has excellent performance in cascade refrigeration system and can be used widely as low GWP refrigerant.