NH_3/CO_2和R507/CO_2复叠式制冷系统性能模拟分析

Performance simulation analysis of NH_3/CO_2 and R507/CO_2 superposition refrigeration systems

建立了NH_3/CO_2和R507/CO_2复叠式制冷系统热力学模型,并改变冷凝蒸发器换热温差、低温级蒸发温度和高温级冷凝温度来研究两种系统的性能。结果表明,冷凝蒸发器换热温差对R507/CO_2复叠式制冷系统效率影响更大,相同工况下,R507/CO_2复叠式制冷系统的COP略低于NH_3/CO_2复叠式制冷系统,但R507/CO_2复叠式制冷系统随低温级蒸发温度升高的增长速率较大,随高温级冷凝温度增长而降低的速率较小,且R507制冷剂比NH_3制冷剂更加安全,可以通过降低冷凝蒸发器换热温差,提高低温级蒸发温度,降低高温级冷凝温度的方法来提高复叠式制冷系统COP。

In this paper, the performance of NH3/CO2 and R507/CO2 superposition refrigeration systems was studied by changing the heat transfer temperature of condenser evaporators, low-temperature evaporation temperature and high-temperature condensation temperature.The results show that the heat transfer temperature difference of the condenser evaporator has a greater effect on the efficiency of R507/CO2 superposition refrigeration system.Under the same working conditions, the COP of the R507/CO2 superposition refrigeration system is slightly lower than that of the NH3/CO2 superposition refrigeration system.However, the rate of increase with the temperature of low-temperature evaporation is relatively large, the rate of decrease with the increase of high-temperature condensation temperature is relatively small, and the R507 refrigerant is safer than the NH3 refrigerant.By reducing the temperature difference of condensing evaporator heat transfer, increasing the temperature of low-temperature stage evaporation and reducing the high-temperature stage condensing temperature, the COP refrigeration system can be improved.