R134a／R410A复叠式制冷系统模拟研究

Simulation on R134a/R410A cascade refrigeration system

复叠式制冷系统的蒸发温度、中间温度改变,会影响高低压级级间容量比和压缩机的耗功,从而影响压缩机的质量流量,改变系统制冷性能系数。变频压缩机能有效地缓解温度波动的影响,根据工况做出适当的频率调整,有利于系统的优化与节能。通过模拟不同温度工况下R134a/R410A复叠式制冷系统热力学过程,验证温度和输气量变化对系统性能的影响。结果表明:一定温度范围内,蒸发温度和冷凝温度升高,高低压级级间容量比均增大。蒸发温度对级间容量比的影响大于冷凝温度的影响,蒸发温度和冷凝温度均升高20℃,级间容量比分别增大106. 1%和24. 3%。高低压级压缩机实际输气量相等时,总耗功最少为4. 77kW,制冷系数最大为1. 678。另外,冷凝蒸发器的传热温差减小,有利于制冷系数的提高。

The change of evaporation temperature and intermediate temperature of the cascade refrigeration system will affect the capacity ratio of high and low pressure levels and the consumption of compressors, which affects the mass flow of compressors and changes the refrigeration coefficient of the system. Variable frequency compressor can effectively alleviate the influence of temperature fluctuation, and make appropriate adjustment according to working conditions, which is conducive to system optimi- zation and energy saving. The influence of temperature and gas transmission volume on the system performance was verified by simulating the thermodynamic process of R134a/R410A cascade refrigeration system under different temperature conditions. The results show that the increase of evaporation temperature and condensation temperature make the capacity ratio between high and low pressure levels increase in a certain temperature range. The effect of evaporation temperature on the capacity ratio between high and low pressure levels is greater than that of condensing temperature. The evaporation temperature and condensation tem-perature increase by 20 degrees celsius, and the capacity ratios between high and low pressure levels increases by 106.1% and 24.3% respectively. The total consumption of compressors at least is 4.77kW and the maximum refrigeration coefficient is 1. 678 when actual gas transmission of high and low pressure compressors is equal. In addition, the heat transfer temperature of con- denser - evaporator decreases, which is conducive to the improvement of the refrigeration coefficient.