机械过冷CO_(2)引射制冷系统性能研究

Study on performance of mechanical subcooling CO_(2) ejection refrigeration system

利用R134a机械过冷系统对CO_(2)引射制冷系统(energy recycle system,ERS)气体冷却器出口工质进行冷却,实验研究了在不同过冷度、排气压力及蒸发温度下机械过冷CO_(2)引射制冷系统(mechanical refrigeration energy recycle system,MSERS)的性能,并与ERS系统性能进行了对比分析。结果表明:MSERS系统的COP随着过冷度及排气压力的变化存在最大值,最佳过冷度约为16℃,而最佳排气压力约为8.5 MPa;随着蒸发温度升高,MSERS系统的引射比及COP均增大,且引射比随蒸发温度增大的速度在低蒸发温度工况下比较小。MSERS与ERS系统性能的对比表明:在实验蒸发温度范围内MSERS系统的COP大于ERS系统,且在低蒸发温度工况下MSERS系统COP的改善幅度更大;在蒸发温度小于1℃的工况条件下MSERS系统的引射比比ERS系统的引射比提高了约2.5%~6.0%;在不同的一级节流阀前温度工况下,MSERS系统制冷量比ERS系统提高了约27.2%~35.5%,COP增大了约6.2%~17.6%。

The performance of the mechanical subcooling CO_(2)ejector refrigeration(MSER)system,in which the R134a mechanical subcooling system was used to cool the refrigerant from the gas cooler outlet of the CO_(2)ejector refrigeration(ER)system,was studied experimentally under different subcooling degrees,discharge pressures and evaporation temperatures.The performance of the MSER system was compared with that of the ER system.The results indicated that the COP of the MSER system has a maximum value with the subcooling degree and discharge pressure,and the optimal subcooling degree is about 16℃,while the optimal discharge pressure is about 8.5 MPa.The entrainment ratio of the ejector and COP of MSER system increase with the increase in the evaporation temperature,and the entrainment ratio of the ejector increases with the evaporation temperature at a relatively low rate under low evaporation temperature condition.The performance comparison between MSER and ER systems shows that the entrainment ratio of ejector in the MSER system is greater than that in the ER system under the working condition of evaporation temperature less than 1℃,and the improvement is about 2.5%-6.0%,while the COP of MSER system is greater than that of ER system within the range of experimental evaporation temperature.The COP of MSER system is improved more significantly under a low evaporation temperature condition.Compared with the ER system,the cooling capacity of MSER system increases by 27.2%-35.5% and COP increases by 6.2%-17.6% under different pre-primary throttle temperatures.