Performance evaluation of a two-stage CO2 cycle with gas injection in the cooling mode operation
Performance evaluation of a two-stage CO2 cycle with gas injection in the cooling mode operation
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DOI：
10.1016/j.ijrefrig.2008.07.008
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
Honghyun Cho;Changhyun Baek;Chasik Park;Yongchan Kim
中科院分区：
文献类型：
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作者：
Honghyun Cho;Changhyun Baek;Chasik Park;Yongchan Kim
由于跨临界二氧化碳循环的压缩机压差较大，因此通过使用带气体喷射的多级压缩机可以显着提高跨临界二氧化碳循环的冷却性能和可靠性。本研究的目的是研究注气两级 CO2 循环的性能和运行特性。在这项研究中，随着制冷剂充注量、第一级和第二级压缩机频率以及第一级和第二级 EEV 开度在冷却模式操作中的变化，测量了带有气体喷射的两级 CO2 循环（称为“两级气体喷射循环”）的性能。实验中两级注气循环的冷却COP比两级非注气循环最大提高了16.5%。此外，当第一级和第二级EEV开度增加时，压缩比降低，这反过来又提高了两级注气循环的冷却COP。然而，当第一级EEV开度增加时，通过蒸发器的质量流量下降，这反过来又降低了两级注气循环的冷却能力。因此，在两级注气循环中，需要对两个 EEV 开口进行最佳控制。
The cooling performance and reliability of a transcritical CO2cycle can be significantly improved by using a multi-stage compressor with gas injection because the CO2cycle has a large pressure difference across a compressor. The objective of this study is to investigate the performance and operating characteristics of a two-stage CO2cycle with gas injection. In this study, the performances of a two-stage CO2cycle with gas injection (called as “two-stage gas injection cycle”) were measured as the amount of refrigerant charge, first- and second-stage compressor frequencies, and first- and second-stage EEV openings were varied in the cooling mode operation. The cooling COP of the two-stage gas injection cycle was maximally enhanced by 16.5% over that of the two-stage non-injection cycle in the experiments. In addition, when the first- and second-stage EEV openings were increased, the compression ratio decreased and this in turn, improved the cooling COP of the two-stage gas injection cycle. However, when the first-stage EEV opening was increased, the mass flow rate through the evaporator decreased, and this in turn, decreased the cooling capacity of the two-stage gas injection cycle. Therefore, in the two-stage gas injection cycle, an optimum control of both EEV openings is required.