Performance evaluation of a two-stage CO2 cycle with gas injection in the cooling mode operation
- Authors
- Cho, Honghyun; Baek, Changhyun; Park, Chasik; Kim, Yongchan
- Issue Date
- 1월-2009
- Publisher
- ELSEVIER SCI LTD
- Keywords
- Refrigeration system; Compression system; Two-stage system; Carbon dioxide; Transcritical system; Injection; Measurement; Performance
- Citation
- INTERNATIONAL JOURNAL OF REFRIGERATION-REVUE INTERNATIONALE DU FROID, v.32, no.1, pp.40 - 46
- Indexed
- SCIE
SCOPUS
- Journal Title
- INTERNATIONAL JOURNAL OF REFRIGERATION-REVUE INTERNATIONALE DU FROID
- Volume
- 32
- Number
- 1
- Start Page
- 40
- End Page
- 46
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/120861
- DOI
- 10.1016/j.ijrefrig.2008.07.008
- ISSN
- 0140-7007
- Abstract
- The cooling performance and reliability of a transcritical CO2 cycle can be significantly improved by using a multi-stage compressor with gas injection because the CO2 cycle 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 CO2 cycle with gas injection. in this study, the performances of a two-stage CO2 cycle 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. (C) 2008 Elsevier Ltd and IIR. All rights reserved.
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