Performance evaluation of a two-stage CO2 cycle with gas injection in the cooling mode operation

Honghyun Cho, Changhyun Baek, Chasik Park, Yong Chan Kim

Research output: Contribution to journalArticle

50 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)40-46
Number of pages7
JournalInternational Journal of Refrigeration
Volume32
Issue number1
DOIs
Publication statusPublished - 2009 Jan 1

Fingerprint

Cooling
Compressors
Refrigerants
Evaporators
Flow rate
Experiments

Keywords

  • Carbon dioxide
  • Compression system
  • Injection
  • Measurement
  • Performance
  • Refrigeration system
  • Transcritical system
  • Two-stage system

ASJC Scopus subject areas

  • Mechanical Engineering
  • Building and Construction

Cite this

Performance evaluation of a two-stage CO2 cycle with gas injection in the cooling mode operation. / Cho, Honghyun; Baek, Changhyun; Park, Chasik; Kim, Yong Chan.

In: International Journal of Refrigeration, Vol. 32, No. 1, 01.01.2009, p. 40-46.

Research output: Contribution to journalArticle

@article{c8c04fb467554e1fa6a6f6d43b1e1894,
title = "Performance evaluation of a two-stage CO2 cycle with gas injection in the cooling mode operation",
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.",
keywords = "Carbon dioxide, Compression system, Injection, Measurement, Performance, Refrigeration system, Transcritical system, Two-stage system",
author = "Honghyun Cho and Changhyun Baek and Chasik Park and Kim, {Yong Chan}",
year = "2009",
month = "1",
day = "1",
doi = "10.1016/j.ijrefrig.2008.07.008",
language = "English",
volume = "32",
pages = "40--46",
journal = "International Journal of Refrigeration",
issn = "0140-7007",
publisher = "Elsevier Limited",
number = "1",

}

TY - JOUR

T1 - Performance evaluation of a two-stage CO2 cycle with gas injection in the cooling mode operation

AU - Cho, Honghyun

AU - Baek, Changhyun

AU - Park, Chasik

AU - Kim, Yong Chan

PY - 2009/1/1

Y1 - 2009/1/1

N2 - 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.

AB - 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.

KW - Carbon dioxide

KW - Compression system

KW - Injection

KW - Measurement

KW - Performance

KW - Refrigeration system

KW - Transcritical system

KW - Two-stage system

UR - http://www.scopus.com/inward/record.url?scp=56049111063&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=56049111063&partnerID=8YFLogxK

U2 - 10.1016/j.ijrefrig.2008.07.008

DO - 10.1016/j.ijrefrig.2008.07.008

M3 - Article

AN - SCOPUS:56049111063

VL - 32

SP - 40

EP - 46

JO - International Journal of Refrigeration

JF - International Journal of Refrigeration

SN - 0140-7007

IS - 1

ER -