Cooling and heating performances of a CO2 heat pump with the variations of operating conditions

Honghyun Cho; Changhyun Baek; Eungchan Lee; Hun Kang; Yongchan Kim

doi:10.3795/KSME-B.2008.32.6.454

Cooling and heating performances of a CO₂ heat pump with the variations of operating conditions

Honghyun Cho, Changhyun Baek, Eungchan Lee, Hun Kang, Yongchan Kim

School of Mechanical Engineering

Research output: Contribution to journal › Article › peer-review

Abstract

Since operating conditions are significantly different for heating and cooling mode operations in a CO₂ heat pump system, it is difficult to optimize the performance of the CO₂ cycle. In addition, the performance of a CO₂ heat pump is very sensitive to outdoor temperature and gascooler pressure. In this study, the cooling and heating performances of a variable speed CO₂ heat pump with a twin-rotary compressor were measured and analyzed with the variations of EEV opening and compressor frequency. As a result, the cooling and heating COPs were 2.3 and 3.0, respectively, when the EEV opening was 22%. When the optimal EEV openings for heating and cooling were 28% and 16%, the cooling and heating COPs increased by 3.3% and 3.9%, respectively, over the COPs at the EEV opening of 22%. Beside, the heating performance was more sensitive to EEV opening than the cooling performance. As the compressor speed decreased by 5 Hz, the cooling COP increased by 2%, while the heating COP decreased by 8%.

Original language	English
Pages (from-to)	454-462
Number of pages	9
Journal	Transactions of the Korean Society of Mechanical Engineers, B
Volume	32
Issue number	6
DOIs	https://doi.org/10.3795/KSME-B.2008.32.6.454
Publication status	Published - 2008 Jun

Keywords

Carbon dioxide
Coefficient of performance(COP)
Electronic expansion valve(EEV)
Transcritical cycle

ASJC Scopus subject areas

Mechanical Engineering

Access to Document

10.3795/KSME-B.2008.32.6.454

Cite this

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title = "Cooling and heating performances of a CO2 heat pump with the variations of operating conditions",

abstract = "Since operating conditions are significantly different for heating and cooling mode operations in a CO2 heat pump system, it is difficult to optimize the performance of the CO2 cycle. In addition, the performance of a CO2 heat pump is very sensitive to outdoor temperature and gascooler pressure. In this study, the cooling and heating performances of a variable speed CO2 heat pump with a twin-rotary compressor were measured and analyzed with the variations of EEV opening and compressor frequency. As a result, the cooling and heating COPs were 2.3 and 3.0, respectively, when the EEV opening was 22%. When the optimal EEV openings for heating and cooling were 28% and 16%, the cooling and heating COPs increased by 3.3% and 3.9%, respectively, over the COPs at the EEV opening of 22%. Beside, the heating performance was more sensitive to EEV opening than the cooling performance. As the compressor speed decreased by 5 Hz, the cooling COP increased by 2%, while the heating COP decreased by 8%.",

keywords = "Carbon dioxide, Coefficient of performance(COP), Electronic expansion valve(EEV), Transcritical cycle",

author = "Honghyun Cho and Changhyun Baek and Eungchan Lee and Hun Kang and Yongchan Kim",

year = "2008",

month = jun,

doi = "10.3795/KSME-B.2008.32.6.454",

language = "English",

volume = "32",

pages = "454--462",

journal = "Transactions of the Korean Society of Mechanical Engineers, B",

issn = "1226-4881",

publisher = "Korean Society of Mechanical Engineers",

number = "6",

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T1 - Cooling and heating performances of a CO2 heat pump with the variations of operating conditions

AU - Cho, Honghyun

AU - Baek, Changhyun

AU - Lee, Eungchan

AU - Kang, Hun

AU - Kim, Yongchan

PY - 2008/6

Y1 - 2008/6

N2 - Since operating conditions are significantly different for heating and cooling mode operations in a CO2 heat pump system, it is difficult to optimize the performance of the CO2 cycle. In addition, the performance of a CO2 heat pump is very sensitive to outdoor temperature and gascooler pressure. In this study, the cooling and heating performances of a variable speed CO2 heat pump with a twin-rotary compressor were measured and analyzed with the variations of EEV opening and compressor frequency. As a result, the cooling and heating COPs were 2.3 and 3.0, respectively, when the EEV opening was 22%. When the optimal EEV openings for heating and cooling were 28% and 16%, the cooling and heating COPs increased by 3.3% and 3.9%, respectively, over the COPs at the EEV opening of 22%. Beside, the heating performance was more sensitive to EEV opening than the cooling performance. As the compressor speed decreased by 5 Hz, the cooling COP increased by 2%, while the heating COP decreased by 8%.

AB - Since operating conditions are significantly different for heating and cooling mode operations in a CO2 heat pump system, it is difficult to optimize the performance of the CO2 cycle. In addition, the performance of a CO2 heat pump is very sensitive to outdoor temperature and gascooler pressure. In this study, the cooling and heating performances of a variable speed CO2 heat pump with a twin-rotary compressor were measured and analyzed with the variations of EEV opening and compressor frequency. As a result, the cooling and heating COPs were 2.3 and 3.0, respectively, when the EEV opening was 22%. When the optimal EEV openings for heating and cooling were 28% and 16%, the cooling and heating COPs increased by 3.3% and 3.9%, respectively, over the COPs at the EEV opening of 22%. Beside, the heating performance was more sensitive to EEV opening than the cooling performance. As the compressor speed decreased by 5 Hz, the cooling COP increased by 2%, while the heating COP decreased by 8%.

KW - Carbon dioxide

KW - Coefficient of performance(COP)

KW - Electronic expansion valve(EEV)

KW - Transcritical cycle

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