Effects of vapor injection techniques on the heating performance of a CO2 heat pump at low ambient temperatures

Changhyun Baek; Jaehyeok Heo; Jongho Jung; Eungchan Lee; Yongchan Kim

doi:10.1016/j.ijrefrig.2014.03.009

Effects of vapor injection techniques on the heating performance of a CO₂ heat pump at low ambient temperatures

Changhyun Baek, Jaehyeok Heo, Jongho Jung, Eungchan Lee, Yongchan Kim

School of Mechanical Engineering

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

43 Citations (Scopus)

Abstract

The objective of this study is to investigate the effects of vapor injection techniques on the heating performance of a CO₂ heat pump. The performances of the flash tank vapor injection (FTVI), sub-cooler vapor injection (SCVI) and FTVI with a suction line heat exchanger (FTSX) cycles were measured and analyzed with variations of the outdoor temperature, compressor frequency, and injection mass flow rate. At the outdoor temperature of -15 °C and compressor frequency of 55 Hz, the heating capacity and COP of the optimized SCVI cycle were 12.1% and 12.7% higher than those of the optimized FTVI cycle, respectively, because the total mass flow rate in the SCVI cycle was higher than that in the FTVI cycle by the large temperature and pressure differences in the sub-cooler of the SCVI cycle. In addition, the optimum injection flow rate ratios in the vapor injection CO₂ cycles yielding the maximum COP were determined at various compressor frequencies.

Original language	English
Pages (from-to)	26-35
Number of pages	10
Journal	International Journal of Refrigeration
Volume	43
DOIs	https://doi.org/10.1016/j.ijrefrig.2014.03.009
Publication status	Published - 2014 Jul

Keywords

Compressor frequency
Heating performance
Injection ratio
Two-stage
Vapor injection

ASJC Scopus subject areas

Building and Construction
Mechanical Engineering

Access to Document

10.1016/j.ijrefrig.2014.03.009

Cite this

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title = "Effects of vapor injection techniques on the heating performance of a CO2 heat pump at low ambient temperatures",

abstract = "The objective of this study is to investigate the effects of vapor injection techniques on the heating performance of a CO2 heat pump. The performances of the flash tank vapor injection (FTVI), sub-cooler vapor injection (SCVI) and FTVI with a suction line heat exchanger (FTSX) cycles were measured and analyzed with variations of the outdoor temperature, compressor frequency, and injection mass flow rate. At the outdoor temperature of -15 °C and compressor frequency of 55 Hz, the heating capacity and COP of the optimized SCVI cycle were 12.1% and 12.7% higher than those of the optimized FTVI cycle, respectively, because the total mass flow rate in the SCVI cycle was higher than that in the FTVI cycle by the large temperature and pressure differences in the sub-cooler of the SCVI cycle. In addition, the optimum injection flow rate ratios in the vapor injection CO2 cycles yielding the maximum COP were determined at various compressor frequencies.",

keywords = "Compressor frequency, Heating performance, Injection ratio, Two-stage, Vapor injection",

author = "Changhyun Baek and Jaehyeok Heo and Jongho Jung and Eungchan Lee and Yongchan Kim",

note = "Funding Information: This work was supported by the Human Resources Development program (No. 20124010203250 ) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea Government Ministry of Trade, Industry and Energy . ",

year = "2014",

month = jul,

doi = "10.1016/j.ijrefrig.2014.03.009",

language = "English",

volume = "43",

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AU - Baek, Changhyun

AU - Heo, Jaehyeok

AU - Jung, Jongho

AU - Lee, Eungchan

AU - Kim, Yongchan

N1 - Funding Information: This work was supported by the Human Resources Development program (No. 20124010203250 ) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea Government Ministry of Trade, Industry and Energy .

PY - 2014/7

Y1 - 2014/7

N2 - The objective of this study is to investigate the effects of vapor injection techniques on the heating performance of a CO2 heat pump. The performances of the flash tank vapor injection (FTVI), sub-cooler vapor injection (SCVI) and FTVI with a suction line heat exchanger (FTSX) cycles were measured and analyzed with variations of the outdoor temperature, compressor frequency, and injection mass flow rate. At the outdoor temperature of -15 °C and compressor frequency of 55 Hz, the heating capacity and COP of the optimized SCVI cycle were 12.1% and 12.7% higher than those of the optimized FTVI cycle, respectively, because the total mass flow rate in the SCVI cycle was higher than that in the FTVI cycle by the large temperature and pressure differences in the sub-cooler of the SCVI cycle. In addition, the optimum injection flow rate ratios in the vapor injection CO2 cycles yielding the maximum COP were determined at various compressor frequencies.

AB - The objective of this study is to investigate the effects of vapor injection techniques on the heating performance of a CO2 heat pump. The performances of the flash tank vapor injection (FTVI), sub-cooler vapor injection (SCVI) and FTVI with a suction line heat exchanger (FTSX) cycles were measured and analyzed with variations of the outdoor temperature, compressor frequency, and injection mass flow rate. At the outdoor temperature of -15 °C and compressor frequency of 55 Hz, the heating capacity and COP of the optimized SCVI cycle were 12.1% and 12.7% higher than those of the optimized FTVI cycle, respectively, because the total mass flow rate in the SCVI cycle was higher than that in the FTVI cycle by the large temperature and pressure differences in the sub-cooler of the SCVI cycle. In addition, the optimum injection flow rate ratios in the vapor injection CO2 cycles yielding the maximum COP were determined at various compressor frequencies.

KW - Compressor frequency

KW - Heating performance

KW - Injection ratio

KW - Two-stage

KW - Vapor injection

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