Optimal control of the gas-cooler pressure of a CO2 heat pump using EEV opening and outdoor fan speed in the cooling mode

Changhyun Baek, Jaehyeok Heo, Jongho Jung, Honghyun Cho, Yongchan Kim

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)


The objective of this study is to investigate the control methods of the gas-cooler pressure in a CO2 heat pump. The cooling performance of the CO2 heat pump was measured by varying the refrigerant charge amount, EEV opening, compressor frequency, and outdoor fan speed at various outdoor temperatures. The effects of the EEV opening and the outdoor fan speed on the gas-cooler pressure and the COP were analyzed by using the experimental data. In the standard cooling condition at the compressor frequency of 45 Hz, the optimum gas-cooler pressure and the maximum COP were 9200 kPa and 3.04, respectively, at the optimum EEV opening of 41% and outdoor fan speed of 500 rpm. As the compressor frequency increased from 45 Hz to 55 Hz at the standard cooling condition, the optimum outdoor fan speed increased from 500 rpm to 700 rpm.

Original languageEnglish
Pages (from-to)1276-1284
Number of pages9
JournalInternational Journal of Refrigeration
Issue number4
Publication statusPublished - 2013 Jun


  • CO heat pump
  • Compressor frequency
  • Electronic expansion valve opening
  • Gas-cooler pressure
  • Outdoor fan speed
  • Refrigerant charge

ASJC Scopus subject areas

  • Building and Construction
  • Mechanical Engineering


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