Cooling performance of a variable speed CO2 cycle with an electronic expansion valve and internal heat exchanger

Honghyun Cho, Changgi Ryu, Yong Chan Kim

Research output: Contribution to journalArticle

44 Citations (Scopus)

Abstract

The cooling performance of a CO2 cycle must be improved to develop a competitive air-conditioning system with the conventional air-conditioners using HFCs. In this study, the cooling performance of a variable speed CO2 cycle was measured and analyzed by varying the refrigerant charge amount, compressor frequency, EEV opening, and length of an internal heat exchanger (IHX). The basic CO2 system without the IHX showed the maximum cooling COP of 2.1 at the compressor discharge pressure of 9.2 MPa and the optimum normalized charge of 0.282. The cooling COP decreased with the increase of compressor frequency at all normalized charges. The optimum EEV opening increased with compressor frequency. Simultaneous control of EEV opening and compressor frequency allowed optimum control of the compressor discharge pressure. The optimal compressor discharge pressure of the modified CO2 cycle with the IHX was reduced by 0.5 MPa. The IHX increased the cooling capacity and COP of the CO2 cycle by 6.2-11.9% and 7.1-9.1%, respectively, at the tested compressor frequencies from 40 to 60 Hz.

Original languageEnglish
Pages (from-to)664-671
Number of pages8
JournalInternational Journal of Refrigeration
Volume30
Issue number4
DOIs
Publication statusPublished - 2007 Jun 1

Fingerprint

compressors
heat exchangers
valves (equipment)
electronics
Heat exchangers
Compressors
cooling
Hot Temperature
carbon dioxide
Cooling
Pressure
Air Conditioning
Air
air conditioning
Refrigerants
Air conditioning
air

Keywords

  • Air-conditioning
  • CO
  • Electronic expansion valve
  • Experiment
  • Optimization
  • Performance
  • R744
  • Refrigeration
  • Thermodynamic cycle
  • Transcritical cycle
  • Variable speed

ASJC Scopus subject areas

  • Food Science
  • Mechanical Engineering

Cite this

Cooling performance of a variable speed CO2 cycle with an electronic expansion valve and internal heat exchanger. / Cho, Honghyun; Ryu, Changgi; Kim, Yong Chan.

In: International Journal of Refrigeration, Vol. 30, No. 4, 01.06.2007, p. 664-671.

Research output: Contribution to journalArticle

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