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Study on the steady state performance of a CO2 heat pump system.

[ In Korean. / En coréen.]

Author(s) : LEE J. S., HAN Y. H., KIM M. S.

Summary

Environmental issues of stratospheric ozone depletion and global warming have been the primary motivations for recent research in the refrigeration industry and have driven us to find and develop new alternative refrigerants. Carbon dioxide has environmentally good characteristics and excellent thermodynamic properties. However, carbon dioxide cycle is a transcritical cycle, and this transcritical CO2 cycle has lower efficiency than conventional cycles. Thus, improving performance of CO2 heat pump system is indispensable, and it is necessary to find optimum operating condition. Experiments were conducted, and system characteristics were investigated under various combinations of opening of expansion valve and compressor inverter frequency. Mass flow rate and pressure ratio increased as compressor frequency increased. The COP decreased at high compressor frequency operation. Degree of superheat is controlled by the expansion valve opening. Degree of superheat at internal heat exchanger outlet is the best state variable to control expansion valve for maximum COP.

Details

  • Original title: [ In Korean. / En coréen.]
  • Record ID : 2009-1308
  • Languages: Korean
  • Source: The 3rd Korean Congress of Refrigeration.
  • Publication date: 2009/03/19

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