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Nozzle design and applicable empirical theories of frictional pressure drop for supersonic two-phase flow of CO2.

Author(s) : NAKAGAWA M., BERANA M.

Summary

CO2 is a promising natural replacement of ozone-depleting, global-warming and hazardous refrigerants. Using it in the ejector-refrigeration cycle gives a higher coefficient of performance than in the vapour compression cycle. An efficient nozzle leads to a high ejector pressure recovery. Energy-conversion efficiencies of rectangular converging-diverging ejector nozzles were calculated from measured pressure profiles. The momentum-conservation equation containing empirical theories for frictional pressure drop of two-phase flow were used. Homogeneous Model, Chrisholm-Sutherland and Martinelli-Nelson were the theories tested. This paper presents the applicable empirical theories and the dependence of efficiency and optimal divergence angle to pressure difference between the inlet and the outlet. Four nozzles with different divergence angle were tested in a blowdown apparatus. Homogeneous Model and Chrisholm-Sutherland were applicable. Each efficiency curve showed a maximum value at an optimum pressure difference. There was an optimum divergence angle for each pressure difference. The optimum divergence angle increased with pressure difference.

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Pages: 2008-2

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Details

  • Original title: Nozzle design and applicable empirical theories of frictional pressure drop for supersonic two-phase flow of CO2.
  • Record ID : 2009-0608
  • Languages: English
  • Source: 8th IIR-Gustav Lorentzen Conference on Natural Working Fluids (GL2008)
  • Publication date: 2008/09/07

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