Shock waves in supersonic two-phase flow of CO2 in converging-diverging nozzles.


CO2 is a promising alternative to hazardous, ozone-depleting and global-warming refrigerants. It is more suitable to the ejector-refrigeration cycle than to the vapour compression cycle. However, shock waves significantly reduce the ejector-nozzle efficiency. Therefore, they must be characterized to improve the COP and the nozzle efficiency. This paper elucidates the types of CO2 shock waves and their relation to nozzle inlet conditions and two-phase thermodynamic states. Shock waves in supersonic liquid-vapour flows through the diverging sections of rectangular converging-diverging nozzles with the same divergence angle were investigated. They increased with supercritical inlet entropy. Equilibrium shock waves were calculated in the nozzles. The pressure behind these waves increased with decreasing diverging-section length. Two-phase-flow equilibrium shock waves, which both sides are two-phase fluid, were calculated in long nozzles. Equilibrium shock waves were very strong and thin but they were not experimentally observed. Instead, relaxation phenomena and both weak pseudo-shock waves and dispersed shock waves were experimentally observed.

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  • Original title: Shock waves in supersonic two-phase flow of CO2 in converging-diverging nozzles.
  • Record ID : 2009-0515
  • Languages: English
  • Source: 2008 Purdue Conferences. 19th International Compressor Engineering Conference at Purdue & 12th International Refrigeration and Air-Conditioning Conference at Purdue [CD-ROM].
  • Publication date: 2008/07/14


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