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Ammonia two-phase flow in a horizontal smooth tube: flow pattern observations, diabatic and adiabatic frictional pressure drops and assessment of prediction methods.

Author(s) : SILVA LIMA R. J. da, MORENO QUIBÉN J., KUHN C., et al.

Type of article: Article

Summary

This study illustrates new experimental two-phase flow pattern observations together with diabatic boiling and adiabatic two-phase frictional pressure drop results for ammonia (R717) flowing inside a 14-mm internal diameter, smooth horizontal stainless steel tube. The flow pattern observations were made for mass velocities of 50, 100 and 160 kg/s.m2 and saturation temperatures of -14, -2 and 12°C for vapour qualities ranging from 0.05 to 0.6. The flow patterns observed during the study included: stratified-wavy, slug-stratified-wavy, slug, intermittent and annular. For all the experimental conditions, the flow structure observations were compared against the predictions of the flow pattern map model of Wojtan et al. and showed very good correspondence. The frictional pressure drop measurements were obtained for vapour qualities from 0.05 to 0.6, saturation temperatures from -14 to 14°C, mass velocities from 50 to 160 kg/s.m2 and heat fluxes from 12 to 25 kW/m2. The experimental results show the traditional pressure drop trends: the frictional pressure drop increases with vapour quality and mass velocity. Moreover, the results also show that both diabatic and adiabatic frictional pressure drop values are similar, that is, the boiling process in itself does not affect the frictional pressure drop. The correlations of Friedel and Müller-Steinhagen and Heck predicted only 54, 52 and 60% of the experimental data within ±30%, respectively. The correlation of Grönnerud predicted 93% of the data and the flow pattern based method of Moreno Quibén and Thome predicted more than 97% of the experimental data within the same error band, while the latter method captures almost 89% of the data within plus or minus 20%. [Reprinted with permission from Elsevier. Copyright, 2008].

Details

  • Original title: Ammonia two-phase flow in a horizontal smooth tube: flow pattern observations, diabatic and adiabatic frictional pressure drops and assessment of prediction methods.
  • Record ID : 2009-1932
  • Languages: English
  • Source: International Journal of Heat and Mass Transfer - vol. 52 - n. 9-10
  • Publication date: 2009/04
  • DOI: http://dx.doi.org/10.1016/j.ijheatmasstransfer.2008.12.001

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