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New prediction methods for CO2 evaporation inside tubes. II. An updated general flow boiling heat transfer model based on flow patterns.

Author(s) : CHENG L., RIBATSKI G., THOME J. R.

Type of article: Article

Summary

Corresponding to the updated flow pattern map presented in Part I of this study (see this Bulletin, reference 2008-1204), an updated general flow pattern based flow boiling heat transfer model was developed for CO2 using the Cheng-Ribatski-Wojtan-Thome flow boiling heat transfer model as the starting basis. The flow boiling heat transfer correlation in the dryout region was updated. In addition, a new mist flow heat transfer correlation for CO2 was developed based on the CO2 data and a heat transfer method for bubbly flow was proposed for completeness sake. The updated general flow boiling heat transfer model for CO2 covers all flow regimes and is applicable to a wider range of conditions for horizontal tubes: tube diameters from 0.6 to 10 mm, mass velocities from 50 to 1500 kg/m2.s, heat fluxes from 1.8 to 46 kW/m2 and saturation temperatures from -28 to 25°C (reduced pressures from 0.21 to 0.87). The updated general flow boiling heat transfer model was compared to a new experimental database which contains 1124 data points (790 more than that in the previous model) in this study. Good agreement between the predicted and experimental data was found in general with 71.4% of the entire database and 83.2% of the database without the dryout and mist flow data predicted within plus or minus 30%. However, the predictions for the dryout and mist flow regions were less satisfactory due to the limited number of data points, the higher inaccuracy in such data, scatter in some data sets ranging up to 40%, significant discrepancies from one experimental study to another and the difficulties associated with predicting the inception and completion of dryout around the perimeter of the horizontal tubes. [Reprinted with permission from Elsevier. Copyright, 2007].

Details

  • Original title: New prediction methods for CO2 evaporation inside tubes. II. An updated general flow boiling heat transfer model based on flow patterns.
  • Record ID : 2008-1203
  • Languages: English
  • Source: International Journal of Heat and Mass Transfer - vol. 51 - n. 1-2
  • Publication date: 2008/01

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