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Model for prediction of flow boiling heat transfer coefficient of carbon dioxide at pre-dryout region inside horizontal tubes.

Number: pap. D2-132

Author(s) : LI M., DANG C., TANAKA S., et al.

Summary

Carbon dioxide is utilized as an efficient and environmentally safe refrigerant in mobile air-conditioning units, heat pump water heaters, and commercial cascade refrigeration systems. Numerous studies on the prediction of the flow boiling heat transfer coefficient of pure carbon dioxide have been carried out in order to investigate the mechanism of flow boiling of carbon dioxide. In this study, the flow boiling heat transfer coefficient of pure carbon dioxide obtained using the existing correlations is compared with the experimental data. This paper proposes a new model for the prediction of flow boiling heat transfer of CO2 at the pre-dryout region inside horizontal tubes. This model not only describes the flow boiling characteristics but also gives a good estimate of the flow boiling heat transfer coefficient. The relation between the mass flux and the heat flux is taken into account in this model. New factors are introduced in the correlation in order to reflect the effect of mass flux and heat flux on both nucleate boiling and convective heat transfer. The calculated results indicate that the mass and heat fluxes influence nucleate boiling and convection boiling. The results of the proposed model are in good agreement with the CO2 experimental database, with the maximum deviation of about 30%. The flow boiling heat transfer model is effective under the following conditions: tube diameter = 1–6 mm, mass velocity = 100–1440 kg/m2.s, heat flux = 5–36 kW/m2, and saturation temperature = 15°C.

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Pages: 8 p.

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Details

  • Original title: Model for prediction of flow boiling heat transfer coefficient of carbon dioxide at pre-dryout region inside horizontal tubes.
  • Record ID : 30005467
  • Languages: English
  • Source: ACRA2010. Asian conference on refrigeration and air conditioning: Tokyo, Japan, June 7-9, 2010.
  • Publication date: 2010/06/07

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