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Subcooled flow boiling heat transfer and visualization of R134a in a vertical transparent heated tube of small diameter.

Author(s) : MARTÍN-CALLIZO C., OWHAIB W., PALM B.

Summary

Subcooled flow boiling heat transfer of refrigerant R134a in a vertical cylindrical channel of 1.3 mm internal diameter has been experimentally investigated. Quartz tubes with ITO-coating (indium tin oxide) are used allowing heating and simultaneous visualization. The effects of the wall heat flux and refrigerant mass flux on the onset of nucleate boiling, ONB, flow patterns and subcooled boiling heat transfer are explored in detail. The heat transfer coefficient was found to be a function of both heat and mass flux. This indicates that both forced convection and nucleate boiling heat transfer contribute extensively to the total heat transfer. From the visualization results six distinct flow patterns could be observed: isolated bubbly flow, confined bubbly flow, plug flow, churn flow, slug-annular flow and annular flow.

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Pages: 2005-3

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Details

  • Original title: Subcooled flow boiling heat transfer and visualization of R134a in a vertical transparent heated tube of small diameter.
  • Record ID : 2006-0602
  • Languages: English
  • Source: Commercial Refrigeration. Thermophysical Properties and Transfer Processes of Refrigerants. Proceedings of the IIR International Conferences.
  • Publication date: 2005/08/02

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