Scientific Research and Essays

  • Abbreviation: Sci. Res. Essays
  • Language: English
  • ISSN: 1992-2248
  • DOI: 10.5897/SRE
  • Start Year: 2006
  • Published Articles: 2750

Full Length Research Paper

Entrainment mass transfer in annular flow regime of two-phase carbon dioxide

Zahra Baniamerian1*, Ramin Mehdippour1 and Cyrus Aghanajafi2
1Department of Mechanical Engineering, Tafresh University of Technology, Tafresh, Iran. 2Department of Mechanical Engineering, Khaje Nasir Toosi University of Technology, Tehran, Iran.
Email: [email protected], [email protected]

  •  Accepted: 15 December 2011
  •  Published: 17 December 2012

Abstract

Having more heat transfer rate and lower pressure drop, along with better environmental treatment, carbon dioxide has drawn the attention of many researchers. Most of the two-phase heat transfer analyses are involved in estimation of dry-out phenomenon in order to avoid heat transfer drops. Entrainment, because of having great influence on dry-out occurrence, is studied in this article. Most of the available models for entrainment are experiment-based and therefore applicable in restricted conditions. In the present study, a physical model is proposed for simulation of entrainment in annular flow regime of liquid-vapor in a vertical tube. The tube is supposed to be warming up by a constant and uniform heat flux applied on its lateral area. The proposed model is general and can be applied to all kind of fluids of different working conditions; it is verified with some experimental data available in the literature. Entrainment contribution of mass transfer is compared with evaporation contribution through introducing a factor which is called “Mass Transfer Ratio” (MTR). The magnitude of this factor demonstrates the significance of entrainment phenomenon. MTR factor is compared with some widely-used working fluids.

 

Key words: Carbon dioxide, working fluid, entrainment, dry out, mass transfer.