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Flow visualization and local measurement of forced convection heat transfer in a microtube / Boris Schilder in Journal of heat transfer, Vol. 132 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031702-1/9] Titre : Flow visualization and local measurement of forced convection heat transfer in a microtube Type de document : texte imprimé Auteurs : Boris Schilder, Auteur Article en page(s) : pp. [031702-1/9] Note générale : Physique Langues : Anglais (eng) Mots-clés : Boiling  Bubbles  Flow  visualisation  Forced  convection  Friction  Liquid  films  Microchannel  flow  Organic  compounds  Pattern  formation  Pipe  flow  Poiseuille  flow  Two-phase  flow  Water Index. décimale : 536 Chaleur. Thermodynamique Résumé : The pressure drop and the convective heat transfer characteristics of ethanol and water in a circular tube with a diameter of 600 µm with and without phase change have been studied experimentally. The test section consists of a glass tube coated with a transparent indium tin oxide heater film. For single-phase liquid flow (including superheated liquid) it was found that the measured Nusselt numbers and friction factors are in good agreement with the theoretical values expected from Poiseuille flow. Subsequently, the boiling heat transfer of ethanol was studied. It was found that boiling with bubble growth in both upstream and downstream directions leaving behind a thin evaporating liquid film on the tube wall is the dominant phase change process. Wavy patterns on the film surface indicate shear forces between vapor and liquid phase during slug flow. Temporary dryout phenomena occur even at a low mean vapor quality due to film rupture as a result of film instabilities. Local Nusselt numbers are calculated for the two-phase flow at different heat fluxes and Reynolds numbers. Compared with single-phase flow the heat transfer is enhanced by a factor of 3–8. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Flow visualization and local measurement of forced convection heat transfer in a microtube [texte imprimé] / Boris Schilder, Auteur . - pp. [031702-1/9]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031702-1/9] Mots-clés : Boiling  Bubbles  Flow  visualisation  Forced  convection  Friction  Liquid  films  Microchannel  flow  Organic  compounds  Pattern  formation  Pipe  flow  Poiseuille  flow  Two-phase  flow  Water Index. décimale : 536 Chaleur. Thermodynamique Résumé : The pressure drop and the convective heat transfer characteristics of ethanol and water in a circular tube with a diameter of 600 µm with and without phase change have been studied experimentally. The test section consists of a glass tube coated with a transparent indium tin oxide heater film. For single-phase liquid flow (including superheated liquid) it was found that the measured Nusselt numbers and friction factors are in good agreement with the theoretical values expected from Poiseuille flow. Subsequently, the boiling heat transfer of ethanol was studied. It was found that boiling with bubble growth in both upstream and downstream directions leaving behind a thin evaporating liquid film on the tube wall is the dominant phase change process. Wavy patterns on the film surface indicate shear forces between vapor and liquid phase during slug flow. Temporary dryout phenomena occur even at a low mean vapor quality due to film rupture as a result of film instabilities. Local Nusselt numbers are calculated for the two-phase flow at different heat fluxes and Reynolds numbers. Compared with single-phase flow the heat transfer is enhanced by a factor of 3–8. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]