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Flow and heat transfer in microchannels with dimples and protrusions / Jibing Lan in Journal of heat transfer, Vol. 134 N° 2 (Fevrier 2012) 

Public ISBD [article]  in Journal of heat transfer > Vol. 134 N° 2 (Fevrier 2012) . - 09 p. Titre : Flow and heat transfer in microchannels with dimples and protrusions Type de document : texte imprimé Auteurs : Jibing Lan, Auteur ; Yonghui Xie, Auteur ; Di Zhang, Auteur Année de publication : 2012 Article en page(s) : 09 p. Note générale : Heat transfer Langues : Anglais (eng) Mots-clés : Computational  fluid  dynamics  Heat  transfer  Laminar  flow  Microchannel  flow  Navier-Stokes  equations  Numerical  analysis Index. décimale : 536 Chaleur. Thermodynamique Résumé : Flow characteristics and heat transfer performances in a rectangular microchannel with dimples/protrusions are studied numerically in this research. The height and the width of the microchannel is 200 µm and 50 µm, respectively. The dimple/protrusion diameter is 100 µm, and the depth is 20 µm. The effects of Reynolds number, streamwise pitch, and arrangement pattern are examined. The numerical simulations are conducted using water as the coolant with the Reynolds number ranging from 100 to 900. The results show that dimple/protrusion technique in mcirochannel has the potential to provide heat transfer enhancement with low pressure penalty. The normalized Nusselt number is within the range from 1.12 to 4.77, and the corresponding normalized friction factor is within the range from 0.94 to 2.03. The thermal performance values show that the dimple + protrusion cases perform better than the dimple + smooth cases. The flow characteristics of the dimples/protrusions in microchannel are similar to those in conventional channel. Furthermore, from the viewpoint of energy saving, dimples/protrusions in microchannel behave better than those in conventional channel. Also from the viewpoint of field synergy principle, the synergy of the dimple + protrusion cases are much better than the dimple + smooth cases. Moreover, the synergy becomes worse with the increase in the Reynolds number and decrease in the streamwise pitch. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JHTRAO000134000002 [...] [article] Flow and heat transfer in microchannels with dimples and protrusions [texte imprimé] / Jibing Lan, Auteur ; Yonghui Xie, Auteur ; Di Zhang, Auteur . - 2012 . - 09 p. Heat transfer Langues : Anglais (eng) in Journal of heat transfer > Vol. 134 N° 2 (Fevrier 2012) . - 09 p. Mots-clés : Computational  fluid  dynamics  Heat  transfer  Laminar  flow  Microchannel  flow  Navier-Stokes  equations  Numerical  analysis Index. décimale : 536 Chaleur. Thermodynamique Résumé : Flow characteristics and heat transfer performances in a rectangular microchannel with dimples/protrusions are studied numerically in this research. The height and the width of the microchannel is 200 µm and 50 µm, respectively. The dimple/protrusion diameter is 100 µm, and the depth is 20 µm. The effects of Reynolds number, streamwise pitch, and arrangement pattern are examined. The numerical simulations are conducted using water as the coolant with the Reynolds number ranging from 100 to 900. The results show that dimple/protrusion technique in mcirochannel has the potential to provide heat transfer enhancement with low pressure penalty. The normalized Nusselt number is within the range from 1.12 to 4.77, and the corresponding normalized friction factor is within the range from 0.94 to 2.03. The thermal performance values show that the dimple + protrusion cases perform better than the dimple + smooth cases. The flow characteristics of the dimples/protrusions in microchannel are similar to those in conventional channel. Furthermore, from the viewpoint of energy saving, dimples/protrusions in microchannel behave better than those in conventional channel. Also from the viewpoint of field synergy principle, the synergy of the dimple + protrusion cases are much better than the dimple + smooth cases. Moreover, the synergy becomes worse with the increase in the Reynolds number and decrease in the streamwise pitch. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JHTRAO000134000002 [...]

In situ observation of the formation of intragranular acicular ferrite at non-metallic inclusions in C–Mn steel / Di Zhang in Acta materialia, Vol. 58 N° 4 (Fevrier 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 4 (Fevrier 2010) . - pp. 1369–1378 Titre : In situ observation of the formation of intragranular acicular ferrite at non-metallic inclusions in C–Mn steel Type de document : texte imprimé Auteurs : Di Zhang, Auteur ; Hidenori Terasaki, Auteur ; Yu-ichi Komizo, Auteur Année de publication : 2011 Article en page(s) : pp. 1369–1378 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : In  situ  observation  Nucleation  and  growth  Intragranular  acicular  ferrite  Phase  transformation  Steels Résumé : Intragranular acicular ferrite is regarded as a most desirable microstructure feature, in view of its strength and toughness, both in weld metals and in the heat-affected zone. This paper systematically investigated the effect of Ti addition on the evolution of intragranular acicular ferrite in the heat-affected zone of C–Mn steel. We also systematically studied the effects of austenite grain size, alloy content and the characteristic of inclusions on the formation of intragranular acicular ferrite. The nucleation and growth of intragranular acicular ferrite was directly observed by laser scanning confocal microscopy. Subsequently, microscopy analysis was used to quantitatively determine and distinguish the potent and inactive inclusions with respect to the nucleation of intragranular acicular ferrite. Finally, some possible reasons are given to explain the formation of intragranular acicular ferrite in the C–Mn steel. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409007460#cor1 [article] In situ observation of the formation of intragranular acicular ferrite at non-metallic inclusions in C–Mn steel [texte imprimé] / Di Zhang, Auteur ; Hidenori Terasaki, Auteur ; Yu-ichi Komizo, Auteur . - 2011 . - pp. 1369–1378. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 4 (Fevrier 2010) . - pp. 1369–1378 Mots-clés : In  situ  observation  Nucleation  and  growth  Intragranular  acicular  ferrite  Phase  transformation  Steels Résumé : Intragranular acicular ferrite is regarded as a most desirable microstructure feature, in view of its strength and toughness, both in weld metals and in the heat-affected zone. This paper systematically investigated the effect of Ti addition on the evolution of intragranular acicular ferrite in the heat-affected zone of C–Mn steel. We also systematically studied the effects of austenite grain size, alloy content and the characteristic of inclusions on the formation of intragranular acicular ferrite. The nucleation and growth of intragranular acicular ferrite was directly observed by laser scanning confocal microscopy. Subsequently, microscopy analysis was used to quantitatively determine and distinguish the potent and inactive inclusions with respect to the nucleation of intragranular acicular ferrite. Finally, some possible reasons are given to explain the formation of intragranular acicular ferrite in the C–Mn steel. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409007460#cor1