Documents disponibles écrits par cet auteur

Air-side heat-transfer enhancement by a new winglet-type vortex generator array in a plain-fin round-tube heat exchanger / J. He in Journal of heat transfer, Vol. 132 N° 7 (Juillet 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 7 (Juillet 2010) . - pp. [071801-1/9] Titre : Air-side heat-transfer enhancement by a new winglet-type vortex generator array in a plain-fin round-tube heat exchanger Type de document : texte imprimé Auteurs : J. He, Auteur ; L. Liu, Auteur ; A. M. Jacobi, Auteur Article en page(s) : pp. [071801-1/9] Note générale : Physique Langues : Anglais (eng) Mots-clés : Heat  exchanger  Fin-and-tube  V  formation  Vortex  generator  Winglet  array Index. décimale : 536 Chaleur. Thermodynamique Résumé : The impact of a vortex-generation technique for air-side heat-transfer improvement is experimentally investigated through full-scale wind-tunnel testing of a plain-fin round-tube heat exchanger under dry-surface conditions. Inspired by the formation locomotion of animals in nature, a new vortex generator (VG) array deployed in a “V” is proposed in the present work, aiming to create constructive interference between vortices. The array is composed of two delta-winglet pairs and placed at an attack angle of 10 deg or 30 deg. Its effectiveness is compared with a baseline configuration and two conventional single-pair designs placed at 30 deg, a small pair with half the area of the array and a large pair with the same area as the array. The frontal air velocity considered ranges from 2.3 m/s to 5.5 m/s, corresponding to a Reynolds number range based on the hydraulic diameter of 1400–3400. The experimental results show little impact of the 10 deg array and a moderate heat-transfer improvement of up to 32% for the small pair, both introducing additional pressure loss of approximately 20–40%. For the 30 deg array and the large pair, similar augmentation of 25–55% in air-side heat-transfer coefficient is obtained accompanied by average pressure drop penalties of 90% and 140%, respectively. Performance evaluation using the criteria of the modified area goodness factor and the volume goodness factor indicates the superiority of the heat exchanger enhanced by the 30 deg array among all the investigated VGs. The VG array is found more effective at comparatively low Reynolds numbers, representative of many heating, ventilation, air-conditioning, and refrigeration applications and compact heat-exchanger designs. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Air-side heat-transfer enhancement by a new winglet-type vortex generator array in a plain-fin round-tube heat exchanger [texte imprimé] / J. He, Auteur ; L. Liu, Auteur ; A. M. Jacobi, Auteur . - pp. [071801-1/9]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 7 (Juillet 2010) . - pp. [071801-1/9] Mots-clés : Heat  exchanger  Fin-and-tube  V  formation  Vortex  generator  Winglet  array Index. décimale : 536 Chaleur. Thermodynamique Résumé : The impact of a vortex-generation technique for air-side heat-transfer improvement is experimentally investigated through full-scale wind-tunnel testing of a plain-fin round-tube heat exchanger under dry-surface conditions. Inspired by the formation locomotion of animals in nature, a new vortex generator (VG) array deployed in a “V” is proposed in the present work, aiming to create constructive interference between vortices. The array is composed of two delta-winglet pairs and placed at an attack angle of 10 deg or 30 deg. Its effectiveness is compared with a baseline configuration and two conventional single-pair designs placed at 30 deg, a small pair with half the area of the array and a large pair with the same area as the array. The frontal air velocity considered ranges from 2.3 m/s to 5.5 m/s, corresponding to a Reynolds number range based on the hydraulic diameter of 1400–3400. The experimental results show little impact of the 10 deg array and a moderate heat-transfer improvement of up to 32% for the small pair, both introducing additional pressure loss of approximately 20–40%. For the 30 deg array and the large pair, similar augmentation of 25–55% in air-side heat-transfer coefficient is obtained accompanied by average pressure drop penalties of 90% and 140%, respectively. Performance evaluation using the criteria of the modified area goodness factor and the volume goodness factor indicates the superiority of the heat exchanger enhanced by the 30 deg array among all the investigated VGs. The VG array is found more effective at comparatively low Reynolds numbers, representative of many heating, ventilation, air-conditioning, and refrigeration applications and compact heat-exchanger designs. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Lab and field investigations on localized corrosion of casing / C. Q. Ren in Materials and corrosion, Vol. 63 N° 2 (Fevrier 2012) 

Public ISBD [article]  in Materials and corrosion > Vol. 63 N° 2 (Fevrier 2012) . - pp. 168–172 Titre : Lab and field investigations on localized corrosion of casing Type de document : texte imprimé Auteurs : C. Q. Ren, Auteur ; X. Wang, Auteur ; L. Liu, Auteur Année de publication : 2012 Article en page(s) : pp. 168–172 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Localized  corrosion;  microstructure;  steel Résumé : The corrosion of casing was investigated in the laboratory and oilfield by series methods of EIS, SEM, EDS, well logging, and field coupon test. Data reveal the middle vertical profile along the casing is greatly threatened by localized form rather than generalized corrosion. The pit initiates in the micro-pore of the corrosion scale on the surface of the steel. The development of pitting depends on the water type classified by geochemist. The calcium chloride water shows highest acceleration to pitting due to the two orders of magnitude higher concentration of chloride ion by comparing sodium sulfate and sodium bicarbonate water types. The element analysis and microstructure observation were used to further describe the pit propagation. It is proposed to get a better understanding of the corrosion damage of casing in the petroleum industry. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005713/abstract [article] Lab and field investigations on localized corrosion of casing [texte imprimé] / C. Q. Ren, Auteur ; X. Wang, Auteur ; L. Liu, Auteur . - 2012 . - pp. 168–172. Génie mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 63 N° 2 (Fevrier 2012) . - pp. 168–172 Mots-clés : Localized  corrosion;  microstructure;  steel Résumé : The corrosion of casing was investigated in the laboratory and oilfield by series methods of EIS, SEM, EDS, well logging, and field coupon test. Data reveal the middle vertical profile along the casing is greatly threatened by localized form rather than generalized corrosion. The pit initiates in the micro-pore of the corrosion scale on the surface of the steel. The development of pitting depends on the water type classified by geochemist. The calcium chloride water shows highest acceleration to pitting due to the two orders of magnitude higher concentration of chloride ion by comparing sodium sulfate and sodium bicarbonate water types. The element analysis and microstructure observation were used to further describe the pit propagation. It is proposed to get a better understanding of the corrosion damage of casing in the petroleum industry. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005713/abstract

Template-free Synthesis and photocatalytic application of rutile TiO2 hierarchical nanostructures / M. Ge in Industrial & engineering chemistry research, Vol. 50 N° 11 (Juin 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 11 (Juin 2011) . - pp 6681–6687 Titre : Template-free Synthesis and photocatalytic application of rutile TiO2 hierarchical nanostructures Type de document : texte imprimé Auteurs : M. Ge, Auteur ; J. W. Li, Auteur ; L. Liu, Auteur Année de publication : 2011 Article en page(s) : pp 6681–6687 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Photocatalytic  rutile  Nanostructures Résumé : A simple template-free hydrothermal method was employed to synthesize flower-shaped single-crystal rutile TiO2 hierarchical nanostructures without calcination process. Scanning electron microscope and transmission electron microscope images show that rutile TiO2 nanostructures with diameters of 1–1.5 μm are composed of nanorods with a wimble shape. The band gap of the as-prepared rutile TiO2 is about 3.02 eV by ultraviolet–visible absorption spectrum. The photocatalytic performance of the as-obtained samples as catalysts for Rhodamine B (RhB) degradation under simulated solar light was greatly enhanced with the assistance of a small amount of H2O2. In the H2O2-containing system, the as-prepared rutile TiO2 photocatalyst was more efficient in the photodegradation of RhB than commercial P25. The stability and recycle of the rutile TiO2/H2O2 system were also investigated. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1023113 [article] Template-free Synthesis and photocatalytic application of rutile TiO2 hierarchical nanostructures [texte imprimé] / M. Ge, Auteur ; J. W. Li, Auteur ; L. Liu, Auteur . - 2011 . - pp 6681–6687. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 11 (Juin 2011) . - pp 6681–6687 Mots-clés : Photocatalytic  rutile  Nanostructures Résumé : A simple template-free hydrothermal method was employed to synthesize flower-shaped single-crystal rutile TiO2 hierarchical nanostructures without calcination process. Scanning electron microscope and transmission electron microscope images show that rutile TiO2 nanostructures with diameters of 1–1.5 μm are composed of nanorods with a wimble shape. The band gap of the as-prepared rutile TiO2 is about 3.02 eV by ultraviolet–visible absorption spectrum. The photocatalytic performance of the as-obtained samples as catalysts for Rhodamine B (RhB) degradation under simulated solar light was greatly enhanced with the assistance of a small amount of H2O2. In the H2O2-containing system, the as-prepared rutile TiO2 photocatalyst was more efficient in the photodegradation of RhB than commercial P25. The stability and recycle of the rutile TiO2/H2O2 system were also investigated. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1023113