Documents disponibles écrits par cet auteur

An experimental and numerical investigation on the thermal-hydraulic performance of double notched plate / Zhang, Lei in Journal of heat transfer, Vol 134 N° 9 (Septembre 2012) 

Public ISBD [article]  in Journal of heat transfer > Vol 134 N° 9 (Septembre 2012) . - 07 p. Titre : An experimental and numerical investigation on the thermal-hydraulic performance of double notched plate Type de document : texte imprimé Auteurs : Zhang, Lei, Auteur ; Defu Che, Auteur Année de publication : 2012 Article en page(s) : 07 p. Note générale : heat transfer Langues : Anglais (eng) Mots-clés : rotary  air  preheater;  double  notched  plate;  single-blow  technique;  numerical  simulation;  heat  transfer;  friction  factor Index. décimale : 536 Chaleur. Thermodynamique Résumé : The double notched (DN) plate is commonly used in rotary air preheaters, but relevant investigations are rare. Thus, thermal-hydraulic performances of the DN plate are investigated in this paper. A single-blow, transient technique is refined and then used to measure the overall mean heat transfer coefficients and friction factors. A validated numerical method is also utilized to provide local information. The measured results show that the performance of the DN plate approaches that of the double undulated (DU) plate and lies between that of the cross corrugated (CC) plate and the parallel plate. No swirling flow pattern is identified in the predicted velocity fields. Basically, two types of flow are observed: wavy channel flow and pipe flow. High or low Nusselt numbers, Nu, are obtained at the luff or lee side of undulations and notches, respectively. Nu values increase and Nu distributions become more homogenous with increasing Reynolds numbers, Re. A recommendation is made that the DN plate be operated under moderate Re to achieve homogenous and enhanced heat transfer, given the allowable pressure drop. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JHTRAO000134000009 [...] [article] An experimental and numerical investigation on the thermal-hydraulic performance of double notched plate [texte imprimé] / Zhang, Lei, Auteur ; Defu Che, Auteur . - 2012 . - 07 p. heat transfer Langues : Anglais (eng) in Journal of heat transfer > Vol 134 N° 9 (Septembre 2012) . - 07 p. Mots-clés : rotary  air  preheater;  double  notched  plate;  single-blow  technique;  numerical  simulation;  heat  transfer;  friction  factor Index. décimale : 536 Chaleur. Thermodynamique Résumé : The double notched (DN) plate is commonly used in rotary air preheaters, but relevant investigations are rare. Thus, thermal-hydraulic performances of the DN plate are investigated in this paper. A single-blow, transient technique is refined and then used to measure the overall mean heat transfer coefficients and friction factors. A validated numerical method is also utilized to provide local information. The measured results show that the performance of the DN plate approaches that of the double undulated (DU) plate and lies between that of the cross corrugated (CC) plate and the parallel plate. No swirling flow pattern is identified in the predicted velocity fields. Basically, two types of flow are observed: wavy channel flow and pipe flow. High or low Nusselt numbers, Nu, are obtained at the luff or lee side of undulations and notches, respectively. Nu values increase and Nu distributions become more homogenous with increasing Reynolds numbers, Re. A recommendation is made that the DN plate be operated under moderate Re to achieve homogenous and enhanced heat transfer, given the allowable pressure drop. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JHTRAO000134000009 [...]

Determination of Sustainable Yield in Urban Groundwater Systems: Beijing, China / Zhang, Lei in Journal of hydrologic engineering, Vol. 11, N°1 (Janvier/Fevrier 2006) 

Public ISBD [article]  in Journal of hydrologic engineering > Vol. 11, N°1 (Janvier/Fevrier 2006) . - 21-28 p. Titre : Determination of Sustainable Yield in Urban Groundwater Systems: Beijing, China Titre original : Détermination de Rendement Soutenable dans les Systèmes Urbains d'eaux Souterraines : Pékin, Chine Type de document : texte imprimé Auteurs : Zhang, Lei, Auteur ; Kennedy, Christopher, Auteur Article en page(s) : 21-28 p. Note générale : Hydrologie Langues : Anglais (eng) Mots-clés : Ground-water  management  Urban  areas  Uncertainty  principles  China  Environmental  issues  Hydrology  Monte  Carlo  methodGestion  d'eaux  souterraines  Secteurs  urbains  Principes  d'incertitude  Chine  Issues  environnementales  Hydrologie  Méthode  de  Monte  Carlo Index. décimale : 551.4 Résumé : The City OF beijing has long-term concerns over the sustainable yield from its groundwater aquifers. The Aquifers provide half of the city's water supply and have seen falling water tablesover the past century. The Sustainable yield of aquiufers below urban Beijing is assessed based on changes to the groundwater budget equation from virgin conditions. Sources of anthropogenic recharge, including leakage from water mains and sewer pipes, seepage from septic tanks, irrigation, gardening, and artificial recharge, are together as large as changes to the groundwater flux as a result of groundwater withdrawals. Changes to natural recharge, and to a lesser extent natural discharge, also significantly impact the water budget. Uncertainty persists in several components of the budget equation, in particular changes to the groundwater flux. Estimates of the upper and lower bounds for sustainable yield are relatively unchanged for the years 2000, 2010, and 2015. However, the components of the budget will change as seepage from septic tanks is expected to decrease. Uncertainty in the likely range of sustainable yield is reduced by conducting Monte Carlo simulations. The Simulations indicate there is a 96% chance that the lower pumping rate established in 1990 is sustainable. However, with between 30 and 60% of the water budget provided by treated or untreated wastewater, there must be long-term concerns over the quality of the groundwater supply. La ville de beijing a des soucis à long terme au-dessus du rendement soutenable de ses couches aquifères d'eaux souterraines. Les couches aquifères fournissent la moitié de l'approvisionnement en eau de la ville et ont vu l'excédent en chute de tables de l'eau le siècle passé. Le rendement soutenable de couches aquifères au-dessous de Pékin urbain est évalué a basé sur des changements à l'équation de budget d'eaux souterraines des conditions vierges. Les sources de recharge anthropogène, y compris la fuite des forces de l'eau et des conduits d'égout, infiltration des réservoirs septiques, irrigation, jardinage, et recharge artificielle, sont ensemble aussi grandes que des changements au flux d'eaux souterraines en raison des retraits d'eaux souterraines. Les changements à la recharge normale, et à un moindre degré la décharge normale, effectuent également de manière significative le budget de l'eau. L'incertitude persiste dans plusieurs composants de l'équation de budget, change en particulier en le flux d'eaux souterraines. Les évaluations des limites supérieures et inférieures pour le rendement soutenable sont relativement inchangées pendant les années 2000, 2010, et 2015. Cependant, les composants du budget changeront comme on s'attend à ce que l'infiltration des réservoirs septiques diminue. L'incertitude dans la gamme probable du rendement soutenable est réduite en conduisant des simulations de Monte Carlo. Les simulations indiquent qu'il y a une chance de 96% qui le taux de pompage inférieur établi en 1990 est soutenable. Cependant, en entre 30 et 60% du budget de l'eau a fourni par traité ou l'eau usagée non traitée, là doit être des soucis à long terme au-dessus de la qualité de l'offre d'eaux souterraines. En ligne : christopher.kennedy@utoronto.ca [article] Determination of Sustainable Yield in Urban Groundwater Systems: Beijing, China = Détermination de Rendement Soutenable dans les Systèmes Urbains d'eaux Souterraines : Pékin, Chine [texte imprimé] / Zhang, Lei, Auteur ; Kennedy, Christopher, Auteur . - 21-28 p. Hydrologie Langues : Anglais (eng) in Journal of hydrologic engineering > Vol. 11, N°1 (Janvier/Fevrier 2006) . - 21-28 p. Mots-clés : Ground-water  management  Urban  areas  Uncertainty  principles  China  Environmental  issues  Hydrology  Monte  Carlo  methodGestion  d'eaux  souterraines  Secteurs  urbains  Principes  d'incertitude  Chine  Issues  environnementales  Hydrologie  Méthode  de  Monte  Carlo Index. décimale : 551.4 Résumé : The City OF beijing has long-term concerns over the sustainable yield from its groundwater aquifers. The Aquifers provide half of the city's water supply and have seen falling water tablesover the past century. The Sustainable yield of aquiufers below urban Beijing is assessed based on changes to the groundwater budget equation from virgin conditions. Sources of anthropogenic recharge, including leakage from water mains and sewer pipes, seepage from septic tanks, irrigation, gardening, and artificial recharge, are together as large as changes to the groundwater flux as a result of groundwater withdrawals. Changes to natural recharge, and to a lesser extent natural discharge, also significantly impact the water budget. Uncertainty persists in several components of the budget equation, in particular changes to the groundwater flux. Estimates of the upper and lower bounds for sustainable yield are relatively unchanged for the years 2000, 2010, and 2015. However, the components of the budget will change as seepage from septic tanks is expected to decrease. Uncertainty in the likely range of sustainable yield is reduced by conducting Monte Carlo simulations. The Simulations indicate there is a 96% chance that the lower pumping rate established in 1990 is sustainable. However, with between 30 and 60% of the water budget provided by treated or untreated wastewater, there must be long-term concerns over the quality of the groundwater supply. La ville de beijing a des soucis à long terme au-dessus du rendement soutenable de ses couches aquifères d'eaux souterraines. Les couches aquifères fournissent la moitié de l'approvisionnement en eau de la ville et ont vu l'excédent en chute de tables de l'eau le siècle passé. Le rendement soutenable de couches aquifères au-dessous de Pékin urbain est évalué a basé sur des changements à l'équation de budget d'eaux souterraines des conditions vierges. Les sources de recharge anthropogène, y compris la fuite des forces de l'eau et des conduits d'égout, infiltration des réservoirs septiques, irrigation, jardinage, et recharge artificielle, sont ensemble aussi grandes que des changements au flux d'eaux souterraines en raison des retraits d'eaux souterraines. Les changements à la recharge normale, et à un moindre degré la décharge normale, effectuent également de manière significative le budget de l'eau. L'incertitude persiste dans plusieurs composants de l'équation de budget, change en particulier en le flux d'eaux souterraines. Les évaluations des limites supérieures et inférieures pour le rendement soutenable sont relativement inchangées pendant les années 2000, 2010, et 2015. Cependant, les composants du budget changeront comme on s'attend à ce que l'infiltration des réservoirs septiques diminue. L'incertitude dans la gamme probable du rendement soutenable est réduite en conduisant des simulations de Monte Carlo. Les simulations indiquent qu'il y a une chance de 96% qui le taux de pompage inférieur établi en 1990 est soutenable. Cependant, en entre 30 et 60% du budget de l'eau a fourni par traité ou l'eau usagée non traitée, là doit être des soucis à long terme au-dessus de la qualité de l'offre d'eaux souterraines. En ligne : christopher.kennedy@utoronto.ca

Sol – gel derived boehmite as an efficient and robust carrier for enzyme encapsulatioe / Yuanyuan Zhu in Industrial & engineering chemistry research, Vol. 51 N° 1 (Janvier 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 1 (Janvier 2012) . - pp. 255-261 Titre : Sol – gel derived boehmite as an efficient and robust carrier for enzyme encapsulatioe Type de document : texte imprimé Auteurs : Yuanyuan Zhu, Auteur ; Zhongyi Jiang, Auteur ; Zhang, Lei, Auteur Année de publication : 2012 Article en page(s) : pp. 255-261 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Encapsulation Résumé : Boehmite particles were prepared by a facile sol-gel method using sodium aluminate as the precursor under ambient Conditions, and they were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), nitrogen adsorption, etc. It is found that the boehmite particles consist of flat nanostrips, which are about 230 nm in length and 30 nm in width. The nanostrips are composed of nanoneedles of about 7 nm in diameter and 24 nm in length. The Brunauer―Emmett―Teller (BET) specific surface area, pore size, and pore volume of boehmite particles are 165 m2 g―1, 3.8 nm, and 0.11 cm3 g―1, respectively. Moreover, these boehmite particles are used as an efficient and robust carrier to encapsulate a model enzyme: bovine liver catalase. The catalase encapsulated in boehmite particles exhibits higher pH, thermal, and storage stabilities compared to its free counterpart. These results indicate that boehmite may become a competitive carrier for biological and technological applications. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25476469 [article] Sol – gel derived boehmite as an efficient and robust carrier for enzyme encapsulatioe [texte imprimé] / Yuanyuan Zhu, Auteur ; Zhongyi Jiang, Auteur ; Zhang, Lei, Auteur . - 2012 . - pp. 255-261. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 1 (Janvier 2012) . - pp. 255-261 Mots-clés : Encapsulation Résumé : Boehmite particles were prepared by a facile sol-gel method using sodium aluminate as the precursor under ambient Conditions, and they were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), nitrogen adsorption, etc. It is found that the boehmite particles consist of flat nanostrips, which are about 230 nm in length and 30 nm in width. The nanostrips are composed of nanoneedles of about 7 nm in diameter and 24 nm in length. The Brunauer―Emmett―Teller (BET) specific surface area, pore size, and pore volume of boehmite particles are 165 m2 g―1, 3.8 nm, and 0.11 cm3 g―1, respectively. Moreover, these boehmite particles are used as an efficient and robust carrier to encapsulate a model enzyme: bovine liver catalase. The catalase encapsulated in boehmite particles exhibits higher pH, thermal, and storage stabilities compared to its free counterpart. These results indicate that boehmite may become a competitive carrier for biological and technological applications. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25476469

Sorption characteristics and separation of rhenium ions from aqueous solutions using modified nano - Al2O3 / Zhang, Lei in Industrial & engineering chemistry research, Vol. 51 N° 15 (Avril 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 15 (Avril 2012) . - pp. 5577-5584 Titre : Sorption characteristics and separation of rhenium ions from aqueous solutions using modified nano - Al2O3 Type de document : texte imprimé Auteurs : Zhang, Lei, Auteur ; Xiao Q. Jiang, Auteur ; Tian C. Xu, Auteur Année de publication : 2012 Article en page(s) : pp. 5577-5584 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Aqueous  solution  Sorption Résumé : A novel adsorbent was prepared by NH4HCO3-modifying nanoalumina dioxide and was employed for the separation/preconcentration of ReVII ions from aqueous solution. It was found that ReVII ions could be adsorbed quantitatively (above 94%) on modified nano-Al2O3 in the pH range of 2.0—3.0, while only 8.3% of ReVII ions were adsorbed on unmodified nano-Al2O3. Effects of the pH, concentration of elution solution, and interfering ions on the recovery of ReVII were systematically investigated. Adsorption kinetics for ReVII was found to be very fast, and equilibrium was reached within 5 min following the pseudo-second-order model with observed rate constants (k2) of 14.44 g·mg-1·min-1 at 298 K. The overall rate process appeared to be influenced by both external mass transfer and intraparticle diffusion. The sorption data could be well interpreted by the Langmuir model with a maximum adsorption capacity of 1.94 mg·g-1 of ReVII on modified nano-Al2O3. Moreover, the thermodynamic parameters showed the spontaneous and endothermic nature of the adsorption process. Finally, modified nano-Al2O3 as the sorbent was successfully applied to the separation of ReVII from the ore samples with satisfactory results. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25815837 [article] Sorption characteristics and separation of rhenium ions from aqueous solutions using modified nano - Al2O3 [texte imprimé] / Zhang, Lei, Auteur ; Xiao Q. Jiang, Auteur ; Tian C. Xu, Auteur . - 2012 . - pp. 5577-5584. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 15 (Avril 2012) . - pp. 5577-5584 Mots-clés : Aqueous  solution  Sorption Résumé : A novel adsorbent was prepared by NH4HCO3-modifying nanoalumina dioxide and was employed for the separation/preconcentration of ReVII ions from aqueous solution. It was found that ReVII ions could be adsorbed quantitatively (above 94%) on modified nano-Al2O3 in the pH range of 2.0—3.0, while only 8.3% of ReVII ions were adsorbed on unmodified nano-Al2O3. Effects of the pH, concentration of elution solution, and interfering ions on the recovery of ReVII were systematically investigated. Adsorption kinetics for ReVII was found to be very fast, and equilibrium was reached within 5 min following the pseudo-second-order model with observed rate constants (k2) of 14.44 g·mg-1·min-1 at 298 K. The overall rate process appeared to be influenced by both external mass transfer and intraparticle diffusion. The sorption data could be well interpreted by the Langmuir model with a maximum adsorption capacity of 1.94 mg·g-1 of ReVII on modified nano-Al2O3. Moreover, the thermodynamic parameters showed the spontaneous and endothermic nature of the adsorption process. Finally, modified nano-Al2O3 as the sorbent was successfully applied to the separation of ReVII from the ore samples with satisfactory results. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25815837

Strontium-Doped Lanthanum Cobaltite and Manganite: Highly Active Catalysts for Toluene Complete Oxidation / Deng Jiguang in Industrial & engineering chemistry research, Vol. 47 n°21 (Novembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°21 (Novembre 2008) . - p. 8175–8183 Titre : Strontium-Doped Lanthanum Cobaltite and Manganite: Highly Active Catalysts for Toluene Complete Oxidation Type de document : texte imprimé Auteurs : Deng Jiguang, Auteur ; Zhang, Lei, Auteur ; Hongxing Dai, Auteur Année de publication : 2008 Article en page(s) : p. 8175–8183 Note générale : Chemical engineering Langues : Anglais (eng) Résumé : La1−xSrxMO3−δ (M = Co, Mn; x = 0, 0.4) catalysts have been fabricated via a strategy of citric acid complexing and hydrothermal treatment. The oxidation of toluene was used as a probe reaction for the evaluation of catalytic performance. The materials were characterized by a number of techniques. We observed that the catalytic activity (evaluated by the temperature required for 80% conversion of toluene, T80%) increased in the sequence of LaMnO3.10 (T80% = 295 °C) < LaCoO2.89 (T80% = 246 °C) < La0.6Sr0.4MnO3.03 (T80% = 233 °C) < La0.6Sr0.4CoO2.76 (T80% = 219 °C) at toluene/O2 molar ratio = 1/400 and space velocity = 20 000 h−1. Moreover, CO2 and H2O were the only products for toluene oxidation over the catalysts. It is concluded that factors such as enriched structural defects (oxygen vacancies) and good Mn4+/Mn3+ or Co3+/Co2+ redox ability are responsible for the excellent catalytic performance of the La1−xSrxMO3−δ nanomaterials. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800585x [article] Strontium-Doped Lanthanum Cobaltite and Manganite: Highly Active Catalysts for Toluene Complete Oxidation [texte imprimé] / Deng Jiguang, Auteur ; Zhang, Lei, Auteur ; Hongxing Dai, Auteur . - 2008 . - p. 8175–8183. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°21 (Novembre 2008) . - p. 8175–8183 Résumé : La1−xSrxMO3−δ (M = Co, Mn; x = 0, 0.4) catalysts have been fabricated via a strategy of citric acid complexing and hydrothermal treatment. The oxidation of toluene was used as a probe reaction for the evaluation of catalytic performance. The materials were characterized by a number of techniques. We observed that the catalytic activity (evaluated by the temperature required for 80% conversion of toluene, T80%) increased in the sequence of LaMnO3.10 (T80% = 295 °C) < LaCoO2.89 (T80% = 246 °C) < La0.6Sr0.4MnO3.03 (T80% = 233 °C) < La0.6Sr0.4CoO2.76 (T80% = 219 °C) at toluene/O2 molar ratio = 1/400 and space velocity = 20 000 h−1. Moreover, CO2 and H2O were the only products for toluene oxidation over the catalysts. It is concluded that factors such as enriched structural defects (oxygen vacancies) and good Mn4+/Mn3+ or Co3+/Co2+ redox ability are responsible for the excellent catalytic performance of the La1−xSrxMO3−δ nanomaterials. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800585x

Variables affecting biodiesel production from zanthoxylum bungeanum seed oil with high free fatty acids / Junhua Zhang in Industrial & engineering chemistry research, Vol. 51 N° 9 (Mars 2012) 

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