Documents disponibles écrits par cet auteur

Experimental characterization of fuel-air mixing in a multihole tube / Chi Zhang in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 134 N° 3 (Mars 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 3 (Mars 2012) . - 05 p. Titre : Experimental characterization of fuel-air mixing in a multihole tube Type de document : texte imprimé Auteurs : Chi Zhang, Auteur ; Quanhong Xu, Auteur ; Yuzhen Lin, Auteur Année de publication : 2012 Article en page(s) : 05 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Aerospace  engines  Combustion  Computational  fluid  dynamics  Confined  flow  Flow  simulation  Gas  turbines  Jets  Mixing  Pipe  flow  Sprays Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The multihole tube is an important component used for lean premixed prevaporized low-emission combustion in micro gas turbines, as it plays a key role in establishing uniform fuel-air mixture before flowing into the combustor. Recognizing that poor fuel-air mixing leads to increased emissions, it is therefore imperative to characterize the extent of fuel-air mixing at the exit of the multihole tube. In the present investigation, mixing characterization experiments were conducted by mapping the distribution of fuel-air equivalence ratios at the tube exit with gas analysis technique. Two different multihole tube configurations were tested and compared using aviation kerosene. Experiments were performed under atmospheric pressure, with an inlet air temperature of 480 K and an overall fuel-air equivalence ratio of 0.6. While the baseline configuration yielded the maximum magnitude of equivalence ratio deviation close to 35% at the tube exit, the modified configuration demonstrated much improved mixing uniformity with the maximum extent of equivalence ratio deviation being reduced to ~10%. A three-dimensional computational fluid dynamics simulation was also carried out to illustrate the resulting flow field associated with the baseline configuration and suggest the needed configuration modifications for performance improvement. Experimental and computational results indicate that the matching of fuel atomization and flow field is the primary factor affecting fuel-air mixture uniformity. By optimizing the flow rate ratio of the axial jet air in the nozzle section to the swirling jet air in the tube section as well as the axial jet momentum, enhanced fuel-air mixture uniformity can be achieved. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000003 [...] [article] Experimental characterization of fuel-air mixing in a multihole tube [texte imprimé] / Chi Zhang, Auteur ; Quanhong Xu, Auteur ; Yuzhen Lin, Auteur . - 2012 . - 05 p. Génie mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 3 (Mars 2012) . - 05 p. Mots-clés : Aerospace  engines  Combustion  Computational  fluid  dynamics  Confined  flow  Flow  simulation  Gas  turbines  Jets  Mixing  Pipe  flow  Sprays Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The multihole tube is an important component used for lean premixed prevaporized low-emission combustion in micro gas turbines, as it plays a key role in establishing uniform fuel-air mixture before flowing into the combustor. Recognizing that poor fuel-air mixing leads to increased emissions, it is therefore imperative to characterize the extent of fuel-air mixing at the exit of the multihole tube. In the present investigation, mixing characterization experiments were conducted by mapping the distribution of fuel-air equivalence ratios at the tube exit with gas analysis technique. Two different multihole tube configurations were tested and compared using aviation kerosene. Experiments were performed under atmospheric pressure, with an inlet air temperature of 480 K and an overall fuel-air equivalence ratio of 0.6. While the baseline configuration yielded the maximum magnitude of equivalence ratio deviation close to 35% at the tube exit, the modified configuration demonstrated much improved mixing uniformity with the maximum extent of equivalence ratio deviation being reduced to ~10%. A three-dimensional computational fluid dynamics simulation was also carried out to illustrate the resulting flow field associated with the baseline configuration and suggest the needed configuration modifications for performance improvement. Experimental and computational results indicate that the matching of fuel atomization and flow field is the primary factor affecting fuel-air mixture uniformity. By optimizing the flow rate ratio of the axial jet air in the nozzle section to the swirling jet air in the tube section as well as the axial jet momentum, enhanced fuel-air mixture uniformity can be achieved. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000003 [...]

Plantwide control system design and performance evaluation for ammonia synthesis process / Chi Zhang in Industrial & engineering chemistry research, Vol. 49 N° 24 (Décembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 24 (Décembre 2010) . - pp. 12538-12547 Titre : Plantwide control system design and performance evaluation for ammonia synthesis process Type de document : texte imprimé Auteurs : Chi Zhang, Auteur ; Suraj Vasudevan, Auteur ; G.P. Rangaiah, Auteur Année de publication : 2011 Article en page(s) : pp. 12538-12547 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : System  design  Control  system  Process  control Résumé : The emphasis on process economics in modem chemical plants has led to the increased use of material recycle and energy integration that significantly alter process dynamics and add complexity. As a result, many plantwide control (PWC) methodologies have emerged. However, there are very few comparative studies to evaluate the effectiveness of alternate methodologies. In this study, a PWC structure for the ammonia synthesis process is developed using the integrated framework of simulation and heuristics [Konda et al. Ind. Eng. Chem. Res. 2005, 44, 8300-8313], which is then compared with that developed by Araújo and Skogestad [Araújo and Skogestad, Comput. Chem. Eng. 2008, 32, 2920-2932] using the self-optimizing control procedure. The different control structures are evaluated in a comprehensive manner including assessment of the dynamic performance and steady-state profit. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23692009 [article] Plantwide control system design and performance evaluation for ammonia synthesis process [texte imprimé] / Chi Zhang, Auteur ; Suraj Vasudevan, Auteur ; G.P. Rangaiah, Auteur . - 2011 . - pp. 12538-12547. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 24 (Décembre 2010) . - pp. 12538-12547 Mots-clés : System  design  Control  system  Process  control Résumé : The emphasis on process economics in modem chemical plants has led to the increased use of material recycle and energy integration that significantly alter process dynamics and add complexity. As a result, many plantwide control (PWC) methodologies have emerged. However, there are very few comparative studies to evaluate the effectiveness of alternate methodologies. In this study, a PWC structure for the ammonia synthesis process is developed using the integrated framework of simulation and heuristics [Konda et al. Ind. Eng. Chem. Res. 2005, 44, 8300-8313], which is then compared with that developed by Araújo and Skogestad [Araújo and Skogestad, Comput. Chem. Eng. 2008, 32, 2920-2932] using the self-optimizing control procedure. The different control structures are evaluated in a comprehensive manner including assessment of the dynamic performance and steady-state profit. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23692009