Documents disponibles écrits par cet auteur

Compartment modeling and flow characterization in nonisothermal underground coal gasification cavities / Sateesh Daggupati in Industrial & engineering chemistry research, Vol. 51 N° 12 (Mars 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 12 (Mars 2012) . - pp. 4493–4508 Titre : Compartment modeling and flow characterization in nonisothermal underground coal gasification cavities Type de document : texte imprimé Auteurs : Sateesh Daggupati, Auteur ; Ramesh N. Mandapati, Auteur ; Sanjay M. Mahajani, Auteur Année de publication : 2012 Article en page(s) : pp. 4493–4508 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Gas  flow  Cavities Résumé : Characterization of reactant gas flow patterns in the underground coal gasification (UCG) cavity is important, because the flow is highly nonideal and likely to influence the quality of the product gas. In our earlier work [Daggupati et al., Energy2010, 35, 2374–2386], we have demonstrated a computational fluid dynamics (CFD)-based modeling approach to analyze the flow patterns in the cavity. A compartment model (network of ideal reactors) for the UCG cavity was developed based on the CFD simulation results. These studies were performed assuming that the UCG cavity is isothermal. In reality, large temperature gradients may prevail under certain conditions and, in turn, may influence the flow patterns. In this work, we consider different possible nonisothermal scenarios in the UCG cavity and propose a simplified compartment modeling strategy to reduce the computational burden. We also examine the effect of various operating and design parameters such as coal spalling, feed flow rate, feed temperature, and orientation of the inlet nozzle. All these effects are quantified by determining the corresponding compartment model parameters. The sensitivity of the compartment model parameters, with respect to the changes in various conditions, is studied. Furthermore, we validate the compartment modeling approach by comparing predicted conversions for a water-gas shift reaction with that of reaction-enabled CFD simulations under nonisothermal conditions. The results presented here provide adequate insight into the UCG process and can be conveniently used in the development of a computationally inexpensive phenomenological process model for the complex UCG process. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie200410u [article] Compartment modeling and flow characterization in nonisothermal underground coal gasification cavities [texte imprimé] / Sateesh Daggupati, Auteur ; Ramesh N. Mandapati, Auteur ; Sanjay M. Mahajani, Auteur . - 2012 . - pp. 4493–4508. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 12 (Mars 2012) . - pp. 4493–4508 Mots-clés : Gas  flow  Cavities Résumé : Characterization of reactant gas flow patterns in the underground coal gasification (UCG) cavity is important, because the flow is highly nonideal and likely to influence the quality of the product gas. In our earlier work [Daggupati et al., Energy2010, 35, 2374–2386], we have demonstrated a computational fluid dynamics (CFD)-based modeling approach to analyze the flow patterns in the cavity. A compartment model (network of ideal reactors) for the UCG cavity was developed based on the CFD simulation results. These studies were performed assuming that the UCG cavity is isothermal. In reality, large temperature gradients may prevail under certain conditions and, in turn, may influence the flow patterns. In this work, we consider different possible nonisothermal scenarios in the UCG cavity and propose a simplified compartment modeling strategy to reduce the computational burden. We also examine the effect of various operating and design parameters such as coal spalling, feed flow rate, feed temperature, and orientation of the inlet nozzle. All these effects are quantified by determining the corresponding compartment model parameters. The sensitivity of the compartment model parameters, with respect to the changes in various conditions, is studied. Furthermore, we validate the compartment modeling approach by comparing predicted conversions for a water-gas shift reaction with that of reaction-enabled CFD simulations under nonisothermal conditions. The results presented here provide adequate insight into the UCG process and can be conveniently used in the development of a computationally inexpensive phenomenological process model for the complex UCG process. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie200410u

Experiments and kinetic modeling for CO2 gasification of indian coal chars in the context of underground coal gasification / Ramesh Naidu Mandapati in Industrial & engineering chemistry research, Vol. 51 N° 46 (Novembre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 46 (Novembre 2012) . - pp. 15041-15052 Titre : Experiments and kinetic modeling for CO2 gasification of indian coal chars in the context of underground coal gasification Type de document : texte imprimé Auteurs : Ramesh Naidu Mandapati, Auteur ; Sateesh Daggupati, Auteur ; Sanjay M. Mahajani, Auteur Année de publication : 2013 Article en page(s) : pp. 15041-15052 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Modeling  Coal  Coal  gasification  Carbon  dioxide  Kinetic  model Résumé : Gasification of four Indian coals is carried out in a CO2 atmosphere, using a thermogravimetric analyzer (TGA) to determine the intrinsic kinetics over a temperature range of 800―1050 °C with different partial pressures of CO2. The applicability of three models, viz., the volumetric reaction model, the shrinking core model and the random pore model, is evaluated. Of these three models, the random pore model is found to be the most suitable for all the coals considered in the current study. The dependence of the reaction rate on the gas-phase partial pressures is explained by the Langmuir― Hinshelwood model, and the parameters for the inhibition due to CO and CO2 are determined by performing experiments at different partial pressures. In underground coal gasification, the reaction takes place on reasonably large sized coal particles, wherein diffusion effects are significant. A one-dimensional reaction diffusion model is therefore developed in order to determine the diffusional resistance in the coal particle, and values of diffusivity are estimated. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26679623 [article] Experiments and kinetic modeling for CO2 gasification of indian coal chars in the context of underground coal gasification [texte imprimé] / Ramesh Naidu Mandapati, Auteur ; Sateesh Daggupati, Auteur ; Sanjay M. Mahajani, Auteur . - 2013 . - pp. 15041-15052. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 46 (Novembre 2012) . - pp. 15041-15052 Mots-clés : Modeling  Coal  Coal  gasification  Carbon  dioxide  Kinetic  model Résumé : Gasification of four Indian coals is carried out in a CO2 atmosphere, using a thermogravimetric analyzer (TGA) to determine the intrinsic kinetics over a temperature range of 800―1050 °C with different partial pressures of CO2. The applicability of three models, viz., the volumetric reaction model, the shrinking core model and the random pore model, is evaluated. Of these three models, the random pore model is found to be the most suitable for all the coals considered in the current study. The dependence of the reaction rate on the gas-phase partial pressures is explained by the Langmuir― Hinshelwood model, and the parameters for the inhibition due to CO and CO2 are determined by performing experiments at different partial pressures. In underground coal gasification, the reaction takes place on reasonably large sized coal particles, wherein diffusion effects are significant. A one-dimensional reaction diffusion model is therefore developed in order to determine the diffusional resistance in the coal particle, and values of diffusivity are estimated. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26679623