Documents disponibles écrits par cet auteur

Dynamics of mixing-limited pattern formation in nonisothermal homogeneous autocatalytic reactors / Anwesha Chaudhury in Industrial & engineering chemistry research, Vol. 50 N° 8 (Avril 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 8 (Avril 2011) . - pp. 4335–4344 Titre : Dynamics of mixing-limited pattern formation in nonisothermal homogeneous autocatalytic reactors : a low-dimensional computational analysis Type de document : texte imprimé Auteurs : Anwesha Chaudhury, Auteur ; Saikat Chakraborty, Auteur Année de publication : 2011 Article en page(s) : pp. 4335–4344 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Dynamics  Homogeneous  autocatalytic  reactors Résumé : This work studies the temporal evolution of concentration and temperature patterns in fast, homogeneous, nonisothermal, autocatalytic, adiabatic tubular reactors. Transverse patterns are simulated using a two-dimensional unsteady-state model, called the regularized model, obtained by averaging the 3-D convection−diffusion−reaction equations axially using a Liapunov−Schmidt based averaging technique, followed by regularization. Steady state bifurcation and linear stability analysis show that the patterns emerge from the unstable middle branch of the S-shaped steady state bifurcation diagrams of concentration/temperature versus reactor Damkohler number. This unstable steady state is then slightly perturbed to analyze the evolution dynamics of various symmetric and asymmetric concentration and temperature patterns. Our simulations show how zones with slightly differing concentrations and temperature evolve over time into intensely segregated patterns that slowly diffuse into the homogeneous ignited branch of the steady state curve. Our parametric analysis quantifies the effects of process parameters such as transverse and axial Peclet numbers, Damkohler number, Zeldovich number, and Lewis number on the dynamics and intensity of pattern formation and dissolution. Interesting differences between the mechanics of pattern formation in isothermal and nonisothermal autocatalysis are also discussed. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101861x [article] Dynamics of mixing-limited pattern formation in nonisothermal homogeneous autocatalytic reactors : a low-dimensional computational analysis [texte imprimé] / Anwesha Chaudhury, Auteur ; Saikat Chakraborty, Auteur . - 2011 . - pp. 4335–4344. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 8 (Avril 2011) . - pp. 4335–4344 Mots-clés : Dynamics  Homogeneous  autocatalytic  reactors Résumé : This work studies the temporal evolution of concentration and temperature patterns in fast, homogeneous, nonisothermal, autocatalytic, adiabatic tubular reactors. Transverse patterns are simulated using a two-dimensional unsteady-state model, called the regularized model, obtained by averaging the 3-D convection−diffusion−reaction equations axially using a Liapunov−Schmidt based averaging technique, followed by regularization. Steady state bifurcation and linear stability analysis show that the patterns emerge from the unstable middle branch of the S-shaped steady state bifurcation diagrams of concentration/temperature versus reactor Damkohler number. This unstable steady state is then slightly perturbed to analyze the evolution dynamics of various symmetric and asymmetric concentration and temperature patterns. Our simulations show how zones with slightly differing concentrations and temperature evolve over time into intensely segregated patterns that slowly diffuse into the homogeneous ignited branch of the steady state curve. Our parametric analysis quantifies the effects of process parameters such as transverse and axial Peclet numbers, Damkohler number, Zeldovich number, and Lewis number on the dynamics and intensity of pattern formation and dissolution. Interesting differences between the mechanics of pattern formation in isothermal and nonisothermal autocatalysis are also discussed. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101861x

Mixing effects in cellulase - mediated hydrolysis of cellulose for bio - ethanol production / Saikat Chakraborty in Industrial & engineering chemistry research, Vol. 49 N° 21 (Novembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 10818-10825 Titre : Mixing effects in cellulase - mediated hydrolysis of cellulose for bio - ethanol production Type de document : texte imprimé Auteurs : Saikat Chakraborty, Auteur ; Ashwin Gaikwad, Auteur Année de publication : 2011 Article en page(s) : pp. 10818-10825 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Production  Hydrolysis  Mixing Résumé : Conversion of cellulose to glucose is the rate-limiting step in converting biomass into fuel. In this paper, we explore the effects of micro- and macro-mixing on the enzymatic hydrolysis of various cellulosic substrates to glucose by using a spatially averaged low-dimensional CSTR model. We quantify the effects of mixing on glucose yield, cellulose depolymerization rate and the synergy between the enzymes. We conclude that micromixing limitations provide an important mechanism to increase yield, reduce the dominance of synergy and guide optimum process design by offsetting inhibitory effects by preventing the inhibitors from coming in contact with the enzymes. On quantifying the effects of inhibition type (competitive vs noncompetitive) and mixing type (macro- vs micro-), we find that noncompetitive inhibition inhibits glucose yield more strongly than competitive inhibition, and that unlike micromixing limitations, macromixing limitations reduce glucose yield. On the basis of our analysis, we recommend 2 tank reactors in series with minimal local mixing in each tank and glucose removal at the exit of the first tank as the optimal reactor configuration for maximizing glucose yield from enzymatic hydrolysis of cellulose. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23447974 [article] Mixing effects in cellulase - mediated hydrolysis of cellulose for bio - ethanol production [texte imprimé] / Saikat Chakraborty, Auteur ; Ashwin Gaikwad, Auteur . - 2011 . - pp. 10818-10825. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 10818-10825 Mots-clés : Production  Hydrolysis  Mixing Résumé : Conversion of cellulose to glucose is the rate-limiting step in converting biomass into fuel. In this paper, we explore the effects of micro- and macro-mixing on the enzymatic hydrolysis of various cellulosic substrates to glucose by using a spatially averaged low-dimensional CSTR model. We quantify the effects of mixing on glucose yield, cellulose depolymerization rate and the synergy between the enzymes. We conclude that micromixing limitations provide an important mechanism to increase yield, reduce the dominance of synergy and guide optimum process design by offsetting inhibitory effects by preventing the inhibitors from coming in contact with the enzymes. On quantifying the effects of inhibition type (competitive vs noncompetitive) and mixing type (macro- vs micro-), we find that noncompetitive inhibition inhibits glucose yield more strongly than competitive inhibition, and that unlike micromixing limitations, macromixing limitations reduce glucose yield. On the basis of our analysis, we recommend 2 tank reactors in series with minimal local mixing in each tank and glucose removal at the exit of the first tank as the optimal reactor configuration for maximizing glucose yield from enzymatic hydrolysis of cellulose. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23447974