Documents disponibles écrits par cet auteur

Effect of periodic variation of the Inlet concentration on the performance of reverse flow reactors / Geng Chen in Industrial & engineering chemistry research, Vol. 50 N° 9 (Mai 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 9 (Mai 2011) . - pp. 5448–5458 Titre : Effect of periodic variation of the Inlet concentration on the performance of reverse flow reactors Type de document : texte imprimé Auteurs : Geng Chen, Auteur ; Yong Chi, Auteur ; Jian-hua Yan, Auteur Année de publication : 2011 Article en page(s) : pp. 5448–5458 Note générale : Chimie Langues : Anglais (eng) Mots-clés : Reverse  flow  reactors Résumé : Reverse flow reactors are regarded as an appropriate tool for removing gaseous pollutants from industrial effluents. This paper presents the results of an experimental study on a particular reverse flow reactor with periodic variations in inlet concentration; these experimental results are compared with those obtained by numerical simulation studies. Catalytic oxidation of methane is chosen as model reaction. When the inlet concentration is low (i.e., close to extinction limits) and periodically varied, the interaction between the feeding cycle period and the flow-reversal cycle period may lead to reactor instability; adjusting the period of flow reversal is one way to maintain thermal stability in such situations. Results of numerical investigations reveal that if the flow-reversal cycle time is an odd multiple of the inlet variation cycle time, a harmonic response will occur, with sharply increased variation of the maximum temperature. Basically, it is the inequality of total methane input during the two half-cycles during flow-reversal operations that cause reactor instability. Adjusting the phase between the two cycle periods may ease the inequality of the inlet concentration values, which procures a second strategy to enhance reactor stability. The temperature maximum is very sensitive to the heat-transfer parameters, when periodic inlet variations are introduced. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie102342w [article] Effect of periodic variation of the Inlet concentration on the performance of reverse flow reactors [texte imprimé] / Geng Chen, Auteur ; Yong Chi, Auteur ; Jian-hua Yan, Auteur . - 2011 . - pp. 5448–5458. Chimie Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 9 (Mai 2011) . - pp. 5448–5458 Mots-clés : Reverse  flow  reactors Résumé : Reverse flow reactors are regarded as an appropriate tool for removing gaseous pollutants from industrial effluents. This paper presents the results of an experimental study on a particular reverse flow reactor with periodic variations in inlet concentration; these experimental results are compared with those obtained by numerical simulation studies. Catalytic oxidation of methane is chosen as model reaction. When the inlet concentration is low (i.e., close to extinction limits) and periodically varied, the interaction between the feeding cycle period and the flow-reversal cycle period may lead to reactor instability; adjusting the period of flow reversal is one way to maintain thermal stability in such situations. Results of numerical investigations reveal that if the flow-reversal cycle time is an odd multiple of the inlet variation cycle time, a harmonic response will occur, with sharply increased variation of the maximum temperature. Basically, it is the inequality of total methane input during the two half-cycles during flow-reversal operations that cause reactor instability. Adjusting the phase between the two cycle periods may ease the inequality of the inlet concentration values, which procures a second strategy to enhance reactor stability. The temperature maximum is very sensitive to the heat-transfer parameters, when periodic inlet variations are introduced. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie102342w

Experimental study of mass transfer in membrane absorption process using membranes with different porosities / Zhang, Weidong in Industrial & engineering chemistry research, Vol. 49 N° 14 (Juillet 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 14 (Juillet 2010) . - pp. 6641–6648 Titre : Experimental study of mass transfer in membrane absorption process using membranes with different porosities Type de document : texte imprimé Auteurs : Zhang, Weidong, Auteur ; Li Jiang, Auteur ; Geng Chen, Auteur Année de publication : 2010 Article en page(s) : pp. 6641–6648 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Mass  transfer  Membrane  absorption Résumé : Experimental study has been carried out to investigate the mass transfer behavior when carbon dioxide (CO2) is absorbed through microporous membranes with different porosities. Deionized water and sodium hydroxide (NaOH) aqueous solutions are chosen as absorbents. The effects of membrane porosity, absorbent pH value, and liquid velocity on mass transfer are studied. The effect of membrane porosity on mass transfer depends on both the absorbent pH value and liquid velocity. In the case of low pH values (7−11) in absorbent, membrane porosity almost has no effect on mass transfer at relatively lower liquid velocity, namely, the mass transfer coefficients based on the whole membrane area remain almost the same at different membrane porosities; the effect of membrane porosity on mass transfer becomes obvious with the increasing liquid velocity. Contrarily, as the absorbent pH value increases to 12 or 13, the influence of porosity on mass transfer coefficient becomes significant at varied liquid velocity. The modified mass transfer correlations are obtained with consideration of the effect of porosity over a varying membrane porosity range. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1001026 [article] Experimental study of mass transfer in membrane absorption process using membranes with different porosities [texte imprimé] / Zhang, Weidong, Auteur ; Li Jiang, Auteur ; Geng Chen, Auteur . - 2010 . - pp. 6641–6648. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 14 (Juillet 2010) . - pp. 6641–6648 Mots-clés : Mass  transfer  Membrane  absorption Résumé : Experimental study has been carried out to investigate the mass transfer behavior when carbon dioxide (CO2) is absorbed through microporous membranes with different porosities. Deionized water and sodium hydroxide (NaOH) aqueous solutions are chosen as absorbents. The effects of membrane porosity, absorbent pH value, and liquid velocity on mass transfer are studied. The effect of membrane porosity on mass transfer depends on both the absorbent pH value and liquid velocity. In the case of low pH values (7−11) in absorbent, membrane porosity almost has no effect on mass transfer at relatively lower liquid velocity, namely, the mass transfer coefficients based on the whole membrane area remain almost the same at different membrane porosities; the effect of membrane porosity on mass transfer becomes obvious with the increasing liquid velocity. Contrarily, as the absorbent pH value increases to 12 or 13, the influence of porosity on mass transfer coefficient becomes significant at varied liquid velocity. The modified mass transfer correlations are obtained with consideration of the effect of porosity over a varying membrane porosity range. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1001026

Intensification of mass transfer in hollow fiber modules by adding solid particles / Zhang, Weidong in Industrial & engineering chemistry research, Vol. 48 N° 18 (Septembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8655–8662 Titre : Intensification of mass transfer in hollow fiber modules by adding solid particles Type de document : texte imprimé Auteurs : Zhang, Weidong, Auteur ; Geng Chen, Auteur ; Jiang Li, Auteur Année de publication : 2010 Article en page(s) : pp. 8655–8662 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hollow  fiber  contactor  Absorption  performance  Shell  side  absorbent  Ultrasound Résumé : A method of improving the absorption performance in hollow fiber contactor by adding a third solid phase into the shell side absorbent is proposed. Powdered kieselgur, graphite, and BaSO4 are chosen as the additives to intensify the absorption process of the CO2/NaOH(aq) system. Ultrasound is used in this work as an approach to make the solid particles suspend in the liquid absorbent. The mass-transfer rate is enhanced about 40% by adding solid particles into the absorbent liquid in the presence of ultrasound. As for different types of particles, the smaller the density difference between the absorbent and the solid, the higher enhancement factor obtained. The enhancement factor is a function of the solids loading as well as the liquid velocity in the shell side of the module. The mass-transfer coefficient and enhancement factor remain almost the same with increasing pH from 7 to 11; as pH further increases, both the mass-transfer coefficient and the enhancement factor are increasing dramatically. The results also indicate that the enhancement factors increase with an increase of the packing density. The residence time distribution (RTD) curves are measured to observe the flow status in the shell side; the results demonstrate that addition of solid particles can improve the flow conditions in the shell side. A mathematical model for the intensification process based on surface renewal theory is developed; the calculated results have a good agreement with the experimental results under the present experimental conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004964 [article] Intensification of mass transfer in hollow fiber modules by adding solid particles [texte imprimé] / Zhang, Weidong, Auteur ; Geng Chen, Auteur ; Jiang Li, Auteur . - 2010 . - pp. 8655–8662. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8655–8662 Mots-clés : Hollow  fiber  contactor  Absorption  performance  Shell  side  absorbent  Ultrasound Résumé : A method of improving the absorption performance in hollow fiber contactor by adding a third solid phase into the shell side absorbent is proposed. Powdered kieselgur, graphite, and BaSO4 are chosen as the additives to intensify the absorption process of the CO2/NaOH(aq) system. Ultrasound is used in this work as an approach to make the solid particles suspend in the liquid absorbent. The mass-transfer rate is enhanced about 40% by adding solid particles into the absorbent liquid in the presence of ultrasound. As for different types of particles, the smaller the density difference between the absorbent and the solid, the higher enhancement factor obtained. The enhancement factor is a function of the solids loading as well as the liquid velocity in the shell side of the module. The mass-transfer coefficient and enhancement factor remain almost the same with increasing pH from 7 to 11; as pH further increases, both the mass-transfer coefficient and the enhancement factor are increasing dramatically. The results also indicate that the enhancement factors increase with an increase of the packing density. The residence time distribution (RTD) curves are measured to observe the flow status in the shell side; the results demonstrate that addition of solid particles can improve the flow conditions in the shell side. A mathematical model for the intensification process based on surface renewal theory is developed; the calculated results have a good agreement with the experimental results under the present experimental conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004964

Intensification of mass transfer in hollow fiber modules by adding solid particles / Zhang, Weidong in Industrial & engineering chemistry research, Vol. 48 N° 18 (Septembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8655–8662 Titre : Intensification of mass transfer in hollow fiber modules by adding solid particles Type de document : texte imprimé Auteurs : Zhang, Weidong, Auteur ; Geng Chen, Auteur ; Jiang Li, Auteur Année de publication : 2010 Article en page(s) : pp. 8655–8662 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hollow  fiber  contactor  Absorption  performance  Shell  side  absorbent  Ultrasound Résumé : A method of improving the absorption performance in hollow fiber contactor by adding a third solid phase into the shell side absorbent is proposed. Powdered kieselgur, graphite, and BaSO4 are chosen as the additives to intensify the absorption process of the CO2/NaOH(aq) system. Ultrasound is used in this work as an approach to make the solid particles suspend in the liquid absorbent. The mass-transfer rate is enhanced about 40% by adding solid particles into the absorbent liquid in the presence of ultrasound. As for different types of particles, the smaller the density difference between the absorbent and the solid, the higher enhancement factor obtained. The enhancement factor is a function of the solids loading as well as the liquid velocity in the shell side of the module. The mass-transfer coefficient and enhancement factor remain almost the same with increasing pH from 7 to 11; as pH further increases, both the mass-transfer coefficient and the enhancement factor are increasing dramatically. The results also indicate that the enhancement factors increase with an increase of the packing density. The residence time distribution (RTD) curves are measured to observe the flow status in the shell side; the results demonstrate that addition of solid particles can improve the flow conditions in the shell side. A mathematical model for the intensification process based on surface renewal theory is developed; the calculated results have a good agreement with the experimental results under the present experimental conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004964 [article] Intensification of mass transfer in hollow fiber modules by adding solid particles [texte imprimé] / Zhang, Weidong, Auteur ; Geng Chen, Auteur ; Jiang Li, Auteur . - 2010 . - pp. 8655–8662. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8655–8662 Mots-clés : Hollow  fiber  contactor  Absorption  performance  Shell  side  absorbent  Ultrasound Résumé : A method of improving the absorption performance in hollow fiber contactor by adding a third solid phase into the shell side absorbent is proposed. Powdered kieselgur, graphite, and BaSO4 are chosen as the additives to intensify the absorption process of the CO2/NaOH(aq) system. Ultrasound is used in this work as an approach to make the solid particles suspend in the liquid absorbent. The mass-transfer rate is enhanced about 40% by adding solid particles into the absorbent liquid in the presence of ultrasound. As for different types of particles, the smaller the density difference between the absorbent and the solid, the higher enhancement factor obtained. The enhancement factor is a function of the solids loading as well as the liquid velocity in the shell side of the module. The mass-transfer coefficient and enhancement factor remain almost the same with increasing pH from 7 to 11; as pH further increases, both the mass-transfer coefficient and the enhancement factor are increasing dramatically. The results also indicate that the enhancement factors increase with an increase of the packing density. The residence time distribution (RTD) curves are measured to observe the flow status in the shell side; the results demonstrate that addition of solid particles can improve the flow conditions in the shell side. A mathematical model for the intensification process based on surface renewal theory is developed; the calculated results have a good agreement with the experimental results under the present experimental conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004964