Documents disponibles écrits par cet auteur

Hydrodynamics of liquid–liquid dispersion in an advanced-flow reactor / Maria José Nieves-Remacha in Industrial & engineering chemistry research, Vol. 51 N° 50 (Décembre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 50 (Décembre 2012) . - pp 16251–16262 Titre : Hydrodynamics of liquid–liquid dispersion in an advanced-flow reactor Type de document : texte imprimé Auteurs : Maria José Nieves-Remacha, Auteur ; Amol A. Kulkarni, Auteur ; Klavs F. Jensen, Auteur Année de publication : 2013 Article en page(s) : pp 16251–16262 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Hydrodynamics  Mass  transfer Résumé : Hydrodynamics and mass transfer of immiscible liquid–liquid flows are explored in an Advanced-Flow Reactor (AFR). These systems are emerging as one of the major commercial systems for small scale continuous flow chemistry, and characterization of the transport phenomena is critical for reaction implementation. With hexane/water as a model system, we use flow visualization techniques to determine drop size distribution, hexane holdup, and specific interfacial areas for a phase flow rate range of 10–80 mL/min. The complex geometry of the AFR with its continuously changing cross section along the flow path and strategically placed obstacles creates pressure changes that cause drop breakup and enhance mass transfer. Observations show that a wide range of average drop size (0.33–1.3 mm) can be achieved in the AFR depending upon the inlet flow rates and inlet composition. Pressure drop measurements are performed to estimate the power consumption and are used to compare the efficiency of AFR with conventional liquid–liquid contactors. The analysis shows that, similar to microreactors, the AFR can provide specific interfacial areas (1000–10 000 m–1) and overall mass transfer coefficients (1.9–41 s–1) a few orders of magnitude larger than conventional stirred tank reactors and also the static mixers. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie301821k [article] Hydrodynamics of liquid–liquid dispersion in an advanced-flow reactor [texte imprimé] / Maria José Nieves-Remacha, Auteur ; Amol A. Kulkarni, Auteur ; Klavs F. Jensen, Auteur . - 2013 . - pp 16251–16262. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 50 (Décembre 2012) . - pp 16251–16262 Mots-clés : Hydrodynamics  Mass  transfer Résumé : Hydrodynamics and mass transfer of immiscible liquid–liquid flows are explored in an Advanced-Flow Reactor (AFR). These systems are emerging as one of the major commercial systems for small scale continuous flow chemistry, and characterization of the transport phenomena is critical for reaction implementation. With hexane/water as a model system, we use flow visualization techniques to determine drop size distribution, hexane holdup, and specific interfacial areas for a phase flow rate range of 10–80 mL/min. The complex geometry of the AFR with its continuously changing cross section along the flow path and strategically placed obstacles creates pressure changes that cause drop breakup and enhance mass transfer. Observations show that a wide range of average drop size (0.33–1.3 mm) can be achieved in the AFR depending upon the inlet flow rates and inlet composition. Pressure drop measurements are performed to estimate the power consumption and are used to compare the efficiency of AFR with conventional liquid–liquid contactors. The analysis shows that, similar to microreactors, the AFR can provide specific interfacial areas (1000–10 000 m–1) and overall mass transfer coefficients (1.9–41 s–1) a few orders of magnitude larger than conventional stirred tank reactors and also the static mixers. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie301821k

Microreactor system for high - pressure continuous flow homogeneous catalysis measurements / Jaroslav Keybl in Industrial & engineering chemistry research, Vol. 50 N° 19 (Octobre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 19 (Octobre 2011) . - pp. 11013–11022 Titre : Microreactor system for high - pressure continuous flow homogeneous catalysis measurements Type de document : texte imprimé Auteurs : Jaroslav Keybl, Auteur ; Klavs F. Jensen, Auteur Année de publication : 2011 Article en page(s) : pp. 11013–11022 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Homogeneous  catalyst  kinetic Résumé : A high-pressure gas–liquid system is presented for determining homogeneous catalyst kinetic parameters. Microreactors enable segmented flow with very predictable gas–liquid contacting, reducing the effects of mass transfer as well as facilitating isothermal operation. The system is capable of studying homogeneous catalysis at high temperature and pressure (<350 °C and <100 bar) under continuous flow. By varying the pressure, temperature, and concentrations of both gas and liquid species, it is possible to determine kinetic parameters. Both inline and offline analyses are performed using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and gas chromatography (GC). The hydroformylation of 1-octene is studied to demonstrate the utility of this microreactor system as a laboratory tool for kinetic measurements. The system is capable of providing both parameter estimation and mechanistic insight. A discussion is also included that explores the types of chemical systems that can be studied practically in microreactors. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie200936b [article] Microreactor system for high - pressure continuous flow homogeneous catalysis measurements [texte imprimé] / Jaroslav Keybl, Auteur ; Klavs F. Jensen, Auteur . - 2011 . - pp. 11013–11022. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 19 (Octobre 2011) . - pp. 11013–11022 Mots-clés : Homogeneous  catalyst  kinetic Résumé : A high-pressure gas–liquid system is presented for determining homogeneous catalyst kinetic parameters. Microreactors enable segmented flow with very predictable gas–liquid contacting, reducing the effects of mass transfer as well as facilitating isothermal operation. The system is capable of studying homogeneous catalysis at high temperature and pressure (<350 °C and <100 bar) under continuous flow. By varying the pressure, temperature, and concentrations of both gas and liquid species, it is possible to determine kinetic parameters. Both inline and offline analyses are performed using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and gas chromatography (GC). The hydroformylation of 1-octene is studied to demonstrate the utility of this microreactor system as a laboratory tool for kinetic measurements. The system is capable of providing both parameter estimation and mechanistic insight. A discussion is also included that explores the types of chemical systems that can be studied practically in microreactors. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie200936b

A pH - sensitive laser - induced fluorescence technique to monitor mass transfer in multiphase flows in microfluidic devices / Simon Kuhn in Industrial & engineering chemistry research, Vol. 51 N° 26 (Juillet 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp. 8999-9006 Titre : A pH - sensitive laser - induced fluorescence technique to monitor mass transfer in multiphase flows in microfluidic devices Type de document : texte imprimé Auteurs : Simon Kuhn, Auteur ; Klavs F. Jensen, Auteur Année de publication : 2012 Article en page(s) : pp. 8999-9006 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Fluid  mechanics  Microfluidics  Multiphase  flow  Mass  transfer  Surveillance  Laser  induced  fluorescence  pH Résumé : We present a pH-sensitive laser-induced fluorescence (LIF) technique to investigate mass transfer in reactive flows. As a fluorescent dye, we used 5-(and-6)-carboxy SNARF-1, which, when excited with a pulsed Nd:YAG laser at 532 nm, provides good sensitivity in the range 4 ≤ pH ≤ 12. For validation, we first applied the dye to single-phase reactive flows by investigating the neutralization of sodium hydroxide with hydrochloric acid. Comparison to the classical passive mixing case showed that this dye was able to capture the reaction progress and to quantify the mass transport. Next, we investigated the absorption of CO2 in an alkaline solution using gas―liquid flow and found that the LIF technique is able to quantify the local mass-transfer rate in microfluidic systems. Results for different microchannel geometries highlight the strong connection between local mass transfer and secondary flow structures in gas―liquid Taylor flow. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26107457 [article] A pH - sensitive laser - induced fluorescence technique to monitor mass transfer in multiphase flows in microfluidic devices [texte imprimé] / Simon Kuhn, Auteur ; Klavs F. Jensen, Auteur . - 2012 . - pp. 8999-9006. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp. 8999-9006 Mots-clés : Fluid  mechanics  Microfluidics  Multiphase  flow  Mass  transfer  Surveillance  Laser  induced  fluorescence  pH Résumé : We present a pH-sensitive laser-induced fluorescence (LIF) technique to investigate mass transfer in reactive flows. As a fluorescent dye, we used 5-(and-6)-carboxy SNARF-1, which, when excited with a pulsed Nd:YAG laser at 532 nm, provides good sensitivity in the range 4 ≤ pH ≤ 12. For validation, we first applied the dye to single-phase reactive flows by investigating the neutralization of sodium hydroxide with hydrochloric acid. Comparison to the classical passive mixing case showed that this dye was able to capture the reaction progress and to quantify the mass transport. Next, we investigated the absorption of CO2 in an alkaline solution using gas―liquid flow and found that the LIF technique is able to quantify the local mass-transfer rate in microfluidic systems. Results for different microchannel geometries highlight the strong connection between local mass transfer and secondary flow structures in gas―liquid Taylor flow. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26107457

Portable thermoelectric power generator based on a microfabricated silicon combustor with low resistance to flow / Christopher H. Marton in Industrial & engineering chemistry research, Vol. 50 N° 14 (Juillet 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 14 (Juillet 2011) . - pp. 8468-8475 Titre : Portable thermoelectric power generator based on a microfabricated silicon combustor with low resistance to flow Type de document : texte imprimé Auteurs : Christopher H. Marton, Auteur ; George S. Haldeman, Auteur ; Klavs F. Jensen, Auteur Année de publication : 2011 Article en page(s) : pp. 8468-8475 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Thermoelectric  Silicon  Combustor Résumé : A portable-scale thermoelectric power generator is designed, fabricated, and tested. The basis of the system is a mesoscale silicon reactor for the combustion of butane over an alumina-supported platinum catalyst. The system is integrated with commercial bismuth telluride thermoelectric modules to produce 5.8 W of electrical power with a chemical-to-electrical conversion efficiency of 2.5% (based on LHV). The energy and power densities of the demonstrated system are 321 W h kg―1 and 17 W kg―1, respectively. The pressure drop through the system is 130 Pa for the highest flow rate used, resulting in a parasitic power requirement for air-pressurization of ∼0.1 W. The demonstration represents an order-of-magnitude improvement in portable-scale electrical power from thermoelectrics and hydrocarbon fuels, and a notable increase in the conversion efficiency compared with previous studies. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24346886 [article] Portable thermoelectric power generator based on a microfabricated silicon combustor with low resistance to flow [texte imprimé] / Christopher H. Marton, Auteur ; George S. Haldeman, Auteur ; Klavs F. Jensen, Auteur . - 2011 . - pp. 8468-8475. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 14 (Juillet 2011) . - pp. 8468-8475 Mots-clés : Thermoelectric  Silicon  Combustor Résumé : A portable-scale thermoelectric power generator is designed, fabricated, and tested. The basis of the system is a mesoscale silicon reactor for the combustion of butane over an alumina-supported platinum catalyst. The system is integrated with commercial bismuth telluride thermoelectric modules to produce 5.8 W of electrical power with a chemical-to-electrical conversion efficiency of 2.5% (based on LHV). The energy and power densities of the demonstrated system are 321 W h kg―1 and 17 W kg―1, respectively. The pressure drop through the system is 130 Pa for the highest flow rate used, resulting in a parasitic power requirement for air-pressurization of ∼0.1 W. The demonstration represents an order-of-magnitude improvement in portable-scale electrical power from thermoelectrics and hydrocarbon fuels, and a notable increase in the conversion efficiency compared with previous studies. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24346886