Documents disponibles écrits par cet auteur

Approach to Improve Speed of Sound Calculation within PC-SAFT Framework / Xiaodong Liang in Industrial & engineering chemistry research, Vol. 51 N° 45 (Novembre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 45 (Novembre 2012) . - pp. 14903–14914 Titre : Approach to Improve Speed of Sound Calculation within PC-SAFT Framework Type de document : texte imprimé Auteurs : Xiaodong Liang, Auteur ; Bjorn Maribo-Mogensen, Auteur ; Kaj Thomsen, Auteur Année de publication : 2013 Article en page(s) : pp. 14903–14914 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Speed  sound  data  parameter  estimation Résumé : An extensive comparison of SRK, CPA, and PC-SAFT for the speed of sound in normal alkanes has been performed. The results reveal that PC-SAFT captures the curvature of the speed of sound better than cubic EoS, but the accuracy is not satisfactory. Two approaches have been proposed to improve PC-SAFT’s accuracy for speed of sound: (i) putting speed of sound data into parameter estimation; (ii) putting speed of sound data into both universal constants regression and parameter estimation. The results have shown that the second approach can significantly improve the speed of sound (3.2%) prediction while keeping acceptable accuracy for the primary properties, i.e. vapor pressure (2.1%) and liquid density (1.5%). The two approaches have also been applied to methanol, and both give very good results. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie3018127 [article] Approach to Improve Speed of Sound Calculation within PC-SAFT Framework [texte imprimé] / Xiaodong Liang, Auteur ; Bjorn Maribo-Mogensen, Auteur ; Kaj Thomsen, Auteur . - 2013 . - pp. 14903–14914. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 45 (Novembre 2012) . - pp. 14903–14914 Mots-clés : Speed  sound  data  parameter  estimation Résumé : An extensive comparison of SRK, CPA, and PC-SAFT for the speed of sound in normal alkanes has been performed. The results reveal that PC-SAFT captures the curvature of the speed of sound better than cubic EoS, but the accuracy is not satisfactory. Two approaches have been proposed to improve PC-SAFT’s accuracy for speed of sound: (i) putting speed of sound data into parameter estimation; (ii) putting speed of sound data into both universal constants regression and parameter estimation. The results have shown that the second approach can significantly improve the speed of sound (3.2%) prediction while keeping acceptable accuracy for the primary properties, i.e. vapor pressure (2.1%) and liquid density (1.5%). The two approaches have also been applied to methanol, and both give very good results. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie3018127

Comparison of the debye – hückel and the mean spherical approximation theories for electrolyte solutions / Bjorn Maribo-Mogensen in Industrial & engineering chemistry research, Vol. 51 N° 14 (Avril 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 14 (Avril 2012) . - pp. 5353-5363 Titre : Comparison of the debye – hückel and the mean spherical approximation theories for electrolyte solutions Type de document : texte imprimé Auteurs : Bjorn Maribo-Mogensen, Auteur ; Georgios M. Kontogeorgis, Auteur ; Kaj Thomsen, Auteur Année de publication : 2012 Article en page(s) : pp. 5353-5363 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Electrolyte  solution  Approximation Résumé : The thermodynamics of electrolyte solutions has been investigated by many scientists throughout the last century. While several theories have been presented, the most popular models for the electrostatic interactions are based on the Debye-Hückel and mean spherical approximation (MSA) theories. In this paper we investigate the differences between the Debye-Hückel and the MSA theories, and comparisons of the numerical results for the Helmholtz energy and its derivatives with respect to temperature, volume and composition are presented. The investigation shows that the nonrestricted primitive MSA theory performs similarly to Debye―Hückel, despite the differences in the derivation. We furthermore show that the static permittivity is a key parameter for both models and that in many cases it completely dominates the results obtained from the two models. Consequently, we conclude that the simpler Debye―Hückel theory may be used in connection with electrolyte equations of state without loss of accuracy. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25783445 [article] Comparison of the debye – hückel and the mean spherical approximation theories for electrolyte solutions [texte imprimé] / Bjorn Maribo-Mogensen, Auteur ; Georgios M. Kontogeorgis, Auteur ; Kaj Thomsen, Auteur . - 2012 . - pp. 5353-5363. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 14 (Avril 2012) . - pp. 5353-5363 Mots-clés : Electrolyte  solution  Approximation Résumé : The thermodynamics of electrolyte solutions has been investigated by many scientists throughout the last century. While several theories have been presented, the most popular models for the electrostatic interactions are based on the Debye-Hückel and mean spherical approximation (MSA) theories. In this paper we investigate the differences between the Debye-Hückel and the MSA theories, and comparisons of the numerical results for the Helmholtz energy and its derivatives with respect to temperature, volume and composition are presented. The investigation shows that the nonrestricted primitive MSA theory performs similarly to Debye―Hückel, despite the differences in the derivation. We furthermore show that the static permittivity is a key parameter for both models and that in many cases it completely dominates the results obtained from the two models. Consequently, we conclude that the simpler Debye―Hückel theory may be used in connection with electrolyte equations of state without loss of accuracy. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25783445

Inhibition of methane hydrate formation by ice-structuring proteins / Jensen, Lars in Industrial & engineering chemistry research, Vol. 49 N° 4 (Fevrier 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 4 (Fevrier 2010) . - pp 1486–1492 Titre : Inhibition of methane hydrate formation by ice-structuring proteins Type de document : texte imprimé Auteurs : Jensen, Lars, Auteur ; Ramlov, Hans, Auteur ; Kaj Thomsen, Auteur Année de publication : 2010 Article en page(s) : pp 1486–1492 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Methane  hydrate  Ice  structuring  proteins. Résumé : In the oil and gas industry there is ample motivation for moving toward greener kinetic inhibitors of gas hydrates as many of those used today suffer from poor biodegradability. In this work, we have investigated experimentally whether ice-structuring proteins (ISPs) found in fish and insect, assumed biodegradable, are capable of inhibiting the growth of methane hydrate (a structure I hydrate). The ISPs investigated were type III HPLC12 (originally identified in ocean pout) and ISP type III found in meal worm (Tenebrio molitor). These were compared to polyvinylpyrrolidone (PVP) a well-known kinetic hydrate inhibitor. The results revealed that adding ISP in sufficient amounts caused the appearance of an initial nonlinear growth period. At a certain point during the growth process the growth pattern changed to linear which is identical to the growth observed for methane hydrate in the absence of inhibitors. The profile of the nonlinear growth was concentration-dependent but also dependent on the stirring rate. ISP type III HPLC12 decreased the growth rate of methane hydrate during the linear growth period by 17−75% at concentrations of 0.01−0.1 wt % (0.014−0.14 mM) while ISP from Tenebrio molitor and PVP decreased the growth rate by 30% and 39% at concentrations of 0.004 wt % (0.005 mM) and 0.1 wt % (0.1 mM), respectively. Considering the low concentration of Tenebrio molitor ISP used, these results indicate that ISP from Tenebrio molitor is the most effective hydrate inhibitor among those investigated. Thermal hysteresis ice formation experiments revealed that ISP from Tenebrio molitor causes higher thermal hysteresis for ice formation compared to type III ISP identified in ocean pout while PVP did not cause thermal hysteresis. This indicates that there might be a direct relationship between ISP performance for ice and hydrate inhibition, and that thermal hysteresis experiments can be used to screen ISPs as kinetic inhibitors. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901321p [article] Inhibition of methane hydrate formation by ice-structuring proteins [texte imprimé] / Jensen, Lars, Auteur ; Ramlov, Hans, Auteur ; Kaj Thomsen, Auteur . - 2010 . - pp 1486–1492. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 4 (Fevrier 2010) . - pp 1486–1492 Mots-clés : Methane  hydrate  Ice  structuring  proteins. Résumé : In the oil and gas industry there is ample motivation for moving toward greener kinetic inhibitors of gas hydrates as many of those used today suffer from poor biodegradability. In this work, we have investigated experimentally whether ice-structuring proteins (ISPs) found in fish and insect, assumed biodegradable, are capable of inhibiting the growth of methane hydrate (a structure I hydrate). The ISPs investigated were type III HPLC12 (originally identified in ocean pout) and ISP type III found in meal worm (Tenebrio molitor). These were compared to polyvinylpyrrolidone (PVP) a well-known kinetic hydrate inhibitor. The results revealed that adding ISP in sufficient amounts caused the appearance of an initial nonlinear growth period. At a certain point during the growth process the growth pattern changed to linear which is identical to the growth observed for methane hydrate in the absence of inhibitors. The profile of the nonlinear growth was concentration-dependent but also dependent on the stirring rate. ISP type III HPLC12 decreased the growth rate of methane hydrate during the linear growth period by 17−75% at concentrations of 0.01−0.1 wt % (0.014−0.14 mM) while ISP from Tenebrio molitor and PVP decreased the growth rate by 30% and 39% at concentrations of 0.004 wt % (0.005 mM) and 0.1 wt % (0.1 mM), respectively. Considering the low concentration of Tenebrio molitor ISP used, these results indicate that ISP from Tenebrio molitor is the most effective hydrate inhibitor among those investigated. Thermal hysteresis ice formation experiments revealed that ISP from Tenebrio molitor causes higher thermal hysteresis for ice formation compared to type III ISP identified in ocean pout while PVP did not cause thermal hysteresis. This indicates that there might be a direct relationship between ISP performance for ice and hydrate inhibition, and that thermal hysteresis experiments can be used to screen ISPs as kinetic inhibitors. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901321p

Modeling of the mixed solvent electrolyte system CO2−Na2CO3−NaHCO3−monoethylene glycol−water / Philip L. Fosbøl in Industrial & engineering chemistry research, Vol. 48 N° 9 (Mai 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4565–4578 Titre : Modeling of the mixed solvent electrolyte system CO2−Na2CO3−NaHCO3−monoethylene glycol−water Type de document : texte imprimé Auteurs : Philip L. Fosbøl, Auteur ; Kaj Thomsen, Auteur ; Erling H. Stenby, Auteur Année de publication : 2009 Article en page(s) : pp. 4565–4578 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Electrolyte  system  Solid−liquid  equilibrium  Vapor−liquid  equilibrium  CO2−NaHCO3−Na2CO3−monoethylene  glycol−H2O  electrolyte  system Résumé : The extended UNIQUAC electrolyte activity coefficient model has been correlated to 751 experimental solid−liquid equilibrium (SLE), vapor−liquid equilibrium (VLE), and excess enthalpy data for the mixed solvent CO2−NaHCO3−Na2CO3−monoethylene glycol(MEG)−H2O electrolyte system. The model was validated by predicting the excess heat capacity. The model is consistent, and one set of binary interaction parameters are used for calculating all the properties between −50 and 90 °C. The model is compared to experimental data of infinite dilution activity coefficient measurements of MEG and may be used for calculating activities, solubility, salt hydrate properties, pH, and CO2 solubility in the NaHCO3−Na2CO3−MEG−H2O system. A simple density model of NaHCO3−Na2CO3−NaCl−MEG−water is given. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801168e [article] Modeling of the mixed solvent electrolyte system CO2−Na2CO3−NaHCO3−monoethylene glycol−water [texte imprimé] / Philip L. Fosbøl, Auteur ; Kaj Thomsen, Auteur ; Erling H. Stenby, Auteur . - 2009 . - pp. 4565–4578. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4565–4578 Mots-clés : Electrolyte  system  Solid−liquid  equilibrium  Vapor−liquid  equilibrium  CO2−NaHCO3−Na2CO3−monoethylene  glycol−H2O  electrolyte  system Résumé : The extended UNIQUAC electrolyte activity coefficient model has been correlated to 751 experimental solid−liquid equilibrium (SLE), vapor−liquid equilibrium (VLE), and excess enthalpy data for the mixed solvent CO2−NaHCO3−Na2CO3−monoethylene glycol(MEG)−H2O electrolyte system. The model was validated by predicting the excess heat capacity. The model is consistent, and one set of binary interaction parameters are used for calculating all the properties between −50 and 90 °C. The model is compared to experimental data of infinite dilution activity coefficient measurements of MEG and may be used for calculating activities, solubility, salt hydrate properties, pH, and CO2 solubility in the NaHCO3−Na2CO3−MEG−H2O system. A simple density model of NaHCO3−Na2CO3−NaCl−MEG−water is given. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801168e

Solubility measurements in the mixed solvent electrolyte system Na2CO3-NaHCO3-monoethylene glycol-water / Philip L. Fosbøl in Industrial & engineering chemistry research, Vol. 48 N°4 (Février 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°4 (Février 2009) . - p. 2218–2228 Titre : Solubility measurements in the mixed solvent electrolyte system Na2CO3-NaHCO3-monoethylene glycol-water Type de document : texte imprimé Auteurs : Philip L. Fosbøl, Auteur ; Kaj Thomsen, Auteur ; Erling H. Stenby, Auteur Année de publication : 2009 Article en page(s) : p. 2218–2228 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Electrolyte  system  Atmospheric  pressure  Schreinemakers  method Résumé : 212 new data points for solubility and density have been measured in the mixed solvent electrolytic CO2−NaHCO3−Na2CO3−monoethylene glycol (MEG)−water system. Measurements were conducted at 2−60 °C at atmospheric pressure. An overview of methods available for determining the carbon dioxide and sodium content is given and the reverse Schreinemakers method was chosen. The method gives the amounts of all the species in the liquid. The solutions have a tendency to form metastable mixtures from which sodium carbonate salt hydrates may precipitate. Thirty metastable data points are reported. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8011648 [article] Solubility measurements in the mixed solvent electrolyte system Na2CO3-NaHCO3-monoethylene glycol-water [texte imprimé] / Philip L. Fosbøl, Auteur ; Kaj Thomsen, Auteur ; Erling H. Stenby, Auteur . - 2009 . - p. 2218–2228. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°4 (Février 2009) . - p. 2218–2228 Mots-clés : Electrolyte  system  Atmospheric  pressure  Schreinemakers  method Résumé : 212 new data points for solubility and density have been measured in the mixed solvent electrolytic CO2−NaHCO3−Na2CO3−monoethylene glycol (MEG)−water system. Measurements were conducted at 2−60 °C at atmospheric pressure. An overview of methods available for determining the carbon dioxide and sodium content is given and the reverse Schreinemakers method was chosen. The method gives the amounts of all the species in the liquid. The solutions have a tendency to form metastable mixtures from which sodium carbonate salt hydrates may precipitate. Thirty metastable data points are reported. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8011648