Documents disponibles écrits par cet auteur

Methane gas visualization using infrared imaging system and evaluation of temperature dependence of methane gas emissivity / Anisa Safitri in Industrial & engineering chemistry research, Vol. 49 N° 8 (Avril 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 8 (Avril 2010) . - pp. 3926–3935 Titre : Methane gas visualization using infrared imaging system and evaluation of temperature dependence of methane gas emissivity Type de document : texte imprimé Auteurs : Anisa Safitri, Auteur ; M. Sam Mannan, Auteur Année de publication : 2010 Article en page(s) : pp. 3926–3935 Note générale : Industrial Chemistry Langues : Anglais (eng) Mots-clés : Methane  Gas  Visualization  Infrared  Imaging  System  Temperature  Methane  Gas  Emissivity  Methane  Gas Résumé : Infrared (IR) camera has been used widely in the industry to visualize gases that cannot be seen by the naked eye or a visual camera. The use of an infrared camera for gas imaging offers several advantages such as faster locating of gas leaks and easier understanding on how the gas travels and disperses. In addition, several types of infrared cameras have the capability to measure the temperature of target objects especially solid body objects. However, this facility has not been applied for measurement of gas temperature due to complex analysis on the physics of infrared imaging and some uncertainties related to the radiation heat transfer processes during temperature measurement that have not been well understood. The objective of this research is to make use of the infrared or thermal imaging system to provide a concise temperature distribution of a methane gas plume presented in the infrared image. However, the current technology in infrared imaging cannot provide the true temperature of a gas plume because the emissivity value is always assumed as unity, and the actual emissivity value of the gas is not integrated in the camera’s algorithm. The visualization of dispersed liquefied natural gas (LNG) vapor from LNG spills on the ground using a midwave thermal camera is presented in this work. Two types of infrared cameras were used: Amber Radiance 1 and GasFindIR, also known in industry as hydrocarbon camera. The infrared images or thermograms show that several factors affecting the temperature measurement are weather conditions, wind rose, atmospheric attenuation due to the presence of other radiation absorbing gases along the optic path, and gas emissivity. Gas emissivity is the main uncertainty in gas temperature measurement using thermal cameras. This research proposed a method to correct the gas temperature measured by a thermal camera by applying the emissivity factor calculated from a theoretical analysis on methane gas emissivity using the band absorption method. The study demonstrates that methane gas emissivity is a strong function of gas temperature; however, the effect of optical depth is insignificant. Because in this work, the infrared camera is used to visualize the LNG vapor, temperature dependence of methane emissivity at temperatures 110−300 K is evaluated and presented in this paper. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901340g [article] Methane gas visualization using infrared imaging system and evaluation of temperature dependence of methane gas emissivity [texte imprimé] / Anisa Safitri, Auteur ; M. Sam Mannan, Auteur . - 2010 . - pp. 3926–3935. Industrial Chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 8 (Avril 2010) . - pp. 3926–3935 Mots-clés : Methane  Gas  Visualization  Infrared  Imaging  System  Temperature  Methane  Gas  Emissivity  Methane  Gas Résumé : Infrared (IR) camera has been used widely in the industry to visualize gases that cannot be seen by the naked eye or a visual camera. The use of an infrared camera for gas imaging offers several advantages such as faster locating of gas leaks and easier understanding on how the gas travels and disperses. In addition, several types of infrared cameras have the capability to measure the temperature of target objects especially solid body objects. However, this facility has not been applied for measurement of gas temperature due to complex analysis on the physics of infrared imaging and some uncertainties related to the radiation heat transfer processes during temperature measurement that have not been well understood. The objective of this research is to make use of the infrared or thermal imaging system to provide a concise temperature distribution of a methane gas plume presented in the infrared image. However, the current technology in infrared imaging cannot provide the true temperature of a gas plume because the emissivity value is always assumed as unity, and the actual emissivity value of the gas is not integrated in the camera’s algorithm. The visualization of dispersed liquefied natural gas (LNG) vapor from LNG spills on the ground using a midwave thermal camera is presented in this work. Two types of infrared cameras were used: Amber Radiance 1 and GasFindIR, also known in industry as hydrocarbon camera. The infrared images or thermograms show that several factors affecting the temperature measurement are weather conditions, wind rose, atmospheric attenuation due to the presence of other radiation absorbing gases along the optic path, and gas emissivity. Gas emissivity is the main uncertainty in gas temperature measurement using thermal cameras. This research proposed a method to correct the gas temperature measured by a thermal camera by applying the emissivity factor calculated from a theoretical analysis on methane gas emissivity using the band absorption method. The study demonstrates that methane gas emissivity is a strong function of gas temperature; however, the effect of optical depth is insignificant. Because in this work, the infrared camera is used to visualize the LNG vapor, temperature dependence of methane emissivity at temperatures 110−300 K is evaluated and presented in this paper. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901340g

QSPR flash point prediction of solvents using topological indices for application in computer aided molecular design / Suhani J. Patel in Industrial & engineering chemistry research, Vol. 48 N° 15 (Août 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7378–7387 Titre : QSPR flash point prediction of solvents using topological indices for application in computer aided molecular design Type de document : texte imprimé Auteurs : Suhani J. Patel, Auteur ; Dedy Ng, Auteur ; M. Sam Mannan, Auteur Année de publication : 2009 Article en page(s) : pp. 7378–7387 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Solvents  Computer  aided  molecular  design  Quantitative  structure  property  relationship  Topological  indices Résumé : Incorporating consideration for safety issues while selecting solvents for processes has become crucial in light of the chemical process accidents involving solvents that have taken place in recent years. Computer aided molecular design (CAMD) is a methodology that has been researched recently for designing compounds with required target properties and can be applied for selection of safer solvents as well. An important aspect of this methodology concerns the prediction of properties given the structure of the molecule. This paper utilizes one such emerging method for prediction of a hazardous property, flash point, which is indicative of the flammability of solvents. Quantitative structure property relationship (QSPR) and topological indices have been used in this paper to predict flash point properties of different classes of solvents. Multiple linear regression and back-propagation neural network analysis were used to model the flash point. The neural network model showed higher accuracy (training set, r = 0.948, R2 = 0.898). However, there are certain limitations associated with using QSPR in CAMD which have been discussed and need further work. This paper advances the “forward problem” of CAMD using QSPR which has not been researched extensively in the past. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9000794 [article] QSPR flash point prediction of solvents using topological indices for application in computer aided molecular design [texte imprimé] / Suhani J. Patel, Auteur ; Dedy Ng, Auteur ; M. Sam Mannan, Auteur . - 2009 . - pp. 7378–7387. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7378–7387 Mots-clés : Solvents  Computer  aided  molecular  design  Quantitative  structure  property  relationship  Topological  indices Résumé : Incorporating consideration for safety issues while selecting solvents for processes has become crucial in light of the chemical process accidents involving solvents that have taken place in recent years. Computer aided molecular design (CAMD) is a methodology that has been researched recently for designing compounds with required target properties and can be applied for selection of safer solvents as well. An important aspect of this methodology concerns the prediction of properties given the structure of the molecule. This paper utilizes one such emerging method for prediction of a hazardous property, flash point, which is indicative of the flammability of solvents. Quantitative structure property relationship (QSPR) and topological indices have been used in this paper to predict flash point properties of different classes of solvents. Multiple linear regression and back-propagation neural network analysis were used to model the flash point. The neural network model showed higher accuracy (training set, r = 0.948, R2 = 0.898). However, there are certain limitations associated with using QSPR in CAMD which have been discussed and need further work. This paper advances the “forward problem” of CAMD using QSPR which has not been researched extensively in the past. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9000794

Study on the reaction mechanism and kinetics of the thermal decomposition of nitroethane / Qingsheng Wang 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. 8745–8751 Titre : Study on the reaction mechanism and kinetics of the thermal decomposition of nitroethane Type de document : texte imprimé Auteurs : Qingsheng Wang, Auteur ; Dedy Ng, Auteur ; M. Sam Mannan, Auteur Année de publication : 2010 Article en page(s) : pp. 8745–8751 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Nitroethane  Thermal  decomposition  Density  functional  theory  calculations  Automatic  pressure  tracking  adiabatic  calorimeter  measurements  Gas  chromatography  analysis Résumé : Despite many theoretical and experimental advances in understanding the macroscopic properties of energetic materials, much work remains to be done to understand their microscale mechanism. In this work, the reaction mechanism and kinetics of thermal decomposition of nitroethane were studied by density functional theory (DFT) calculations, automatic pressure tracking adiabatic calorimeter (APTAC) measurements, and gas chromatography (GC) analysis. The APTAC results were used to determine Arrhenius parameters of A = 1013.5±0.2 and Ea = 46.2 ± 0.5 kcal/mol. The decomposition process includes three initial steps: concerted molecular elimination of HONO, nitro−nitrite isomerization, and rupture of C−NO2. Followed these initial reactions, a detailed mechanism that consists of 23 elementary steps was proposed. Numerical simulations of the proposed mechanism reproduce reasonably well the distributions of major products over the temperature range. It was found that the relative concentrations of NO and C2H4 depend on the reaction temperatures. Combining theoretical and experimental studies, it is concluded that elimination of HONO is predominant at low temperature and dissociation of C−NO2 becomes significant at high temperature. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900849n [article] Study on the reaction mechanism and kinetics of the thermal decomposition of nitroethane [texte imprimé] / Qingsheng Wang, Auteur ; Dedy Ng, Auteur ; M. Sam Mannan, Auteur . - 2010 . - pp. 8745–8751. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8745–8751 Mots-clés : Nitroethane  Thermal  decomposition  Density  functional  theory  calculations  Automatic  pressure  tracking  adiabatic  calorimeter  measurements  Gas  chromatography  analysis Résumé : Despite many theoretical and experimental advances in understanding the macroscopic properties of energetic materials, much work remains to be done to understand their microscale mechanism. In this work, the reaction mechanism and kinetics of thermal decomposition of nitroethane were studied by density functional theory (DFT) calculations, automatic pressure tracking adiabatic calorimeter (APTAC) measurements, and gas chromatography (GC) analysis. The APTAC results were used to determine Arrhenius parameters of A = 1013.5±0.2 and Ea = 46.2 ± 0.5 kcal/mol. The decomposition process includes three initial steps: concerted molecular elimination of HONO, nitro−nitrite isomerization, and rupture of C−NO2. Followed these initial reactions, a detailed mechanism that consists of 23 elementary steps was proposed. Numerical simulations of the proposed mechanism reproduce reasonably well the distributions of major products over the temperature range. It was found that the relative concentrations of NO and C2H4 depend on the reaction temperatures. Combining theoretical and experimental studies, it is concluded that elimination of HONO is predominant at low temperature and dissociation of C−NO2 becomes significant at high temperature. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900849n

Study on the reaction mechanism and kinetics of the thermal decomposition of nitroethane / Qingsheng Wang 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. 8745–8751 Titre : Study on the reaction mechanism and kinetics of the thermal decomposition of nitroethane Type de document : texte imprimé Auteurs : Qingsheng Wang, Auteur ; Dedy Ng, Auteur ; M. Sam Mannan, Auteur Année de publication : 2010 Article en page(s) : pp. 8745–8751 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Nitroethane  Thermal  decomposition  Density  functional  theory  calculations  Automatic  pressure  tracking  adiabatic  calorimeter  measurements  Gas  chromatography  analysis Résumé : Despite many theoretical and experimental advances in understanding the macroscopic properties of energetic materials, much work remains to be done to understand their microscale mechanism. In this work, the reaction mechanism and kinetics of thermal decomposition of nitroethane were studied by density functional theory (DFT) calculations, automatic pressure tracking adiabatic calorimeter (APTAC) measurements, and gas chromatography (GC) analysis. The APTAC results were used to determine Arrhenius parameters of A = 1013.5±0.2 and Ea = 46.2 ± 0.5 kcal/mol. The decomposition process includes three initial steps: concerted molecular elimination of HONO, nitro−nitrite isomerization, and rupture of C−NO2. Followed these initial reactions, a detailed mechanism that consists of 23 elementary steps was proposed. Numerical simulations of the proposed mechanism reproduce reasonably well the distributions of major products over the temperature range. It was found that the relative concentrations of NO and C2H4 depend on the reaction temperatures. Combining theoretical and experimental studies, it is concluded that elimination of HONO is predominant at low temperature and dissociation of C−NO2 becomes significant at high temperature. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900849n [article] Study on the reaction mechanism and kinetics of the thermal decomposition of nitroethane [texte imprimé] / Qingsheng Wang, Auteur ; Dedy Ng, Auteur ; M. Sam Mannan, Auteur . - 2010 . - pp. 8745–8751. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8745–8751 Mots-clés : Nitroethane  Thermal  decomposition  Density  functional  theory  calculations  Automatic  pressure  tracking  adiabatic  calorimeter  measurements  Gas  chromatography  analysis Résumé : Despite many theoretical and experimental advances in understanding the macroscopic properties of energetic materials, much work remains to be done to understand their microscale mechanism. In this work, the reaction mechanism and kinetics of thermal decomposition of nitroethane were studied by density functional theory (DFT) calculations, automatic pressure tracking adiabatic calorimeter (APTAC) measurements, and gas chromatography (GC) analysis. The APTAC results were used to determine Arrhenius parameters of A = 1013.5±0.2 and Ea = 46.2 ± 0.5 kcal/mol. The decomposition process includes three initial steps: concerted molecular elimination of HONO, nitro−nitrite isomerization, and rupture of C−NO2. Followed these initial reactions, a detailed mechanism that consists of 23 elementary steps was proposed. Numerical simulations of the proposed mechanism reproduce reasonably well the distributions of major products over the temperature range. It was found that the relative concentrations of NO and C2H4 depend on the reaction temperatures. Combining theoretical and experimental studies, it is concluded that elimination of HONO is predominant at low temperature and dissociation of C−NO2 becomes significant at high temperature. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900849n

Upper flammability limits of hydrogen and light hydrocarbons in air at subatmospheric pressures / Hai Le in Industrial & engineering chemistry research, Vol. 51 N° 27 (Juillet 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 27 (Juillet 2012) . - pp. 9396-9402 Titre : Upper flammability limits of hydrogen and light hydrocarbons in air at subatmospheric pressures Type de document : texte imprimé Auteurs : Hai Le, Auteur ; Subramanya Nayak, Auteur ; M. Sam Mannan, Auteur Année de publication : 2012 Article en page(s) : pp. 9396-9402 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Subatmospheric  pressure  Flammability  limit Résumé : The upper flammability limits (UFL) of hydrogen―air, methane―air, ethane―air, n-butane―air, and ethylene―air were determined experimentally at room temperature (20 °C) and initial pressure of 1.0, 0.7, 0.5, 0.3, 0.1, and 0.05 atm. Experiments were conducted in a closed cylindrical stainless steel vessel (i.d. 10.22 cm, length 100 cm) with upward flame propagation. The UFL of hydrogen was observed to be inversely proportional to the initial pressure in the range from 1.0 to 0.3 atm and proportional to the initial pressure from 0.3 to 0.05 atm. In contrast, the UFLs of the lower alkanes and ethylene decreased with the initial pressure. The average flame propagation velocities at UFL concentrations of hydrogen, methane, ethane, n-butane, and ethylene in air at reduced pressures were also examined. It was found that the flame propagation velocity of hydrogen was larger than those of the hydrocarbons, increased when the initial pressure decreased from 1.0 to 0.3 atm, and then decreased with further decrease of pressure. Flame propagation velocities at UFL concentrations of the hydrocarbons decreased with the initial pressure. Finally, based on the behavior of the UFLs and flame propagation velocities, the relative risk and hazards of ignition and flame escalation of hydrogen and the light hydrocarbons at subatmospheric pressures were discussed. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26132276 [article] Upper flammability limits of hydrogen and light hydrocarbons in air at subatmospheric pressures [texte imprimé] / Hai Le, Auteur ; Subramanya Nayak, Auteur ; M. Sam Mannan, Auteur . - 2012 . - pp. 9396-9402. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 27 (Juillet 2012) . - pp. 9396-9402 Mots-clés : Subatmospheric  pressure  Flammability  limit Résumé : The upper flammability limits (UFL) of hydrogen―air, methane―air, ethane―air, n-butane―air, and ethylene―air were determined experimentally at room temperature (20 °C) and initial pressure of 1.0, 0.7, 0.5, 0.3, 0.1, and 0.05 atm. Experiments were conducted in a closed cylindrical stainless steel vessel (i.d. 10.22 cm, length 100 cm) with upward flame propagation. The UFL of hydrogen was observed to be inversely proportional to the initial pressure in the range from 1.0 to 0.3 atm and proportional to the initial pressure from 0.3 to 0.05 atm. In contrast, the UFLs of the lower alkanes and ethylene decreased with the initial pressure. The average flame propagation velocities at UFL concentrations of hydrogen, methane, ethane, n-butane, and ethylene in air at reduced pressures were also examined. It was found that the flame propagation velocity of hydrogen was larger than those of the hydrocarbons, increased when the initial pressure decreased from 1.0 to 0.3 atm, and then decreased with further decrease of pressure. Flame propagation velocities at UFL concentrations of the hydrocarbons decreased with the initial pressure. Finally, based on the behavior of the UFLs and flame propagation velocities, the relative risk and hazards of ignition and flame escalation of hydrogen and the light hydrocarbons at subatmospheric pressures were discussed. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26132276