Documents disponibles écrits par cet auteur

Effects of catalyst bed failure on thermochemical phenomena for a hydrazine monopropellant thruster using Ir / A l2O3 catalysts / Chang Hwan Hwang in Industrial & engineering chemistry research, Vol. 51 N° 15 (Avril 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 15 (Avril 2012) . - pp. 5382–5393 Titre : Effects of catalyst bed failure on thermochemical phenomena for a hydrazine monopropellant thruster using Ir / A l2O3 catalysts Type de document : texte imprimé Auteurs : Chang Hwan Hwang, Auteur ; Sung Nam Lee, Auteur ; Seung Wook Baek, Auteur Année de publication : 2012 Article en page(s) : pp. 5382–5393 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Propellants  Catalysts Résumé : Hydrazine monopropellant has been used in thrusters for maneuvering satellites and landing spacecraft. Testing and handling procedures for hydrazine monopropellant thrusters are complicated, because of the toxicity of the hydrazine and its decomposition product gases. Therefore, simulated numerical analysis can help elucidate the effects of various thruster design parameters and can reduce both development time and expenses. In this study, a simulated numerical analysis was performed in which the catalyst bed was modeled as a one-dimensional porous medium. The resulting physical phenomena were examined by considering variations in catalyst bed characteristics incurred by catalyst pellet failure. From observations of various hot-firing experiments, it was determined that the upper region of the decomposition chamber was preferentially damaged in failure situations, which led to the conclusion that catalyst failure occurs in the upper region only. We simulated various cases based on the crushing and mass loss of catalyst pellets. The distributions of temperature, species mass fraction, heterogeneous reaction rate, and pressure were calculated after catalyst bed failure. The pressures at the decomposition chamber exit and the thrust at the nozzle exit were monitored with time. Through these analyses, the thermochemical phenomena inside a hydrazine monopropellant thruster system were interpreted in detail. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie202347f [article] Effects of catalyst bed failure on thermochemical phenomena for a hydrazine monopropellant thruster using Ir / A l2O3 catalysts [texte imprimé] / Chang Hwan Hwang, Auteur ; Sung Nam Lee, Auteur ; Seung Wook Baek, Auteur . - 2012 . - pp. 5382–5393. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 15 (Avril 2012) . - pp. 5382–5393 Mots-clés : Propellants  Catalysts Résumé : Hydrazine monopropellant has been used in thrusters for maneuvering satellites and landing spacecraft. Testing and handling procedures for hydrazine monopropellant thrusters are complicated, because of the toxicity of the hydrazine and its decomposition product gases. Therefore, simulated numerical analysis can help elucidate the effects of various thruster design parameters and can reduce both development time and expenses. In this study, a simulated numerical analysis was performed in which the catalyst bed was modeled as a one-dimensional porous medium. The resulting physical phenomena were examined by considering variations in catalyst bed characteristics incurred by catalyst pellet failure. From observations of various hot-firing experiments, it was determined that the upper region of the decomposition chamber was preferentially damaged in failure situations, which led to the conclusion that catalyst failure occurs in the upper region only. We simulated various cases based on the crushing and mass loss of catalyst pellets. The distributions of temperature, species mass fraction, heterogeneous reaction rate, and pressure were calculated after catalyst bed failure. The pressures at the decomposition chamber exit and the thrust at the nozzle exit were monitored with time. Through these analyses, the thermochemical phenomena inside a hydrazine monopropellant thruster system were interpreted in detail. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie202347f

Experimental study on evaporation characteristics of ammonium formate—urea—water solution droplet for selective catalytic reduction applications / Seung Yeol Lee in Industrial & engineering chemistry research, Vol. 50 N° 13 (Juillet 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 13 (Juillet 2011) . - pp. 8285-8294 Titre : Experimental study on evaporation characteristics of ammonium formate—urea—water solution droplet for selective catalytic reduction applications Type de document : texte imprimé Auteurs : Seung Yeol Lee, Auteur ; Seung Wook Baek, Auteur Année de publication : 2011 Article en page(s) : pp. 8285-8294 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Selective  catalytic  reduction  Droplet  Evaporation Résumé : The evaporation behavior of ammonium formate-urea-water solution (AFUWS) droplet was studied for applications to selective catalytic reduction (SCR) systems. A number of experiments were performed with single AFUWS droplet suspended on the tip of a fine quartz fiber. To cover the temperature range of real diesel exhausts, droplet ambient temperature was regulated from 373 to 873 K using an electrical furnace. As a result of this investigation, AFUWS droplet revealed different evaporation characteristics depending on its ambient temperature. As ambient temperature increases, in addition to evaporation of water content, thermal decompositions of ammonium formate and urea were additionally observed. At high temperatures, it showed quite complicated behaviors such as bubble formation, distortion, and partial rupture after a linear D -law period. However, as temperature decreases, these phenomena became weak and finally disappeared. Also, droplet evaporation coefficients were retrieved from transient evaporation histories for various ambient temperatures, which yield a quantitative evaluation on evaporation characteristics of AFUWS droplet as well as provide valuable empirical data required for modeling or simulation works on SCR systems. DEWEY : 660 ISSN : 088-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24332154 [article] Experimental study on evaporation characteristics of ammonium formate—urea—water solution droplet for selective catalytic reduction applications [texte imprimé] / Seung Yeol Lee, Auteur ; Seung Wook Baek, Auteur . - 2011 . - pp. 8285-8294. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 13 (Juillet 2011) . - pp. 8285-8294 Mots-clés : Selective  catalytic  reduction  Droplet  Evaporation Résumé : The evaporation behavior of ammonium formate-urea-water solution (AFUWS) droplet was studied for applications to selective catalytic reduction (SCR) systems. A number of experiments were performed with single AFUWS droplet suspended on the tip of a fine quartz fiber. To cover the temperature range of real diesel exhausts, droplet ambient temperature was regulated from 373 to 873 K using an electrical furnace. As a result of this investigation, AFUWS droplet revealed different evaporation characteristics depending on its ambient temperature. As ambient temperature increases, in addition to evaporation of water content, thermal decompositions of ammonium formate and urea were additionally observed. At high temperatures, it showed quite complicated behaviors such as bubble formation, distortion, and partial rupture after a linear D -law period. However, as temperature decreases, these phenomena became weak and finally disappeared. Also, droplet evaporation coefficients were retrieved from transient evaporation histories for various ambient temperatures, which yield a quantitative evaluation on evaporation characteristics of AFUWS droplet as well as provide valuable empirical data required for modeling or simulation works on SCR systems. DEWEY : 660 ISSN : 088-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24332154