Oxidative photomineralization of dichloroacetic acid in an externally-irradiated rectangular bubble tank reactor: computational fluid dynamics modeling and experimental verification studies / Francisco J. Trujillo in Industrial & engineering chemistry research, Vol. 49 N° 15 (Août 2010)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6722–6734 Titre : Oxidative photomineralization of dichloroacetic acid in an externally-irradiated rectangular bubble tank reactor: computational fluid dynamics modeling and experimental verification studies Type de document : texte imprimé Auteurs : Francisco J. Trujillo, Auteur ; Tomasz Safinski, Auteur ; Adesoji A. Adesina, Auteur Année de publication : 2010 Article en page(s) : pp 6722–6734 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Oxidative photomineralization Fluid dynamics. Résumé : The effect of antecedent factors on the performance of an aerated tank photoreactor containing externally irradiated suspended titania particles has been carried out using the oxidative photomineralisation of dichloroacetic acid (DCA) as the model reaction. The phase hold-up contours, velocity distribution profiles, and the spatial variation of the incident radiative flux as well as the local volumetric rate of photon absorption (LVPRA) inside the reactor were obtained from computational fluid dynamics (CFD) simulation based on the simultaneous solution of the Navier−Stokes equation (NSE) and radiation transport equation (RTE). The species modeling equation (SME) for the oxidative decomposition of DCA to HCl and CO2 was then coupled to the NSE and RTE to determine the influence of catalyst loading, air superficial velocity, pollutant concentration, and radiation intensity on the reactor performance. The SME utilized the intrinsic kinetic expression provided by Zalazar et al. [Chem. Eng. Sci. 2005, 60, 5240−5254] with rate parameters secured from a preliminary fit of our experimental data. The good agreement between numerical results and empirical data for practically all predictor variables suggest that CFD modeling is a reliable and valid tool for the design and evaluation of the new photoreactor system and may in fact be used as a surrogate for subsequent optimization studies. Within the range of variables examined, it is evident that although reaction rate initially increased with air flow rate, a “plateau” was attained after about 30 L min−1. The rate also exhibited a maximum at a catalyst loading of about 2.5 g L−1 while a characteristic Langmuir-type dependency on DCA concentration was observed. However, reaction rate varied only linearly with light intensity indicating the absence of deleterious hole−electron recombination at the relatively low values (20−80 W m−2) employed. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901364z [article] Oxidative photomineralization of dichloroacetic acid in an externally-irradiated rectangular bubble tank reactor: computational fluid dynamics modeling and experimental verification studies [texte imprimé] / Francisco J. Trujillo, Auteur ; Tomasz Safinski, Auteur ; Adesoji A. Adesina, Auteur . - 2010 . - pp 6722–6734. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6722–6734 Mots-clés : Oxidative photomineralization Fluid dynamics. Résumé : The effect of antecedent factors on the performance of an aerated tank photoreactor containing externally irradiated suspended titania particles has been carried out using the oxidative photomineralisation of dichloroacetic acid (DCA) as the model reaction. The phase hold-up contours, velocity distribution profiles, and the spatial variation of the incident radiative flux as well as the local volumetric rate of photon absorption (LVPRA) inside the reactor were obtained from computational fluid dynamics (CFD) simulation based on the simultaneous solution of the Navier−Stokes equation (NSE) and radiation transport equation (RTE). The species modeling equation (SME) for the oxidative decomposition of DCA to HCl and CO2 was then coupled to the NSE and RTE to determine the influence of catalyst loading, air superficial velocity, pollutant concentration, and radiation intensity on the reactor performance. The SME utilized the intrinsic kinetic expression provided by Zalazar et al. [Chem. Eng. Sci. 2005, 60, 5240−5254] with rate parameters secured from a preliminary fit of our experimental data. The good agreement between numerical results and empirical data for practically all predictor variables suggest that CFD modeling is a reliable and valid tool for the design and evaluation of the new photoreactor system and may in fact be used as a surrogate for subsequent optimization studies. Within the range of variables examined, it is evident that although reaction rate initially increased with air flow rate, a “plateau” was attained after about 30 L min−1. The rate also exhibited a maximum at a catalyst loading of about 2.5 g L−1 while a characteristic Langmuir-type dependency on DCA concentration was observed. However, reaction rate varied only linearly with light intensity indicating the absence of deleterious hole−electron recombination at the relatively low values (20−80 W m−2) employed. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901364z

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Potential for energy cost savings by utilising alternative temperature control strategies for controlled atmosphere stored apples / A. R. East in International journal of refrigeration, Vol. 36 N° 3 (Mai 2013)  

Public ISBD [article]  inInternational journal of refrigeration > Vol. 36 N° 3 (Mai 2013) . - pp. 1109–1117 Titre : Potential for energy cost savings by utilising alternative temperature control strategies for controlled atmosphere stored apples Titre original : Economies d'énergie potentielles générées à l'aide de nouvelles stratégies de régulation de la température pour les pommes entreposées sous atmosphère contrôlée Type de document : texte imprimé Auteurs : A. R. East, Auteur ; N. J. Smale, Auteur ; Francisco J. Trujillo, Auteur Année de publication : 2013 Article en page(s) : pp. 1109–1117 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Load shifting  Demand management  Fruit physiology  Malus domestica Résumé : Optimal storage conditions for apples are usually defined as those that maximise possible storage duration, but could be redefined as those conditions that result in sufficient preservation whilst minimising energy costs. A review of research on controlled atmosphere (CA) storage suggests that temperature changes in CA have less impact on product deterioration than in air. This paper reviews the underpinning observations of fruit physiology in CA and the possible approaches to reducing energy costs through temperature manipulation. Experimental results indicate that minor increases in temperature during CA storage have little influence on apple quality outcomes across a number of apple cultivars. Calculations for applying a 9 h on 15 h off cycle estimated an approximate 40% of electricity cost savings whilst only incurring a 0.5 °C average fruit temperature swing. These results suggest that opportunities for substantial energy cost savings in controlled atmosphere apple stores exist. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002885 [article] Potential for energy cost savings by utilising alternative temperature control strategies for controlled atmosphere stored apples = Economies d'énergie potentielles générées à l'aide de nouvelles stratégies de régulation de la température pour les pommes entreposées sous atmosphère contrôlée [texte imprimé] / A. R. East, Auteur ; N. J. Smale, Auteur ; Francisco J. Trujillo, Auteur . - 2013 . - pp. 1109–1117. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 3 (Mai 2013) . - pp. 1109–1117 Mots-clés : Load shifting  Demand management  Fruit physiology  Malus domestica Résumé : Optimal storage conditions for apples are usually defined as those that maximise possible storage duration, but could be redefined as those conditions that result in sufficient preservation whilst minimising energy costs. A review of research on controlled atmosphere (CA) storage suggests that temperature changes in CA have less impact on product deterioration than in air. This paper reviews the underpinning observations of fruit physiology in CA and the possible approaches to reducing energy costs through temperature manipulation. Experimental results indicate that minor increases in temperature during CA storage have little influence on apple quality outcomes across a number of apple cultivars. Calculations for applying a 9 h on 15 h off cycle estimated an approximate 40% of electricity cost savings whilst only incurring a 0.5 °C average fruit temperature swing. These results suggest that opportunities for substantial energy cost savings in controlled atmosphere apple stores exist. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002885

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