CINDECA

URI permanente para esta comunidad

https://digital.cic.gba.gob.ar/handle/11746/6741
El Centro de InvestigaciĆ³n y Desarrollo en Ciencias Aplicadas ā€œDr. Jorge J. Roncoā€ (CINDECA) es un Centro de InvestigaciĆ³n que realiza investigaciĆ³n bĆ”sica y aplicada de excelencia, con desarrollos tecnolĆ³gicos al servicio de la innovaciĆ³n, la producciĆ³n y el trabajo en armonĆ­a con el medio ambiente, forma recursos humanos de calidad en las Ć”reas de CatĆ”lisis y Ciencias Aplicadas, para contribuir dar las respuestas que demanda el desarrollo socio-econĆ³mico de nuestro paĆ­s, con la participaciĆ³n de personal altamente calificado, el uso de tecnologĆ­as de avanzada, la colaboraciĆ³n con instituciones nacionales y extranjeras y la vinculaciĆ³n con los diferentes sectores de la sociedad.

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  • ArtĆ­culo
    Acceso Abierto
    Efficient deprotection of phenol methoxymethyl ethers using a solid acid catalyst with Wells-Dawson structure
    (MDPI (Multidisciplinary Digital Publishing Institute), 2001) Romanelli, Gustavo; Autino, Juan Carlos; Baronetti, Graciela T.; Thomas, Horacio
    Deprotection of various phenols from their respective methoxymethyl ethers using an heteropolyacid catalyst was studied. The catalyst was the Wells-Dawson heteropolyacid, used both in bulk or supported on silica. Yields were high to quantitative after less than one hour reaction time and the catalyst was easily recoverable and reusable.
  • Documento de conferencia
    Acceso Abierto
    CinĆ©tica de la hidrogenaciĆ³n catalĆ­tica selectiva de 1-butino y 1,3-butadieno en presencia de n-butenos
    (2011) Alves, Javier Alberto; Bressa, Sergio Patricio; MartĆ­nez, Osvaldo Miguel; Barreto, Guillermo Fernando
    El objetivo del presente trabajo es ajustar parĆ”metros cinĆ©ticos que no habĆ­an podido ser evaluados anteriormente, especĆ­ficamente energĆ­as de activaciĆ³n y una constante de adsorciĆ³n del BY. Con este fin, se amplĆ­a el rango de condiciones de trabajo, a travĆ©s de ensayos realizados a distintos niveles de temperatura y de mezclas reactivas en las que estĆ”n presentes desde el inicio de la reacciĆ³n el BY y el BD, no analizados previamente
  • ArtĆ­culo
    Acceso Abierto
    Uncertainty studies of topographical measurements on steel surface corrosion by 3D scanning electron microscopy
    (2012) Kang, Kyun Won; Pereda, MarĆ­a Dolores; Canafoglia, MarĆ­a Elena; Bilmes, Pablo David; Llorente, Carlos Luis; Bonetto, Rita
    Pitting corrosion is a damage mechanism quite serious and dangerous in both carbon steel boiler tubes for power plants which are vital to most industries and stainless steels for orthopedic human implants whose demand, due to the increase of life expectation and rate of traffic accidents, has sharply increased. Reliable methods to characterize this kind of damage are becoming increasingly necessary, when trying to evaluate the advance of damage and to establish the best procedures for component inspection in order to determine remaining lives and failure mitigation. A study about the uncertainties on the topographies of corrosion pits from 3D SEM images, obtained at low magnifications (where errors are greater) and different stage tilt angles was carried out by using an in-house software previously developed. Additionally, measurements of pit depths on biomaterial surfaces, subjected to two different surface treatments on stainless steels, were carried out. The different depth distributions observed were in agreement with electrochemical measurements.
  • ArtĆ­culo
    Acceso Abierto
    Backscattered electron images, X-ray maps and Monte Carlo simulations applied to the study of plagioclase composition in volcanic rocks
    (2013) GalvƔn Josa, V.; Fracchia, D.; Castellano, G.; Crespo, E.; Kang, Kyun Won; Bonetto, Rita
    Zoning patterns in plagioclases are related to abrupt changes in the anorthite content along the crystal growing direction. Accurate characterization of these patterns by electron microprobe is useful to identify magma chamber processes such as recharge, mingling and whole-chamber overturn events. In this work, a new procedure to obtain high resolution quantitative maps of anorthite concentration in single plagioclase crystals is developed. The methodology consists in performing a calibration of backscattered electron images using quantitative X-ray maps. The ultimate resolution of charac- teristic X-rays and backscattered electron signals is studied by Monte Carlo simulation. The method is applied to characterize the chemical composition of a volcanic plagioclase from the Cerro Vilama, Argentina. The results obtained are more precise than the values given by the methods commonly used in the study of plagioclase composition, i.e. the classical profiling by electron microprobe point analysis or the modern backscattered electron image calibration by means of quantitative energy or wavelength dispersive X-ray analysis at a few selected points.
  • Documento de conferencia
    Acceso Abierto
    Una revisiĆ³n crĆ­tica de la transferencia de calor en sistemas trickle-bed
    (2013) Mariani, NƩstor Javier; Barreto, Guillermo Fernando; Martƭnez, Osvaldo M.; Taulamet, Marƭa JosƩ
    En diversos sistemas en los cuales se emplean reactores de lecho fijo con flujo bifĆ”sico descendente (trickle-bed) la transferencia de calor cumple un rol significativo en el comportamiento del reactor. La informaciĆ³n bibliogrĆ”fica para predecir la capacidad de transferencia de calor es errĆ”tica. En este trabajo se ha llevado a cabo una revisiĆ³n crĆ­tica sobre el conocimiento del tema. Se han analizado mĆ©todos experimentales para la obtenciĆ³n de datos, modelos empleados para la interpretaciĆ³n de los mismos y correlaciones propuestas. Se determinaron inconsistencias en numerosas correlaciones, falencias en el conocimiento, tanto de informaciĆ³n experimental como de correlaciones, y se propusieron nuevas correlaciones para la conductividad tĆ©rmica efectiva radial del lecho.
  • ArtĆ­culo
    Embargado
    Carbon-supported metal-modified lacunary tungstosilicic polyoxometallates used as catalysts in the selective oxidation of sulfides
    (2015) Frenzel, Romina; Sathicq, Ɓngel G.; Blanco, Mirta Noemƭ; Romanelli, Gustavo; Pizzio, Luis RenƩ
    Lacunary tungstosilicic polyoxometallates modified with transition metal ions [SiW11O39M(H2O)]6āˆ’, where M=Mn2+, Fe2+, Co2+or Cu2+, were synthesized and supported on activated carbon to obtain the SiW11MC catalysts. The samples were characterized by FT-IR, XRD, N2 adsorptionā€“desorption measurements, and the acidic properties were determined using the isopropanol dehydration test reaction. The activity and selectivity of the catalysts were evaluated in the selective oxidation of a series of sulfides to sulfoxides or sulfone. The reaction was carried out in acetonitrile as solvent using H2O2 35% p/V as a clean oxidant. The conversion values decreased in the following order: SiW11MnC> SiW11FeC > SiW11CuC > SiW11CoC. The catalysts were reused without appreciable loss of their catalytic activity. It was found that the activity of the catalysts decreases in parallel with the increment in the reduction temperature values. The most easily reducible catalyst displayed the highest conversion values. We found a convenient and selective procedure for oxidizing sulfides to sulfoxides or sulfones using aqueous hydrogen peroxide and a catalytic amount of lacunary tungstosilicic polyoxometallates supported on carbon at low temperatures (20ā€“50 ā—¦C) in a reasonably short reaction time.
  • Tesis de doctorado
    Acceso Abierto
    FenĆ³menos de transporte y reacciĆ³n quĆ­mica en lechos fijos. Influencia de la forma del relleno catalĆ­tico
    (2015) Taulamet, Marƭa JosƩ
    El modelado, la simulaciĆ³n y el cambio de escala de los lechos rellenos catalĆ­ticos requiere no sĆ³lo conocer el sistema de reacciones involucrado y sus correspondientes parĆ”metros cinĆ©ticos, sino que ademĆ”s resulta necesario disponer de herramientas que permitan evaluar adecuadamente los fenĆ³menos de transporte; tanto a escala del catalizador, donde se produce la difusiĆ³n con simultanea reacciĆ³n quĆ­mica,como a escala del lecho relleno, donde se produce el transporte de materia y de energĆ­a, por ejemplo en el caso de transferencia de calor en lechos rellenos con flujo bifĆ”sico. Existen variados ejemplos en los cuales los aspectos mencionados juegan un rol importante en el desempeƱo global del reactor, por lo que su correcta evaluaciĆ³n es de crucial importancia. En el estudio de los lechos de partĆ­culas, dada la simplicidad de la geometrĆ­a esfĆ©rica y por tratarse de un sistema unidimensional, es abundante la informaciĆ³n sobre estructuras de los lechos y evaluaciĆ³n de fenĆ³menos de transporte para esta geometrĆ­a. Sin embargo, es muy frecuente el empleo de otras formas de pastillas de catalizador, como extrudados, multilobulares o diferentes tipos de anillos,ya que suelen tener importantes ventajas respecto a las esferas. Cuando se analiza la informaciĆ³n bibliogrĆ”fica, se aprecia que existe una clara falencia para la evaluaciĆ³n del comportamiento de lechos con partĆ­culas no esfĆ©ricas. En este contexto se planteĆ³ el objetivo de la presente Tesis. El objetivo general planteado es el estudio de la incidencia de la forma de las pastillas catalĆ­ticas sobre el fenĆ³meno de reacciĆ³n-difusiĆ³n en el interior de las mismas y sobre el transporte de energĆ­a, a escala del lecho relleno. Como objetivos especĆ­ficos se pretende, por un lado, extender la aplicaciĆ³n de modelos geomĆ©tricos unidimensionales para evaluar la velocidad de reacciĆ³n efectiva en catalizadores sĆ³lidos de forma arbitraria estableciendo lĆ­mites de aplicabilidad de los mismos con respecto a la conjunciĆ³n de la forma del catalizador y expresiones cinĆ©ticas, para una Ćŗnica reacciĆ³n y sistemas de reacciones mĆŗltiples. Adicionalmentese propone elaborar correlaciones para predecir la velocidad de transferenciade calor en lechos rellenos con flujo bifĆ”sico para distintas formas depastilla, a partir de la realizaciĆ³n de un programa experimental.
  • Comunicacion
    Acceso Abierto
    EncapsulaciĆ³n de compuestos biocidas en materiales silĆ­ceos mesoporosos
    (2015) Mardones, Lucas; Legnoverde, MarĆ­a Soledad; Basaldella, Elena Isabel
    Se llevĆ³ a cabo la sĆ­ntesis de materiales silĆ­ceos mesoporosos con diferentes grados de ordenamiento (SBA-15, MCF). Se estudiĆ³ su uso como matrices estabilizadoras de un biocida comercial. Mediante adsorciĆ³n/desorciĆ³n de N2 y FTIR se determinĆ³ la variaciĆ³n del volumen de poros y superficie especĆ­fica de las matrices silĆ­ceas ocasionada por la adsorciĆ³n del biocida y la no alteraciĆ³n estructural del mismo cuando se encuentra adsorbido. La actividad antifĆŗngica frente a Aspergillus Niger fue evaluada mediante la determinaciĆ³n de la concentraciĆ³n mĆ­nima inhibitoria. Los materiales tipo MCF incorporan un mayor porcentaje de adsorbato, mientras que el biocida incorporado en las sĆ­lices ordenadas SBA-15 posee mejor comportamiento antifĆŗngico.
  • Comunicacion
    Acceso Abierto
    Transferencia de calor en reactores trickle-bed: influencia de la forma y tamaƱo del relleno
    (2015) Taulamet, Marƭa JosƩ; Mariani, NƩstor Javier; Martƭnez, Osvaldo Miguel; Barreto, Guillermo Fernando
    Se realizaron medidas de transferencia de calor con un equipo experimental del tipo trickle bed. A partir de la mediciones experimentales realizadas de los perfiles radiales de temperatura para distintos tipos de relleno (esferas, cilindros, trilobulares), cubriendo como principales variables operativas los caudales de lĆ­quido y gas, altura de relleno y relaciĆ³n de aspecto (se cubriĆ³ un rango de 4 a 35, tĆ­pico de sistemas con transferencia de calor con el exterior), se aplicarĆ” el modelo bidimensional pseudohomogĆ©neo para interpretar el fenĆ³meno de transferencia de calor. Los parĆ”metros correspondientes al modelo serĆ”n ajustados por regresiĆ³n de la informaciĆ³n experimental, para generar finalmente correlaciones con fines predictivos.
  • ArtĆ­culo
    Embargado
    One-pot synthesis of ferrocenyl-pyrimidones using a recyclable molibdosilicic H4SiMo12O40 heteropolyacid
    (Springer International Publishing, 2016) Jios, Jorge; Metzler-Nolte, Nils; VƔzquez, Patricia Graciela; Romanelli, Gustavo
    A series of ferrocene-containing dihydropyrimidines (DHPs) were prepared by the one-pot Biginelli reaction of formylferrocene, 1,3-dicarbonyl component and urea/thiourea. The reaction was catalyzed by a commercial Keggin heteropolyacid (H4SiMo12O40) as a safe, clean and recyclable catalyst. Three different synthetic protocols were examined in order to improve the yields of the reaction and to elucidate its mechanism. Intermediates of the competitive Knoevenagel reaction were also isolated. The methodology is operationally simple and provides access to highly substituted dihydropyrimidines containing ferrocene in very good yields. The catalyst can be used and recycled without appreciable loss of the catalytic activity.
  • ArtĆ­culo
    Acceso Abierto
    Hydro-Adsorption Study by Dynamic Laser Speckle of Natural Zeolite for Adsorbent and Fertilizer Applications
    (2016) Mojica SepĆŗlveda, Ruth Dary; Mendoza Herrera, Luis JoaquĆ­n; Agosto, MarĆ­a Florencia; Grumel, Eduardo Emilio; Soria, Delia Beatriz; Cabello, Carmen InĆ©s; Trivi, Marcelo Ricardo
    The dynamic behavior caused by hydro-adsorption process of materials based on a rich mineral clinoptilolite together with their acidic, basic and calcinated forms has been studied by the dynamic laser speckle (DLS) technique. We propose a modified Pelegā€™s equation to improve fitting of DLS data. Textural (BET), structural (XRD) and spectroscopic (FTIR) properties were also studied and compared. We demonstrated that DLS was the most sensitive, simple and inexpensive method for comparing the performance of adsorptive materials with slightly modified surfaces. It also allowed the correlation with physicochemical properties.
  • ArtĆ­culo
    Acceso Abierto
    Hydrothermal Stability of Ru/SiO2ā€“C: A Promising Catalyst for Biomass Processing through Liquid-Phase Reactions
    (MDPI (Multidisciplinary Digital Publishing Institute), 2017) Gatti, Martƭn N.; Lombardi, Marƭa BƔrbara; Gazzoli, Delia; Santori, Gerardo FabiƔn; Pompeo, Francisco; Nichio, Nora N.
    In this work, structural and morphological properties of SiO2ā€“C composite material to be used as support for catalysts in the conversion of biomass-derived oxygenated hydrocarbons, such as glycerol, were investigated in liquid water under various temperatures conditions. The results show that this material does not lose surface area, and the hot liquid water does not generate changes in the structure. Neither change in relative concentrations of oxygen functional groups nor in Si/C ratio due to hydrothermal treatment was revealed by X-ray photoelectron spectroscopy (XPS) analysis. Raman analysis showed that the material is made of a disordered graphitic structure in an amorphous silica matrix, which remains stable after hydrothermal treatment. Results of the hydrogenolysis of glycerol using a Ru/SiO2ā€“C catalyst indicate that the support gives more stability to the active phase than a Ru/SiO2 consisting of commercial silica.
  • Documento de conferencia
    Acceso Abierto
    CaracterizaciĆ³n quĆ­mica y espectroscĆ³pica de material particulado en aire extramuros en la ciudad de La Plata y alrededores
    (2017) Giuliani, Daniela; Orte, Marcos; Martins, Enrique; Matamoros, Natalia; Colman, Jorge; Porta, AndrƩs
    Este trabajo se centra en la caracterizaciĆ³n quĆ­mica y espectroscĆ³pica de material particulado (MP10 y MP2.5) en la ciudad de La Plata y alrededores, que cuenta con alto trĆ”nsito vehicular y un polo petroquĆ­mico cercano, diferenciando tres zonas: residencial, urbano e industrial. Se analizĆ³ su contenido en metales pesados (Cd, Cr, Cu, Mn, Ni y Pb) y se realizĆ³ un anĆ”lisis morfolĆ³gico del MP mediante microscopĆ­a electrĆ³nica de barrido (SEM-EDS). Los niveles de MP evidencian mayores valores tanto para MP2.5 como para MP10 en la zona industrial, seguida por la zona urbana y por Ćŗltimo por la zona residencial. Respecto a los metales se confirma la presencia de los metales Cr, Cu, Mn y Pb en ambas fracciones de MP y para las distintas zonas de estudio, con valores de concentraciĆ³n desde 0.0003 Ī¼g/m3 hasta 0.0491 Ī¼g/m3. Mediante la tĆ©cnica SEM-EDS los resultados obtenidos muestran partĆ­culas mayoritariamente ricas en elementos como Si, C y O, y en menor medida en Al, Ca, Na, N y con presencia de partĆ­culas de morfologĆ­a relacionadas al trĆ”fico vehicular.
  • ArtĆ­culo
    Acceso Abierto
    Total Oxidation of Naphthalene with Zirconia-Supported Cobalt, Copper and Nickel Catalysts
    (MDPI (Multidisciplinary Digital Publishing Institute), 2017) LeguizamĆ³n Aparicio, MarĆ­a Silvia del Valle; Ocsachoque, Marco; Gazzoli, Delia; Botto, Irma; Lick, Ileana
    ZrO2 nH2O (hydrogel) impregnated with transition metals (Cu, Co, and Ni) was studied in this work as a precursor for the synthesis of CuO/ZrO2 (CuZ), CoOx/ZrO2 (CoZ), and NiO/ZrO2 (NiZ) catalysts, employed in the naphthalene oxidation reaction. Fresh and catalytically used materials were characterized by different physicochemical techniques, to compare the bulk and surface behavior, with particular attention to the effect of the supported metal speciesā€™ properties on the catalytic activity. Techniques such as X-ray diffraction (XRD), temperature programmed reduction (TPR), differential scanning calorimetry (DSC), Brunauerā€“Emmettā€“Teller (BET) surface area analyzer, diffuse reflectance spectroscopy (DRS UVā€“vis), and Raman spectroscopy, allow for establishing structural and textural aspects of the support, as well as the surface coordination and the accessibility of supported species. Results were in agreement with the CuZ > CoZ > NiZ sequence for the activity in naphthalene oxidation reaction. Electronic properties, ionic sizes, oxide phase deposition on the support surface, reducibility, metalā€“support interaction, and local site symmetry of metals seem to be decisive factors for the catalytic interaction with the gaseous phase.
  • Resumen
    Acceso Abierto
    SĆ­ntesis multicomponente de dihidropirimidonas derivadas de furfurales catalizada por Hā‚ā‚„NaPā‚…Wā‚‚ā‚‰MoOā‚ā‚ā‚€@SiOā‚‚
    (2018) Portilla ZĆŗƱiga, Omar M.; Romanelli, Gustavo; Sathicq, Ɓngel G.
    El furfural (2-furfuraldehĆ­do) es universalmente obtenido a partir de la biomasa representando una forma estĆ”ndar de aprovechar y dar valor aƱadido a residuos agrĆ­colas y forestales. El proceso es simple; de estos residuos se obtienen pentosanos que, mediante hidrĆ³lisis Ć”cida y la posterior ciclo-deshidrataciĆ³n de los monosacĆ”ridos formados termina por generar el aldehĆ­do. A partir del furfural se pueden obtener una gran variedad de compuestos de interĆ©s industrial y tambiĆ©n puede ser usado como material de partida para la sĆ­ntesis de dihidropirimidinonas. Las 2-oxo- y tioxo-1,2,3,4-tetrahidropirimidinas (3,4-dihidropirimidina- 2(1H)-tionas) son compuestos atractivos ya que tienen una amplia gama de actividades biolĆ³gicas; antibacteriales, antiinflamatorias, antivirales y como moduladores de los canales de calcio.
  • Resumen
    Acceso Abierto
    Nuevos materiales magnĆ©ticos basados en heteropoliĆ”cidos tipo Keggin y su aplicaciĆ³n en reacciones de esterificaciĆ³n del Ć”cido levulĆ­nico para valorizaciĆ³n de residuos de biomasa
    (2018) Escobar Caicedo, AngƩlica M.; Blanco, Mirta Noemƭ; Martƭnez Zambrano, JosƩ J.; Cubillos Lobo, Jairo A.; Pizzio, Luis RenƩ; Romanelli, Gustavo
    Este trabajo se encuentra dirigido a valorizar residuos de biomasa, mediante catĆ”lisis heterogĆ©nea a travĆ©s del estudio de un nuevos material sĆ³lido basado en Ć”cido tungstofosfĆ³rico (TPA), un heteropoliĆ”cido tipo Keggin, inmovilizado sobre materiales magnĆ©ticos recubiertos con sĆ­lice mesoporosa sintetizados vĆ­a sol-gel, y su aplicaciĆ³n en reacciones de esterificaciĆ³n para la obtenciĆ³n de compuestos de alto valor agregado derivados de biomasa. La actividad catalĆ­tica se estudiĆ³ en la sĆ­ntesis de levulinato de n-butilo a partir de Ć”cido levulĆ­nico y nbutanol, producto de gran importancia por sus usos, como fragancia o como aditivo en gasolina y biodiesel, entre otros.
  • ArtĆ­culo
    Acceso Abierto
    Preparation and characterization of a supported system of Ni2P/Ni12P5 nanoparticles and their use as the active phase in chemoselective hydrogenation of acetophenone
    (2018) Costa, Dolly Carolina; Soldati, Analƭa L.; Pecchi, Gina; Bengoa, JosƩ Fernando; Marchetti, Sergio Gustavo; Vetere, Virginia
    Ni2P/Ni12P5 nanoparticles were obtained by thermal decomposition of nickel organometallic salt at low temperature. The use of different characterization techniques allowed us to determine that this process produced a mixture of two nickel phosphide phases: Ni2P and Ni12P5. These nickel phosphides nanoparticles, supported on mesoporous silica, showed activity and high selectivity for producing the hydrogenation of the acetophenone carbonyl group to obtain 1-phenylethanol. This is a first report that demonstrates the ability of supported Ni2P/Ni12P5 nanoparticles to produce the chemoselective hydrogenation of acetophenone. We attribute these special catalytic properties to the particular geometry of the Niā€“P sites on the surface of the nanoparticles. This is an interesting result because the nickel phosphides have a wide composition range (from Ni3P to NiP3), with different crystallographic structures, therefore we think that different phases could be active and selective to hydrogenate many important molecules with more than one functional group.
  • Documento de conferencia
    Acceso Abierto
    PresentaciĆ³n institucional del CINDECA: desarrollo de la lĆ­nea de investigaciĆ³n en valorizaciĆ³n catalĆ­tica de biomasa
    (2018) Casella, MĆ³nica Laura
    El CINDECA fue incorporado como Centro de triple dependencia CONICET-UNLP-CIC en diciembre de 2017. En este primer encuentro como Centro CIC, se harĆ” una breve descripciĆ³n de la composiciĆ³n de su planta de personal, su infraestructura y de las lĆ­neas de trabajo que se desarrollan en el instituto. De entre las lĆ­neas de investigaciĆ³n, se harĆ” una presentaciĆ³n del grado de avance del Proyecto de InnovaciĆ³n y Transferencia en Ɓreas Prioritarias de la provincia de Buenos Aires (PIT-APBA) ā€œGeneraciĆ³n de energĆ­as renovables y valorizaciĆ³n de biomasa residual de la regiĆ³n Noroeste de la provincia de Buenos Aires mediante procesos catalĆ­ticos sustentablesā€.
  • ArtĆ­culo
    Acceso Abierto
    Dynamic laser speckle technique as an alternative tool to determine hygroscopic capacity and speciļ¬c surface area of microporous zeolites
    (2018) Mojica SepĆŗlveda, Ruth Dary; Mendoza Herrera, Luis JoaquĆ­n; Grumel, Eduardo Emilio; Soria, Delia Beatriz; Cabello, Carmen InĆ©s; Trivi, Marcelo Ricardo
    Adsorption phenomena have several technological applications such as desiccants, catalysts, sep- aration of gases, etc. Their uses depend on the textural properties of the solid adsorbent and the type of the adsorbed liquid or gas. Therefore, it is important to determine these properties. The most common measurement methods are physicochemical based on adsorption of N2 to determine the surface area and the distribution of pores size. However these techniques present certain limi- tations for microporous materials. In this paper we propose the use of the Dynamic Laser Speckle (DLS) technique to measure the hygroscopic capacity of a microporous natural zeolite and their modi ed forms. This new approach based on the adsorption of water by solids allows determine their speci c surface area (S). To test the DLS results, we compared the obtained S values to those calculated by di erent conventional isotherms using the N2 adsorption-desorption method.
  • ArtĆ­culo
    Acceso Abierto
    A novel one-dimensional model to predict fin efficiency of continuous fin-tube heat exchangers
    (2019) SuƔrez, Felipe; Keegan, Sergio D.; Mariani, NƩstor Javier; Barreto, Guillermo Fernando
    The objective of this contribution is to present a novel one-dimensional (1D) model to predict the heat transfer rate from (or to) continuous fin-and-tube heat exchangers. In this model, called two equivalent radial fins (1D-TERF), it is proposed to represent the thermal behavior of the continuous two dimensional (2D) fin by employing two thermally independent sections of radial fins, while keeping the total surface area of the actual fin and the outer perimeter of the tube. The two geometrical free parameters of the model are obtained by matching the two first terms of the series describing the actual fin efficiency at low values of the modulus, . It is demonstrated that the 1D-TERF model with this criterion allows estimating the fin efficiency with a higher level of precision than any other literature alternative (as the radial equivalent fin model and the sector method) over a wide range of conditions (i.e., values of between 0 and infinity) for circular tubes with in-line and staggered layouts in an extensive range of geometric ratios.