Transesterificación de triglicéridos en una columna de contacto líquido-líquido

Objetivo General. Establecer el porcentaje de ésteres metílicos obtenidos mediante la transesterificación de un aceite vegetal en presencia de un catalizador heterogéneo y en una Columna de contacto líquido-líquido-sólido (DLCR), adaptada como reactor con el fin de disminuir la resistencia a la transferencia de masa líquido-líquido-sólido. Objetivos Específicos. Determinar si la cal viva calcinada presenta actividad catalítica igual o superior al CaO grado reactivo en la transesterificación de un aceite vegetal. Establecer el tipo de aceite, entre cártamo y canola, que favorece la producción de ésteres metílicos. Determinar las condiciones de reacción en las cuales se obtiene un mayor porcentaje de ésteres metílicos en un reactor de tanque agitado. Determinar las condiciones de reacción en las cuales se obtiene un mayor porcentaje de ésteres metílicos en una columna de contacto líquido-líquido-sólido. Establecer el modelo cinético que mejor represente la transesterificación del aceite vegetal estudiado. El presente trabajo comprende 4 capítulos principales, además de una sección de referencias y una de anexos. En el primer capítulo se detallan los antecedentes que no solamente ayudan a justificar la realización del presente trabajo sino también a comprenderlo y a discutir los resultados obtenidos. En el capítulo 2 se detalla la metodología para lograr los objetivos arriba planteados. Los resultados obtenidos se presentan y discuten en el capítulo 3 y las conclusiones en el capítulo 4. Las referencias empleadas se presentan en la penúltima sección de este trabajo. Finalmente, en el apartado de anexos se incluyen datos importantes empleados para los cálculos realizados, principalmente. También se incluyen ejemplos representativos de resultados que no se incluyen en el capítulo 3 como cromatogramas. Para mejor comprensión del presente trabajo también se incluye un glosario y finalmente se presenta constancia de presentación de resultados en un congreso internacional y la evidencia de un artículo publicado en una revista indizada.The relevance in recent years for the minimization of polluting gases and the search for alternative energy sources apart from oil, has led research in various forms of renewable energy including power generated by wind, hydro, solar, biomass and biofuels; and among them biodiesel. Despite extensive research related to the production of biodiesel, there are some issues that desserve to be addressed from the point of view of engineering, especially in the efficiency of mass transfer between the two organic phases (methanol and oil), which plays a critical role during transesterification and thereby controls the rate of reaction in the initial stage, and the use of heterogeneous catalysts which allows an easy and less expensive separation of the product. This thesis aims at studying the efficiency of a cocurrent downflow bubble column as a liquid-liquid contactor reactor in order to carry out the transesterification reaction of canola oil to biodiesel using heterogenous catalysis. The reactor provides great potential for chemical reactions that are limited by mass transfer and has several advantages over typical reactors used for transesterification. At the reactor inlet a high speed liquid flow is produced by venturi effect and this results in a vigorous agitation system with high shear and energy. This high mixing intensity allowed the production of biodiesel according to EN14214 (content greater than or equal of esters ≥ 96.5%), obtaining a 97% of esters in a time of 300 min at a temperature of 50 °C, using CaO from a rather low cost source (quicklime) as heterogeneous catalyst, with a catalyst loading of 8 % (w/w with respect to the reaction mixture oil-methanol), an oil : methanol molar ratio of 1 : 9. In order to understand the effect of the process variables the reaction was also studied in a batch reactor. The studied variables were reagents addition order, methanol quality, methanol-oil molar ratio, amount of catalyst, temperature dependence, type of catalyst and a reaction kinetic model was established. In general there is a minimal difference in the rate of reaction profiles between the lab scale STR and the pilot scale contactor column; beside the desearible content of FAME’s (97% EN14214) was achieve in both reactors after 300 min of reaction. It is worth to be mentioned that the reaction volume in the liquid-liquid contactor was about 24 times higher than the STR volume.proyecto 3685/2014 y al Consejo Nacional de Ciencia y Tecnología por el apoyo financiero y la formación académica a trasvés de la beca No. 383423, así como a la beca mixta para realizar estancias de investigación en Alemania con número (CVU/Becario): 627380/328718.Proyecto UAEM 3685/201

Wet steam drying: Microwave-assisted droplet evaporation in open-cell ceramic foams

In many energy and process engineering systems where fluids are processed, droplet-laden gas flows may occur. As droplets are often detrimental to the system’s operation, they are required to be removed. According to the state-of-the-art, industrial droplet removal is achieved through a sequential arrangement of several separators followed by droplet collection and discharge. This results in a high-quality gas stream, yet at the expense of bulky and expensive systems that are difficult to retrofit to existing facilities. In addition, the multiple sequential separators produce high pressure drops, further increasing operating costs. Alternatively, a single droplet separation stage and in situ evaporation would provide compact solutions for facilities. However, compact engineering solutions for the removal of entrained droplets are difficult to achieve with conventional flow control and conduction heat transfer approaches such as Joule heating. Joule heating requires a well-defined and homogeneous electrical resistance to ensure uniform heating, which is technically challenging to apply in fine separators and thus compact removal devices are hence often costly and ineffective. Therefore, it becomes necessary to investigate alternative heating approaches to overcome these challenges, such as volumetric heating using microwaves. The research conducted in this thesis aims to analyze the potential of a compact microwave solution approach for droplet removal. The compactness of the approach relies on a novel fine separator structure enhanced by microwave-heat transfer for efficient in-flow droplet evaporation. The investigation targets at fundamental studies of the combined effect of droplet flow filtering and heat transfer from numerical calculations and experimentation. As novel fine separators, solid open-cell foams are a promising alternative for the separation of liquid droplets suspended in gas flows at comparably low pressure drops. Using susceptors, such as dielectric materials, for the skeleton and exposing them to microwaves is an efficient way to use them as heating elements. Silicon carbide (SiC) based open-cell foam samples were considered for the study as they are good susceptor materials. First, pore-scale fluid numerical simulations on representative foam models were used to obtain a deeper insight into the effects of pore size and pore density on the droplet retention time within foams. Numerical findings were reported considering the pressure gradient and the residence time distribution of droplets under different superficial flow velocities, droplet sizes, porosities and pore densities. Next, the temperature-dependent permittivity of SiC-based foam materials was determined by the cavity perturbation technique using a waveguide resonator at a microwave frequency of 2.45 GHz up to 200 °C. The permittivity was of particular interest as it is a crucial parameter for predicting and designing systems utilizing microwave heating. Along the permittivity measurements, electromagnetic wave propagation simulations were used to derive novel mixing relations describing the effective permittivity of foams while considering their skeletal morphology. The derived relations facilitate an efficient and reliable estimation of the effective permittivity of open-cell foams, producing good agreement to experimental data. Using the foams dielectric properties and the fluid characteristics of droplet-laden streams, a microwave applicator was designed to concentrate the electric field on the open-cell foams. The applicator was constructed for carrying out experimental studies on droplet evaporation removal under different flow velocities, microwave power and different SiC-based foams. Measurements of droplet size, velocity, number density and flux at the inlet and outlet streams of the applicator were performed using a 2D-phase Doppler interferometer. Eventually, it was found from the experimental data analysis that the application of open-cell ceramic foams as a filter medium reduced 99.9 % of the volumetric flow of droplets, while additional microwave exposure increased the reduction to 99.99 %. In addition, microwave-heated foams prevent droplet re-entrainment and structure-borne liquid accumulation within foams, thus avoiding water clogging and flooding. Hence, open-cell foams can be used as fine droplet separators as long as microwave heating may effectively evaporate accumulations of liquid. An important factor in designing future devices based on this microwave heating approach is the temperature, as it changes the arcing breakdown voltage of the gas, thus limiting the microwave input power and droplet flow velocity. Although more investigations are needed to develop an applicable and optimal product, the results presented in this thesis provide a first insight into the viability of using microwave heating and fine filtering as a compact solution for droplet removal

Preparación y caracterización de compuestos poliméricos a base de aceite de linaza epoxidado y nanotubos de carbono

Establecer las condiciones de preparación de compuestos poliméricos a base de aceite de linaza y nanotubos de carbono no modificados y modificados químicamente, y llevar a cabo su caracterización por FT-IR, SEM, propiedades eléctricasSe alcanzó el objetivo del proyecto. Se analizó el efecto de la funcionalización de nanotubos de carbono de pared múltiple (NTCPM) en la dispersión en una matriz polimérica. Esa dispersión se evaluó indirectamente mediante la medición de la resistencia eléctrica y posterior cálculo de la resistividad de películas de los compuestos poliméricos a base de Aceite de linaza epoxidado (ALE) y NTCPM sin modificar y modificados superficialmente por oxidación química, a diferentes composiciones de NTCPM. El método de dispersión y la observación cualitativa de ésta, se realizó como se estableció en la metodología, observando cada hora, en diferentes disolventes, un concentración dada de NTCPM , en un microscopio óptico. Se determinó como el tiempo de dispersión adecuado, aquel en donde se observaron en mayoría, NTCPM individuales, siendo el mejor disolvente la Dimetil Formamida (DMF). El tiempo varió acorde al tipo de NTC empleados. Con los datos de resistividad, se construyeron las curvas de percolación de las tres series de compuestos generadas y se modeló la concentración crítica

Una actividad física eficiente ante el reto de una sociedad de jóvenes influenciada por el modernismo y la tecnología

Actualmente los jóvenes se encuentran influenciados por un estilo de vida dominado por la modernidad y los avances tecnológicos, lo que deriva en una vida sedentaria que produce efectos nocivos en todos los sentidos y todos los ámbitos. Esto, aunado a los programas de un sistema institucional educativo y deportivo con innumerables carencias, nos lleva a una situación más complicada, en la que se añaden factores perjudiciales que abarcan la ignorancia, la incapacidad y los intereses personales, que no nos ayudan a edificar alternativas que comiencen a funcionar. Es primordial el establecimiento de una solución pronta y efectiva, encaminada a sistematizar una actividad física adecuada, basada en argumentos científicos y métodos acordes, que nos provean los diversos beneficios que su práctica otorga y nos ayuden a detener el proceso de deterioro físico, al cual el ritmo de vida actual no arroja

Evolución de los conceptos básicos de la Educación Física de base en los estudiantes de I, V, X semestres de la Licenciatura en educación básica con énfasis en Educación Física Recreación y Deporte de la Universidad Libre

la presente investigación surge la necesidad de aclarar y tener bases que sustenten de forma investigativa y empírica la teoría requerida durante el proceso académico, de la misma manera es preciso conocer las tendencias que manejan los estudiantes del programa, lo cual nos permite develar los significados básicos y su evolució

Factores que se deben tener en cuenta en la formulación de políticas públicas que busquen el mejoramiento de la calidad educativa de Colombia.

El mundo a través de la historio ha encontrado que la única manera de lograr un desarrollo sostenible es generando calidad educativa desde lo público, sin embargo se necesita establecer ciertos elementos que permitan no solo mejorar la calidad en la educación de Colombia sino que también en necesario concretar factores que se deben tener en cuenta para la formulación de políticas públicas que lleven al mejoramiento de la educación no sólo en términos administrativos y de gestión donde se lleven procesos de manera transparentes y eficaces que garanticen la buena prestación de los servicios públicos educativos, consientes que este es un derecho fundamental constitucional si no también en estrategias innovadoras que comulguen con la necesidad de formar un ciudadano más competitivo, líder en la sociedad y protagonista de la solución de la problemáticas locales, solo así se logrará un potencial crecimiento familiar y social en el marco de una sociedad que le brinde a sus ciudadanos la posibilidad de alcanzar sus objetivos y les brinda a cada uno las mismas posibilidades gracias a la educación y a las políticas públicas educativas a corte a las necesidades de nuestra región. Educación, Política Públicas, Calidad, Estado, Innovación, Pertinencia, Formación, Aprendizaje Significativo,The world through history has found that the only way to achieve sustainable development is to generate educational quality from the public, however it is necessary to establish certain elements that not only improve the quality of education in Colombia but also in Necessary to specify factors that must be taken into account for the formulation of public policies that lead to the improvement of education not only in administrative and management terms where processes are carried out transparently and effectively to ensure the good delivery of public educational services, You are aware that this is a fundamental constitutional right if not also in innovative strategies that commune with the need to form a more competitive citizen, leader in society and protagonist of the solution of the local problems, only this way you will achieve potential family and social growth Within the framework of a company providing To its citizens the possibility of reaching its objectives and gives each one the same possibilities thanks to education and public educational policies to meet the needs of our region. Education, Public Policy, Quality, State, Innovation, Relevance, Training, Significant Learning

Modeling of the Effective Permittivity of Open-Cell Ceramic Foams Inspired by Platonic Solids

Open-cell solid foams are rigid skeletons that are permeable to fluids, and they are used as direct heaters or thermal dissipaters in many industrial applications. Using susceptors, such as dielectric materials, for the skeleton and exposing them to microwaves is an efficient way of heating them. The heating performance depends on the permittivity of the skeleton. However, generating a rigorous description of the effective permittivity is challenging and requires an appropriate consideration of the complex skeletal foam morphology. In this study, we propose that Platonic solids act as building elements of the open-cell skeletal structures, which explains their effective permittivity. The new, simplistic geometrical relation thus derived is used along with electromagnetic wave propagation calculations of models that represent real foams to obtain a geometrical, parameter-free relation, which is based only on foam porosity and the material’s permittivity. The derived relation facilitates an efficient and reliable estimation of the effective permittivity of open-cell foams over a large range of porosity

Novel Mixing Relations for Determining the Effective Thermal Conductivity of Open-Cell Foams

This paper proposes a new approach to relate the effective thermal conductivity of open-cell solid foams to their porosity. It is based on a recently published approach for estimating the dielectric permittivity of isotropic porous media. A comprehensive assessment was performed comparing the proposed mixing relation with published experimental data for thermal conductivity and with numerical data from state-of-the-art relations. The mixing relation for the estimation of thermal conductivities based on dodecahedrons as building blocks shows good agreement with experimental data over a wide range of porosity