Análisis de la energía cinética turbulenta en un tanque de agitación aplicando velocimetría por imágenes de partículas

La aplicación de los tanques de agitación se extiende a lo largo de una gran variedad de industrias, como la alimentaria, la química, la minera, la farmacéutica entre otras, teniendo como principal objetivo alcanzar una mezcla homogénea de su contenido, donde la energía mecánica se transforma en energía cinética. Esto produce un incremento de la velocidad y conlleva a la creación de patrones de flujo que se encuentran dentro del tanque. En este trabajo se analizó la energía cinética turbulenta (TKE, por sus siglas en inglés, Turbulent Kinetic Energy) mediante la técnica de la velocimetría por imágenes de partículas (PIV, por sus siglas en inglés, Particle Image Velocimetry), utilizando la metodología de la resolución angular. Lo cual permitirá observar su variación conforme el impulsor cambia su posición angular con respecto al plano de medición.The employment of the stirred tank extends among a wide industry process, such as the food, the chemical, the mineral processing, the pharmaceutical, and so on. Been its principal aim to achieve a homogeneous mixture of its content. Here the mechanical energy is converted to kinetic energy. Yielding to an increase of the velocity flow and the generation of fluid patterns inside the tank. In this work the Turbulent Kinetic Energy (TKE) was evaluated by means of the Particle Image Velocimetry using the angled-resolved approach. This allow to observe the variation of the TKE when the impeller changes its angular position according to the measured plane

Determinación del campo de velocidad de un tanque agitado utilizando velocimetría por imágenes de partículas

Los tanques de agitación se utilizan para una gran variedad de procesos industriales, por lo cual es importante conocer el comportamiento del flujo que se encuentra en su interior. En el presente trabajo se obtuvo el campo de velocidades en la zona cercana al impulsor, debido a que es ahí donde se transfiere la energía mecánica y es convertida en energía cinética, la cual se manifiesta como un incremento de la velocidad del flujo. Para tal efecto se utilizó la técnica de velocimetría por imágenes de partículas, con la cual se obtuvo la variación del flujo para diferentes planos, permitiendo ver el comportamiento de la velocidad axial, radial y de la magnitud de la velocidad como consecuencia del movimiento del impulsor.The stirred tanks are used for a variety of industrial processes, so it is important to know the behavior of the flow that is inside of it. In the present work, the velocity field was obtained in the are anear the impeller, because in this zone the mechanical energy is transferred and converted into kinetic energy, which manifests itself as an increase in the velocity of the flow. For this purpose, the particle image velocimetry technique was used, to obtain the flow variation for different planes, it allows to see the behavior of the axial, radial and the magnitude of the velocity because of the movement of the impeller

Evaluación del efecto de la velocidad de agitación sobre la remoción de cromo hexavalente a escala piloto

Este trabajo experimental se desarrolla en un reactor piloto de laboratorio del 9 L utilizando electrodos estáticos de acero al carbón. Se obtuvo el consumo de potencia, el tiempo de mezclado y la cinética de reducción del Cr(VI) para diferentes velocidades de agitación. Para este trabajo se utilizaron números adimensionales para poder escalar el sistema. De forma experimental, se encontró que a velocidades de agitación mayores de 300 rpm se obtiene un buen mezclado, sin embargo al aumentar a 500 rpm se observa que por cada g de Cr(VI) se requiere menor consumo de energía que en todos los casos.This experimental work was carried out in a laboratory pilot reactor of 19 L using carbon steel static electrodes. Power consumed, mixing time and Cr(VI) reduction kinetic at different agitation speeds were obtained. Dimensionless numbers were used to scale up the system. Experimentally, it was found that at speed of agitation greater than 300 rpm there is good mixing in the reactor, but the power consumed for each g of Cr (VI) was the lowest at 500 rpm

Efecto de la temperatura, tiempo de carbonización, concentración del activador y relación de impregnación en el rendimiento de carbón activado obtenido a partir de residuos de mango (Mangifera indica)

El carbón activado (CA) es un adsorbente con amplia gama de aplicaciones en la industria, empleándose para la adsorción de diversos contaminantes en las aguas residuales, tanto de naturaleza inorgánica como orgánica. En esta investigación se determinaron los efectos de los factores: tiempo de carbonización, temperatura de carbonización, concentración del activador (ácido fosfórico) y relación de impregnación sobre el rendimiento del CA empleando como precursor semillas de mango (Mangifera indica), mediante un diseño experimental factorial completo 2⁴. Las condiciones mediante las cuales se obtuvo un mayor rendimiento de CA, fueron: Temperatura, 400°C; Tiempo, 90 minutos; concentración, 60% y relación de impregnación, 1:1. Por otra parte, el CA preparado, adsorbió el 95% de azul de metileno durante los primeros 5 minutos, mientras que después de este tiempo la velocidad de adsorción decreció, alcanzando el equilibrio a los 150 minutos.Activated carbon (AC) is an adsorbent with a wide range of applications in industry, being used for the adsorption of various pollutants in wastewater, both inorganic and organic. In this research, the effects of factors: carbonization time, carbonization temperature, activator concentration (phosphoric acid), and impregnation ratio on AC yield were determined using mango seeds (Mangifera indica) as a precursor, using a 2⁴ complete factorial design. The conditions by which a higher AC yield was obtained were: Temperature, 400°C; Time, 90 minutes; concentration, 60% and impregnation ratio, 1:1. On the other hand, the prepared AC adsorbed 95% of methylene blue during the first 5 minutes, after this time the adsorption rate decreased, reaching equilibrium at 150 minutes

PIV and dynamic LES of the turbulent stream and mixing induced by a V-grooved blade axial agitator

The hydrodynamic behavior of a turbulent flow and the mixing characteristics generated by a V-grooved axial impeller inside an agitated tank reactor were investigated both experimentally and numerically. Angle resolved Particle Image Velocimetry (PIV) techniques with an angular displacement Δθ = 5° have been applied and two aerodynamic planes along the blades were considered. PIV-based results were compared to those obtained by Large Eddy Simulation (LES), used with the dynamic Smagorinsky-Lilly sub-grid scale (SGS) model. Results showed the existence of distinctive recirculation zones in the aerodynamic planes, and new additional frequencies in the impeller stream, induced by the grooves. A decrease of mixing time of about 11% was obtained experimentally, consequence of the better suction induced by the grooved blades in the early stages of mixing. Mean velocities, vorticity, TKE obtained from LES showed a good agreement with the PIV-based results. The distributions of turbulence dissipation rate ε were similar to those obtained from PIV, however showing high under-predicted magnitudes

Identification of genetic variants associated with Huntington's disease progression: a genome-wide association study

Background Huntington's disease is caused by a CAG repeat expansion in the huntingtin gene, HTT. Age at onset has been used as a quantitative phenotype in genetic analysis looking for Huntington's disease modifiers, but is hard to define and not always available. Therefore, we aimed to generate a novel measure of disease progression and to identify genetic markers associated with this progression measure. Methods We generated a progression score on the basis of principal component analysis of prospectively acquired longitudinal changes in motor, cognitive, and imaging measures in the 218 indivduals in the TRACK-HD cohort of Huntington's disease gene mutation carriers (data collected 2008–11). We generated a parallel progression score using data from 1773 previously genotyped participants from the European Huntington's Disease Network REGISTRY study of Huntington's disease mutation carriers (data collected 2003–13). We did a genome-wide association analyses in terms of progression for 216 TRACK-HD participants and 1773 REGISTRY participants, then a meta-analysis of these results was undertaken. Findings Longitudinal motor, cognitive, and imaging scores were correlated with each other in TRACK-HD participants, justifying use of a single, cross-domain measure of disease progression in both studies. The TRACK-HD and REGISTRY progression measures were correlated with each other (r=0·674), and with age at onset (TRACK-HD, r=0·315; REGISTRY, r=0·234). The meta-analysis of progression in TRACK-HD and REGISTRY gave a genome-wide significant signal (p=1·12 × 10−10) on chromosome 5 spanning three genes: MSH3, DHFR, and MTRNR2L2. The genes in this locus were associated with progression in TRACK-HD (MSH3 p=2·94 × 10−8 DHFR p=8·37 × 10−7 MTRNR2L2 p=2·15 × 10−9) and to a lesser extent in REGISTRY (MSH3 p=9·36 × 10−4 DHFR p=8·45 × 10−4 MTRNR2L2 p=1·20 × 10−3). The lead single nucleotide polymorphism (SNP) in TRACK-HD (rs557874766) was genome-wide significant in the meta-analysis (p=1·58 × 10−8), and encodes an aminoacid change (Pro67Ala) in MSH3. In TRACK-HD, each copy of the minor allele at this SNP was associated with a 0·4 units per year (95% CI 0·16–0·66) reduction in the rate of change of the Unified Huntington's Disease Rating Scale (UHDRS) Total Motor Score, and a reduction of 0·12 units per year (95% CI 0·06–0·18) in the rate of change of UHDRS Total Functional Capacity score. These associations remained significant after adjusting for age of onset. Interpretation The multidomain progression measure in TRACK-HD was associated with a functional variant that was genome-wide significant in our meta-analysis. The association in only 216 participants implies that the progression measure is a sensitive reflection of disease burden, that the effect size at this locus is large, or both. Knockout of Msh3 reduces somatic expansion in Huntington's disease mouse models, suggesting this mechanism as an area for future therapeutic investigation