Design of Zero Head Turbines for Power Generation

Failure analysis of the blades of a horizontal axis hydrokinetic turbine of 1 kW is presented. Analysis consisted of the determination of the pressure on the blade surface using Computational Fluid Dynamics, and the calculation of the stress distribution in the blade due to hydrodynamic, inertial and gravitational loads using the finite element methods. The results indicate that the blade undergoes significant vibration and deflection during the operation, and the centrifugal and hydrodynamic loads considerably affect the structural response of the blade; however, the stresses produced in all of the analysed models did not exceed the safe working stresses of the materials used to manufacture the blade. Modal analysis was conducted to calculate first significant natural frequencies. Results were studied in depth against operating frequency of the turbine. After carrying out the modal analysis, harmonic analysis was also done to see the response of the turbine under dynamic loading. It was observed that the turbine is safe in its entire operating range as far as phenomenon of resonance is concerned. Additionally, it was observed that maximum harmonic response of the turbine on the application of dynamic loading is far lesser than its failure limit within the specified operating range

Computational Fluid Dynamic Simulation of Vertical Axis Hydrokinetic Turbines

Hydrokinetic turbines are one of the technological alternatives to generate and supply electricity for rural communities isolated from the national electrical grid with almost zero emission. These technologies may appear suitable to convert kinetic energy of canal, river, tidal, or ocean water currents into electricity. Nevertheless, they are in an early stage of development; therefore, studying the hydrokinetic system is an active topic of academic research. In order to improve their efficiencies and understand their performance, several works focusing on both experimental and numerical studies have been reported. For the particular case of flow behavior simulation of hydrokinetic turbines with complex geometries, the use of computational fluids dynamics (CFD) nowadays is still suffering from a high computational cost and time; thus, in the first instance, the analysis of the problem is required for defining the computational domain, the mesh characteristics, and the model of turbulence to be used. In this chapter, CFD analysis of a H-Darrieus vertical axis hydrokinetic turbines is carried out for a rated power output of 0.5 kW at a designed water speed of 1.5 m/s, a tip speed ratio of 1.75, a chord length of 0.33 m, a swept area of 0.636 m2, 3 blades, and NACA 0025 hydrofoil profile

Intervención en un niño TEA mediante el modelo DENVER

Treball de Final de Màster Universitari en Psicopedagogia. Codi: SAW020. Curs acadèmic 2015-2016El Trastorno del Espectro Autista (TEA) es uno de los trastornos que podemos encontrarnos hoy en día en los centros educativos, ya que ha experimentado un gran auge en los últimos años gracias a la mejor detección y diagnóstico del mismo. Así pues, este trabajo tiene como objetivo realizar una intervención con un niño de tres años diagnosticado de TEA. Este niño presenta un TEA grado 3 con un CI<50 y no verbal, por lo tanto tiene grandes dificultades en todas las áreas del desarrollo. El objetivo de este trabajo es utilizar un modelo de intervención que cuente con una clara evidencia científica, con la finalidad de mejorar las habilidades del niño en diferentes áreas del desarrollo. Se trata del modelo DENVER, el cual es muy actual y está diseñado específicamente para niños pequeños con autismo. La intervención se compone de 9 sesiones, llevadas a cabo tres días a la semana durante 12 semanas, de 45 minutos cada una de ellas. Se llevó a cabo de manera individual y en un contexto natural, su aula escolar. Los resultados muestran que el niño sí que mejora en algunos aspectos de las diferentes áreas del desarrollo, lo cual demuestra que si se trabaja de manera adecuada con este modelo de intervención se pueden obtener mejoras en los niños pequeños con TEA. Es imprescindible que se continúe con esta manera de trabajo para garantizar que no se pierdan las mejorías obtenidas y conseguir objetivos a largo plazo

Degradation of polycyclic aromatic hydrocarbons in water: Alternative treatments to conventional processes.

Nowadays, polycyclic aromatic hydrocarbons (PAHs) are a group of chemical substances that deserves a great attention. PAHs consist of two or more condensed benzene rings, bonded in linear, cluster or angular arrangements that are ubiquitous in the environment. Due to their low solubility and high affinity for particulate matter, PAHs are found in water in extreme low concentrations, in the range of ng L-1 or µg L-1. However, even at these ultra-trace or trace levels, they exhibit harmful effects on living beings and humans, especially when present as mixtures. That is the case of anthracene (AN), which has been reported as an acute phototoxic compound, and benzo[a]pyrene (BaP), which is a carcinogenic and mutagenic pollutant. Therefore, their presence in the environment and, specifically in aquatic resources must be monitored. For this purpose, the chromatographic behavior of AN and BaP was studied, and three models were found describing the identification of AN and BaP, the quantification of AN and that of BaP. The factors influencing each of the models or indexes were also optimized and a new and fast analytical method allowing the determination of the analytes of interest at ultra-trace concentrations in surface water samples was developed. In addition to monitor the target pollutants, they must be also eliminated from water because of the adverse health effects associated. However, conventional processes water treatment facilities are operating with are not efficient in tackling the problem of AN and BaP pollution in water. In this regard, the implementation of alternative treatments, including advanced oxidation processes (AOPs), provides a very attractive option. AOPs have demonstrated to be highly interesting technologies for water remediation, particularly the combination of ultraviolet radiation in the UV-C range (UV-C) and hydrogen peroxide (H2O2). This Thesis addresses the evaluation of the efficiency of the UV-C/H2O2 oxidation system to treat water sampled from a natural reservoir polluted with AN and BaP. For this purpose, initially, the removal profiles of AN and BaP were investigated, as well as the organic matter mineralization capacity of the oxidation system and the production of innocuous degradation by-products. The system allowed obtaining very positive results in terms of the degradation of the pollutants of interest and the organic matter mineralization, avoiding the production of dangerous reactive intermediates. Furthermore, after the application of this treatment process, a residual H2O2 was observed in the reaction solution, which can be used for additional microbial load removal. The residual H2O2 found within the bulk after the application of the oxidation treatment was analyzed using an analytical method proposed here. Moreover, the oxidation potential of the UV-C/H2O2 process was assessed for the inactivation of wild total coliforms naturally contained in the water of study and the results were compared with the findings obtained from other photochemical technologies based on sonochemical reactions. It was found that the technology achieving the highest microorganism elimination in the shortest time and with the lowest electrical costs results was the UV-C/H2O2 process. Nevertheless, in spite of that, it is worth noting that the implementation of the UV-C/H2O2 oxidation process still requires high electrical needs, which increases the operating costs of the process. Therefore, in order to reduce such as costs, a photovoltaic (PV) array was sized and installed for supplying the energy requirements of the selected water treatment system. The installed PV system allows for the use of renewable energy both in developing and non-developing countries. In this regard, the treatment of water to be drinkable was observed to be plausible in countries with lack of economical resources and in communities far from the electrical grid, which exist in a high number in countries such as Colombia. In the second stage of the research, and taking into account the necessity of having kinetic models for finding out the optimal operating conditions without the necessity of conducting extensive experimentation, a kinetic model for the performance of the UV-C/H2O2 oxidation process was constructed and validated using a model compound. The kinetic model allows calculating the optimal level of H2O2 for efficiently degrading the pollutant of interest, as well as the effective level of HO• to be maintained throughout the reaction time of the UV-C/H2O2 system for achieving an efficient pollutant degradation, contributing to save costs and time.Ingeniería, Industria y Construcció

Kinetic Modeling of the UV/H2O2 Process: Determining the Effective Hydroxyl Radical Concentration

A kinetic model for pollutant degradation by the UV/H2O2 system was developed. The model includes the background matrix effect, the reaction intermediate action, and the pH change during time. It was validated for water containing phenol and three different ways of calculating HO° level time-evolution were assumed (non-pseudo-steady, pseudo-steady and simplified pseudo-steady state; denoted as kinetic models A, B and C, respectively). It was found that the kind of assumption considered was not significant for phenol degradation. On the other hand, taking into account the high levels of HO2° formed in the reaction solution compared to HO° concentration (~10–7 M >>>> ~10–14 M), HO2° action in transforming phenol was considered. For this purpose, phenol-HO2° reaction rate constant was calculated and estimated to be 1.6x103 M-1 s-1, resulting in the range of data reported from literature. It was observed that, although including HO2° action allowed slightly improving the kinetic model degree of fit, HO° developed the major role in phenol conversion, due to their high oxidation potential. In this sense, an effective level of HO° can be determined in order to be maintained throughout the UV/H2O2 system reaction time for achieving an efficient pollutant degradation

Analysis of biochars produced from the gasification of pinus patula pellets and chips as soil amendments

In this work, biochar (BC), a co-product of the fixed bed gasification process of Pinus patula wood pellets (PL) and chips (CH), was characterized as soil amendment. The physicochemical properties and the mineral content of the pellet’s biochar (PL-BC) and the chips biochar (CH-BC) were analyzed following the NTC5167 Colombian technical standard. The BET surface area values of the BCs were 367,33 m2/g and 233,56 m2/g for the PL-BC and the CH-BC, respectively, and the pore volume was 0,20 cm3/g for the PL-BC and 0,13 cm3/g for the CH-BC. These characteristics favor the increase of the BCs water-holding capacity (WHC). Properties such as the pH (8,8-9,0), the WHC (219 % - 186,4 %), the total organic carbon (33,8 % - 23,9 %), the metalloid presence (Ca, Mg, K, Mn, Al, Si, and Fe), and the ash (1,92 wt% - 2,74 wt%) and moisture contents (11,13 wt% - 11,63 wt%) for both BCs were found to be within the limits set by the NTC5167 standard. Furthermore, the presence of micro and macronutrients, such as Fe and phosphorus (P), and the alkaline pH, make possible the use of these BCs as amendments for acid soils

Surrogate modelling for high-lift multi-element hydrofoil shape optimization of a hydrokinetic turbine blade

The hydrodynamic shape of a blade is one of the most important factors in the design process of a horizontal axis hydrokinetic turbine that influences its performance. The present work is focused on the design and hydrodynamic analysis of a high-lift system using the optimization method of surrogate models and computational fluid dynamics (CFD) analysis. The parameters that affect the amount of the lift and the drag force that a hydrofoil can generate are the gap, the overlap, the flap deflection angle (δ), the flap chord length (C2) and the angle of attack of the hydrofoil (α). These factors were varied to examine the turbine performance in terms of the ratio between the lift (CL) and the drag coefficient (CD), and the minimum negative pressure coefficient (min Cpre) in order to avoid the cavitation inception. For this propose, surrogate models were implemented to analyse the CFD results and find the optimal combination of the design parameters of the high-lift hydrofoil. The traditional Eppler 420 hydrofoil was utilized for the design of the multi-element profile, which was composed of a main element and a flap. The multi-element design selected as optimal had a gap of 2.825 %C1, an overlap of 8.52 %C1, a δ of 19.765˚, a C2 of 42.471 %C1 and a α of -4˚, where C1 refers to the chord length of the main element. In comparison with the traditional Eppler 420 hydrofoil, CL/CD ratio increases from 39.050 to 42.517. Key words. Horizontal axis hydrokinetic turbine, surrogate model, computational fluid dynamics, high-lift system, multielement hydrofoi

Kinetic model describing the UV/H2O2 Photodegradation of phenol From water

ABSTRACT: A kinetic model for phenol transformation through the UV/H2O2 system was developed and validated. The model includes the pollutant decomposition by direct photolysis and HO, HO2 and O2 - oxidation. HO scavenging effects of CO32-, HCO3-, SO42- and Cl- were also considered, as well as the pH changes as the process proceeds. Additionally, the detrimental action of the organic matter and reaction intermediates in shielding UV and quenching HO was incorporated. It was observed that the model can accurately predict phenol abatement using different H2O2/phenol mass ratios (495, 228 and 125), obtaining an optimal H2O2/phenol ratio of 125, leading to a phenol removal higher than 95% after 40 min of treatment, where the main oxidation species was HO. The developed model could be relevant for calculating the optimal level of H2O2 efficiently degrading the pollutant of interest, allowing saving in costs and time

Evaluación de la visión binocular tras el uso de filtros cromáticos

En este Trabajo de Fin de Grado se han evaluado los posibles efectos de la fototerapia Syntonics sobre la visión binocular, concretamente, sobre el retraso acomodativo, las vergencias fusionales negativas y la agudeza visual estereoscópica. Para ello, se ha realizado una exhaustiva búsqueda bibliográfica sobre esta técnica y sus supuestos efectos sobre el organismo y el sistema visual, y a su vez, se ha realizado un estudio a una muestra normal de estudiantes universitarios.<br /