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The present dataset is the database and image database used to train and test the Convolutional Neural Network models of the scientific paper: Deep Learning algorithm, based on convolutional neural networks, for electrical equivalent electrical circuit recommendation for Electrochemical Impedance Spectroscopy

The salicylate method has been extensively used for quantifying ammonia in the emerging field of nitrogen (electro)fixation. Alkali metal salts are widely used as supporting electrolytes for nitrogen reduction, especially in the context of electrochemical nitrogen fixation. However, these salts are known to cause interferences on the salicylate method, introducing significant uncertainties in ammonia quantification. In this work, the interference of lithium, sodium and potassium chlorides, perchlorates and sulfates on the ammonia quantification results obtained using the salicylate method was experimentally quantified, and an empirical model was developed to capture the effect of the presence of these interferents on the ammonia quantification by the salicylate method. Based on the obtained experimental interference results, the tested interferents can be ranked from stronger interferent (i.e. lower admissible concentration) to weaker interferent: Li2SO4, KClO4, LiCl, LiClO4, K2SO4, NaClO4, NaCl, Na2SO4, KCl. The developed model can be used to assess the experimental error in ammonia quantification from nitrogen reduction, in samples containing these interferents. This model can be used to correct the interferences on the ammonia quantification, when the interferent concentration in a sample is known (or measurable).

[ES] Se requieren sistemas de almacenamiento de energía rentables y ecológicos para resolver la crisis energética actual. En 1836, el químico británico John Frederic Daniell inventó el modelo básico de la batería de zinc-cobre, conocida hoy como celda de Daniell. Inicialmente, esta batería se utilizó sustancialmente como batería estacionaria para repetidores de telegrafía remotos. Sin embargo, con la invención de las baterías modernas, ha quedado relegada, y hoy en día es solo una batería de demostracin, utilizada en las clases de química de todo el mundo para ilustrar la química redox. A pesar de perder su supremacía en el campo de las baterías, la batería de zinc-cobre presenta varias características (por ejemplo, costo, seguridad, impacto ambiental, densidad de energía, etc.) que la convierten en un sistema de almacenamiento de energía muy prometedor, siempre que se resuelvan sus inconvenientes. El objetivo de este proyecto es optimizar la reacción de la semicelda andica de una celda Daniel. Para lograr esto, se probaron diferentes electrolitos utilizando voltametr as cíclica y lineal, y Espectroscop a de Impedancias Electroqu micas. Para conseguirlo, se llev a cabo una optimización inicial del procedimiento de medida para intentar crear un montaje experimental estable y reproducible. Diversos factores, incluidos el rango de voltaje, la velocidad de barrido, el pretratamiento de los electrodos y la nitrogenación del electrolito, se modificaron para identificar formas de hacer que las mediciones de la celda sean reproducibles y fiables entre experimentos. Post eriormente, se probaron electrolitos ácidos, neutros y alcalinos donde se utilizaron técnicas analíticas, incluido el análisis de Tafel y el análisis de Koutecky-Levich, para determinar cuantitativamente los parámetros cinticos en los diferent es medios. En base a estos result ados, se seleccion el medio ptimo., [CA] Es requerixen sistemes d'emmagatzemament d'energia rendibles i ecològics per a resoldre la crisi energètica actual. En 1836, el químic britànic John Frederic Daniell va inventar el model bàsic de la bateria de zinc-coure, coneguda hui com a cel·la de Daniell. Inicialment, esta bateria es va utilitzar substancialment com a bateria estacionària per a repetidors de telegrafia remots. No obstant això, amb la invenció de les bateries modernes, ha quedat relegada, i hui en dia és només una bateria de demostracin, utilitzada en les classes de química de tot el món per a il·lustrar la química redox. A pesar de perdre la seua supremacia en el camp de les bateries, la bateria de zinc-coure presenta diverses característiques (per exemple, cost, seguretat, impacte ambiental, densitat d'energia, etc.) que la convertixen en un sistema d'emmagatzemament d'energia molt prometedor, sempre que es resolguen els seus inconvenients. L'objectiu d'este projecte és optimitzar la reacció de la semicelda andica d'una cel·la Daniel. Per a aconseguir açò, es van provar diferents electròlits utilitzant voltametr as cíclica i lineal, i Espectroscop a d'Impedàncies Electroqu miques. Per a aconseguir-ho, es llev a cap una optimització inicial del procediment de mesura per a intentar crear un muntatge experimental estable i reproduïble. Diversos factors, inclosos el rang de voltatge, la velocitat d'agranat, el pretractament dels elèctrodes i la nitrogenación de l'electròlit, es van modificar per a identificar formes de fer que els mesuraments de la cel·la siguen reproduïbles i fiables entre experiments. Post eriormente, es van provar electròlits àcids, neutres i alcalins on es van utilitzar tècniques analítiques, inclòs l'anàlisi de Tafel i l'anàlisi de Koutecky-Levich, per a determinar quantitativament els paràmetres cinticos en els diferent és mitjans. Basant-se en estos result ados, se selecció el mig ptimo., [EN] Cost-effective and eco-friendly energy storage systems are required to solve the actual energy crisis. In 1836, the British chemist John Frederic Daniell invented the basic model of the zinc-copper battery, known today as the Daniell cell. Initially, this battery was substantially used as a stationary battery for power remote telegraphy repeaters. However, with the invention of modern batteries, it has been relegated, and today it is just a reference standard battery, used in all-around-the-World chemistry classes to illustrate redox chemistry. Despite losing its supremacy in the battery field, the zinc- copper battery presents several characteristics (e.g., cost, safety, environment impact, energy density, etc.) that make it a very promising energy storage system, provided that its drawbacks are solved. The aim of this project is to optimise the anodic half-cell reaction in a Daniel cell. To achieve this, different supporting electrolytes will be tested of varying pH using cyclic and linear voltammetry and electrochemical impedance spectroscopy. The use of a rotating disc electrode (RDE) will be used to examine the effect of mass transfer limitations within the reaction. To achieve this, initial optimisation of the measurements of the half-cell will be carried out to try to create a stable and reproduceable experimental set-up. Varying factors including voltage range, scan rate, pre-treatment of the electrodes, nitrogenation of the electrolyte, will be altered to identify ways to make the cell measurements reproducible and reliable between experiments. Acidic, neutral, and alkaline electrolytes will be tested where analytical techniques, including Tafel analysis and Koutecky-Levich analysis, will be used to quantitively determine kinetic and mass transfer reaction parameters enabling comparison between the different medias tested. A discussion of the electrolyte media which best supports the anodic half-cell will be concluded.

The salicylate method is one of the ammonia quantification methods that has been extensively used in literature for quantifying ammonia in the emerging field of nitrogen (electro)fixation. The presence of iron in the sample causes a strong negative interference on the salicylate method. Today, the recommended method to deal with such interferences is the experimental correction method: the iron concentration in the sample is measured using an iron quantification method, and then the corresponding amount of iron is added to the calibration samples. The limitation of this method is that when a batch of samples presents a great iron concentration variability, a different calibration curve has to be obtained for each sample. In this work, the interference of iron III on the salicylate method was experimentally quantified, and a model was proposed to capture the effect of iron III interference on the ammonia quantification result. This model can be used to correct the iron III interferences on ammonia quantification. The great advantage of this correction method is that it only requires three experimental curves in order to correct the iron III interference in any sample provided the iron III concentration is below the total peak suppression concentration.

[ES] El objetivo del presente Trabajo Final de Máster ha sido el diseño, dimensionado y estudio de la viabilidad económica de una instalación solar fotovoltaica conectada a red para abastecer de energía eléctrica a una planta de galvanizado en caliente ubicada en Cheste (Valencia). En el proceso de diseño y dimensionado se ha justificado la selección de cada uno de los elementos que componen la instalación (paneles solares, inversores…) teniendo en cuenta la legislación vigente en España y atendiendo a criterios tanto económicos como técnicos, priorizando aquellos componentes que se encuentren disponibles en el mercado. Además, se ha realizado un estudio comparativo de distintas configuraciones de conexión, así como de diferentes sistemas de acumulación de energía. Las opciones de sistemas de acumulación que se han planteado en este trabajo fueron las baterías de ion litio, de plomo ácido, de flujo redox de todo vanadio y la acumulación en forma de hidrógeno. Por último, se ha propuesto un modelo del sistema de generación fotovoltaico y de los diferentes sistemas de almacenamiento. Dicho modelo se ha implementado en el programa informático MATLAB® y se ha empleado para simular los diferentes sistemas considerados. Se han realizado simulaciones con el fin de optimizar todas las alternativas de diseño consideradas siguiendo criterios económicos., [EN] The objective of this Master's Final Project has been the design, dimensioning and study of the economic viability of a grid-connected solar photovoltaic installation to supply electrical energy to a hot-dip galvanizing plant located in Cheste (Valencia). In the design and sizing process, the selection of each of the elements that make up the installation (solar panels, inverters...) has been justified taking into account the current legislation in Spain and taking into account both economic and technical criteria, prioritizing those components that are available in the market. In addition, a comparative study of different connection configurations, as well as different energy storage systems, has been carried out. The accumulation system options that have been considered in this work were lithium ion, lead acid, all vanadium redox flow batteries and accumulation in the form of hydrogen. Finally, a model of the photovoltaic generation system and the different storage systems has been proposed. Said model has been implemented in the MATLAB® computer program and has been used to simulate the different systems considered. Simulations have been carried out in order to optimize all the design alternatives considered following economic criteria.

[ES] En este trabajo se implementó un simulador en tiempo real de una planta piloto de control de conductividad. La planta, que se encuentra en los laboratorios del Departamento de Ingeniería Química y Nuclear de la UPV, consta de dos tanques de almacenamiento, que contienen ácido clorhídrico y agua de red, respectivamente. A su vez, estos cuentan con dos bombas peristálticas que impulsan sendos fluidos a un tanque químico agitado con rebosadero. Es aquí donde, mediante un conductímetro en el interior del tanque, se realiza la medida de conductividad. El sistema cuenta con un sistema de control que controla la conductividad del interior del tanque manipulando el caudal de ácido. El simulador se validó experimentalmente, funcionando tanto en manera manual como automático En primer lugar, fue necesario obtener las ecuaciones diferenciales características del sistema a partir de los balances de materia. Una vez realizados los balances de materia, se realizó una batería de experimentos para proponer un modelo de conductividad, relacionando la concentración de ácido con la conductividad de la disolución. En última instancia, se procedió a implementar todos los modelos en el instrumento virtual mediante LabVIEW®; el que correspondería al simulador en tiempo real de la planta., [EN] In this work, a real-time simulator of a conductivity control pilot plant was implemented. The plant, which is located in the laboratories of the UPV's Department of Chemical and Nuclear Engineering, consists of two storage tanks, which contain hydrochloric acid and tap water, respectively. In turn, these have two peristaltic pumps drive fluids to an agitated chemical tank with an overflow. It is here where, by means of a conductivity meter inside the tank, the conductivity measurement is carried out. The system has a control system that controls the conductivity inside the tank by manipulating the flow of acid. The simulator was experimentally validated, operating in both manual and automatic mode. In the first place, it was necessary to obtain the characteristic differential equations of the system we obtained from the material balances. Once the material balances were determined, a battery of experiments was carried out in order to propose a conductivity model, relating the acid concentration with the conductivity of the solution. Ultimately, all the models were implemented in the virtual instrument using LabVIEW®; which would correspond to the real-time simulator of the plant.

[ES] La leche es un producto básico en la alimentación de los seres humanos especialmente, en los recién nacidos debido a sus cualidades nutricionales que cubren las necesidades básicas aportando los tres nutrientes principales como son los hidratos de carbono, las proteínas y las grasas además de minerales y vitaminas. Debido a su composición química, es un medio perfecto para el crecimiento de una gran variedad de microorganismos patógenos para la salud por lo que es necesario realizar un tratamiento térmico con el objetivo de eliminarlos. En el presente trabajo se ha diseñado un sistema de tratamiento térmico para esterilización de la leche de tipo ultrapasteurización (UHT). Como parte del diseño del sistema UHT se han dimensionado los diferentes equipos que lo componen: un sistema de intercambiadores, un homogeneizador y un tubo de retención. Además, se ha realizado el diseño de un sistema de control de temperaturas. En este caso se ha considerado un sistema de control por realimentación convencional (Feeback control) en el que se estudia la posibilidad de añadir un Predictor de Smith para mejorar la respuesta del sistema tanto en modo servo como en modo regulador., [EN] Milk is a basic product in the diet of human beings especially in newborns due to its nutritional qualities that cover the basic needs providing the three main nutrients such as carbohydrates, proteins and fats as well as minerals and vitamins. Due to its chemical composition, it is a perfect medium for the growth of a wide variety of pathogenic microorganisms, which is why it is necessary to carry out a heat treatment in order to eliminate them. In this work, a heat treatment system for ultrapasteurization (UHT) of milk has been designed. As a part of the design of the UHT system, the different equipments have been sized: a system of heat exchangers, a homogeneizer and a holding tube. In addition, the design of the temperature control system has been carried out. In this case a conventional feeback control system has been cosidered. In addition, the option of using a Smith’s Predictor in order to improve the dynamical responde of the system in both, servo and regulator modes, has been studied., [CA] La llet és un element bàsic en la dieta dels éssers humans especialment en els nounats a causa de les seues qualitats nutricionals que cobreixen les necessitats bàsiques aportant els tres nutrients principals com els hidrats de carboni, les proteïnes i els greixos a més de minerals i vitamines. A causa de la seua composició química, és un mitjà perfecte per al creixement d’una gran varietat de microorganismes patògens per a la salut per la qual cosa és necessari realitzar un tractament tèrmic amb l’objectiu d’eliminar-los. En el present treball s’ha dissenyat un sistema de tractament tèrmic per a la esterilització de la llet de tipus ultrapasteurització (UHT). Com a part del disseny del sistema UHT s’han dimensionat els diferents equips que el componen: un sistema de bescanviadors, un homogeneïtzador i un tub de retenció. A més, s’ha realitzat el disseny d’un sistema de control de temperatures. En quest cas s’ha considerat un sistema de control per realimentació convencional (Feedback control) on s’estudia la possibilitat d’afegir un Predictor de Smith per a millorar la resposta del sistema tant en manera servo com en manera reguladora.

[ES] El PMMA es un polímero de alto interés industrial. Destaca de otros plásticos transparentes por su capacidad de resistencia al rayado, así como a la radiación ultravioleta, y por su alta transparencia entre otras cualidades. Esto convierte a este polímero en un material muy demandado para aplicaciones como vitrinas, letreros luminosos, fibra óptica, etc. En la industria, el PMMA es producido mediante reactores que operan en modo discontinuo a una temperatura de 80 ºC. Dicha temperatura, se controla mediante una camisa de refrigeración y mediante la adición de disolventes. El correcto manejo de los diferentes elementos de la instalación es muy importante para mantener al proceso trabajando dentro del rango de seguridad, ya que la reacción de polimerización del PMMA presenta riesgo de auto-aceleración por efecto Trommsdorff-Norrish, lo que puede provocar un descontrol térmico del reactor de polimerización con graves consecuencias para la planta. Un elemento fundamental para garantizar la seguridad de la planta es el entrenamiento de los operarios. Una herramienta muy útil para llevar a cabo dicho entrenamiento son los simuladores en tiempo real, que facilitan y aceleran la formación de nuevo personal, puesto que, sin este tipo de software, el proceso de capacitación sería mucho más prolongado en el tiempo y más peligroso. El objetivo de este trabajo es el diseño e implementación de un simulador en tiempo real de la unidad de polimerización de una planta de fabricación de PMMA. El simulador tendrá una arquitectura modular, es decir, las partes del código que simulan partes de la instalación unidas físicamente, compartirán la información de manera similar a como lo harían en la realidad, siendo los datos compartidos entre funciones los datos correspondientes a las corrientes que las conectan, y las funciones, los elementos de la instalación tales como bombas, tanques, caudalímetros, etc. Tras la generación de dichas funciones y la puesta en funcionamiento del simul, [EN] The polymethylmethacrylate (PMMA) is a polymer with a high industrial interest. It has better properties that other polymers, such as resistance to scratching and UV beams and high transparency among others. These characteristics make this polymer a material with high demand in applications as showcases, luminous posters, optical bres etc. In the industry, PMMA is produced with reactors that operate in semi-bacth mode and with a 80 °C. This temperature is controlled by a jacket of refrigeration and working in solution. The correct management of the di erent devices of the installation has a huge importance to keep the process in its safe range, since the PMMA polymerization reaction of polymerization presents thermal run away risk. This e ect can cause a failure of control temperature, with catastrophic consequences to the plant. A important element to guaranty security is the training of operators. Real time simulators are a very useful tool to improve operators training is simulators in real time, since they accelerate and meke easier the formation of new operators. Without this type of simulators, the training process will be longer, riskier and more expensive. The goal of this Final Project is the design and implementation of real time simulator of plant of PMMA. The developed simulator has a modular structure, in where the diferent models represent the real life elements of the plant. First, the individual functions were developed and tested to assure their correct behaviour. Two gra cal interfaces were developed: one for the supervisor and the other for the operator. Finally, the entire simulator was tested to assure that the simulator works correctly in real time. To achieve this objective, the language of programmation used is LabVIEW®, to have their graphical interface and the module Control & simulation , this module is design to be applicated resolving di erential equations and control applications. Finally, this nal project has a budget counting the

[EN] The salicylate method is one of the ammonia quantification methods that has been extensively used in literature for quantifying ammonia in the emerging field of nitrogen (electro)fixation. The presence of iron in the sample causes a strong negative interference on the salicylate method. Today, the recommended method to deal with such interferences is the experimental correction method: the iron concentration in the sample is measured using an iron quantification method, and then the corresponding amount of iron is added to the calibration samples. The limitation of this method is that when a batch of samples presents a great iron concentration variability, a different calibration curve has to be obtained for each sample. In this work, the interference of iron III on the salicylate method was experimentally quantified, and a model was proposed to capture the effect of iron III interference on the ammonia quantification result. This model can be used to correct the iron III interferences on ammonia quantification. The great advantage of this correction method is that it only requires three experimental curves in order to correct the iron III interference in any sample provided the iron III concentration is below the total peak suppression concentration.

[EN] In this work, ecotoxicological bioassays based on Lactuca sativa seeds and bioluminescent bacterium (Vibrio fischeri) have been carried out in order to quantify the toxicity of Norfloxacin (NOR) and sodium sulfate solutions, before and after treating them using electrochemical advanced oxidation. The effect of some process variables (anode material, reactor configuration and applied current) on the toxicity evolution of the treated solution has been studied. A NOR solution shows an EC50 (5 days) of 336 mg L-1 towards Lactuca sativa. This threshold NOR concentration decreases with sodium sulfate concentration, in solutions that contain simultaneously Norfloxacin and sodium sulfate. In every case considered in this work, the electrochemical advanced oxidation process increased the toxicity (towards both Lactuca sativa and Vibrio fischeri) of the solution. This toxicity increase is mainly due to the persulfate formation during the electrochemical treatment. From a final solution toxicity point of view, the best results were obtained using a BDD anode in a divided reactor applying the lowest current intensity.

[EN] In this work, a simple Simulink® model of a conductivity control system, based on a Smith’s predictor, is presented. This model has three main didactic outcomes. First, it allows to show to the students how a computational tool can be used to solve problems that would require a fair amount of work if they were solved analytically. Second, it allows to present an example of advanced controller: the Smith’s predictor. Finally, using this model, students can “play” with the system in order to study the effect of the different system and controller parameters on the performance of the controlled system., [ES] En este trabajo se presenta un modelo sencillo de Simulink de un sistema de control de conductividad, basado en un predictor de Smith. Este modelo tiene tres objetivos didácticos principales. En primer lugar, permite mostrar a los estudiantes cómo se puede usar una herramienta computacional para resolver problemas que requerirán una cantidad considerable de trabajo si se resolvieran analíticamente. En segundo lugar, permite presentar un ejemplo de controlador avanzado: el predictor de Smith. En último lugar, empleando este modelo los estudiantes pueden "jugar" con el sistema para estudiar el efecto de los diferentes parámetros del sistema y del controlador sobre el desempeño del sistema controlado.

[ES] En este trabajo, se diseñará un sistema de baterías de flujo redox de todo vanadio de 4 W de potencia, destinado a tareas de investigación en el grupo IEC del departamento de Ingeniería Química y Nuclear de la Universitat Politècnica de València. En primer lugar, se realizará el diseño de la batería de flujo redox de todo vanadio, a partir de la premisa de que la potencia que ha de suministrar debe ser de 4 W. En esta parte, se dimensionarán y seleccionarán los diferentes elementos de instalación: celda electroquímica, tanques de electrolitos, cables eléctricos, conducciones, accesorios, bomba e instrumentos necesarios para realizar las pruebas en la batería. Además, se indicarán las conexiones entre los diferentes elementos diseñados, la disposición de estos en el espacio del laboratorio reservado para las pruebas de esta batería y los protocolos experimentales necesarios para operar dicho sistema. En segundo lugar, se definirán la puesta a punto de los métodos analíticos para la determinación de vanadio, que se requieren durante el funcionamiento del sistema, para poder monitorizar el estado de carga de la batería a través de la cuantificación de la concentración de las diferentes especies del vanadio en el electrólito de la batería. Concretamente, se utilizarán espectrofotometría UV-Visible y de absorción atómica. También se describirá el método de síntesis del electrolito a utilizar en la batería a partir de su precursor, el VOSO4·xH2O. Por último, se detallará el presupuesto requerido para la realización del diseño propuesto que junto con los planos de la plataforma experimental de baterías de flujo redox de todo vanadio, definirá completamente la instalación para su posterior materialización y puesta a punto., [EN] In this work, a 4 W power redox flow all vanadium battery system has been designed for research tasks in the IEC group of the Department of Chemical and Nuclear Engineering of the Universitat Politècnica de València. First of all, the design of the redox flow battery of all vanadium has been carried out, based on the premise that the power to be supplied must be 4 W. In this part, the different elements of Installation are sizing and selected: electrochemical cell, electrolyte tanks, electrical cables, pipes, accessories, pump and instruments necessary to carry out the tests on the battery. In addition, the connections between the different designed elements are indicated, their arrangement in the laboratory space reserved for testing this battery and the experimental protocols necessary to operate such a system. Secondly, the set-up of the analytical methods for the determination of vanadium, which are required during the operation of the system, has been defined to be able to monitor the state of charge of the battery through the quantification of the concentration of the different vanadium species in the battery electrolyte. Specifically, UV-Visible and atomic absorption spectrophotometry has been used. The synthesis method of the electrolyte used in the battery from its precursor, VOSO4 · xH2O, has also been described. Finally, the budget required for the realization of the proposed design is detailed, which together with the plans of the experimental platform for redox flow batteries of all vanadium, completely defines the installation for its subsequent materialization and tuning.

[ES] En el presente trabajo, se ha realizado el diseño de un sistema de generación de energía fotovoltaica de 50 kW para una nave industrial situada en la localidad de Alcalá de Guadaira (Sevilla). En el diseño se ha incluido como sistema de acumulación de energía una batería de flujo redox de Vanadio, con el fin de aumentar la eficiencia energética del sistema global, maximizando el aprovechamiento de la energía producida por la instalación. En primer lugar, se ha realizado el diseño la parte de generación del sistema (i.e. parte fotovoltaica). En una segunda parte, se ha hecho lo propio con la parte de acumulación de energía del sistema (i.e. baterías de flujo redox). Además del diseño, se ha elaborado un modelo matemático del sistema que se ha empleado para validar que el sistema diseñado cumplía con las especificaciones de diseño. Por último, se ha estimado el presupuesto requerido para la realización del diseño propuesto., [CA] En el present treball , es realitza el disseny d’un sistema de generació fotovoltaica de 50 kW per a una nau industrial en la localitat d’Alcalá de Guadaira(Sevilla) . En el disseny s’inclou com a sistema d’acumulació d’energia una bateria de flux redox de Vanadi, amb la fi d’augmentar l’eficiència energètica del sistema global, maximitzant l’aprofitament de l’energia produïda per ‘instal·lació. En primer lloc es realitza el disseny de la part de generació del sistema(i.e. part fotovoltaica). En una segona part, es fa lo propi amb la part d’acumulació d’energia del sistema(i.e. bateries de flux redox. A continuació es valida mitjançant les simulacions pertinents que el sistema dissenyat es capaç d’operar en les condicions requerides per l’aplicació. Per últim, s’estimarà el pressupost requerit per a la realització del disseny proposat., [EN] In this document it’s been designed a photovoltaic energy generating system of 50 kW for an industrial building located in Alcalá de Guadaira (Sevilla). In the design, it’s included as an energy storage system a vanadium redox flow battery for the purpose of increasing the global efficiency of the system by maximizing the usage of the energy produced. Firstly, it’s designed the generating part of the system (i.e. the photovoltaic plant). Secondly, the same is done with the energy storage system (i.e. redox flow battery). Then, the design is validated assuring it’s capable of working under the required conditions based on the mathematic model that has been developed and its simulation. At last, it’s estimated the budget of the proposed design.

[ES] En este trabajo, se ha diseñado un sistema de recuperación que separa los principales metales de un efluente minero. En este caso, se ha considerado la técnica de precipitación fraccionada, con el objeto de poder separar y recuperar los metales de interés de dicho efluente. En primer lugar, se ha elaborado un modelo dinámico del sistema de precipitación completo, que se ha implementado con la herramienta MATLAB® y su aplicación gráfica Simulink®. Una vez validado, dicho modelo se ha empleado para el diseño del proceso de precipitación fraccionada empleando como criterios de diseño la fracción recuperada de cada uno de los metales considerados y la pureza de cada metal en los lodos generados. Posteriormente, se ha diseñado el sistema de control de pH, un elemento clave del proceso de precipitación fraccionada. Por último, se ha estimado el presupuesto requerido para la realización del diseño propuesto para el proceso de precipitación fraccionada., [EN] In this work, it is designed a recovery system that separates the main metals from a mining effluent. In this case, the fractional precipitation technique has been considered, in order to be able to separate and recover the interesting metals from the effluent. Firstly, a dynamic model of the complete precipitation system has been developed, which has been implemented with the MATLAB® tool and its Simulink® graphic application. Once validated, this model has been used for the design of the fractional precipitation process using as design criteria the fraction recovered from each of the metals considered and the purity of each metal in the generated sludge. Subsequently, the pH control system, which is a key element in the fractional precipitation process, was designed. Finally, the budget required to carry out the proposed design for the fractional precipitation process has been estimated.

[EN] Cyclic voltammetry is one of today's standard electrochemical measurement techniques. What characterizes cyclic voltammetry is that potential is linearly ramped in cycles. In general, in this kind of measurements, the system tends to a stationary state, which is known as limit cycle. The common practice for assessing the voltammogram convergence is to perform a multicycle cyclic voltammetry, and visually compare the sequential cycles in order to see if there are significant changes from one cycle to the following one. The main limitation of visual comparison is its limited accuracy and its dependence on the analyst's subjectivity. In this work, an algorithm for quantitatively assessing the convergence of experimental cyclic voltammograms (CVs) was developed. The algorithm was successfully validated experimentally using two systems: it is able to determine whether the CV converged to its limit cycle, and when it converged. Moreover, the algorithm is able to quantify the measurement noise. The low computational cost of the developed algorithm allows to execute it in real time during the cyclic voltammetry measurement. In this way, it can be used in order to automate the measurement process which would decide, according to predefined convergence criteria, when to stop cycling.

[EN] Antimony¿doped tin oxide electrodes with CuO as sintering aid are presented as an economical alternative to metal¿based electrodes, intended for the electrooxidation process of emerging and recalcitrant organic contaminants in wastewaters. The CuO proportion has been optimized to obtain densified electrodes with a mild thermal cycle (Tmax = 1200°C). One of the manufactured electrodes (97.8 mol.% of SnO2, 1.0 mol.% of Sb2O3, and 1.2 mol.% of CuO) was selected for electrochemical characterization from a physical and morphological analysis. The electrochemical behavior of the selected electrode showed that the addition of CuO as sintering aid widens the electrochemical window and increases the electrode ¿inactivity¿, with respect to an (Sn, Sb)O2 electrode synthesized in the same conditions. In return, the (Sn,Sb,Cu)O2 electrode presents a significantly lower electrochemical rugosity factor. Moreover, the addition of CuO does not change the oxygen evolution reaction mechanism, but it modifies the kinetic parameters, leading to a larger accumulation of hydroxyl radicals. Consequently, the addition of CuO as sintering aid significantly improves the electrochemical properties of the electrode as an electrochemical advanced oxidation process anode with respect to the (Sn,Sb)O2 electrode, at the expense of worsening its electrochemical roughness factor. The results of the electrochemical characterization were confirmed by Norfloxacin degradation tests.

This is the peer reviewed version of the following article: Giner-Sanz, J. J., Sanchez-Rivera, M. J., Garcia-Gabaldon, M., Ortega, E. M., Mestre, S., & Perez-Herranz, V. (2019). Improvement of the Electrochemical Behavior of (Sb, Sn, Cu)O Ceramic Electrodes as Electrochemical Advanced Oxidation Anodes. ChemElectroChem, 6(9), 2430-2437. https://doi.org/10.1002/celc.201801766, which has been published in final form at https://doi.org/10.1002/celc.201801766. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving., [EN] This work explores the possibility of increasing the active surface of a Sb-doped SnO2 ceramic electrode using CuO as sintering aid, by incorporating petroleum coke as a pore generator. In order to fulfil this goal, three series of (Sb, Sn, Cu)O electrodes with different coke contents were synthetized. The properties of the electrodes, and their microstructure, change significantly as a function of the coke content before sintering. The electrochemical characterization of the synthesized electrodes showed that the coke addition before sintering causes two antagonist effects on the performance of the (Sn, Sb, Cu)O as anodes in electrochemical advanced oxidation processes (EAOP). On one hand, it significantly improves the electrochemical roughness factor of the electrode, solving the densification problem in this way. On the other hand, it worsens the electrochemical behavior of the electrode: narrowing its electrochemical window; and ¿activating¿ it slightly. The addition of coke before sintering changes the kinetic parameters, leading to a kinetic situation in which the accumulation of hydroxyl radicals is slightly lower. A balance must be sought: an intermediate coke content will improve significantly the electrochemical roughness factor of the electrode, but will only worsen slightly its electrochemical behavior, leading to an optimum (Sn, Sb, Cu)O EAOP anode.

[EN] The great ubiquity and utility of genetic algorithms (GAs) in nearly every field of Sciences and Engineering, makes them essential for future scientists and engineers. For this reason GAs should be covered in scientific and engineering graduate curricula. In this work, a simple NetLogo® model is presented. Its goal is to introduce GAs in such way that students new to the field can grasp the basic concepts behind GAs while they discover the model. This model may be used in a computer lab session, as an online applet for the students to revise the concepts after the class, or in a Massive Open Online Course (MOOC) course., [ES] La gran ubicuidad y utilidad de los algoritmos genéticos (AGs) en casi todos los campos de las Ciencias e Ingenierías, los convierte en una herramienta esencial para los futuros científicos e ingenieros. Por esta razón, los AGs deben incluirse en los planes de estudios de posgrado en Ciencias e Ingenierías. En este trabajo, se presenta un modelo simple de NetLogo®, cuyo objetivo es presentar los GAs de tal manera que los estudiantes nuevos en el campo puedan comprender los conceptos básicos que hay detrás de dichos algoritmos mientras exploran el modelo. Este modelo puede usarse en prácticas informáticas, como una applet en línea para que los estudiantes revisen los conceptos después de clase, o en un curso online masivo y abierto (MOOC, por sus siglas en inglés).

[EN] Despite the importance of Bayesian inference and the growth of Bayesian research, today, most undergraduate teaching is still based on frequentist statistics. A way of facilitating the introduction of students to the Bayesian world is to strongly reinforce the basic concepts behind the Bayesian philosophy. In this work, a simple Labview® program for reinforcing and illustrating the basic concepts underlying Bayesian inference is presented. This program may be used in a computer lab session, or as an online applet for the students to revise the concepts after the class or in a Massive Open Online Course (MOOC) course., [ES] A pesar de la importancia de la inferencia Bayesiana y el crecimiento de la investigación Bayesiana, hoy por hoy, la mayoría de los planes de estudio de grado todavía se basan en la estadística frecuentista. Una forma de facilitar la introducción de los estudiantes al mundo Bayesiano es reforzar los conceptos básicos de la filosofía Bayesiana. En este trabajo, se presenta un programa implementado en Labview® para reforzar e ilustrar los conceptos básicos que subyacen a la inferencia Bayesiana. Este programa se puede usar en prácticas informáticas, o como un applet en línea para que los estudiantes revisen los conceptos después de clase o en un curso online masivo y abierto (MOOC, por sus siglas en inglés).

[EN] Usually, EIS measurements are performed in 2 steps: a stabilization step followed by an acquisition step. The first is necessary in order to ensure that the impedance is determined when the system has reached its stationary state. In this work, a theoretical framework is proposed for estimating the required stabilization time for EIS measurements. Here, it was applied to the simplest case: the simplified Randles cell. In order to calculate the required stabilization time for performing EIS measurements, a theoretical dynamic model of a Randles cell under galvanostatic sinusoidal perturbation was developed. The proposed model can be used to estimate, from a theoretical point of view, the required stabilization time for performing EIS measurements in a Randles-like system. Even though, this work focuses on the simplest case, the developed theoretical framework can be applied to any system, however complex it may be.

[EN] he internal resistance of a PEM fuel cell depends on the operation conditions and on the current delivered by the cell. This work's goal is to obtain a semiempirical model able to reproduce the effect of the operation current on the internal resistance of an individual cell of a commercial PEM fuel cell stack; and to perform a statistical analysis in order to study the effect of the operation temperature and the inlet humidities on the parameters of the model. First, the internal resistance of the individual fuel cell operating in different operation conditions was experimentally measured for different DC currents, using the high frequency intercept of the impedance spectra. Then, a semiempirical model based on Springer and co-workers¿ model was proposed. This model is able to successfully reproduce the experimental trends. Subsequently, the curves of resistance versus DC current obtained for different operation conditions were fitted to the semiempirical model, and an analysis of variance (ANOVA) was performed in order to determine which factors have a statistically significant effect on each model parameter. Finally, a response surface method was applied in order to obtain a regression model.

[EN] Electrochemical impedance spectroscopy (EIS) has been widely used in the fuel cell field since it allows deconvolving the different physic-chemical processes that affect the fuel cell performance. Typically, EIS spectra are modelled using electric equivalent circuits. In this work, EIS spectra of an individual cell of a commercial PEM fuel cell stack were obtained experimentally. The goal was to obtain a mechanistic electric equivalent circuit in order to model the experimental EIS spectra. A mechanistic electric equivalent circuit is a semiempirical modelling technique which is based on obtaining an equivalent circuit that does not only correctly fit the experimental spectra, but which elements have a mechanistic physical meaning. In order to obtain the aforementioned electric equivalent circuit, 12 different models with defined physical meanings were proposed. These equivalent circuits were fitted to the obtained EIS spectra. A 2 step selection process was performed. In the first step, a group of 4 circuits were preselected out of the initial list of 12, based on general fitting indicators as the determination coefficient and the fitted parameter uncertainty. In the second step, one of the 4 preselected circuits was selected on account of the consistency of the fitted parameter values with the physical meaning of each parameter.

[EN] Ohm's generalized law defines the concept of impedance. This law, and thus the definition itself, are only valid if the system fulfills the linearity condition. However, electrochemical systems are typically highly nonlinear. Consequently, the linearity condition can only be achieved in these systems if a low perturbation amplitude is used for performing EIS measurements. Nevertheless, the use of low amplitude perturbations leads to low signal-to-noise ratios, which result in high measurement errors. The concept of optimum amplitude arises from this tradeoff: the perturbation has to have an amplitude big enough in order to minimize the measurement errors (i.e. maximize the SNR), but at the same time, the perturbation has to have an amplitude small enough to avoid the generation of significant nonlinear effects that would distort the measured EIS spectra. In a previous work, a linearity assessment quantitative method based on the total harmonic distortion parameter was developed. In this work, the aforementioned THD method was applied for the perturbation amplitude selection for EIS measurements in a highly nonlinear model system: the cathodic electrode of an alkaline water electrolyzer. The THD method successfully obtained the optimum amplitudes both, for a constant amplitude strategy and for a frequency dependent strategy. The THD method also allowed to obtain the noise structure and to quantify the nonlinear effects. This method is slightly superior to the U-P method, a method based on the harmonic analysis of the output signal that was developed in earlier works. (C) 2018 The Electrochemical Society.

The concept of Hydrogen Economy, coined in the second half of the twentieth century, has gained strength as a solution to the problems derived from the consumption of fossil fuels. The main idea of the Hydrogen Economy is the use of hydrogen as an energy vector. Fuel cells play a leading role in this economy, since today, fuel cells are the most attractive hydrogen final conversion technology. This technology, invented more than 150 years ago, is well established nowadays. However, there is still research to be done in the fuel cell field, in order to make them economically profitable in comparison to the competing technologies. One of the research lines that have attracted a great attention in recent years, is the development of diagnosis and control tools for fuel cells. This Thesis is framed in this research line. This work's main goal is to obtain a semiempirical model of an individual cell of a commercial 300W PEM fuel cell stack. The developed model is meant to be used in diagnosis and control systems. In order to fulfill this goal, a steady state model and a dynamic model were developed. On the one hand, the developed steady state model consists in a semiempirical steady state model coupled with an open circuit loss model, obtained from the open circuit loss experimental characterization. On the other hand, the proposed dynamic model consists in an electric equivalent circuit with a mechanistic meaning, coupled with an empirical model to represent the evolution of the equivalent circuit parameters with the operation current. Since the dynamic model was built using electrochemical impedance spectroscopy (EIS) spectra, two experimental EIS spectra validation methods were developed in this work. Moreover, the EIS measurement was optimized in order to minimize the experimental error related to EIS measurements. Both, the measurement parameters and the perturbation amplitude, were optimized in this work. Finally, a statistical study was performed in order to deter, El concepto de Economía del Hidrógeno, acuñado en la segunda mitad del siglo XX, ha ido cobrando fuerza como solución a los problemas derivados del consumo de combustibles fósiles. La idea central de la Economía del Hidrógeno es el empleo del hidrógeno como vector energético. Las pilas de combustible tienen un papel protagonista en dicha Economía, siendo la tecnología de conversión final de hidrógeno más atractiva en la actualidad. Esta tecnología, inventada hace más de 150 años, está bien establecida actualmente. Sin embargo, aún quedan líneas de investigación abiertas en el campo de las pilas de combustible, para conseguir que sean rentables frente a las tecnologías competidoras. Una de dichas líneas de investigación es la problemática de su diagnóstico y control. Y es precisamente en esta línea de investigación donde se enmarca la presente Tesis. El objetivo central es la elaboración de un modelo semiempírico de una monocelda individual de un stack comercial de tipo PEM de 300 W. La finalidad del modelo desarrollado es su empleo en sistemas de diagnóstico y control. Para conseguir dicho objetivo se elaboró tanto un modelo estacionario del sistema, como uno dinámico. Por una parte, el modelo estacionario corresponde con un modelo semiempírico estacionario acoplado con un modelo de pérdidas de circuito abierto, este último desarrollado a partir de la caracterización experimental de dichas pérdidas. Por otra parte, el modelo dinámico propuesto corresponde con un circuito eléctrico equivalente con sentido mecanístico, dotado de un modelo empírico para representar la evolución de los parámetros del circuito equivalente con la corriente de operación. Puesto que dicho modelo se construyó empleando la técnica de espectroscopia de impedancias electroquímicas, se decidió desarrollar métodos de validación de espectros de impedancias electroquímicas obtenidos experimentalmente; y se optimizó el método de medida de los espectros, tanto los parámetros de medida como la amplitu, El concepte d'Economia de l'Hidrogen, encunyat en la segona mitat del segle XX, ha anat cobrant força com a solució als problemes derivats del consum de combustibles fòssils. La idea central de l'Economia de l'Hidrogen és la utilització de l'hidrogen com a vector energètic. Les piles de combustible tenen un paper protagonista en dita Economia, sent la tecnologia de conversió final d'hidrogen més atractiva en l'actualitat. Esta tecnologia, inventada fa més de 150 anys, està ben establida actualment. No obstant això, encara queden línies d'investigació obertes en el camp de les piles de combustible, per a aconseguir que sigan rendibles enfront de les tecnologies competidores. Una de dites línies d'investigació és la problemàtica del seu diagnòstic i control. I és precisament en esta línia d'investigació on s'emmarca la present Tesi. L'objectiu central és l'elaboració d'un model semiempíric d'una monocel·la individual d'un stack comercial de tipus PEM de 300 W. La finalitat d'aquest model és la seua utilització en sistemes de diagnòstic i control. Per a aconseguir dit objectiu es va elaborar tant un model estacionari del sistema, com un dinàmic. D'una banda, el model estacionari desenrotllat correspon amb un model semiempíric estacionari acoplat amb un model de pèrdues de circuit obert, desenrotllat a partir de la caracterització experimental de dites pèrdues. D'altra banda, el model dinàmic proposat correspon amb un circuit elèctric equivalent amb sentit mecanístic, dotat d'un model empíric per a representar l'evolució dels paràmetres del circuit equivalent amb el corrent d'operació. Ja que dit model es va construir emprant la tècnica d'espectroscòpia d'impedàncies electroquímiques, es va decidir desenrotllar mètodes de validació que permeten validar els espectres d'impedàncies electroquímiques obtinguts experimentalment; i es va optimitzar el mètode de mesura dels espectres, tant els paràmetres de mesura com l'amplitud de la pertorbació. Finalment, es va realitzar un

[EN] The impedance concept is defined by Ohm's generalized law. Ohm's law requires the fulfilment of 3 conditions in order to be valid: causality, linearity and stability. In general, electrochemical systems are highly nonlinear systems; and therefore, in order to achieve linearity low amplitude perturbations have to be used during EIS measurements. However, small amplitude perturbations lead to low signal-to-noise ratios. Consequently, the quality of an EIS measurement is determined by a trade-off: the perturbation amplitude should be big enough in order to obtain a good signal-to-noise ratio; and at the same time, it should be small enough in order to avoid significant nonlinear effects. The optimum perturbation amplitude corresponds with the maximum perturbation amplitude that ensures a pseudo linear response of the system. In this work, a method for experimentally determining the optimum perturbation amplitude for performing EIS measurements of a given system is presented. The presented method is based on the harmonic analysis of the output signals; and in this work, it was applied to a highly nonlinear system: the cathodic electrode of an alkaline water electrolyser. The presented method allows optimising the perturbation amplitude in both, constant amplitude and frequency dependant amplitude strategies. (c) 2017 The Electrochemical Society. All rights reserved.

Electrochemical Impedance Spectroscopy (EIS) is a very powerful tool to study the behaviour of electrochemical systems. Three conditions must be fulfilled during EIS measurements: causality, linearity, and stability. If any of these conditions is not achieved, then the conclusions obtained from the analysis of the measured spectra may be biased, or even misguided. For this reason, the verification of the compliance of these conditions is critical before accepting any analysis performed on an experimental spectrum. In a previous work, an experimental spectrum quantitative validation technique based on Kramers-Kronig relations was presented. The validation method consists in a Kramers-Kronig (KK) validation test, by equivalent electrical circuit fitting, coupled with a Montecarlo error propagation method. The validation technique builds a consistency region for a given confidence level that allows to discriminate between the individual points of the EIS spectrum that are consistent with the four fundamental hypotheses, and the inconsistent ones. The aim of this work is to validate experimentally if the quantitative validation technique is able to detect nonlinearities. In order to achieve this goal, the EIS spectrum of a markedly nonlinear system was measured experimentally using different perturbation amplitudes. The validation technique was applied to each one of the measured spectra. The method successfully managed to identify large nonlinearities; but did not detect slight ones.

Electrochemical Impedance Spectroscopy (EIS) is an electrochemical measurement technique that has been applied to a broad range of applications. Three conditions must be fulfilled in order to obtain valid EIS measurements: causality, linearity and stationarity. The non fulfilment of any of these conditions may lead to distorted and biased EIS spectra. Consequently, the verification of the four fundamental conditions is mandatory before accepting any results extracted from an EIS spectrum. In this work, a harmonic analysis based method for linearity assessment and noise quantification in EIS measurements is presented, and validated both from an experimental point of view and from a theoretical point of view, for Tafelian systems. It was shown that the presented method was able to quantitatively assess the nonlinearity of the system; and to quantify and characterize the noise. Moreover, the presented method is able to determine the threshold frequency of the system above which the system does not present significant nonlinear effects even for very large perturbation amplitudes.

One of the most important measurement parameters in electrochemical impedance spectroscopy (EIS) is the perturbation amplitude. The optimum perturbation amplitude value corresponds with a balance between the signal-to-noise ratio improvement and the reduction of the harmonic generation due to nonlinear effects. Therefore, the optimum perturbation amplitude is the maximum amplitude that ensures a linear response of the system. Two strategies were considered in this work, i.e., a constant amplitude strategy and a frequency dependent amplitude strategy. On the one hand, for the constant amplitude strategy, the optimum perturbation amplitude for EIS measurements of an individual cell of a commercial PEM fuel cell stack was determined. In order to fulfill this aim, the impedance spectra (at different DC currents) of the individual cell of the commercial PEM fuel cell stack were measured using different perturbation amplitudes. The total harmonic distortion of the recorded voltage signal was determined in each case, applying a FFT based method. The optimum amplitude for each DC current corresponds to the amplitude that minimizes the critical total harmonic distortion value. On the other hand, for the frequency dependent amplitude strategy, the optimum amplitude at each frequency for EIS measurements of an individual cell of a commercial PEM fuel cell stack was determined.

Currently, electrochemical Impedance Spectroscopy (EIS) is a widely used tool for the study of electrochemical systems, in general; and fuel cells, in particular. A great effort is typically invested in the analysis of the obtained spectra; whereas, little time is usually spent optimizing the measurement parameters used to obtain these spectra. In general, the default settings provided by the control software used to perform the measurements, or the parameters used in similar systems available in literature, are selected to carry out the measurements. The goal of this work is to determine the optimal measurement parameters for obtaining impedance spectra of a commercial PEM fuel cell. In order to achieve this, a 2^5 factorial design was considered. Five factors were considered, the five impedance spectroscopy measurement parameters: maximum integration time; minimum number of integration cycles; number of stabilization cycles; maximum stabilization time; and minimum cycle fraction. For each factor combination envisaged in the experimental design, the cell spectrum was obtained in given operation conditions, for which the reference spectrum of the system was known, since it had been determined in previous works. The experimentally obtained spectra were fitted to the reference electric equivalent circuit. The mean square error between the experimental data fitting and the reference spectrum fitting was determined in each case, and was used as the dependant variable for the experimental design analysis. An analysis of the variance was performed in order to determine which measurement parameters have a significant effect on the dependant variable; and a model relating the dependant variable and the measurement parameters was built. This model was used in order to obtain the optimal value of each one of the measurement parameters that minimized the mean square error of the fit obtained from the experimental data with respect to the reference fit.

An individual PEM fuel cell 6-parameter mechanistic model was developed. In parallel, experimental polarization curves were obtained at different temperature and inlet gas humidities conditions. The 6 model parameters were determined by fitting the semi empirical model to the experimental curve using a non linear regression method. Finally, a statistical analysis was carried out in order to determine which operating conditions (temperature and inlet humidities) have a significant effect on which model parameters. A black box model was built in order to relate the model parameter values to the significant operating conditions for each one of them. The obtained model was able to satisfactory reproduce the experimental behaviour of the system at low current densities.

Electrochemical Impedance Spectroscopy (EIS) is a very powerful tool to study the behaviour of electrochemical systems. At present, it is widely used in the fuel cell field in order to study challenging cutting edge issues as membrane drying or gas diffusion layer flooding amongst others. The proper analysis of impedance data requires the fulfilment of four fundamental conditions: causality, linearity, stability and finiteness. The non compliance with any of these conditions may lead to biased, or even misguided, conclusions. Therefore it is critical to verify the compliance of these conditions before accepting any analysis performed on an experimental spectrum. This is even more important in a fuel cell experimental spectrum analysis, since fuel cells are markedly non stationary systems. The aim of this work is to establish an impedance spectrum quantitative validation technique to validate the whole experimental spectrum and to identify the individual points within a spectrum that do not comply any of the four conditions, in order to remove these inconsistent points from the analysis. The designed validation method consists in a Kramers Kronig (KK) validation test, by equivalent electrical circuit fitting, coupled with a Montecarlo error propagation method. In a first step, the experimental spectrum is fitted to a particular electrical equivalent circuit, which satisfies the KK relations. Then, in a second step, a statistical Montecarlo method is used in order to propagate the model fitting parameter uncertainty through the model. Using this approach, a consistency region is built for a given confidence level: the experimental points inside this region are considered consistent for the given confidence level, whereas the outside points are rejected. The method was used on PEMFC experimental impedance spectra; and it successfully managed to identify inconsistent points, associated to no stationarities.

Electrochemical Impedance Spectroscopy (EIS) is a widely used electrochemical measurement technique that has been used in a great spectrum of fields since it allows deconvolving the individual physic- chemical processes that take place in a given system. Ohm s generalized law, and thus the impedance concept, are only valid if 4 conditions are fulfilled: causality, finiteness, stationarity and linearity. In the case that any of these conditions is not achieved, the obtained impedance spectra will present distortions that may lead to biased or even erroneous results and conclusions. For this reason it is crucial to verify if the 4 conditions are fulfilled, before accepting the results extracted from impedance spectra. In this work, a linearity assessment quantitative method based in the total harmonic distortion (THD) parameter is presented and verified experimentally. The experimental validation of the implemented method showed that the implemented method is able to assess quantitatively the linearity of the system. In addition, it is also able to determine the threshold frequency above which the system will not present significant nonlinear effects even for large perturbation amplitudes. It was observed that the THD method is more sensitive to nonlinear effects than the spectra themselves.

[EN] Open circuit losses encompass a set of phenomena that reduce PEM fuel cell (PEMFC) efficiency, especially at low current densities. Properly modelling these losses is crucial for obtaining PEMFC models that reproduce accurately the experimental behaviour of PEMFCs operating at low current densities. The open circuit losses can be disaggregated into three distinct contributions: mixed potential, hydrogen crossovers and internal short-circuits. The aim of this work is to obtain a model for the anodic and the cathodic pressure effects on the hydrogen crossovers and the internal short-circuits in a commercial PEMFC. In order to achieve this goal, the hydrogen crossovers and the internal short-circuit were measured experimentally on a commercial PEMFC by linear voltammetry. The measurements were performed at a given temperature and gas inlet humidification level, for different anodic and cathodic pressures.

Proyecto Confidencial

[ES] Se elaboró un modelo semiempirico de una celda individual de combustible tipo PEM en estado estacionario. En primer lugar, se construyó un modelo mecanístico de la celda de combustible, con 7 parámetros. El valor de dichos parámetros se determinó mediante ajuste del modelo teórico a las curvas de polarización experimentalmente obtenidas en diferentes condiciones de temperatura de operación y humedad de los gases de entrada. Tras obtener el valor de los parámetros del modelo en las diferentes condiciones, se realizó un estudio estadístico para determinar qué factores de operación afectaban a que parámetros del modelo. Se obtuvo un modelo de caja negra que relacionaba el valor del parametro del modelo con los valores de temperatura de operación y humedad de los gases de entrada. Por lo tanto, para unas condiciones dadas de temperatura y humedad, se pudo estimar el valor de los coeficientes del modelo y con estos parámetros y el modelo mecanístico se pudo simular la curva de polarización en esas condiciones. Las curvas simuladas de esta manera se ajustaban muy bien a las curvas de polarización experimentales, por lo que el modelo semiempirico construido consigue modelar adecuadamente el comportamiento experimental de la celda de combustible., [EN] A single steady state PEM fuel cell semiempirical model was built. For this purpose a teoretical model was built; then, it was fitted to experimental polarization curves. The temperature and humidity effects on the model parameters were studied.