Diseño e implementación de los sistemas electrónicos de control para refrigeración y humidificación por cortocircuitos en una pila PEM de cátodo abierto

El objetivo del trabajo es desarrollar 2 sistemas de control para pilas de combustible de tipo PEM de baja temperatura. El primero consiste en un sistema de suministro de aire y refrigeración mediante ventiladores axiales que proporcionará el caudal necesario para el funcionamiento óptimo de la pila, y mantendrá la temperatura de trabajo en el rango definido por los fabricantes de los sistemas membrana electrodos (MEAs). El segundo sistema consiste en un método de humidificación de las MEAs mediante cortocircuitos periódicos en los bornes de la pila para mejorar el rendimiento y evitar un sistema extra de humidificación de los gases reactantes.<br /

Response to the comments on “Experimental study of the pressure drop in the cathode side of air-forced open-cathode proton exchange membrane fuel cells” by Dejan Brkić

ver: https://digital.csic.es/handle/10261/50719Response to the comments on “Experimental study of the pressure drop in the cathode side of air-forced open-cathode proton exchange membrane fuel cells” by Dejan BrkicPeer reviewe

Diseño, montaje, puesta en marcha y análisis energético de un sistema de generación y almacenamiento de hidrógeno, y su uso en un vehículo eléctrico con pila PEM

El desarrollo de tecnologías que permitan la producción de hidrógeno a partir de energías renovables responde a una necesidad evidente de buscar nuevas alternativas energéticas con bajos niveles de contaminación, así como para aumentar la eficiencia energética y reducir la dependencia de los combustibles fósiles. En el presente proyecto se ha realizado el diseño, el montaje, así como la puesta a punto y otras pruebas operacionales de un sistema compuesto por una estación de generación y almacenamiento de hidrógeno alimentados por el excedente de energía eléctrica fotovoltaica de una instalación agrícola aislada. El hidrógeno generado se emplea en un vehículo eléctrico de baterías, el cual se ha modificado para convertirse en un FC-PHEV basado en una pila de combustible en lugar de un motor de combustión interna. Para su realización, se han seleccionado todos los equipos para la producción, almacenamiento y suministro de hidrógeno, así como el diseño de diversos elementos para su adecuada instalación y control. Una vez concluido el montaje, se han realizado pruebas operacionales y simulaciones para la correcta puesta a punto. Entre ellas están: el acondicionamiento y caracterización experimental de la pila de hidrógeno en el banco de ensayos del LIFTEC, la verificación del sistema de circulación de gases del vehículo, el repostaje de hidrógeno o el análisis del consumo energético del vehículo. Tras la finalización del proyecto se dispondrá de un sistema aislado de generación y almacenamiento de hidrógeno a pequeña escala que permitirá el uso de este gas como alternativa al gasóleo en la propulsión de un vehículo agrícola. Después de una breve introducción en la que se propone al hidrógeno como alternativa energética, se lleva a cabo la descripción y el estado actual de la tecnología de generación de hidrógeno centrada en la electrólisis, su almacenamiento y posterior aplicación en vehículos eléctricos. Así mismo, se expone el estado del arte de las pilas de combustible de tipo PEM. En el tercer capítulo se detalla el dimensionamiento y el diseño de la hidrogenera, definiendo los equipos necesarios para la producción y almacenamiento de hidrógeno. En el cuarto capítulo se describe el diseño y las modificaciones realizadas en el vehículo eléctrico de baterías para que sea propulsado híbridamente con una pila PEM. En el quinto capítulo se encuentran los cálculos y simulaciones realizadas, y para finalizar, en el sexto capítulo se exponen las conclusiones que se desprenden del trabajo realizado y el trabajo futuro a realizar, seguidos de las referencias bibliográficas y de los anexos, donde se puede encontrar información ampliada y detallada

Experimental study of the pressure drop in the cathode side of air-forced Open-cathode proton exchange membrane fuel cells

An experimental work has been performed in order to study the pressure drop in air-forced open-cathode PEMFC architectures. Measurements have been obtained in an experimental setup specifically designed for the present research. Three different cathode configurations with aspects ratios (wc/h c) from 0.83 to 2.5, as well as different flow conditions have been studied, varying the Reynolds number from 45 to 4000. It has been verified that for the laminar region the pressure drop is proportional to the air velocity. For the present experiments, the boundary between the laminar and the transitional-turbulent region has been established for a Reynolds number of 500. Two different equations have been obtained to estimate the friction factor, f, one for the laminar flow and the other for the transitional-turbulent region. Using these equations, an excellent agreement between measured and predicted friction factors has been achieved for the entire range of experimental conditions (Re,wc,hc) tested in this research. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights.Peer Reviewe

Influence of CrN-coating thickness on the corrosion resistance behavior of aluminium-based bipolar plates.

The electrical and corrosion properties of CrN-coated aluminium alloy Magnal-45 (Al-5083) probes have been evaluated, in order to assess their viability to be used as bipolar plates in polymer electrolyte fuel cells. To this end, ceramic micro-layers of chromium nitride (CrN) with different thicknesses (3, 4. and 5 mu m) have been deposited on the surface of the Al alloy (Al-5083) using the physical vapour deposition (PVD) technique. A decrease in 2 orders of magnitude of I(corr) values for the coated Al has been observed compared to the as-received Al-alloy when the probes have been exposed to simulated anodic conditions in a micro-reactor. On the other hand, when subjected to a cathodic-simulated environment, the Al-CrN probes with 3 mu m and 4 mu m coatings have shown a decrease in I(corr) of one order of magnitude, while a variation of two orders of magnitude has also been obtained for the 5 mu m coating. (C) 2010 Elsevier B.V. All rights reserved.This research has been partially funded by the Spanish Ministry of Science and Innovation under projects CIT-370000-2008-11, ENE2008-06697-C04-01/CON, and ENE2009-14750-C05-02/CON.Peer Reviewe

SiLC R&D: Design present status and perspectives

4 páginas, 2 figuras, 2 tablas.-- El Pdf del artículo es la versión pre print.-- Trabajo presentado al 6th "Hiroshima" Symposium on the Development and Application of Semiconductor Detectors (Carmel, CA, Sep 11-15, 2006).This paper briefly describes the main R&D objectives that are undertaken within the international R&D collaboration SiLC aiming to build the next generation of silicon tracking devices especially in the case of the ILC. Firstly, motivation to use silicon detectors in the tracker is explained. Then basic aspects of the design and solutions proposed are described (sensors, front-end electronics, mechanics, alignment). First results from the tab and beam test of the front-end chips and module prototypes built are shown.The authors would like to thank A. Honma and CERN bonding lab for the possibility to bond the module prototypes there. Furthermore, we are grateful to N. Meyners, J. Sztuk and U. Koetz for their assistance during the beam test at DESY. This work was also partially supported by EU I3 Contract 026 126-R II3 (EUDET) and Czech Science Foundation project Nr. 202/07/0740.Peer reviewe

Development of a novel 2D position-sensitive semiconductor detector concept

Open Access: Trabajo presentado a la "9th International Conference on Position Sensitive Detectors (PSD9)" celebrada en Aberystwyth (Gales) el 14 de septiembre del 2011.A novel 2D position-sensitive semiconductor detector concept has been developed employing resistive electrodes in a single-sided silicon microstrip sensor. The resistive charge division method has been implemented reading out each strip at both ends, in order to get the second coordinate of an ionizing event along the strips length. Two generations of prototypes, with different layout, have been produced and characterized using a pulsed near infra-red laser. The feasibility of the resistive charge division method in silicon microstrip detectors has been demonstrated and the possibility of single-chip readout of the device has been investigated. Experimental data were compared with the theoretical expectations and the electrical simulation of the sensor equivalent circuit coupled to simple electronics readout circuits. The agreement between experimental and simulation results validates the developed simulation as a tool for the optimization of future sensor prototypes. © 2012 IOP Publishing Ltd and Sissa Medialab srl.This work has been supported by the Spanish Ministry of Science and Innovation under grants FPA2010-22163-C02-02 (DET4HEP) and FPA2010-22060-C02-02 and through the GICSERV program “Access to ICTS integrated nano-and micro electronics cleanroom” of the same ministry.Peer Reviewe

Study of the distribution of air flow in a proton exchange membrane fuel cell stack

The flow of air to feed oxygen to the cathode of each plate in a proton exchange membrane fuel cell (PEMFC) is studied for a 300 W stack in a realistic 3D configuration. Two configurations for gas income are solved, a "U" shape, where both the inlet and outlet of the air collectors are at the same end plate, and a "Z" shape, where inlet and outlet are at opposite sides of the stack. Under a simplified assumption for the flow of oxygen entering the gas diffusion layer of each cell, detailed mass flow and pressure distributions are shown, including the possibility of a turbulent flow inside the main collectors. © 2008 Elsevier B.V. All rights reserved.Peer Reviewe

New silicon microstrip detectors optimized for tracker alignment

4 páginas, 7 figuras.The resolution of tracking systems based on layers of silicon microstrips is comparable to the stability of the structures on which they are mounted. Environmental changes during operation will misalign the modules out of their nominal positions. A straight laser beam that sequentially traverses consecutive layers of microstrips can be used as an artificial track to align them. For such a laser track to reach the last sensor, high transmittance of microstrips to infrared (IR) light is needed. We have simulated the passage of a coherent beam of light through a microstrip detector and identified the minimum set of changes to the design that boosts its transmittance. The simulation has been validated against real microstrip detector samples.This work has been supported by the Spanish Ministry of Education and Science through the GICSERV program—Access to ICTS integrated nano-and microelectronics cleanroom.Peer reviewe

Is ball milling a worthy route to produce magnetic semiconductors?

We present a study of the magnetic and structural effects generated by ball milling on different compounds recently reported as room-temperature magnetic semiconductors: a stoichiometric mixture of ZnO and MnO2 and single-phase samples of Zn0.96M0.04O (M{double bond, long}Co and Mn). In general, a dramatic reduction of the average crystal size is observed. None of our samples present a ferromagnetic state induced by ball milling, in contradiction with previous results. © 2007 Elsevier B.V. All rights reserved.Peer Reviewe