Search

Dynamic models of PEM stacks are the basis to design controllers for appropriate performance, maximum efficiency and minimum degradation. Fluid dynamic models of different dimensions can be found in the literature; however, these models are rarely used to improve the control laws and strategies. This work presents a control oriented 1+1D model (distributed in the direction of the stack flow channels). The model is based on a similar model presented by M. Mangold [1], is implemented in MATLAB Simulink. The model is validated using experimental data of a Powercell stack.

Presentado al Fuel Cells Science & Technology: Scientific Advances in Fuel Cell Systems celebrado en Copenague del 8 al 9 de octubre de 2008., This work proposes an experimental methodology for modeling water diffusion transport in a PEMFC, which is applied to a commercially available fuel cell stack. The effective water vapor diffusion coefficient and its dynamical variation for the stack under no load conditions will be determined for the purpose of isolating the transfer of water across the 5 layer MEA (which include the two gas diffusion layers the two catalysts layers and the membrane) in relation to temperature and membrane resistance. This coefficient is dependent on the material properties of the components in the fuel cell, as well as on the membrane temperature and water content. The dynamics of the membrane temperature and water content will be established experimentally. The controlled variables in this experiment are the water vapor partial pressures at the inlets and the temperature of the fuel cell. Experimental procedure is to independently vary the water vapor partial pressures and fuel cell temperature to obtain the water transport across the membrane, membrane resistance, and total resistance. The experimental setup for this study is based on a 21 cell PEMFC stack with a forced flow open cathode. An environmental chamber controls the fuel cell temperature and the inlet dew point temperature of the cathode reactant. The anode reactant inlet water vapor partial pressure is maintained by a membrane based humidifier which is controlled with a dew point sensor. The measured variables are the outlet dew point temperatures, membrane resistance through continual high frequency electrochemical impedance spectroscopy (EIS), and total resistance through full frequency spectrum EIS at steady state conditions. The study determines the in situ effective diffusion coefficient and membrane resistance from 10ºC to 70ºC and 10% to 100% relative humidity. The dynamics of the membrane temperature and water content will be used to determine the movement of water in the 5 layer MEA., This work was supported by the project 'Avances en el modelo y diseño de controladores para sistemas basados en pila de combustible PEM' (4800).

This work presents the development of a nonlinear state observer to estimate the values of the different gas species concentration profiles in a Proton Exchange Membrane Fuel Cell (PEMFC) energy system. The selection of the estimated states is based on the functionality and performance of the observer. The implementation is based on the discretization of a PEMFC distributed 1+1D model. Forward and backwards discretization of the partial derivative equations is performed to take advantage of the boundary conditions of the problem. A second-order sliding-mode control super-twisting corrective input action is implemented to reduce the estimation error to zero in a finite amount of time. Simulation results are presented to show the performance of the observer to estimate the values of the states and to extract conclusions for future research work.// Este trabajo presenta el desarrollo de un observador de estados no lineal para la estimación de los perfiles de concentraciones en un sistema de energía basado en una Pila de Combustible de Membrana de Intercambio Protónico (PEMFC). La selección desempeño del observador. Las ecuaciones en derivadas parciales son discretizadas en dos sentidos un modelo 1+1D para aprovechar las condiciones de contorno del problema. Una acción de en métodos deslizantes de segundo orden es implementada para reducir el error de estimación a cero en un periodo finito de tiempo. Se presentan resultados de simulación para mostrar el rendimiento del observador reconstrucción de los valores de los estados y para extraer conclusiones para futuro trabajo de investigación.

The main contribution of this work is the improvement of the efficiency of a PEMFC power system while guaranteeing conditions that also improve its durability. Adopting the NMPC scheme with the distributed parameter model and the nonlinear observer, the efficiency of the PEMFC-based system can be maximized guaranteeing at the same time the appropriate internal gas concentration profiles to avoid global and local hydrogen and oxygen starvation and proper membrane humidification.

In this work a non-linear, model-based state observer is developed. Dynamics of the system described by a distributed parameter, partial differential equations model. Forward and backward discretization of the model to take advantage of the boundary conditions. Simulation results are presented to show the performance of the observer. Comparison between the linear and nonlinear approaches of the observers.

In this paper, a nonlinear distributed parameter observer (NDOP) is developed for the estimation of the internal condi-tions of a proton exchange membrane fuel cell (PEMFC). In particular, the estimation of the internal concentration values for different gas species is studied. A novel high order sliding mode (HOSM) estimation technique, based on a distributed parameter model of a PEMFC is developed to reconstruct the internal variables. The observer includes the estimation of the reaction and water transport terms, which are considered as disturbances of the PEMFC estimation model. Since the approach is based on a distributed parameter model representation of the PEMFC, the observer is capable of reconstruct the full internal profile of the estimated variables. The performance and robustness of the proposed observation technique is tested through a simulation example around different operation points.

Presentado al V Congreso Nacional de Pilas de Combustible celebrado en Madrid del 21 al 23 de noviembre de 2012., This article presents different diagnosis tools for Proton Exchange Membrane Fuel Cells based on the analysis of their dynamic evolution when the humidification of the inlet gases is interrupted. The diagnosis is aimed to know the internal state of the fuel cell with respect to the water distribution. The proposed diagnosis procedures combine the information of the time response with that extracted from Electrochemical Impedance Spectroscopy and consist in monitoring the evolution of a set of performance indicators during the humidification interruption. The article presents a study for the selection of these performance indicators, which may be related to the physical phenomena inside the PEMFC, and describes the patterns that correspond to proper or improper water distribution., The authors acknowledge financial support from Spanish MICINN (DPI2010-15274 and DPI2011-25649). M.P. is grateful to the Generalitat de Catalunya (AGAUR Dept.) for the PhD Grant support.

Presentado a la 5th International Conference on Fundamentals & Developments of Fuel Cells celebrada en Karlsruhe (Alemania) del 16 al 18 de abril de 2013., The work presented in this article combines experimental analysis and theoretical studies of temperature effects on the performance of an open-cathode, self-humidified PEM fuel cell system for the design of optimization strategies. The experimental analysis shows the great potential of improving the system performance by proper temperature management. The most significant temperature dependent parameters of the system under study are the activation polarization and the water content of the ionomer of the catalyst layer. An Extremum seeking control algorithm is proposed to regulate the temperature to a voltage maximum. However, the slow dynamics of the temperature related catalyst-drying effect on performance complicate the optimal thermal management via model-free control strategies., This work is partially funded by the national project MICINN DPI2011-25649, and by the contract PUMA-MIND FP7 303419 with the European Comission.

1 figura. [EN] The interest in hydrogen technologies has grown in recent years, mainly because an economy based on hydrogen can help to solve important challenges related to the global economy of the future: energy security and climate change. Taking advantage of this momentum, more and more countries are implementing a growing number of policies related to hydrogen. Indeed, the European Hydrogen Strategy establishes hydrogen as essential drivers for the total decarbonization of the current energy system in order to achieve the EU’s commitment related to carbon neutrality by 2050. However, the successful development of the hydrogen technologies requires the collaboration of the public and private sectors to accelerate its deployment and make more competitive its implementation at large-scale. The research groups that take part of the line of work dedicated to hydrogen technologies, within the CSIC Interdisciplinary Thematic Platform PTI Mobility 2030, work in this regard, developing their investigations in several important areas related to the hydrogen technologies such as hydrogen generation, storage, distribution and uses. [ES] El interés por las tecnologías del hidrógeno ha crecido en los últimos años, principalmente porque una economía basada en el hidrógeno puede dar respuesta a los grandes desafíos de la economía global del futuro: seguridad energética y cambio climático. Aprovechando este impulso, cada vez son más los países que están implementando un número creciente de políticas en favor del hidrógeno. Prueba de ello es la Estrategia Europea del Hidrógeno que establece al hidrógeno como un elemento esencial en la descarbonización total del actual sistema energético para alcanzar el compromiso de la UE con la neutralidad de carbono en 2050. No obstante, el desarrollo exitoso de las tecnologías del hidrógeno requiere que todos los actores, incluidos los sectores público y privado, aumenten sus esfuerzos para acelerar su despliegue y hacer que su implantación a gran escala resulte competitiva. Los grupos de investigación que forman parte del área de trabajo de tecnologías del hidrógeno, dentro de la Plataforma Temática Interdisciplinar PTI Mobility 2030 del CSIC, trabajan en este sentido, desarrollando su labor en áreas tan diversas como la generación, el almacenamiento, la distribución y los usos del hidrógeno.

The learning of bimanual robotic tasks, i.e., tasks executed by two manipulators together, can be particularly important in the new scenarios opened by the rise of humanoid robotics, one of the most interesting trend currently in the field. The work presented wants to build a method to simplify the dimensionality of parameter space in this particular context, exploiting the presence of symmetries between the movements executed by the two arms. The aim is to develop a reduced-order representation of the bimanual motion, with the purpose of increase the speed of learning process. In chapter 1, kinematics of the used robots is studied, in order to know how to correctly command the position of the robots while executing a task. Robotic movements are then modeled using Probabilistic Movement Primitives (ProMPs), a stochastic interpretation of robot movements (details in chapter 2). The first objective is to develop a symmetrization method for those kind of policies, and this part is treated in chapter 3. This will give the chance of representing the movement of two robotic arms, with only a single ProMP (instead of two, one for each arm), from which obtain the second policy applying symmetrization. In this way the amount of parameters representing motion can be halved. The most common kind of symmetry is the one defined by a plane, but also other cases can be explored, e.g., spherical or cylindrical symmetry. If the symmetry surface is not explicitly given in the bimanual task description, it is critical to have a reliable method to estimate it in order to exploit it in the learning process. In chapter 4 it is reported a way to obtain this estimation of the parameters describing the symmetry surface from the initially demonstrated trajectories. Finally, in chapter 5 it is defined a symmetric policy representation for bimanual task, that depends only on a single ProMP and a symmetry surface. The effectiveness of this parameter reduction has been tested applying it in reinforcement learning of some tasks, in comparison to the results obtained by the standard way of proceeding, that model the bimanual task with two separated ProMPs, one for each robotic arm