Search

Hydrogen & Fuel Cell systems are very promising clean systems to store intermittent energy and use it in green and decentralized electricity. For the large-scale deployment of these innovative hydrogen-based technologies, it is necessary to bring reliable systems to the market with competitive costs and lifetimes. For this purpose, solutions for tolerance to fault and resistance to degradation shall be developed.

International audience; Les systèmes pile à combustible (SPàC) sont considérés comme une solution viable et une alternative prometteuse autant pour des applications embarquées que stationnaires. Cela dit, ces systèmes doivent répondre à des critères essentiels à leur large développement, à savoir, coût, durabilité et fiabilité. Le présent travail se focalise sur l’aspect fiabilité du système pile à combustible. En effet, une meilleure compréhension des mécanismes de dégradation dans le SPàC permettra de développer les stratégies nécessaires à la réduction des dégradations au sein du SPàC et augmenter sa durée de vie utile. Une analyse des mécanismes de dégradation et leurs effets au niveau du SPàC a été faite dans le but de construire un arbre de défaillances le plus complet possible. Le SPàC étudié comprend le stack (membrane, couche catalytique, plaques bipolaires, couche de diffusion des gaz) le système d’alimentation en air (compresseur, capteurs, régulateurs, électrovannes), le système d’alimentation en hydrogène (capteurs, régulateurs, électrovannes) et le système de refroidissement (pompe de circulation, capteurs, électrovannes, régulateurs). Cette étude permettra de déduire les lois de propagation des défauts dans le SPàC qui permettront une meilleure estimation de sa durée de vie.

International audience; Active fault tolerant control (AFTC) applied on proton exchange membrane fuel cells

The deployment of a FC range extender can be asuited solution to overcome the battery autonomy limitations in electrical vehicles and hybridconfigurations. In the framework of the European project Glantleap, a Polymer Electrolyte MembraneFuel Cell (PEMFC) range extender is integrated in an electrical bus to support the batteries' packload demand. The prediction of both the FC ageing and its interactions with the balance of plant(BoP) is considered as a strategical approach to anticipate and consequently reduce the FC systemperformance degradations. A PEMFC stack model has been developed using the Energetic MacroscopicRepresentation formalism. The model integrates the stack ageing laws and is adapted for on-boardprognostic and health management purposes. This paper presents shortly the model and Itsvalidation. For this purpose, the voltage losses increase with the stack ageing is presented. Toprove the model genericity, two different ageing simulationresults are proposed and compared with long-term test results. Data are referred to two differentdata-sets linked to two PEMFC stacks of the same technology, but of different generation.

International audience; Le vieillissement des systèmes électrochimiques peut être de différent type. Il existe le "vieillissement calendaire" qui intervient lorsque la batterie ou la pile à combustible est au repos (stockage) et le vieillissement « en usage » ou « en cyclage ». Une approche innovante pour analyser le vieillissement « en usage » de sources électrochimiques est proposée : l'entropie de Shannon. Au préalable, la transformée en ondelettes est utilisée pour filtrer le signal afin de suivre l'évolution de la dégradation du système au cours du temps. L'intérêt est d'être capable d'agir sur les paramètres de contrôle du système afin d'en corriger la dégradation ou de détecter l'apparition d'un défaut, en conditions de fonctionnement rées.

International audience; La performance des Piles à Combustible (PàC) dépend fortement des conditions de fonctionnement: notamment la température T, la pression des gaz à l'entrée, la surstœchiométrie de l'oxygène Sc et de l'hydrogène Sa , l'humidité relative des gaz entrants HR et le courant I. Un choix judicieux de ces paramètres peut décélérer le vieillissement de la pile et empêcher certaines dégradations. L'objectif de ce travail est d'étudier l'effet des conditions opératoires (T, Sc , Sa , I) sur la tension de la pile (indicateur de viellissement). Une campagne d'essai a été menée pour collecter une base de données expérimentale dédiée à valider un modèle quasi-statique de la pile. Un algorithme d'optimisation Big Bang-Big Crunch (BBBC) a été utilisé pour le calcul des paramètres du modèle. Le modèle choisi pour réaliser cette étude dépend des conditions opératoires (T, Sc, I, P et HRair). Néanmoins, dans le cadre de notre étude, on va s'intéresser uniquement aux effets de (T, Sc , Sa , I) sur la tension de la pile.

GIANTLEAP aims to integrate fuel cells (FCs) systems in public transport developing a FCrange extender to support electric buses batteries (B) on load demand. In this context toevaluate the FC stack ageing and its interactions with the balance of plant (BoP) is a mandatory point. As a consequence a model-based prognostic approach for on-boardapplications has been developed. The Prognostic model is developed through the EnergeticMacroscopic Representation (EMR) tool [1]. The PEMFC stack model proposed by Boulon etal. [1] is then adapted for prognostic and health management (PHM) purposes [2], integratingthe FC ageing behavior with respect to the load demand. The impact of the different voltagelosses (activation, ohmic and mass transport) evolution with ageing are then analyzed. Consequently, the ageing laws are created and integrated into the model. Long-term test dataare used to identify the ageing parameters. Results of the simulation showed the capability ofthe model to fit the stack voltage drop induced by ageing (figure 1). Subsequently the trend ofthe voltage drop is exploited to predict the stack end-of-life. Moreover, depending on the load demand control strategy, also the variations of the FC operations and the relatedconsumptions with ageing are analyzed. Currently, the BoP components are also modelledand future works are oriented to study and integrate the impact of the FC ageing into the ancillaries operations and vice-versa.

keine

International audience; Reservoir Computing applied to diagnostic of fuel cells

International audience; La pile à combustible (PàC) à membrane échangeuse de protons PEMFC est une alternative prometteuse aux modes de production d’énergie classiques. Elle a attiré beaucoup d'attention ces dernières décennies en raison de ses multiples avantages [1]. Néanmoins, certaines limites concernant sa durée de vie, sa fiabilité et son coût empêchent son déploiement à grande échelle. Il est donc important d'aborder ces freins et de proposer des solutions pour optimiser sa durée de vie, sachant que le vieillissement de ses composants est un processus inévitable et qu’il dépend en grande partie des conditions opératoires. La tension des PàCs dépend aussi fortement des conditions opératoires: notamment la température T, la pression des gaz à l’entrée, la sur-stœchiométrie de l'oxygène CSF, l’humidité relative des gaz entrants et le courant I. Ainsi, un choix judicieux de ces paramètres peut empêcher certaines dégradations et limiter le vieillissement des composants. L'objectif de ce travail est de déterminer les valeurs optimales de (T, CSF, I) pour fournir la puissance requise par la charge, tout en prolongeant la durée de vie de la PàC et en maximisant son rendement. La technique proposée permet d'éviter les dégradations et de ralentir le taux de vieillissement des composants en maintenant la valeur de la tension à une valeur optimale.

FDFC 2017, 7th International Conference on Fundamentals & Development of Fuel Cells,, STUTTGART, ALLEMAGNE, 31-/01/2017 - 02/02/2017; Proton exchange membrane fuel cells (PEMFCs) appear nowadays to be a promising solution to face energy transition challenges in automotive applications. In this scenario, PEMFCs lifespan and their remaining Useful Life (RUL) under dynamic operations is currently object of main interest. This work introduces the fundamentals to design a generic strategy to support PEMFC durability enhancement in case of bus transportation applications. To this purpose, the energetic macroscopic formalism (EMR) is used to represent and model both the stack and the balance of plant (BoP) interactions. Based on power exchanges, each element will be related to another according to the action-reaction principle. The expected model will be able to simulate the system' response under a given load mission profile. Ageing behavior will be also considered in the model development. The model is expected to predict the voltage degradation profile with respect to the operating time and/or the produced energy. The voltage trend will be subsequently exploited by prognostic techniques to evaluate the PEMFC and BOP RUL and support their maintenance. This kind of approach is useful to integrate the existing diagnostic algorithms and support PEMFC makers in control decisions and maintenance scheduling as illustrated below. The research leading to these results has received funding from the European Union's Horizon2020 Programme (H2020-JTI-FCH-2015-1) for the Fuel Cells and Hydrogen Joint Undertaking, under grant agreement n° 700101 - Project : GIANTLEAP (Giantleap Improves Automation of Non-polluting Transportation with Lifetime Extension of Automotive PEM fuel cells).

International audience; Proton Exchange Membrane Fuel Cell (PEMFC) is widely studied as the hydrogen fuel used to generate electricity should be an alternative solution to fossil fuels [1]. Moreover, the technology is dedicated to transport as well as to stationary applications [2]. Unfortunately, a large-scale deployment stays limited due to the restricted lifetime and reliability of the PEMFC system [3]. Therefore, ensuring nominal operating conditions for PEMFC system during operation is necessary to guarantee a better efficiency, reliability and a longer lifetime. Diagnostic approaches are developed to reach nominal operating conditions by detecting and isolating failures [4]. Different kind of faults could appear when a fuel cell system operates [5]. The aim is to perform long-term tests in laboratory and to design diagnostic algorithms able to detect a failure as soon as possible to avoid irreversible degradation. Non-model based diagnosis methods are well adapted when large amount of data collected during multiple experimental tests are available. This paper presents a non-model based approach for diagnosis of PEMFC system based wavelet analysis [6]. The results are validated on in-lab tests and prove that the method is able to diagnose different faults in a fuel cell system. The philosophy of this paper is to extend the study to a fault tolerant control approach; i. e. after fault occurrence, act on relevant parameters of the system, in order to recover performance and bring the system as close as possible near the nominal operation condition, or to shut down the system and schedule a maintenance operation [7-8].

International audience; As fuel cell technologies continue advancing, people are pursuing ways to extend their lifespan, especially for Proton Exchange Membrane (PEM) fuel cells. Within a prognostics and health management (PHM) approach, several techniques can provide an estimation of its state of health (SOH) and a prediction for the fuel cell’s remaining useful life (RUL) in order to help the manufacturers improving fuel cell performance. Before developing a solution for estimation and prediction, PHM issues for PEM fuel cells need to be firstly properly defined, in particular in terms of deterioration/ageing indicators used for the state estimation and prediction. This paper provides a benchmarking study of degradation/ageing indicators regarding PHM problems of PEM fuel cell by comparing with the ones of batteries since numbers of approaches are presented and developed to monitor battery health and charge status. The aim of this work is to investigate how the definition of suitable degradation indicators and the development of PHM solutions for the PEM fuel cell can benefit from the knowledge and the experience feedback in the field of battery PHM, with the final goal to develop a prognostic method for PEM fuel cells. To achieve this goal, the State of Charge (SOC), a key degradation indicator to battery prognostic assessment, is firstly studied.

International audience; High fuel utilisation is a local phenomenon that comes from a fuel supply dysfunction or from blocked gas distribution channels. It results in anode re-oxidation and Nickel surface reduction that in turn lower performances and shorten the Solid Oxide Fuel Cells (SOFC) stack lifetime. Identifying this degradation early enough allows counteracting its causes and thus extending the lifetime of the stack. In deed, assuring a maximum lifetime of the SOFC remains one of the key issues to achieve competitiveness and massive market entry of the SOFC technology.This paper aims at describing an approach based on signal processing in order to identify signatures of insidious abnormal operating conditions linked to low fuel utilisation in SOFCs.The approach presented in this work is based on the analysis of stack voltage by wavelet processing (Fig. 1) which is suitable for the analysis of non-stationary signals having transient behaviour (Mallat 1999). It offers the possibility to examine the different components of the signal and then study each of them with a resolution matched to its scale. It has already been used in several applications (Aydin, Marvasti et al. 2004; Yousfi Steiner, Hissel et al. 2011, Antoni et al. 2013)

International audience; The present study focuses on developing a reliable fault identification and localisation tool for Proton Exchange Membrane Fuel Cell (PEMFC). This diagnosis tool relies on 2 steps: first, a 3D model for a single PEMFC, that allows estimating local parameters (temperature, current and voltage distributions within the single cell). An experimental set-up allows reliable monitoring of different parameters used by the model to estimate the current density distributions over the 3D space zones of the cell. Furthermore, this 3D fault-sensitive model allows to simulate faults linked to poor water management (drying out and flooding) with 2 severity levels (“flooding”, “drying”, “high flooding” and “high drying”).Then, the second step consists of developing a two-layer feed-forward ANN that has been with an adapted database to localize each fault within the different segments of the single cell. The results show good recognition and localization rate for the considered fault, which allows to conclude that this approach is very promising for fault localization, which is one of the key points regarding diagnosis.

In proton exchange membrane fuel cells (PEMFC) domain, to predict the Remaining Useful Life (RUL) under dynamic operations is currently object of main interest both for research and PEMFC’ makers applications.

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 proton exchange membrane fuel cells (PEMFC) domain, to predict the Remaining Useful Life (RUL) under dynamic operations is currently object of main interest both for research and PEMFC’ makers applications.