<p>The production of chlorate, chlorine and sodium hydroxiderelies heavily on electrical energy, so that savings in thisarea are always a pertinent issue. This can be brought aboutthrough increased mass transfer of reacting species to therespective electrodes, and through increased catalytic activityand uniformity of current density distribution at theseelectrodes. This thesis will present studies involvingmathematical modelling and experimental investigations of theseprocesses. They will show the effect that hydrodynamicbehaviour has on the total current density and cell voltages,along with the effects on current density distributions andindividual overpotentials atthe respective electrodes.</p><p>Primary, secondary and psuedo-tertiary current densitydistribution models of a chlor-alkali anode are presented anddiscussed. It is shown that the secondary model presentsresults rather similar to the pseudo-tertiary model, when thecurrent density distribution is investigated, although thepotential distribution differs rather markedly. Furthermore, itis seen that an adequate description of the hydrodynamicsaround the anode is required if the potential distribution, andthereby the prevalence of side-reactions, is to be reasonablepredicted.</p><p>A rigorous tertiary current density distribution model ofthe chlorate cell is also presented, which takes into accountthe developing hydrodynamic behaviour along the height of thecell. This shows that an increased flowrate gives more uniformcurrent density distributions. This is due to the fact that theincreased vertical flowrate of electrolyte replenishes ioncontent at the electrode surfaces, thus reducing concentrationoverpotentials. Furthermore, results from the model lead to theconclusion that it is the hypochlorite ion that partakes in themajor oxygen producing side-reaction.</p><p>A real-scale cross-section of a segmented anode-cathode pairfrom a chlorate cell was designed and built in order to studythe current density distribution in industrial conditions.These experiments showed that increased flowrate brought aboutmore even current density distributions, reduced cell voltageand increased the total current density. An investigation ofthe hydrodynamic effects on the respective electrodeoverpotentials shows the anode reactions being more favoured byincreased flowrate. This leads to the conclusion that theuniform current density distribution, caused by increasedflowrate, occurs primarily through decreasing the concentrationoverpotential at the anode rather than by decreasing thebubble-induced ohmic drop at the cathode.</p><p>Finally, results from experiments investigating thebubble-induced free convection from a small electrochemicalcell are presented. These experiments show that Laser DopplerVelocimetry is the most effective instrument for investigatingthe velocity profiles in bubble-containing electrochemicalsystems. The results also show that the flow can transform fromlaminar to turbulent behaviour on both the vertical andhorizontal planes, in electrochemical systems where bubbles areevolved.</p>

We present the results of a new and high sensitivity study of the neutral hydrogen (HI) gas in three early type edge-on spiral galaxies, NGC 4157, NGC 3600 and NGC 2683. All three galaxies reveal HI disks that extend nearly or more than twice the length of the optical disk, which ubiquitously reveal asymmetries and warps. We model each galaxy using a three-dimensional kinematic model to derive the empirical parameters of the density distribution functions and rotation curves. A Gaussian function is unanimously found to best represent the density distribution in the plane of the galaxies. We also find that there is in fact a thick HI disk extending into the halo of two of three of these galaxies with scale heights on kpc. scales. This gas suggests the existence of two separate widespread components: a thin, high intensity disk component, normally rotating, and a vast, low intensity halo component, rotating at slower velocities with respect to the disk. This vertical velocity gradient is perhaps our most significant finding in addition to the discovery of the two new HI halos. We also find an unevenly distributed small-scale component of the gas in the form of shell-like and filamentary structures that extend from the disk into the halo. In all three systems we find unique kinematic and structural peculiarities including an HI disk extending four times the optical disk, a declining rotation curve, a companion, expanding bubbles, disk warps, etc. Several physical parameters are derived such as neutral hydrogen and dynamic masses, systemic velocities, HI radii, HI halo masses, etc. All of our findings are investigated and discussed in depth for each of the three galaxies. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2009-09-03 19:47:31.786

Commercial ebullated bed hydroprocessors, such as the LC-Finer, are used for the production of synthetic crude oil by upgrading bitumen extracted from the Canadian oil sands. The objectives of this thesis were to experimentally determine bubble characteristics at industrially relevant operating conditions for the design and optimization of the reactor’s recycle pan, as well as to investigate the impact of a catalyst density distribution on the reactor’s fluidization behaviour. High gas holdups have been reported for this type of industrial unit. As a result, high gas holdup conditions were required to assess the commercial unit fluid dynamics. Industrial conditions for the bubble characteristics in the reactor freeboard were simulated in a high pressure gas-liquid bubble column operating at 6.5 MPa using nitrogen and a 0.5 wt.% aqueous ethanol solution. Local bubble characteristics, including gas holdups, bubble rise velocities, and chord lengths, were investigated under various operating conditions using a novel monofibre optical probe designed for high gas holdup and elevated pressure. High gas holdups were achieved (up to 60%) and relatively narrow chord length distributions were observed, where 90% of the bubbles diameters were 1.0 mm or less. The energy dissipated through the distributor plate was shown to have a significant impact on the initial bubble size generated and high gas holdups were also achieved at atmospheric pressure by varying the open-surface area of the distributor. As a result, the impact of catalyst density distribution on local fluidization behaviour was investigated at atmospheric pressure using the previously designed high energy dissipation gas-liquid distributor plate and a 0.5 wt.% aqueous ethanol solution. Fresh and spent hydroprocessing catalysts having relatively narrow and wide density distributions were compared. The introduction of gas greatly impacted the fluidized bed dynamic by rendering the bed-freeboard interface diffuse at low superficial liquid velocity. Bed interface fluctuations were significantly reduced at elevated liquid flow rate due to average bubble size reduction caused by high shearing through the gas-liquid distributor plate. Solid holdup was most affected by the density distribution where bed expansion/contraction was dependent of the liquid flow rate due to varying particle-bubble dynamics.

Geomagnetically Induced Currents (GIC) have been a growing concern within power system operators and researchers as they have been widely reported to lead to power system related issues and material damage to system components like power transformers. In power transformers, GIC impacts are evidenced by part-wave saturation, resulting in transformers experiencing increased presence of odd and even harmonics. The three-phase three-limb (3p3L) transformer has been found to be the most tolerant to high dc values compared to other core types. The research was based on a hypothesis which reads “transformer laboratory testing results can be used as a guide towards developing suitable Finite Element Matrix (FEM) models to be used for conducting GIC/DC experiments”. This study thus investigates the response of a 15 kVA 3p3L laboratory transformer to dc current, emulating the effects of GICs. GIC and dc current are the same under steady state conditions, and hence mentioned interchangeably. Laboratory tests conducted identified two critical saturation points when the transformer is exposed to dc. The early saturation point was identified to be at around 1.8 A/phase of dc (18% of rated current), while the deep saturation point was at around 15 to 20 A/phase of dc (about 72% of rated current). Further analysis showed that holes drilled on the transformer can lower the transformer knee-point by about 26%, depending on the size and location of the holes. The holes hence end up affecting the operating point of the transformer due to losses occurring around the holes. A transformer FEM model was developed following the laboratory exercise, where it was concluded that a 2D model leads to grossly erroneous results, distorting the magnetizing current by about 60% compared to the laboratory results. A solid 3D model improved performance by about 30% as it took the transformer's topological structure into consideration. The 3D model was then refined further to include joints and laminations. It was discovered that laminations on the transformer need to be introduced as stacks of the core, with each core step split into two, allocating a 4% air gap space between stacks. Refinement of the T-joints proved that the joints have a relatively high influence on the transformer behaviour, with their detailed refinement improving the transformer behaviour by about 60%. The final FEM model was used for dc experiments. The results of such experiments showed close resemblance to the laboratory results, with saturation points identified in FEM lying within 10% of the laboratory identified saturation points. Overall, the various investigation methods explored showed that the hypothesis was satisfactorily proven true. Laboratory results functioned as a guide in developing the model, offering a reference case.

GPS integrated Total Electron Content measurements received at the ground or in space are used for tomographic reconstruction of the ionospheric electron density distribution. The IRI/GCPM model is used as initialisation of the tomographic MART algorithm. During the procedure GPS TEC data are iteratively assimilated to the model. To test the potential of the reconstruction, electron density profiles from IRI/GCPM and the assimilation are compared with ionosonde measurements and CHAMP radio occultation profiles for dates during the HIRAC campaign in April 2001. All profiling methods show electron density values of similar magnitude. It is shown that including TEC GPS data corrects the model towards the ionosonde measurements. / Integrale Messungen der Elektronendichte aus GPS-Boden- sowie Radio-Okkultations-Messungen bilden die Datenbasis der hier vorgestellten 3-dimensionalen Tomographie der ionosphärischen Elektronendichteverteilung. Zur Initialisierung des verwendeten iterativen MART Algorithmus wird das IRI/GCPM Modell verwendet, wobei das Modell während der Iteration sukzessiv an die Messdaten angepasst wird. Um das Potential des Verfahrens abzuschätzen, werden Elektronendichteprofile des IRI/GCPM Modells und der Rekonstruktion mit Ionosondenmessungen und CHAMP Okkultationsprofilen verglichen. Dafür wurden Messungen während der HIRAC Kampagne im April 2001 genutzt. Alle hier gezeigten Profilableitungen geben Elektronendichtewerte der selben Größe wieder. Eine Annäherung des IRI/GCPM Modells an die Messwerte der Ionosonde durch die Assimilation der TEC GPS Daten wird gezeigt.

"We cannot afford the luxury any longer of ignoring the nature of the bonding in these interesting compounds .... " P.E.D. Morgan, (1974). An understanding of bonding is paramount to furthering our understanding of materials (Morgan, 1974). The properties of materials are governed by the interactions between atoms. These interactions are governed by the nature of the bonds. In this study, two methods are explored which provide insight into chemical interactions. First, promolecule radii, calculated for nitride, oxide, and sulfide coordinated polyhedra with bond lengths fixed at the sums of effective ionic and crystal radii, are analyzed. Radii calculated for transition and non-transition cations for the first four rows of the periodic table are highly correlated with crystal radii derived for oxide and sulfide crystals and with ionic radii derived for nitride crystals. Promolecule radii calculated for the coordination polyhedra match experimentally determined bonded radii to within ~0.02Å, on average. Calculated radii anions tend to match ionic radii when bonded to highly electropositive cations and atomic radii when bonded to highly electronegative cations. In the second study, molecular orbital calculations were completed on a series of small molecules containing the nitride anion. Bond type can be characterized by studying the systematics of parameters derived from the bond critical point properties of the electron density distributions. A set of criteria is established to suggest how covalent or ionic a bond is. This criteria is based on bond critical point properties such as the Laplacian of the electron density distribution evaluated at the bond critical point, the electron density distribution at the critical point, the local energy density at the critical point, the relative electronegativity of the cation, the curvatures of the electron density distribution, and the distance from the nucleus of the nitride anion to the bond critical point, (the bonded radius of the nitrogen atom). Parameters computed for promolecule data indicate that these easily obtained results offer a method of calculating bond critical properties which are close in value to the more extensive results derived from molecular orbital calculations. / Ph. D.

Since single nanopores were firstly proposed as a potential rapid and low-cost tool for DNA sequencing in 1990s (PNAS, 1996, 93, 13770), extensive studies on both biological and synthetic nanopores and nanochannels have been reported. Nanochannel based stochastic sensing at single molecular level has been widely reported through the detection of transient ionic current changes induced by geometry blockage due to analytes translocation. Novel properties, including ion current rectification (ICR), memristive and memcapacitive behaviors were reported. These fundamental properties of nanochannels arise from the nanoscale dimensions and enables applications not only in single molecule sensing, but also in drug delivery, electrochemical energy conversion, concentration enrichment and separation, nanoprecipitation, nanoelectronics etc. Electrostatic interactions at nanometer-scale between the fixed surface charges and mobile charges in solution play major roles in those applications due to high surface to volume ratio. However, the knowledge of surface charge density (SCD) at nanometer scale is inaccessible within nanoconfinement and often extrapolated from bulk planar values. The determination of SCD at nanometer scale is urgently needed for the interpretation of aforementioned phenomena. This dissertation mainly focuses on the determination of SCD confined at a nanoscale device with known geometry via combined electroanalytical measurements and theoretical simulation. The measured currents through charged nanodevices are different for potentials with the same amplitude but opposite polarities, which deviates away from linear Ohm's behavior, known as ICR. Through theoretical simulation of experiments by solving Poisson and Nernst-Planck equations, the SCD within nanoconfinement is directly quantified for the first time. An exponential gradient SCD is introduced on the interior surface of a conical nanopre based on the gradient distribution of applied electric field. The physical origin is proposed based on the facilitated deprotonation of surface functional groups by the applied electric field. The two parameters that describe the non-uniform SCD distribution: maximum SCD and distribution length are determined by fitting high- and low-conductivity current respectively. The model is validated and applied successfully for quantification and prediction of mass transport behavior in different electrolyte solutions. Furthermore, because the surface charge distribution, the transport behaviors are intrinsicaly heterogeneous at nanometer scale, the concept is extended to noninvasively determine the surface modification efficacy of individual nanopore devices. Preliminary results of single molecule sensing based on streptavidin-iminobiotin are included. The pH dependent binding affinity of streptavidin-iminobiotin binding is confirmed by different current change signals ("steps" and "spikes") observed at different pHs. Qualitative concentration and potential dependence have been established. The chemically modified nanopores are demonstrated to be reusable through regenerating binding surface.

Le gaz électrogénéré dans les réacteurs électrochimiques est un phénomène à la fois électrochimique et hydrodynamique. La chute ohmique dans la solution électrolyte est l'un des paramètres importants à évaluer pour l'optimisation des réacteurs électrochimiques. Elle est due à la résistance de la solution, donc, à sa conductivité électrique et la distance entre les deux électrodes. Pour réduire la consommation énergétique de la cellule de réduction électrolytique de particules d'hématite en fer métallique, on a étudié la conception des anodes, sièges de la production des bulles d'oxygène, dans deux cellules équivalentes d'électrolyse d'eau dans un milieu alcalin. Les résultats ont montré que seulement 25% de l'anode est réellement active et que le taux de rétention augmente le long de l'anode et les bulles atteignent leur vitesse terminale dès 50% de la hauteur de l'anode. Ceci nous a permis de formuler des recommandations qui permettent d'avoir les meilleures conditions de désengagement des bulles électrogénérées, pour une consommation énergétique plus faible du procédé électrochimique / Electrogenerated gas in electrochemical reactors is considered as an electrochemical and hydrodynamic phenomenon. The ohmic drop in the electrolyte solution is one of important parameter to evaluate for the optimization design of electrochemical reactors. It is due to the resistance of the solution, therefore, its electrical conductivity and of the distance between the two electrodes. To reduce the energy consumption of the electrolytic reduction cell of hematite particles to metallic iron, we studied the design of anode, the location of oxygen bubbles production, in two equivalent cells for water electrolysis in an alkali media. The results showed that the gas hold up increases along the anode and only 25% of the initial anode height is actually active. Moreover the bubbles reach their terminal velocity after 50% of the initial anode height. This allowed us to formulate recommendations that allow the best conditions of bubbles electrogenerated disengagement and low energy consumption

Wir betrachten folgende Teile: die zusätzlichen Kohlenstoff(C)-emissionen, welche aus der Umwandlung von natürlichem Umland durch Stadtwachstum resultieren, und die Änderung des C-Flusses durch 'urbanisierte' Ökosysteme, soweit atmosphärisches C durch diese in umliegende natürliche Ökosysteme entlang der Kette &ldquo;Atmosphäre -> Vegetation -> abgestorbene organische Substanzen&rdquo; gepumpt wird: d.h. C-Export; für den Zeitraum von 1980 bis 2050. Als Szenario nutzen wir Prognosen der regionalen Stadtbevölkerung, welche durch ein 'Hybridmodell' generiert werden für acht Regionen. Alle Schätzungen der C-Flüsse basieren auf zwei Modellen: das Regression Modell und das sogenannte G-Modell. Die Siedlungsfläche, welche mit dem Wachstum der Stadtbevölkerung zunimmt, wird in 'Grünflächen' (Parks, usw.), Gebäudeflächen und informell städtisch genutzte Flächen (Slums, illegale Lagerplätze, usw.) unterteilt. Es werden jährlich die regionale und globale Dynamik der C-Emissionen und des C-Exports sowie die C-Gesamtbilanz berechnet. Dabei liefern beide Modelle qualitativ ähnliche Ergebnisse, jedoch gibt es einige quantitative Unterschiede. Im ersten Modell erreicht die globale Jahresemission für die Dekade 2020-2030 resultierend aus der Landnutzungsänderung ein Maximum von 205 Mt/a. Die maximalen Beiträge zur globalen Emission werden durch China, die asiatische und die pazifische Region erbracht. Im zweiten Modell erhöht sich die jährliche globale Emission von 1.12 GtC/a für 1980 auf 1.25 GtC/a für 2005 (1Gt = 109 t). Danach beginnt eine Reduzierung. Vergleichen wir das Emissionmaximum mit der Emission durch Abholzung im Jahre 1980 (1.36 GtC/a), können wir konstatieren, daß die Urbanisierung damit in vergleichbarer Grösse zur Emission beiträgt. Bezogen auf die globale Dynamik des jährlichen C-Exports durch Urbanisierung beobachten wir ein monotones Wachstum bis zum nahezu dreifachen Wert von 24 MtC/a für 1980 auf 66 MtC/a für 2050 im ersten Modell, bzw. im zweiten Modell von 249 MtC/a für 1980 auf 505 MtC/a für 2050. Damit ist im zweiten Fall die Transportleistung der Siedlungsgebiete mit dem C-Transport durch Flüsse in die Ozeane (196 .. 537 MtC/a) vergleichbar. Bei der Abschätzung der Gesamtbilanz finden wir, daß die Urbanisierung die Bilanz in Richtung zu einer 'Senke' verschiebt. Entsprechend dem zweiten Modell beginnt sich die C-Gesamtbilanz (nach annähernder Konstanz) ab dem Jahre 2000 mit einer fast konstanten Rate zu verringern. Wenn das Maximum im Jahre 2000 bei 905MtC/a liegt, fällt dieser Wert anschliessend bis zum Jahre 2050 auf 118 MtC/a. Bei Extrapolation dieser Dynamik in die Zukunft können wir annehmen, daß am Ende des 21. Jahrhunderts die &ldquo;urbane&rdquo; C-Gesamtbilanz Null bzw. negative Werte erreicht. / We calculate the additional carbon emissions as a result of the conversion of natural land in a process of urbanisation; and the change of carbon flows by &ldquo;urbanised&rdquo; ecosystems, when the atmospheric carbon is exported to the neighboring territories, from 1980 till 2050 for the eight regions of the world. As a scenario we use combined UN and demographic model&prime;s prognoses for regional total and urban population growth. The calculations of urban areas dynamics are based on two models: the regression model and the Gamma-model. The urbanised area is sub-divided on built-up, &bdquo;green&ldquo; (parks, etc.) and informal settlements (favelas) areas. The next step is to calculate the regional and world dynamics of carbon emission and export, and the annual total carbon balance. Both models give similar results with some quantitative differences. In the first model, the world annual emissions attain a maximum of 205 MtC/year between 2020-2030. Emissions will then slowly decrease. The maximum contributions are given by China and the Asia and Pacific regions. In the second model, world annual emissions increase to 1.25 GtC in 2005, beginning to decrease afterwards. If we compare the emission maximum with the annual emission caused by deforestation, 1.36GtC per year, then we can say that the role of urbanised territories (UT) is of a comparable magnitude. Regarding the world annual export of carbon by UT, we observe its monotonous growth by three times, from 24 MtC to 66 MtC in the first model, and from 249 MtC to 505 MtC in the second one. The latter, is therefore comparable to the amount of carbon transported by rivers into the ocean (196-537 MtC). By estimating the total balance we find that urbanisation shifts the total balance towards a &ldquo;sink&rdquo; state. The urbanisation is inhibited in the interval 2020-2030, and by 2050 the growth of urbanised areas would almost stop. Hence, the total emission of natural carbon at that stage will stabilise at the level of the 1980s (80 MtC per year). As estimated by the second model, the total balance, being almost constant until 2000, then starts to decrease at an almost constant rate. We can say that by the end of the XXI century, the total carbon balance will be equal to zero, when the exchange flows are fully balanced, and may even be negative, when the system begins to take up carbon from the atmosphere, i.e., becomes a &ldquo;sink&rdquo;.

Les piles à combustible à membrane échangeuse de protons (PEMFC) constituent une alternative aux moteurs thermiques utilisés dans le cadre d’applications transport ou dans le cadre d’applications stationnaires. Cependant, une large commercialisation des PEMFC dépend des progrès qui peuvent être réalisés pour améliorer leur fiabilité et leur durabilité. La PEMFC est sujette à plusieurs types de dégradations complexes et non entièrement maitrisées qui varient en fonction des conditions de fonctionnement. Cependant, il est admis qu’il est souhaitable de faire fonctionner la PEMFC à distributions de courant uniformes car des distributions de courant hétérogènes entraînent une mauvaise utilisation des réactifs et des catalyseurs, une diminution des performances globales et une possible dégradation des matériaux constitutifs du coeur de la pile. De nouvelles stratégies de diagnostic doivent donc être proposées en s’appuyant sur les distributions de courant. Mes travaux de recherche consistent à développer un nouvel outil de diagnostic s’appuyant sur une mesure du champ électromagnétique externe (non invasive) rayonné par la pile PEMFC. Le champ magnétique possède l’intérêt d’être corrélé à la distribution locale du courant circulant à l’intérieur de la pile, et permet d’avoir des informations sur les performances locales. Cette distribution est liée aux conditions opératoires de la pile. Il est alors possible, à partir d’une signature magnétique de remonter à une information locale et à la cause des distributions de courant non uniformes. Des bases (vecteurs) qui contiennent les données des champs magnétiques issues des 30 capteurs disposés autour de la PAC sont construites à partir de distributions de courant spécifiques. Ces bases constituent un espace de représentation du comportement anormal de la PEMFC et permettront de d’élaborer des signatures caractérisant les fonctionnements indésirables. Ainsi, deux méthodes ont été développées pour permettre : (i) d’extraire des paramètres pertinents sur la répartition de la densité de courant traduisant les performances locales de la PAC, (ii) de classifier les différents modes de fonctionnements indésirables. La première méthode consiste à générer des résidus vectoriels en comparant le comportement réel du système (caractérisé par un vecteur mesure) avec les bases générées. Des variables qualitatives ont été élaborées pour classifier les modes de fonctionnement indésirables de la pile. La deuxième méthode consiste à extraire des paramètres à partir de la projection du vecteur mesure dans la direction des bases. La classification est réalisée dans des espaces 2D. Une validation des deux méthodes proposées a été effectuée à partir de mesures expérimentales sur une PEMFC de taille industrielle (stack GENEPAC de 40 cellules construit par le CEA et PSA). La pertinence des paramètres extraits a été vérifiée en s’appuyant sur des distributions de courant mesurées directement. Les modes de fonctionnement indésirables prédéfinis permettent de localiser les paramètres opératoires ayant conduit à l’évolution de la distribution de courant. Les outils ainsi réalisés sont très facilement transposables à d’autres piles PEMFC. / Proton exchange membrane fuel cell (PEMFC) is a potential alternative energy conversion device for stationary and automotive applications. Wide commercialization of PEMFC depends on progress that can be achieved to enhance its reliability and durability. The PEM fuel cell is subject to several types of complex and not fully mastered degradations which vary with operating conditions. It is desirable to operate the PEMFC at uniform current distribution because non uniform current distribution over the MEA could result in poor reactant and catalyst utilization, overall cell performance degradation as well as corrosion processes inside the PEM fuel cell. Therefore, new diagnostic strategies must be proposed, including choice of information gathered on the system and the fuel cell operation representation. My research is to develop a new diagnostic tool based on a measure of the external electromagnetic field (non-invasive) radiated by the fuel cell. The magnetic field has the advantage of being correlated to the local distribution of the current flowing inside the fuel cell (a physical indicator to obtain information on local performance of a fuel cell); it is linked to the local operating conditions: relative humidity level, temperature etc. It is then possible, from a magnetic signature to trace local information. Baselines (vectors) which contain the magnetic fields data generated by specific current distribution are built to characterize the magnetic field generated by the undesirable operation of the fuel cell. Baselines constitute a representation space of abnormal system behavior. Two methods have been developed to enable: (i) to extract the relevant parameters on the distribution of the current density resulting from PEM fuel cell stack local performance, (ii) to classify different types of undesirables operations. The first method is to generate vector residuals by comparing the actual behavior of the system (characterized by a measurement vector) with the baselines generated. Qualitative variables were created to classify the undesirable modes of PEM fuel cell stack operation. The second method is to extract parameters from the projection of the vector in the direction of measurement baselines. The classification is performed in 2D space. Validation from experimental measurements of the two proposed methods has been carried out on a commercial scale PEMFC (GENEPAC stack of 40 cells built by the CEA and PSA). The relevance of the extracted parameters was verified based on current density distributions measured directly. The undesirable predefined operating modes were used to locate the operating conditions parameters that led to the evolution of the current density distribution. The tools are made easily transferable to other PEMFC stack.