Surrogate Modeling for Spatially Distributed Fuel Cell Models With Applications to Uncertainty Quantification

Author(s):  
A. A. Shah

Detailed physics-based computer models of fuel cells can be computationally prohibitive for applications such as optimization and uncertainty quantification. Such applications can require a very high number of runs in order to extract reliable results. Approximate models based on spatial homogeneity or data-driven techniques can serve as surrogates when scalar quantities such as the cell voltage are of interest. When more detailed information is required, e.g., the potential or temperature field, computationally inexpensive surrogate models are difficult to construct. In this paper, we use dimensionality reduction to develop a surrogate model approach for high-fidelity fuel cell codes in cases where the target is a field. A detailed 3D model of a high-temperature polymer electrolyte membrane (PEM) fuel cell is used to test the approach. We develop a framework for using such surrogate models to quantify the uncertainty in a scalar/functional output, using the field output results. We propose a number of alternative methods including a semi-analytical approach requiring only limited computational resources.

Processes ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 608
Author(s):  
Andrea Ramírez-Cruzado ◽  
Blanca Ramírez-Peña ◽  
Rosario Vélez-García ◽  
Alfredo Iranzo ◽  
José Guerra

In this work, a comprehensive experimental analysis on the performance of a 50 cm2 polymer electrolyte membrane (PEM) fuel cell is presented, including experimental results for a dedicated load cycling test. The harmonized testing protocols defined by the Joint Research Centre (JRC) of the European Commission for automotive applications were followed. With respect to a reference conditions representative of automotive applications, the impact of variations in the cell temperature, reactants pressure, and cathode stoichiometry was analyzed. The results showed that a higher temperature resulted in an increase in cell performance. A higher operating pressure also resulted in higher cell voltages. Higher cathode stoichiometry values negatively affected the cell performance, as relatively dry air was supplied, thus promoting the dry-out of the cell. However, a too low stoichiometry caused a sudden drop in the cell voltage at higher current densities, and also caused significant cell voltage oscillations. No significant cell degradation was observed after the load cycling tests.


Author(s):  
Mohamed Gadalla ◽  
Nabil Al Aid

This paper studies the performance of a hybrid system that comprises a SOFC (Solid-Oxide-Fuel-Cell) combined with a PEMFC (polymer electrolyte membrane fuel Cell) which is integrated into a Gas Turbine power plant. Detailed modeling, thermodynamic, kinetic, geometric models are developed, implemented and validated for the synthesis/design and operational analysis of the combined hybrid system. In this system, the PEMFC makes use of the internal reforming ability of the SOFC to produce hydrogen which is necessary for the PEMFC operation. The heat released in the SOFC is utilized in the internal reforming process. Different levels of modeling for the SOFC, the PEMFC and the integrated system are presented. The overall system performance is analyzed by employing individual models and further applying thermodynamic laws for the entire cycle. The paper also introduces different methods of using shift reactors where CO reacts with H2O to produce CO2 and H2 to further increase the efficiency of the system by introducing a new factor to control parasitic energy consumption. In addition to this, the paper also suggests cooling the H2 stream before entering the PEMFC stack using the exhaust air of the Gas turbine. The main components of the SOFC+PEMFC system are a SOFC stack, shift reactors, selective oxidizer and a PEMFC stack. The fuel cells are connected in series for fuel feeding. Furthermore, although the efficiency of the SOFC increases with increasing operating pressures, the paper describes that the efficiency of the SOFC-PEMFC combination also varies with changing the temperatures. Energy and entropy balances are performed not only for the whole system but also for each component to evaluate the distribution of irreversibility and thermodynamic inefficiencies. According to the study, around 5% efficiency improvement was obtained with a parallel SOFC-PEMFC system as compared with a stand-alone SOFC. Alternative methods of improving the efficiencies are also introduced.


2007 ◽  
Vol 544-545 ◽  
pp. 993-996
Author(s):  
Hong Gun Kim ◽  
Lee Ku Kwac ◽  
Sung Soo Kang ◽  
Young Woo Kang

An experimental study is carried out to investigate the performance and the practical application of polymer electrolyte membrane fuel cell(PEMFC) with the double-tied catalyst layers in a Membrane Electrolyte Assembly (MEA). Characteristics of PEMFC depend highly on the conditions such as gas pressure, temperature, thickness, supplied oxidant type (Oxygen/Air) as well as humidification. They are controlled under the same condition for the comparison of the simulation. Testing condition is fixed at 60sccm and 70°C in anode and cathode, respectively. The humidification about 15% the performance is improved no humidification rather. The current density is increased around 20% significantly when pure oxygen gas is provided as an oxidant. It is found that measured values of unit cell voltage and current are influenced strongly by the type and amount of oxidant, which give more enhanced values in case of oxygen compared to the ambient air as oxidant.


Author(s):  
N. Rajalakshmi ◽  
R. Rajini ◽  
K. S. Dhathathreyan

Several methods are being attempted to improve the performance of PEM Fuel cell electrodes so that the cost of the overall system can be brought down. The performance can be improved if the utilization of the catalyst in the electrode increases. One of the early successful method was to add a proton conducting polymer, such as NafionR to the catalyst layer. However there is a limit to the amount of NafionR that can be added as too much NafionR affect the gas diffusion. The other method is to increase the surface area of the catalyst used which has also been adequately demonstrated. Alternative methods for providing increased proton conductivity and catalyst utilization are thus of great interest, and a number of them have been investigated in the literature. One method that is being extensively investigated is to introduce the catalyst onto the polymer electrolyte membrane followed by lamination with gas diffusion electrode. In the present work, we have carried out two methods i) screen print the catalyst ink on the NafionR membrane ii) catalyze the NafionR membranes by reducing a suitable platinum salt on the membrane. Standard gas diffusion electrodes were then laminated onto this membrane. The performances of Membrane Electrode Assemblies (MEAs) prepared by these routes have been compared with the commercially available Gore catalysed membrane. It was observed that catalysed NafionR membranes show a better performance compared to the catalyst ink screen printed on the NafionR membrane and commercial Gore membrane under identical operating conditions. However MEAs with Gore membrane give a better performance in the iR region compared to the other MEAs prepared using NafionR membrane. The lesser performance with Gore membrane is probably due to the limitations in the lamination method employed.


Author(s):  
S. B. Beale ◽  
U. Reimer ◽  
D. Froning ◽  
H. Jasak ◽  
M. Andersson ◽  
...  

Code stability is a matter of concern for three-dimensional (3D) fuel cell models operating both at high current density and at high cell voltage. An idealized mathematical model of a fuel cell should converge for all potentiostatic or galvanostatic boundary conditions ranging from open circuit to closed circuit. Many fail to do so, due to (i) fuel or oxygen starvation causing divergence as local partial pressures and mass fractions of fuel or oxidant fall to near zero and (ii) nonlinearities in the Nernst and Butler–Volmer equations near open-circuit conditions. This paper describes in detail, specific numerical methods used to improve the stability of a previously existing fuel cell performance calculation procedure, at both low and high current densities. Four specific techniques are identified. A straight channel operating as a (i) solid oxide and (ii) polymer electrolyte membrane fuel cell is used to illustrate the efficacy of the modifications.


Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2777 ◽  
Author(s):  
Lei Mao ◽  
Lisa Jackson

This paper presents a comparative study on the performance of different sizes of sensor sets on polymer electrolyte membrane (PEM) fuel cell fault diagnosis. The effectiveness of three sizes of sensor sets, including fuel cell voltage only, all the available sensors, and selected optimal sensors in detecting and isolating fuel cell faults (e.g., cell flooding and membrane dehydration) are investigated using the test data from a PEM fuel cell system. Wavelet packet transform and kernel principal component analysis are employed to reduce the dimensions of the dataset and extract features for state classification. Results demonstrate that the selected optimal sensors can provide the best diagnostic performance, where different fuel cell faults can be detected and isolated with good quality.


Author(s):  
Mathias Gerard ◽  
Jean-Philippe Poirot-Crouvezier ◽  
Daniel Hissel ◽  
Marie-Cecile Péra

Polymer electrolyte membrane fuel cells’ (PEMFCs) systems usually require power conditioning by a dc-dc boost converter to increase the output fuel cell voltage, especially for automotive applications and stationary applications. The output fuel cell current is then submitted to the high frequency switching leading to a current ripple. The ripple current effects on fuel cell are studied by experimental ripple current aging test on a five cell stack (membrane electrode assembly (MEA) surface of 220 cm2) and compared with a reference aging test. The stack is run in nominal conditions but an ac component is added to the dc load. The ac component is a 5 kHz triangle, amplitude of which is ±20% of the dc component, in order to simulate a boost waveform. Fuel cell characterizations (polarization curves, impedance spectra, and voltammetry) provide information on the PEMFC aging and the performance evolution. Local conditions are computed through a dynamic stack model. The model takes into account transport phenomena, heat transfer, and semi-empirical electrochemical reactions and includes a meshing to calculate local conditions on the MEA surface (gas reactant pressures, local temperature, gas molar fractions, water activity, and local electronic current density). The consequences about performance and aging during high frequency ripple current are explained.


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