An official website of the United States government
Proton exchange membrane (PEM) fuel cells have emerged as a viable alternative energy production source for stationary and transportation applications. Reliable and sustainable fuel cell operation requires effective water management. Membrane water content can vary along the stack during transients which can lead to losses in fuel cell performance. To control these variations, a model that predicts the internal humidity dynamics of the stack is needed. In this study, a control-oriented model for predicting membrane water content variation was developed and implemented in MATLAB/Simulink. A lumped parameter model was initially developed and then further discretized into smaller control volumes to track humidity distribution along the stack. To validate the model’s predictions, the predicted results were compared to computer simulation results from GT-Suite. The root mean square error (RMSE) between the model’s prediction and GT-Suite’s simulation results was found to be within 1.5 membrane water content for all cases, demonstrating the model’s capability to capture the variation in membrane water content along the stack. The developed model will be useful for real-time control of membrane water content distribution in PEM fuel cells.
more »
« less
This content will become publicly available on October 8, 2026
Impact of Cathode Inlet Relative Humidity on Water Management and Performance of an Open-Cathode Fuel Cell
Proton exchange membrane fuel cells (PEMFCs) have become a practical and promising alternative energy source for the automotive industry, offering high efficiency and zero-carbon emissions compared to internal combustion engines. Sustainable fuel cell (FC) operation in vehicles is dependent on effective water management. This study investigates impact of local, ambient relative humidity (RH) level variation on the water content and overall performance of a 5-kW open-cathode PEMFC. A Simcenter Amesim model of the FC was first developed, calibrated, and validated using experimental data. The model was tested under various scenarios to comprehensively analyze how changes in local RH affect membrane water content, reflected in the polarization curve, FC power, and ohmic losses. The results show that FC efficiency improves by 23%, while ohmic resistance drops from 0.72 Ω·cm² to 0.26 Ω·cm² as the local RH increases from 10% to 90%.
more »
« less
- Award ID(s):
- 2135735
- PAR ID:
- 10644222
- Publisher / Repository:
- IFAC
- Date Published:
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Increased energy demand and environmental concerns are driving the search for cleaner, more efficient power generation. Fuel cells (FCs) offer a solution by converting chemical energy from fuel and oxidant directly into electricity with high efficiency (40-70%) and zero carbon emissions. Enhancing the performance and durability of polymer electrolyte membrane fuel cells (PEMFC) while reducing costs remains a significant challenge. The current planar FC design presents various issues, including high costs and weight due to metal or graphite bipolar plates, high-pressure drop-in reactant gas diffusion channels, reactant gas transport losses in the agglomerate-type catalyst layers, water flooding, to name just a few. Exploring novel biomimetic designs may offer solutions to these challenges. This research is inspired by vascular plant structures to improve mass transport and efficiency. The cathode uses carbon nanofibers (CNF) made via electrospinning, with Pt nanorod catalyst on the surface in an open electrode layout. This CNF-type cathode was used to create a membrane electrode assembly (MEA), using a commercial membrane and typical anode. A number of parameters were varied, including overall Pt loading, Pt concentration on the fibers, design with and without gas diffusion layer, using CNF mat. The MEAs were tested to establish links between structure, properties, and performance. Performance was evaluated through polarization curves and electrochemical impedance spectroscopy, while beginning of test and end of test structure was investigated using microscopy. CNF-based MEAs achieved a higher current density compared to the commercial MEA at lower Pt loading. This suggests that reduced loading still maintained acceptable Pt utilization, reducing the Pt amount in the MEA. In summary, the CNF catalyst support displayed improved durability, mass transport, Pt utilization, and efficiency thanks to its porous mesh structure.more » « less
-
Abstract Proton‐exchange membrane fuel cell vehicles offer a low‐carbon alternative to traditional oil fuel vehicles, but their performances still need improvement to be competitive. Raising their operating temperature to 120 °C will enhance their efficiency but is currently unfeasible due to the poor mechanical properties at high temperatures of the state‐of‐the‐art proton‐exchange membranes consisting of perfluorosulfonic acid (PFSA) ionomers. To address this issue, xx designed composite membranes made of two networks: a mat of hybrid fibers to maintain the mechanical properties filled with a matrix of PFSA‐based ionomer to ensure the proton conductivity. The hybrid fibers obtained by electrospinning are composed of intermixed domains of sulfonated silica and a fluorinated polymer. The inter‐fiber porosity is then filled with a PFSA ionomer to obtain dense composite membranes with a controlled fibers‐to‐ionomer ratio. At 80 °C, these obtained composite membranes show comparable performances to a pure PFSA commercial membrane. At 120 °C however, the tensile strength of the PFSA membrane drastically drop down to 0.2 MPa, while it is maintained at 7.0 MPa for the composite membrane. In addition, the composite membrane shows a good conductivity of up to 0.1 S cm −1 at 120 °C/90% RH, which increases with the ionomer content.more » « less
-
Abstract In this study, pentablock terpolymers with methylpyrrolidinium cations were characterized and investigated as anion exchange membranes and ionomers for solid‐state alkaline fuel cells. The pentablock terpolymer (with methylpyrrolidinium cations) membranes exhibited higher fuel cell power density and durability than commercial FuMA‐Tech (with quaternary ammonium cations) membranes at 30 °C, 100% relative humidity (RH). Optimization of the catalyst ink composition (i.e., solids and solvent ratio) and fuel cell performance of membrane electrode assemblies (MEAs) with pentablock terpolymers as both the membrane and ionomer were also investigated. Optimization of the fuel cell operating conditions corroborates with thein situelectrochemical impedance spectroscopy results. The pentablock terpolymer MEA exhibited a maximum power density of 83.3 mW cm−2and voltage decay rate of 0.7 mV h−1after 100 h of operation under 40 °C, 100% RH. These results show promise for pentablock terptolymers with methylpyrrolidinium cations as a commercially attractive low‐cost alternative anion exchange membrane and ionomer for solid‐state alkaline fuel cells.more » « less
-
In this study, a novel application of the Koopman operator for control-oriented modeling of proton exchange membrane fuel cell (PEMFC)stacks is proposed. The primary contributions of this paper are: (1) the design of Koopman-based models for a fuel cell stack, incorporating K-fold cross-validation, varying lifted dimensions, radial basis functions (RBFs), and prediction horizons; and (2) comparison of the performance of Koopman based approach with a more traditional physics-based model. The results demonstrate the high accuracy of the Koopman-based model in predicting fuel cell stack behavior, with an error of less than 3%. The proposed approach offers several advantages, including enhanced computational efficiency, reduced computational burden, and improved interpretability. This study demonstrates the suitability of the Koopman operator for the modeling and control of PEMFCs and provides valuable insights into a novel control-oriented modeling approach that enables accurate and efficient predictions for fuel cell stacks.more » « less
