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The Proton Exchange Membrane Fuel Cell (PEMFC) is a fast-developing battery technology, and the key to its reliability and lifespan improvement lies in the accurate assessment of durability. However, the degradation mechanism of the PEMFC is hard to determine and its internal parameters are highly coupled. Thus, the development of a more accurate life prediction model that meets the actual scenarios is to be investigated urgently. To solve this problem, a multi-feature fusion life prediction method based on the Temporal Convolutional Network-Gated Recurrent Unit (TCN-GRU) is proposed. A TCN algorithm is used as the prediction base model, and two GRU modules are included with the model to strengthen the model's expression ability and improve its predictive accuracy. Two widely recognized datasets and two operating conditions are utilized for model training and prediction, respectively. Comparisons are made with single-feature parameter models in terms of Root Mean Square Error (RMSE) and the Determination Coefficient (R2). The results show that the prediction accuracy of the TCN-GRU multi-feature fusion model is higher than that of the single-feature models in terms of stability and anti-interference under both operating conditions. The accuracy of the TCN-GRU (three-feature) model is the most optimal in a steady-state condition at 80% of the training set ratio (RMSE = 3.27 × 10−3, R2 = 0.965). Furthermore, with the increase in the input feature parameter, the TCN-GRU model is closer to the real value, which proves once again that the proposed model can meet the accuracy requirements of the life prediction of the PEMFC. [ABSTRACT FROM AUTHOR]

Flow channel optimization is an important method to improve the water-gas transport capacity and enhance the performance of proton exchange membrane fuel cells. In this study, the size ratio of the opposite sinusoidal wave flow channel (OSWFC) is optimized, and three-dimensional numerical models are developed to evaluate the comprehensive performance. The results show that OSWFCs obtain performance enhancement compared to the parallel flow channel. 1:1 wave channel has a maximum improvement of 19.53% in mass transfer capacity by the most frequent flow disturbance, while 1:3 has a maximum increasement of 37.5% in water removal performance by the virtue of gentle wave structure. Large pressure loss decreases the mass transfer efficiency, although it with the maximum mass transfer capacity, the mass transfer evaluation criterion of 1:1 wave channel is less than that of 1:3. Moreover, a significant correlation between water-gas transport capacity and electrochemical performance is demonstrated by Pearson correlation coefficient. [Display omitted] • The OSWFC has a significant performance enhancement at high current densities. • The wave flow channel with ratio of 1:1 has the best mass transfer capacity. • The wave flow channel with ratio of 1:3 has the best water removal performance. • MTEC is proposed to evaluate the mass transfer efficiency. • PCC is proposed to evaluate the comprehensive performance of PEMFC. [ABSTRACT FROM AUTHOR]

Summary: Proton exchange membrane fuel cell (PEMFC) generates a lot of heat during power generation. It is necessary to control PEMFC to operate at proper temperature through effective thermal management. CFD model of flow field plates with different structures is established; the heat transfer performance of different flow fields was analyzed by numerical simulation. The index of uniformity temperature (IUT) was introduced to further evaluate the heat transfer effect. The results showed that the parallel flow field was not suitable for cooling due to its poor performance at high coolant flow rate. The pressure difference of serpentine flow field was more than 10 times that of other flow fields, which lead to the highest cost in practical cooling application. The wave flow field with the best comprehensive cooling effect at high flow velocity, and the average temperature and IUT were 2.22% and 37.97% lower than the parallel flow field, respectively. The cooling effect of point flow field followed the second, and its average temperature and IUT were 1.65% and 29.71% lower than those of parallel flow field, respectively. In practice application, the wavy flow field showed better heat transfer performance within the required coolant flow range. [ABSTRACT FROM AUTHOR]

Summary: The lumped parameter model of the hydrogen system based on exhaust hydrogen recirculation and the CFD model of PEMFC stack were established in this paper. The system simulation results were used as the input of the stack model. The purge characteristics of the stack were studied and the purge strategy was formulated considering the hydrogen utilization and performance characteristics. The results show that during anode purging, the anode pressure fluctuated significantly and the nitrogen concentration decreased rapidly. The output voltage of the stack fluctuates greatly, and the fluctuation of voltage intensifies with the extension of emission duration. In addition, the voltage fluctuation range of unit cell decreases gradually from inlet to outlet. After the system stabilizes, the component distribution of anode was improved and the stack performance was recovered to the initial state. During the purge interval, the performance of the stack degrades due to the increase of anode nitrogen concentration. The hydrogen utilization rate of the hydrogen system was directly related to the purge strategy, and the purge strategy of short period‐short duration was beneficial to reduce the fluctuation of the stack performance in the purging process, and reduce the differences of performance and component distribution of different single cell. [ABSTRACT FROM AUTHOR]

Summary: Experimental and numerical studies are the main methods to obtain the polarization curves of proton exchange membrane fuel cell (PEMFC) stack for the application of balance of plant (BOP) selection, system matching, and controller design. A novel methodology of polarization curve fitting for PEMFC is proposed based on genetic algorithm, and a rated power of 62 kW fuel cell stack is used for identification experiments. The exchange current density and charge transfer coefficient are selected as optimization variables. The results show that the two optimization variables can effectively replace the four empirical parameters in the calculation of activation overpotential and demonstrate good agreement between the proposed model and experimental data within 3% error. In addition, a group of polarization curves is obtained by considering the relationship between the exchange current density and reactant concentration, activation energy, and temperature, which is of great significance in the engineering application of PEMFC for quick and accurate control. Furthermore, a dynamic model is also used to investigate the transient response of PEMFC, and the simulation results show a transition region of voltage drop at step current densities, coinciding with the experimental data and indicating the reliability of the method for polarization curve fitting. [ABSTRACT FROM AUTHOR]

In this paper, the model of a proton exchange membrane fuel cell (PEMFC) with single straight channel is established to investigate the effect of dimensionless size factor of baffles on PEMFC performance. The influence of dimensionless length and height of baffles is discussed. Results show that adding baffles could dramatically optimize the mass transfer in PEMFC. The dimensionless length and height of the baffle have much influence on PEMFC performance. [ABSTRACT FROM AUTHOR]

In this study, a three-dimensional multi-phase proton exchange membrane fuel cell (PEMFC) electrochemical model coupled with a cooling channel (CC) was developed, to comprehensively analyze the heat transfer characteristics. The membrane temperature, index of uniform temperature (IUT), net power, and the Nusselt number were applied to evaluate the heat transfer performance. The results indicate that a smaller IUT value achieves better PEMFC performance at close temperatures, and the best performance is achieved with a coolant inlet temperature of 343.15 K. Although increasing the coolant flow velocity improves the cooling effect, thereby enhancing PEMFC performance. However, it inevitably leads to an increase in parasitic power, resulting in a decrease in the output power of the PEMFC system. Moreover, with the coolant temperature difference less than 6K, PEMFC shows better performance when the coolant flow direction is the same as O 2. On the contrary, with the coolant temperature difference greater than 6K, the coolant flow direction should be the same as H 2 to ensure good performance. In addition, with the temperature difference between the coolant inlet and outlet of 10K, 6K, and 3K, respectively, the surface Nusselt number of wavy CC is 5.46%, 8.92%, and 18.71% higher than the straight CC, respectively. • A three-dimensional multi-phase PEMFC electrochemical model coupled with cooling channel is developed. • IUT, net power and Nusselt number are applied to evaluate the heat transfer performance. • The effect of coolant flow direction on performance depends on the flow velocity. • Performance of PEMFC with wave cooling channel is slightly better than that of straight cooling channel. [ABSTRACT FROM AUTHOR]

The optimal design of the flow field is of great significance for the performance enhancement and commercial application of proton exchange membrane fuel cells (PEMFCs). The optimization of water-gas transport characteristics in the flow field is the key research content and the key to enhancing the performance and durability of PEMFC. Flow field design evaluation criteria are the mainstream methods for judging the water-gas transport characteristics of flow fields. This paper reviews the current status of PEMFC flow field optimization design research, emphasizes multiple flow field design evaluation criteria, and is dedicated to achieving a standardized, integrated and commercialized design of commercial flow field plates (FFP). Further, a flow field design criterion with a cost-effectiveness index as an important criterion is proposed to optimize the high cost of commercial FFP and poor water-gas transport performance at high current densities. In order to obtain a commercial FFP with better comprehensive performance and better cost-effectiveness, and ultimately promote the commercialization of PEMFC. • An overview of PEMFC flow field optimization research is presented. • Multiple flow field design evaluation criteria are introduced and analyzed. • The concept of optimized design of commercial FFP for SIC is proposed. • CEI is used as an important design criterion for commercial FFP. • Achieving the goal of commercial FFP design with high performance and low cost. [ABSTRACT FROM AUTHOR]

• Cathode flow fields of PEMFCs with great water–gas transfer capacity are optimized. • PEMFC obtains 9.30% performance enhancement with the optimal cathode flow field. • Visualization experiment verify water removal advantage and performance benefits. • PCC is firstly proposed to evaluate the correlation of PEMFC performance indexes. Flow field design plays a key role in enhancing the performance of proton exchange membrane fuel cell (PEMFC). In this work, the cathode flow field is optimized to enhance the performance of PEMFC by improving the capacity of mass transfer and water removal, and a three-dimensional, two-phase, isothermal numerical model is established to evaluate its performance. Additionally, visualization experiment is carried out to verify the simulation results. It shows that the opposite sinusoidal wave flow fields (OSWFFs) with single-inlet, dual-inlet and the block provide 6.86%, 1.26%, and 2.31% performance enhancement, respectively, compared with the parallel flow fields (PFFs), which positively affects the mass transfer capacity and water removal performance. Among them, the dual-inlet OSWFF with block is the most helpful for performance enhancement, with an enhancement of 9.30% at 2.2 A cm−2 compared to the PFF. Moreover, Pearson correlation coefficient (PCC) is proposed for the first time to evaluate the correlation between each index and PEMFC performance. The comparison of stoichiometric ratios shows that the more significantly correlated indexes contribute to the dual-inlet OSWFF outperforming the single-inlet OSWFF at high inlet velocities, verifying the applicability of PCC in PEMFC. [ABSTRACT FROM AUTHOR]

The optimized design of the flow field structure helps to enhance the mass transfer and water removal capacity of the proton exchange membrane fuel cell (PEMFC). A novel opposite sinusoidal wave flow channel is proposed in this study, and the influence of amplitudes and periods of the sinusoidal function on performance of PEMFC is explored by numerical simulation. The research results show that the mass transfer capacity of the opposite sinusoidal wave channel is better than that of the straight channel. By increasing the amplitude, combined with decreasing the period, the mass transfer capacity and the performance of the PEMFC can be effectively enhanced. Compared with the straight channel, for an amplitude of 0.8 mm and a period of 0.5Π mm at 2.0 A cm−2, the net power density is increased by 16.61% and 12.01% respectively. Moreover, based on the volume of fluid model, the transport process and distribution characteristics of liquid water in the straight channel and the opposite sinusoidal wave channel are compared and analyzed. The results show the drainage period of the opposite sinusoidal wave channel is half shorter compared to the straight channel. Therefore, the proposed opposite sinusoidal wave channel has better water removal capacity. • A novel opposite sinusoidal wave flow channel is proposed for performance enhancement. • The influence of amplitudes and periods of the sine function on performance of PEMFC is explored. • The proposed sinusoidal wave channel shows excellent mass transfer and water removal capacity. [ABSTRACT FROM AUTHOR]

The operating parameters of proton exchange membrane fuel cell (PEMFC) are critical to its performance and working life. This study presents a data-driven modeling approach combining a surrogate model with the particle swarm optimization algorithm to optimize operating parameters for PEMFC and obtain the maximum power density. The results show that the operating parameters significantly influence power density under high current densities, with inlet temperature having the most significant effect. Lower inlet temperature, relative humidity in the cathode and anode, along with higher operating pressure yield improved output performance. The Genetic Algorithm-Backpropagation Neural Network based surrogate model exhibits excellent predictive performance with correlation coefficients of 0.99896 and 0.99815 for the training and test sets, respectively. Optimized conditions achieve a 3.3% increase in power density compared to initial settings, with only a 0.15% error in simulation calculations. This data-driven approach provides valuable insights for maximizing PEMFC efficiency and performance. • An approach combining surrogate model with PSO algorithm to predict PEMFC performance is proposed. • The GA-BP-based surrogate model exhibits excellent predictive performance. • Maximum power density and corresponding operating parameters are achieved. [ABSTRACT FROM AUTHOR]

Gaskets are compressed in proton exchange membrane fuel cells (PEMFCs) to keep fuel, oxidant and coolant within their respective regions and are very important for sealing and maintaining electrochemical performance of fuel cells during their long-term operation. It has been proved that the gas leakage caused by the failure of the gaskets following long-term operation is one of the main reasons for PEMFC performance degradation. In this work, degradation of silicone rubbers, the potential gasket materials for PEMFCs, were investigated in the simulated PEMFC environment solution, weak acid solution, de-ionized water and air, respectively, under alternating temperature cycling from −20 °C to 90 °C. The changes in hardness, weight, chemical properties, mechanical behavior and surface morphology of the samples of silicone rubbers were studied after a certain number of temperature cycles. The results show that with the increase in temperature cycles, the hardness of the samples increases and the weight of the samples decreases gradually. Scanning electron microscopy reveals that cracks and caves constantly appear on the surface of the samples. Attenuated total reflection Fourier transform infrared spectra (ATR-FTIR) results demonstrate that the surface chemistry changes via de-crosslinking and chain scission in the backbone due to the exposure of samples to the environments over time under alternating temperature cycles. [ABSTRACT FROM AUTHOR]

Water management is important to achieve excellent performance and durability of proton exchange membrane fuel cells (PEMFCs). Due to the complexity of the two-phase water transport process, a rapid assessment of the water transport characteristics inside the fuel cell is essential for its stable operation. Based on the dynamic equilibrium process of water transfer and the relationship between the membrane water content and the water saturation in the gas phase, a multi-state water transport model is proposed to quickly evaluate and quantitatively analyze the net water transport characteristics based on genetic algorithm. The results indicate that the water produced by the electrochemical reaction can be partially removed through the anode at low current densities and relative humidity. The proportion of water removed through the anode decreases with the increase of anode relative humidity, current density, temperature, membrane thickness, and the decrease of back pressure. Considering the effect of water transport on cell performance, it's found that membrane dehydration and a significant increase in ohmic loss are the main reasons for the performance degradation at high temperatures, and the attenuation could be mitigated by cathode humidification. Quantitative analysis of water transport guides the formulation of efficient water management strategies of PEMFC. • A water transport model is proposed to predict the water distribution in PEMFC. • Genetic algorithm is used to quantify the net water transfer flux. • The product water can be partially removed through the anode. • Membrane dehydration is the main reason for performance degradation at high temperatures. [ABSTRACT FROM AUTHOR]

· The heat transfer characteristics in the concentration polarization zone are analyzed. · IUT, Nusselt number and Field synergy angle are applied for heat transfer performance evaluation. · Cooling capacity is improved by increasing the twists and turns in the cooling flow field. Heat management plays a vital role in the efficient and stable operation of proton exchange membrane fuel cells (PEMFCs), especially at high current densities, which is directly related to the cooling flow field (CFF). In this paper, a non-isothermal electrochemical model coupled with CFF of PEMFC is developed, and the effects of CFF structures on the water and heat transfer performance enhancement of PEMFC at high current densities are studied. In addition, an Evaluation Criteria is expected to be applied to evaluate the heat transfer capacity of CFFs. The results indicate that high temperatures effectively alleviate PEMFC concentration polarization. Due to the twists and turns design within the channel, the heat transfer capability of the Wave CFF performs well, Nusselt number and field synergy angle values respectively 35.7 % higher and 3.34 % lower than those of Parallel CFF. Additionally, the heat transfer performance factor is used to evaluate the heat transfer capability of different cooling flow field structures. The performance factor of the Wave CFF reaches 1.44 at a coolant temperature difference of 1 K. [ABSTRACT FROM AUTHOR]

• Novel flow field designs for PEMFC have been proposed and optimized to enhance performance. • A multi-objective optimization algorithm is employed to refine key features of the channel structure. • ANN's surrogate model accurately predicted outcomes with small errors. • The optimized channel structure yields significant enhancements in performance and drainage capacity. This research aims to improve the performance of proton exchange membrane fuel cells (PEMFCs) by multi-objective optimization of the flow channel structure. The accomplishment involves employing a three-dimensional multi-phase PEMFC model for performance estimation, optimizing it using artificial neural networks (ANN), and validating the water removal capacity through the volume of fluid (VOF) method. By investigating the simulation of different necking acceleration structures with their arrangements of PEMFC, it is found that U-shaped array arrangement performed better compared to other structures. The optimization of key structural features employs ANN to attain improved performance, specifically targeting enhancements in net power density and the uniformity index of oxygen. The optimized case predicts a net power of 0.8659 and simulates a net power of 0.8675 with an error of 0.184 %, an increase of 3.84 % compared to the conventional (Conv) straight channel simulation result of 0.8354. The predicted oxygen uniformity index is 0.6932, while the simulated oxygen uniformity coefficient is 0.6919, resulting in a slight error of 0.188 %. It represents a 1.91 % improvement compared to Conv's simulation result of 0.6789. Furthermore, according to the VOF model, the presence of turbulence caused by the structure significantly decreased the saturation of liquid water, and the drainage period of the optimized case was nearly half as short as that of the straight channel configuration. [ABSTRACT FROM AUTHOR]

The gas diffusion layer structure has a significant impact on water and gas transport in proton exchange membrane fuel cell (PEMFC). In this study, a multi-objective optimization (MOO) method is applied to optimize the PEMFC gas diffusion layer (GDL) structures for performance enhancement. Nine design parameters are studied to analyses the output performance of the fuel cell and the average water content of the membrane, oxygen concentration non-uniformity, power density and system efficiency are used as performance indexes. The MOO forms the response surface regression model based on the three-dimensional numerical model of PEMFC, and the response surface methodology after processing through the non-dominated sorting genetic algorithm-III (NSGA-III) to obtain the Pareto frontier, and prioritizes the best operating conditions and structures based on technique for order preference by similarity to an ideal solution (TOPSIS). Compared with the reference point, the performance indexes of the decision point obtained by the NSGA-III algorithm and TOPSIS algorithm is enhanced by 0.45 %, 42.06 %, 2.99 % and 0.25 %, respectively. This study presents a new multi-objective optimization method for optimizing operating conditions combine with GDL structures for building efficient PEMFC, which provides a solution for achieving higher performance. The optimal results in this paper can provide some guidance for fuel cell performance improvement and control optimization. • The original data are obtained by establishing a three-dimensional two-phase non-isothermal model. • RSM and NSGA-ⅡI are combined for MOO of PEMFC gradient gas diffusion layer structures. • There are nine design variables and four optimization objectives are considered. • Optimal GDL structures and operating conditions selected by TOPSIS from the Pareto front. • Decision point from TOPSIS have 0.45 %, 42.06 %, 2.99 %, and 0.25 % enhancement. [ABSTRACT FROM AUTHOR]

• Novel flow fields are designed with experimental and numerical investigation. • EMTC and EEC are proposed to evaluate the mass transfer capacity and efficiency. • Dual-inlet mode is good to the water removal and with uniform velocity distribution. • PEMFC obtain performance enhancement for the advantages of water-gas transport. The performance of the proton exchange membrane fuel cell (PEMFC) depends on the water-gas transport capacity of flow fields. In this paper, the performance of the designed PEMFC with novel flow fields is tested by experimental methods. The experimental results show that the PEMFC with opposite sinusoidal wave flow field (OSWFF) and intercepted flow field (ICFF) are improved compared to the parallel flow field. The PEMFC with single-inlet OSWFF and ICFF show 19% and 11% performance enhancement at 2.0 A cm−2, respectively. A 3D numerical model for the validation experiment is established to analyze the water-gas transport characteristics of the flow field. The mass transfer performance of ICFF with 3D structural optimization is much better than that of OSWFF with 2D structural optimization, and the effective mass transfer coefficient and efficiency evaluation criterion are improved by 106% and 258%, respectively. The 7% improvement in oxygen uniformity in the dual-inlet mode compared to the single-inlet mode enhances the stability of the electrochemical reaction and the 28% improvement in velocity uniformity, which contributes to the uniform distribution and discharge of liquid water, which in turn enhances the PEMFC performance. [ABSTRACT FROM AUTHOR]