ac Impedance Study of a Proton Exchange Membrane Fuel Cell Stack Under Various Loading Conditions

Author(s):  
N. V. Dale ◽  
M. D. Mann ◽  
H. Salehfar ◽  
A. M. Dhirde ◽  
T. Han

This paper presents the ac impedance study and analysis of a proton exchange membrane (PEM) fuel cell operated under various loading conditions. Ballard’s 1.2 kW Nexa™ fuel cell used for this study is integrated with a control system. The PEM fuel cell stack was operated using room air and pure hydrogen (99.995%) as input. Impedance data were collected for the fuel cell to study the behavior of the stack and groups of cells under various loads. Single cell impedance analysis was also performed for individual cells placed at different locations in the stack. The ac impedance analysis, also known as electrochemical impedance analysis, showed low frequency inductive effects and mass transport losses due to liquid water accumulation at high current densities. Results show that the stack run time to achieve steady state for impedance measurements is important. Using impedance plots, the average Ohmic resistance for the whole stack was estimated to be 41 mΩ, the same value obtained when summing the resistance value of all individual cells. Impedance analysis for groups of cells at different locations in the stack shows changes in both polarization resistance and capacitive component only in the low frequency region. At high frequencies, single cell inductive and capacitive behavior varied as a function of location in the stack. The effects of artifacts on the high frequency loop and on the high and low frequency intercept loops are also discussed.

2019 ◽  
Vol 250 ◽  
pp. 1176-1189 ◽  
Author(s):  
Cinthia Alegre ◽  
Antonio Lozano ◽  
Ángel Pérez Manso ◽  
Laura Álvarez-Manuel ◽  
Florencio Fernández Marzo ◽  
...  

Author(s):  
Georgiy Diloyan ◽  
Luis Breziner ◽  
Parsaoran Hutapea

The objective of this project is to develop a proton exchange membrane (PEM) fuel cell powered scooter with a designed digital controller to regulate the air supply to PEM fuel cell stack. A 500-Watt (W) electric power train was chosen as a platform for the scooter. Two 300 W PEM fuel cell systems, each containing 63 cells, were used to charge 48-Volt batteries that powered an electric motor. The energy carrier (hydrogen) was stored in two metal hydride tanks, each one containing 85 gs of hydrogen pressurized to 250 psig. The output hydrogen pressure from each tank was maintained at 5.8 psi by a two-stage pressure regulator, and then delivered to each fuel cell stack. To regulate the voltage of each PEM fuel cell under different load conditions, two step down DC/DC converters were used. These converters were connected in series to power the motor controller and charge the batteries. The batteries then supplied power to the 500 W brushless motor mounted to the hub of the rear wheel to save space. After all modifications were completed, most of the parts of the scooter stayed the same except for the panel under the seat—where larger space is needed for accommodating the hydrogen tanks. The weight of the scooter did not change significantly, because the weight of the hydrogen tanks (6.5 kg each) and fuel cell stacks (1.7 kg each) was partially compensated by replacing the batteries from the old ones that weighed 17.5 kg to new ones that weighed 9 kg.


2021 ◽  
Vol 11 (14) ◽  
pp. 6348
Author(s):  
Zijun Yang ◽  
Bowen Wang ◽  
Xia Sheng ◽  
Yupeng Wang ◽  
Qiang Ren ◽  
...  

The dead-ended anode (DEA) and anode recirculation operations are commonly used to improve the hydrogen utilization of automotive proton exchange membrane (PEM) fuel cells. The cell performance will decline over time due to the nitrogen crossover and liquid water accumulation in the anode. Highly efficient prediction of the short-term degradation behaviors of the PEM fuel cell has great significance. In this paper, we propose a data-driven degradation prediction method based on multivariate polynomial regression (MPR) and artificial neural network (ANN). This method first predicts the initial value of cell performance, and then the cell performance variations over time are predicted to describe the degradation behaviors of the PEM fuel cell. Two cases of degradation data, the PEM fuel cell in the DEA and anode recirculation modes, are employed to train the model and demonstrate the validation of the proposed method. The results show that the mean relative errors predicted by the proposed method are much smaller than those by only using the ANN or MPR. The predictive performance of the two-hidden-layer ANN is significantly better than that of the one-hidden-layer ANN. The performance curves predicted by using the sigmoid activation function are smoother and more realistic than that by using rectified linear unit (ReLU) activation function.


Author(s):  
Frano Barbir ◽  
Haluk Gorgun ◽  
Xinting Wang

Pressure drop on the cathode side of a PEM (Proton Exchange Membrane) fuel cell stack has been studied and used as a diagnostic tool. Since the Reynolds number at the beginning of the flow field channel was <250, the flow through the channel is laminar, and the relationship between the pressure drop and the flow rate is linear. Some departure from linearity was observed when water was either introduced in the stack or produced inside the stack in the electrochemical reaction. By monitoring the pressure drop in conjunction with the cell resistance in an operational fuel cell stack, it was possible to diagnose either flooding or drying conditions inside the stack.


2018 ◽  
Vol 43 (7) ◽  
pp. 2605-2614 ◽  
Author(s):  
Kailin Fu ◽  
Tian Tian ◽  
Yanan Chen ◽  
Shang Li ◽  
Chao Cai ◽  
...  

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