Electrolyte Membrane Fuel Cell System Research Articles

Common cause analysis of the air supply system of fuel cell-powered propulsion systems in electrified aviation

By means of a Common Cause Analysis (CCA), potential safety challenges of the air supply system for polymer electrolyte membrane fuel cell systems (PEMFCSs) as the primary energy provider in electric aero engines are identified and mitigated. The design of an exemplary hydrogen-fuelled PEMFCS-powered aero engine is described, focusing on the air supply system. The safety assessment method CCA, consisting of a Zonal Safety Analysis (ZSA), a Particular Risk Analysis (PRA) and a Common Mode Analysis (CMA), is described and conducted on the PEMFCS aero engine’s air supply system. Failure modes and external events, which can have safety effects are identified, and potential design adaptations for mitigation are presented.

Numerical and experimental investigation on condensation inside a turbine designed for an 100 kW polymer electrolyte membrane fuel cell system

This work presents mathematical modelling of moist air condensation process in a fuel cell turbine. A condensation model based on the classical nucleation theory and the Hertz–Knudsen droplet growth model is established. The numerical approach is validated through experimental results of the MS nozzle and a fuel cell turbine, and the simulation fits the experimental data well. Influences of inlet temperature and pressure on condensation process in the turbine is examined. Results show that increase of inlet temperature apparently weakens condensation and inlet heating can be realized by arranging a gas-to-gas heat exchanger in the air supply subsystem without consuming additional energy. Moreover, at the same mass flow rate increase of inlet pressure reduces the expansion ratio, thereby curbing the condensation. Compared with the matching scheme of a bypass valve, turbocharger matching with a back-pressure valve allows higher inlet pressure to be achieved and can effectively suppress the condensation.

Water management issues during load cycling under high temperature and low humidity conditions relevant for heavy-duty applications of PEMFC

To meet the increased requirements for efficiency and compactness of the Polymer Electrolyte Membrane Fuel Cell (PEMFC) system for heavy-duty vehicles (HDVs) application, PEMFC has to operate under high temperature and low humidity (HTLH) conditions to reduce the parasitic power consumption of radiators and the size of humidifier. However, HTLH would negatively affect the performance and durability of PEMFC. Through conducting in-situ current mapping, this paper found highly inhomogeneous current in-plane distribution during current cycling under HTLH conditions, which is attributed to the self-reinforced feedback of local current density and membrane water content. Instead, under the situations where current increase is prior to the temperature increase, PEMFC would have much more uniform in-plane current distribution and membrane water distribution, resulting in more efficient utilization of the produced water in a dry environment.

Functional and Safety Challenges of Hydrogen Fuel Cell Systems for Application in Electrified Regional Aircraft

This paper identifies potential weaknesses and challenges of hydrogen fuel cell systems as main energy provider for electrified aircraft propulsion and presents potential solutions. The general design, operating principles and main characteristics of hydrogen-fuelled low-temperature polymer electrolyte membrane fuel cell systems (PEMFCSs) are described. The safety assessment process in aviation according to Aerospace Recommended Practices ARP4754A and selected methods according to ARP4761 are introduced. The functions of fuel cell systems in electrified aircraft powertrains are analysed in functional structure trees on aircraft, powertrain and fuel cell system level. By means of a Functional Hazard Analysis (FHA), potential malfunctions and their effects are investigated and their severity is evaluated. Critical failure modes are identified and requirements for acceptable failure probabilities are stipulated. Solution options to mitigate failure effects are stated. The results of the mentioned analyses reveal design challenges associated with the application of fuel cell systems in electrified aircraft propulsion, for instance, concerning functional independence as well as solutions for cold start conditions, heat transfer and lightweight design. Furthermore, safety challenges arise due to the utilisation of cryogenic hydrogen as fuel and the high amount of electric energy.

A Critical Review of Polymer Electrolyte Membrane Fuel Cell Systems for Automotive Applications: Components, Materials, and Comparative Assessment

The development of innovative technologies based on employing green energy carriers, such as hydrogen, is becoming high in demand, especially in the automotive sector, as a result of the challenges associated with sustainable mobility. In the present review, a detailed overview of the entire hydrogen supply chain is proposed, spanning from its production to storage and final use in cars. Notably, the main focus is on Polymer Electrolyte Membrane Fuel Cells (PEMFC) as the fuel-cell type most typically used in fuel cell electric vehicles. The analysis also includes a cost assessment of the various systems involved; specifically, the materials commonly employed to manufacture fuel cells, stacks, and hydrogen storage systems are considered, emphasizing the strengths and weaknesses of the selected strategies, together with assessing the solutions to current problems. Moreover, as a sought-after parallelism, a comparison is also proposed and discussed between traditional diesel or gasoline cars, battery-powered electric cars, and fuel cell electric cars, thus highlighting the advantages and main drawbacks of the propulsion systems currently available on the market.

Potential global warming impact of 1 kW polymer electrolyte membrane fuel cell system for residential buildings on operation phase

This study established global warming potential(GWP) emission factors through a life cycle assessment on the operation phases of two different 1 kW polymer electrolyte membrane fuel cell (PEMFC) systems for residential buildings (NG-PEMFC, fed with hydrogen from natural gas reforming; WE-PEMFC, fed with hydrogen from photovoltaics-powered water electrolyzer). Their effectiveness was also compared with conventional power grid systems in Korea, specifically in the area of greenhouse gas emissions.The operation phases of the NG-PEMFC and the WE-PEMFC were divided into burner, reformer, and stack, and into water electrolysis and stack, respectively. The functional unit of each fuel cell system was defined as 1 kWh of electricity production. In the case of NG-PEMFC, the GWP was 3.72E-01 kg-CO2eq/kWh, the embodied carbon emissions due to using city gas during the life cycle process was about 20.87 %, the carbon emission ratio according to the reformer's combustion burner was 6.07 %, and the direct carbon emission ratio of the air emissions from the reformer was 73.06 %, indicating that the carbon emission from the reformer contributed over 80 % of the total GWP. As for the WE-PEMFC, the GWP was 1.76E-01 kg-CO2eq/kWh, and the embodied carbon emissions from photovoltaic power generation during the life cycle process contributed over 99 % of the total GWP.

Startup optimization of an automotive polymer electrolyte membrane fuel cell system with dynamic hydrogen reference electrodes

Efficient polymer electrolyte membrane fuel cell (PEM-FC) systems with minimal degradation are indispensable for automotive applications. A decisive measure to achieve this goal is the optimization of the startup procedure as part of the system operating strategy. This applies in particular to startups where the anode is partly or completely filled with ambient air after long downtimes. When displacing the air in the anode with hydrogen, damage to the cathode is inevitable and should be minimized. Basic approaches for this optimization are known from literature but are mainly derived from single cell and short stack experiments. In this paper, we optimize a full PEM-FC system by utilizing Dynamic Hydrogen Electrodes and show how gas replacement speed and half cell voltage evolution can be improved to mitigate degradation. The experimental results show that a homogeneous flow of the hydrogen/air front across the stack is to prioritize over its speed as only this enables additional upper voltage control in large stacks. The system optimum is achieved by maximizing startup pressure and purge valve flow, adapting the anode recirculation rate and precise voltage clipping. This study thus forms a procedural template for the optimization of the SUSD procedure in automotive fuel cell systems.

Severity-based fault diagnostic method for polymer electrolyte membrane fuel cell systems

This research suggests a severity-based multi-stage fault diagnostic method for polymer electrolyte membrane fuel cell systems. By separating the diagnostic stage depending on the fault severity, robustness and sensitivity of the diagnosis algorithm on each stage can be designed with flexibility. The details of the fault diagnosis algorithm development process are described and validated with fault experimental data using a 1 kW class fuel cell system. First, a nominal model is developed to generate a residual between the predicted normal state and the observed state. Second, expected fault responses of the system are organized in the form of residual patterns. These residual patterns are used for training neural networks that diagnose critical faults, significant faults, and minor faults. Third, the generated residuals are standardized and moving averaged to be used as inputs for the neural networks at each stage. Lastly, diagnosis results from the neural network-based algorithm are compared with the fault experimental data. As a result, 17 different faults are all successfully diagnosed. More specifically, five critical faults, seven significant faults, and 13 minor faults are diagnosed. In addition, a diagnosis method for multi-faults is suggested. Double faults and triple faults are experimentally simulated and diagnosed with the diagnosis algorithm.

Observer‐based event‐triggered adaptive output feedback control of oxygen excess ratio for uncertain polymer electrolyte membrane fuel cell system

Observer‐based event‐triggered adaptive output feedback control of oxygen excess ratio for uncertain polymer electrolyte membrane fuel cell system

Effect of uniformity and surface morphology of Pt nanoparticles to enhance oxygen reduction reaction in polymer electrolyte membrane fuel cells

Platinum (Pt)-based electrocatalysts supported by reduced graphene oxide (rGO) is fabricated under microwave-assisted polyol method with various nucleation and growth conditions. The surface morphologies of the Pt nanoparticles (NPs) under various reaction conditions owing to different Pt NP sizes and inter-particle spacings are investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, cyclic and linear sweep voltammetry, and electrochemical impedance spectroscopy. The synthesized Pt/rGO catalyst under nucleation and growth times of 10 s and 50 s, respectively, exhibits excellent catalytic activity with increased electrochemical surface area, high density, good uniformity and surface morphology with a particle size and inter-particle spacing of 2.16 nm and 17.2 nm, respectively. These results elucidate the relationship between the Pt NP morphology distribution and oxygen reduction reaction of catalysts in polymer electrolyte membrane fuel cell systems. We also highlight the important role of size and inter-particle spacing on the Pt electrochemical catalystic performance.

A framework for the replacement analysis of a hydrogen-based polymer electrolyte membrane fuel cell technology on board ships: A step towards decarbonization in the maritime sector

Maritime transport is one of the largest greenhouse gas emitting sectors of the global economy, responsible for around 1 GtCO2eq every year. To comply with the reduction of carbon dioxide emissions, the research is devoted introducing low and zero-carbon fuels and innovative propulsion technologies. In this context, hydrogen fuel cell powertrains can play a crucial role due to their high energy and environmental performances. In this paper, a techno-economic feasibility analysis for replacing an 8.3 MW diesel engine with a polymer electrolyte membrane fuel cell system is performed for a chemical tanker ship. For this purpose, a detailed method, that aims to estimate the volume and mass of the fuel cell system as well as of the hydrogen storage technologies, is developed. Three on board hydrogen storage technologies are considered: i) compressed hydrogen, ii) liquid hydrogen, iii) metal hydrides. Results highlight that the fuel cell-based powertrain is characterized by 60% less volume and 56% less mass compared to the diesel engine. As far as the hydrogen storage technologies are concerned, all solutions present significantly lower volumetric and gravimetric energy densities and therefore, additional volume and mass are required in comparison with diesel fuel configuration. These results involve a reduction of the total cargo capacity to comply with tanker ship physical constraints. The cargo should be reduced by 1.3%-1.1% for compressed hydrogen (at 350 bar and 700 bar, respectively), 0.1% for liquid hydrogen, and 9% for metal hydrides. Finally, the economic assessment in terms of Operational Expenditures, based upon the predicted hydrogen price reduction as well as the diesel price increase, in different cost scenarios (2020–2050), are evaluated. Results show that the competitiveness of the hydrogen solution with a retail price of 4 $/kg can be achieved by considering an incentive for the avoided CO2 equal to 112 $/tons.

Experimental analysis of the performance of the air supply system in a 120 kW polymer electrolyte membrane fuel cell system

For analyzing the performance of 120 kW polymer electrolyte membrane fuel cell (PEMFC) system and its air supply system, an air system test bench was built, then applied on a 120 kW PEMFC system test bench composed of air supply subsystem, hydrogen supply subsystem, stack, cooling subsystem and electronic control subsystem. The strategy composed of feedforward table and Piecewise proportional integral (PI) feedback control strategy is employed to regulate the flow rate and pressure of air supply system. Firstly, the air compressor map and the mapping relationship between the speed of air compressor, opening of back-pressure valve and stack current are obtained by carrying out experiments on the PEMFC air system bench. Then, the max output performance, steady-state performance, the startup performance, the dynamic response abilities of PEMFC system are tested, respectively. During the experiments, performances under different test conditions were analyzed by comparing parameters such as voltage inconsistency, average voltage, minimum voltage, voltage range, net power of the PEMFC system, and stack power. The test results show that the air supply system can provide qualified flow rate and pressure for the PEMFC stack. The peak power of the stack is 120 kW and net power of the system is 97 kW when the current is 538 A. The response time from rated net power to idle net power is 12 s and from idle net power to rated net power is 23 s. The overshoot of average voltage and minimum voltage in the process of increasing load is both 0.01 V, which are 0.015 V and 0.02 V lower than that when the load is decreased, respectively. The dynamic response speed and stability of the PEMFC system in the process of decreasing the load are better than those in the process of increasing the load.

System-level comparison of ammonia, compressed and liquid hydrogen as fuels for polymer electrolyte fuel cell powered shipping

With the aim to reduce emissions from marine transport, electric propulsion systems for a water taxi and container ship powered by a hydrogen polymer electrolyte membrane fuel cell system are designed and analyzed compared to the current fuel-oil engine systems in terms of system energy and exergy efficiency, fuel consumption, mass and volume, environmental impacts and cost. Hydrogen is stored either as a compressed gas (GH 2 ), cryogenic liquid (LH 2 ) or produced from liquid ammonia (LNH 3 ) and can deliver 91%,91% and 88% greenhouse gas reductions, respectively. All hydrogen sources fit within ship volume and mass constraints apart from GH 2 in the cargo ship. In the absence of carbon policy measures, the costs over a 25-year system life are 108% (GH 2 ), 112% (LH 2 ), 116% (LNH 3 ) greater for the container ship and 43% (GH 2 ), 105% (LNH 3 ) greater for the water taxi. A carbon tax of £75-191/tonne CO 2 eq would allow the low carbon options to become cost competitive. • Comparison of diesel and fuel cell propulsion for marine freighter and water taxi. • Liquid/gaseous H 2 and cracked NH 3 compared to fuel oil (with/without) NH 3 . • Fuel cell power plants meet all operational requirements (weight, volume,power). • Fuel cell propulsion reduces lifecycle greenhouse gas emission by 88%–91%. • A CO 2 tax of 75-191 £/tonne CO 2 eq would equalise total cost over a 25 year lifespan.

Optimization of PEMFC Model Parameters Using Meta-Heuristics

The present study introduces an economical–functional design for a polymer electrolyte membrane fuel cell system. To do so, after introducing the optimization problem and solving the problem based on the presented equations in the fuel cell, a cost model is presented. The final design is employed for minimizing the construction cost of a 50 kW fuel cell stack, along with the costs of accessories regarding the current density, stoichiometric coefficient of the hydrogen and air, and pressure of the system as well as the temperature of the system as optimization parameters. The functional–economic model is developed for the studied system in which all components of the system are modeled economically as well as electrochemically–mechanically. The objective function is solved by a newly improved metaheuristic technique, called converged collective animal behavior (CCAB) optimizer. The final results of the method are compared with the standard CAB optimizer and genetic algorithm as a popular technique. The results show that the best optimal cost with 0.1061 $/kWh is achieved by the CCAB. Finally, a sensitivity analysis is provided for analyzing the consistency of the method.

High-Efficiency Combined Heat and Power through a High-Temperature Polymer Electrolyte Membrane Fuel Cell and Gas Turbine Hybrid System

High-temperature proton-exchange membrane fuel cells are a promising technology for distributed power generation thanks to their high-power density, high efficiency, low emissions, fast start-up, and excellent dynamic characteristics, together with their high tolerance to CO poisoning (i.e., CO in the feed up to 3%). In this paper, we present an innovative, simple, and efficient hybrid high-temperature proton-exchange membrane fuel cell gas turbine combined heat and power system whose fuel processor relies on partial oxidation. Moreover, we demonstrate that the state-of-the-art fuel processors based on steam reformation may not be the optimal choice for high-temperature proton-exchange membrane fuel cells’ power plants. Through steady-state modeling, we determine the optimal operating conditions and the performance of the proposed innovative power plant. The results show that the proposed hybrid combined heat and power system achieves an electrical efficiency close to 50% and total efficiency of over 85%, while a state-of-the-art system based on steam reformation has an electrical efficiency lower than 45%. The proposed innovative plant consists of a regenerative scheme with a limited power ratio between the turbine and fuel cell and limited optimal compression ratio. Therefore, micro-gas turbines are the most fitting type of turbomachinery for the hybrid system.

A twin-nozzle ejector for hydrogen recirculation in wide power operation of polymer electrolyte membrane fuel cell system

The ejector-driven hydrogen recirculation in the polymer electrolyte membrane fuel cell (PEMFC) system is a promising alternative to the pump-driven approach due to its advantages of small volume, low cost, parasitic power free, and low noise. However, the fixed structure of the ejector limits its application to the dynamic operation of the PEMFC system. To overcome this drawback, a twin-nozzle ejector with two nozzles placed symmetrically in the suction chamber is proposed for hydrogen recirculation under different PEMFC power outputs. A three-dimensional Computational Fluid Dynamics model for the proposed twin-nozzle ejector is developed and verified with experiment results. The hydrogen recirculation performance of single-nozzle and two-nozzle working modes is analyzed by a simulation study. The simulation results indicate that the single-nozzle mode can provide acceptable recirculation performance under low power outputs of the PEMFC system, and the two-nozzle mode is more suitable for the high-power outputs with lower supply hydrogen pressure. Compared with conventional ejector, the proposed twin-nozzle ejector can be used in a wider power output range from 17.00 to 85.00 kW with supply hydrogen pressure from 250 to 700 kPa by switching the two working modes. The proposed ejector provides an effective way to extend the application of ejector in hydrogen recirculation of PEMFC system.

A new strategy of carbon – Pb composite as a bipolar plate material for unitized regenerative fuel cell system

In this study, we investigated the possibilities and combination of cost-effective materials of carbon (C) and lead (Pb) with polypropylene (PP) polymer as a new kind of bipolar plate for unitized regenerative fuel cell and polymer electrolyte membrane fuel cell systems. The homogeneous composite structure of C:Pb developed through facile mechanical milling process, and optimized. The new bipolar plate was fabricated with PP using compression molding process with hot pressing techniques. A dense and smooth surface morphology of C:Pb bipolar plate was acquired with the uniform thickness of 1.33 (±0.17) mm. Compared to C, an improved electrical properties (~20%) obtained to the powdered C:Pb composite materials because of homogeneous composition of Pb metal particles with large surface area of C. The C:Pb bipolar plate revealed an efficient water contact angle behavior than the C bipolar plate, where the water contact angle for C and C:Pb bipolar plates are 82.4° and 93.1°, respectively. A sophisticated electrochemical stability performance has obtained to the C:Pb bipolar plate in acidic condition. According to Tafel plots analysis, higher corrosion resistance has observed to the C:Pb bipolar plate than the C bipolar plate. The fabricated new kind of C:Pb bipolar plate provides the many advantageous, thus it proves the insights for further developments and applicability in the practical application. In the perspective view, the performances of C:Pb bipolar plate can be further altered through modification of different carbon structures together with impregnation of Pb nanostructured materials into the pores and/or embedded throughout the surface, and efficient conductive polymers.

Controller design for polymer electrolyte membrane fuel cell systems for automotive applications

Continuous developments in Proton Exchange Membrane Fuel Cells (PEMFC) make them a promising technology to achieve zero emissions in multiple applications including mobility. Incremental advancements in fuel cells materials and manufacture processes make them now suitable for commercialization. However, the complex operation of fuel cell systems in automotive applications has some open issues yet. This work develops and compares three different controllers for PEMFC systems in automotive applications. All the controllers have a cascade control structure, where a generator of setpoints sends references to the subsystems controllers with the objective to maximize operational efficiency. To develop the setpoints generators, two techniques are evaluated: off-line optimization and Model Predictive Control (MPC). With the first technique, the optimal setpoints are given by a map, obtained off-line, of the optimal steady state conditions and corresponding setpoints. With the second technique, the setpoints time profiles that maximize the efficiency in an incoming time horizon are continuously computed. The proposed MPC architecture divides the fast and slow dynamics in order to reduce the computational cost. Two different MPC solutions have been implemented to deal with this fast/slow dynamics separation. After the integration of the setpoints generators with the subsystems controllers, the different control systems are tested and compared using a dynamic detailed model of the automotive system in the INN-BALANCE project running under the New European Driving Cycle.

Constrained extended Kalman filter design and application for on-line state estimation of high-order polymer electrolyte membrane fuel cell systems

In this paper an alternative approach to extended Kalman filtering (EKF) for polymer electrolyte membrane fuel cell (FC) systems is proposed. The goal is to obtain robust real-time capable state estimations of a high-order FC model for observer applications mixed with control or fault detection. The introduced formulation resolves dependencies on operating conditions by successive linearization and constraints, allowing to run the nonlinear FC model at significantly lower sampling rates than with standard approaches. The proposed method provides state estimates for challenging operating conditions such as shut-down and start-up of the fuel cell for which the unconstrained EKF fails. A detailed comparison with the unscented Kalman filter shows that the proposed EKF reconstructs the outputs equally accurate but nine times faster. An application to measured data from an FC powered passenger car is presented, yielding state estimates of a real FC system, which are validated based on the applied model.

Dynamic Reliability Assessment of PEM Fuel Cell Systems

In this paper, a novel model for the dynamic reliability analysis of a polymer electrolyte membrane fuel cell system is developed to account for multi-state dynamics and ageing. The modelling approach involves the combination of physical and stochastic sub-models with shared variables. The physical model consists of deterministic calculations of the system state described by variables such as temperature, pressure, mass flow rates and voltage output. Additionally, estimated component degradation rates are also taken into account. The non-deterministic model is implemented with stochastic Petri nets which model the failures of the balance of plant components within the fuel cell system. Using this approach, the effects of the operating conditions on the reliability of the system were investigated. Monte Carlo simulations of the process highlighted a clear influence of both purging and load cycles on the longevity of the fuel cell system.