Fuel Cell Stack Research Articles

Data-Driven Load-Current Sharing Control for Multi-Stack Fuel Cell System with Circulating Current Mitigation

The global trend toward renewable power generation has drawn great attention to hydrogen Fuel Cells (FCs), which have a wide variety of applications, from utility power stations to laptops. The Multi-stack Fuel Cell System (MFCS), which is an assembly of FC stacks, can be a remedy for obstacles in high-power applications. However, the output voltage of FC stacks varies dramatically under variable load conditions; hence, in order for MFCS to be efficiently operated and guarantee an appropriate load-current sharing among the FC stacks, advanced converter controllers for power conditioning need to be designed. An accurate circuit model is essential for controller design, which accounts for the fact that the parameters of some converter components may change due to aging and repetitive stress in long-term operations. Existing control frameworks and parametric and non-parametric system identification techniques do not consider the aforementioned challenges. Thus, this paper investigates the potential of a data-driven method that, without system identification, directly implements control on paralleled converters using raw data. Based on pre-collected input/output trajectories, a non-parametric representation of the overall circuit is produced for implementing predictive control. To achieve proper current sharing, the proposed method considers also the mitigation of circulating current within the MFCS. Simulation results verify the effectiveness of the proposed method.

Preventive control method for stable operation of proton exchange membrane fuel-cell stacks

<abstract> <p>Flooding and dry-out are major drawback issues in proton exchange membrane fuel cells (PEMFC), which necessitate adequate prevention control techniques. In a fuel-cell stack, as flooding and dry-out occur on the inlet and outlet sides, respectively, both faults can exist simultaneously. Therefore, the timely detection of these two contradictory faults is crucial for implementing timely control measures. In this study, we propose a preventive control method that detects the fault signs early for more effective prevention. The proposed method uses a curve-fitting method, which uses overpotential as the control index. As the control index can be obtained by measuring the current, voltage, and temperature, the evaluation can be performed quickly, making it easy to implement in a PEMFC system. Under a single fault, the stack output power, hydrogen consumption, and power efficiency of the proposed preventive control method and the previous study on flooding were compared. The results showed that our preventive control method could detect flooding sooner and was superior in stack output power, hydrogen consumption, and power generation compared to the fault control method. Under conditions of mixed flooding and dry-out, both flooding and dry-out were detected using the overpotential as the control index. Thus, because the proposed method initiates control measures before the fault progresses, it is possible to ensure the continued stable operation of the fuel cells.</p> </abstract>

Design of high voltage gain converter for fuel cell based EV application with hybrid optimization MPPT controller

From the previously available articles, the fuel cell dependent power supply systems are increasing every year. Also, these systems are playing a major focus on the microgrid renewable energy networks. However, the fuel cell gives less output power extraction at different operating temperature values. In addition, the working point of the fuel cell vary with respect to the hydrogen supply, and water membrane content. In order to achieve the high output power of the fuel stack, a Maximum Power Point Tracking (MPPT) is used to track the peak power point of the proposed system. In this article, Artificial Neuro Fuzzy Inference System (ANFIS) controller is utilized in order to generate the smooth output voltage waveform of the fuel cell stack. The optimization of ANFIS controller have been done by using the Genetic Algorithm (GA). The advantages of ANFIS based MPPT controller are high output power extraction, and less distortions of converter voltages. Here, the Proton Exchange Membrane Fuel Cell (PEMFC) device is used as a source. The features of PEMFC are fast start-up, and high efficient. The PEMFC generates less voltage which is enhanced by using the interleaved non-isolated boost converter. The proposed fuel cell based interleaved system is analyzed by using the MATLAB/Simulink software.

A modeling study on water and thermal management and cold startup of unmanned aerial vehicle fuel cell system

The water and thermal management of hydrogen/air proton exchange membrane fuel cell (PEMFC) system in a variable environment and its fast and efficient cold start at low temperature are the key issues in the practical design and integration of unmanned aerial vehicle (UAV) fuel cell power system. Herein, a complete mathematical model of fuel cell stack and balance of plant (BOP) is established, then the nonlinear relationship between cooling water flow rate, coolant bypass valve opening, and stack temperature at different flight altitudes is studied for a typical UAV configuration, and the safe working range of stack is pointed out. In addition, a cold-start model supporting operation at the high current density is proposed. After analyzing the cold start-up process of the fuel cell, it is found that a reduction of active reaction area caused by icing is the main reason for voltage loss. The optimal self-start current densities of the fuel cell at different low temperatures are detected by the galvanostatic method, as a result, a successful self-startup of the fuel cell is achieved at a temperature of 263.15 K.

К вопросу проектирования энергетической установки на основе водородных топливных элементов для малых беспилотных летательных аппаратов

Рассмотрены вопросы проектирования энергетической установки на основе водородных топливных элементов с протонообменной мембраной для беспилотного летательного аппарата вертолетного типа, киловаттного класса мощности. Представлены различные варианты конструкции энергоустановки, обоснован выбор оптимального варианта. Дано сравнение энергоэффективности силовой установки с различным числом двигателей, предложен способ выбора их оптимального количества. Приведена формула для выбора емкости литий-ионных аккумуляторов, работающих совместно с топливным элементом в режиме комплексирования. Решена задача оптимизации основных параметров стека топливных элементов – числа и площади ячеек. Методика может быть использована на начальном этапе проектирования для оценки характеристик и параметров системы электропитания энергетической установки на водородных топливных элементах.

Theoretical analysis on energy saving of cold energy utilization system for a liquid hydrogen heavy-duty truck

• Model of on-board liquid hydrogen cold energy utilization system is established. • Energy saving effect of cold energy utilization system is illustrated. • Three system states corresponding to different energy saving features are defined. • Annual energy saving under C-WTVC in four typical cities across China are analyzed. In this paper, a model of a novel on-board cold energy utilization system for a liquid hydrogen (LH 2 ) heavy-duty fuel cell truck is established to evaluate the energy saving effect comprehensively compared to the original LH 2 system without cold energy utilization. The cold energy is used for cooling the inlet air of compressor and the coolant of the accessories cooling system through a two-stage vaporizer to reduce the parasitic power. The related influencing factors, such as ambient temperature and fuel cell stack load are taken into consideration. In addition, the effect of cold energy distribution ratio, which is closely related to the design of two-stage LH 2 vaporizer, is also analyzed. The system is divided into three states corresponding to different energy saving features under these influencing factors. The simulation results show that the total parasitic power consumption can be saved by up to 15% under steady state. Based on that, the annual energy saving of this system in heavy-duty fuel cell truck is simulated under Chinese-World Transient Vehicle Cycle (C-WTVC) in four typical cities across China. It is found that annual energy saving can be realized even in extremely cold areas like Harbin (126.6°E, 45.8°N) and annual average saving energy could reach 9∼15% in different cities.

An approach inspired by Design Thinking methodologies to improve the company-wide collaboration applied in a Hydrogen Electrolyzer project

The research project FertiRob aims to develop a fully automated production plant for hydrogen electrolyzer manufacturing. One of the main subprojects is to develop a prototype of an automated production assembly line for an electrolyzer stack. Compared to a fuel cell stack there are only few solutions for the automated assembly. For the first planning of such a system, a workshop was created and conducted, where all partners within the project got the task to conceptualize a fully automated stacking assembly line. Inspired by design thinking and innovation methodologies, the workshop was created to improve the productivity of the collaboration. As a result, several high valuable production line layouts were developed with different assembly solutions. With this industrial use case, the following paper presents an approach how the workshop was planned and conducted to increase the level of productive collaboration based on the proposed methodology.

A comparison of strategies to extend the operating range of radial compressors for turbocharging

The operating range extension of radial compressors is a crucial aspect in turbocharging the internal combustion engines in order to extend the operating range of the system at high efficiency for fuel and environmental impact reduction. The future scenario of automotive propulsion will have the fuel cells at the top of the ranking of possible reference systems in substitution of thermal reciprocating engines. Proton exchange membrane fuel cells for automotive or aerospace vehicles are frequently turbocharged because compressed air for the fuel cell stack is required in the cathode system. Therefore, like in turbocharged internal combustion engines, a radial compressor is combined and connected with a radial turbine to exploit the thermal energy of the exhaust gas from the fuel cell. The study and the development of this sort of radial turbomachinery is still strategic to guarantee high performance of the overall propulsion system. The operating range is an important issue and current turbocharger design must be adapted to the new requirements of the fuel cells systems with a need for extending it. Various techniques to extend the operating range of the centrifugal compressor have been investigated and a summary is reported in this work, with a focus on the casing treatment. Through a CFD simulation campaign with appropriate simplified models, the effects of installing the ported shroud, the shutter or the axial groove have been calculated with respect to a baseline configuration. These simulations have supported the identification of the main limits and advantages for each of these solutions at different operating regimes. The performance maps and some physical parameters of interest have been compared.

Mechanical behavior of YSZ-glass composite seals for solid oxide fuel cell application

The long-term operation of solid oxide fuel cell stack critically depends on the joint strength between cells and interconnect alloy. In this work, 20 wt% YSZ (Y 2 O 3 stabilized ZrO 2 ) was added into different kinds of glass to form H1-20 and H4-20 composite seals. It was focused on the mechanical behavior between YSZ-glass composite seals and Fe–16Cr alloy under various thermal cycles by shear force testing and tensile force testing. The shear strength and the tensile strength between H4-20 seals and Fe–16Cr alloy were higher than that of H1-20. Two composite seals differed in characteristic temperature, viscosity, and crystalline phase with possible impacts on the joint strength. The interfacial composition between H1-20 and Fe–16Cr alloy was different from that of H4-20. Based on examination results, four possible fracture modes were proposed to illustrate the failure mechanism between composite seals and alloy.

Water management in a novel proton exchange membrane fuel cell stack with moisture coil cooling

Water flooding causes severe degradation of the performance and lifetime of proton exchange membrane fuel cell (PEMFC). In this study, a novel PEMFC stack with in-built moisture coil cooling was designed and the effects of moisture coil cooling on water management in the new PEMFC stack under various operating conditions were investigated. The result showed that the performance of the PEMFC stack was significantly improved due to the moisture condensation under high current density, high operating temperature, high relative humidity and high operating pressure. The output power was increases by 21.62% (525.71 W) at 1600·mA cm−2 while the increased parasitic power was no more than 35W. Moreover, degradation of the cathode catalyst layer after 100 h operation was also reduced by using moisture coil cooling. Compared with the situation without moisture condensation, the maximum decay rate of the cathode catalyst layer thickness after 100 h operation was reduced by 13.01%. Accordingly, the novel design is valuable and can be widely used in the future design of PEMFC.

Mitigating performance deterioration analysis of VC-PEMFC with dead-ended anode by pulsation fuel supplying mode

Hydrogen starvation and water flooding are two principal factors resulting in performance deterioration of the proton exchange membrane fuel cell stack at the dead-end anode. This paper proposes a novel hydrogen supply mode called the pulsation mode aimed at mitigating the problems of performance deterioration in a 10-cell open-cathode vapor chamber proton exchange membrane fuel cell stack to increase the performance. This method does not require complex equipment and structure, only four controllable solenoid valves are sufficient to generate periodic pulsation inside the anode channels. The experiments were used to validate the effectiveness of the new mode and to compare the effects of different pulsation frequencies on the performance of the stack. A series of parameters such as voltage, power growth rate, and voltage stability index are used to analyze the operating characteristics of the stack. The results show that the periodic pulsations generated by the new mode are potent of increasing the species mass transfer rate within the anode channels, and the species mass transfer rate increases with the increase of pulsation frequency. Meanwhile, selection of a suitable pulsation frequency can effectively improve stack water management and reduce the probability of hydrogen starvation. Finally, the new mode is able to enhance the voltage down valley of the stack under large external load variation. The ohmic resistance of the stack in the new mode has proved to be lower by the current interruption method. Furthermore, it is capable of increasing the net power of the stack by up to 7.71%.

Mitigating distortions during debinding of a monolithic solid oxide fuel cell stack using a multiscale, multiphysics model

Improving the power density of solid oxide fuel cell stacks would significantly enhance this technology for transportation. Using a monolithic structure to downsize the stack dimension offers a key to elevate the power density of solid oxide fuel cell stacks. This innovative design is promising but manufacturing is a challenge. The monolith is co-sintered in one firing step, and the gas channels are formed by burning off sacrificial organic materials. Structure distortion or fracture was observed in post-mortem investigations. In this work a multiscale, multiphysics modelling approach is proposed to describe and resolve this challenge in the debinding process occurring in a monolithic stack, i.e. the burning of organics and transportation of gases through the gradually opening microstructure, as well as the pressure build-up in the microstructure due to gas development. Simulation results show that a prominent pressure peak is experienced in the stack when a plasticiser (polyethylene glycol) and a pore-former (polymethyl methacrylate) are decomposed simultaneously. To reduce the high pressures, we investigate two possible strategies: (i) changing the mixture of organic additives; (ii) modifying the debinding temperature profile. Three tapes with different pore-formers are prepared, and the generated pressures during debinding of the three stacks are compared. The corresponding stack shapes after debinding are recorded. Numerical investigations show a good agreement with the post-mortem observations. By changing the composition of organics the distortion or fracturing of the stack can be avoided. Furthermore, to facilitate stack manufacturing, the high pressures can also be reduced by adjusting the heating rates and dwell temperatures of debinding. By using the new temperature profile suggested by the simulation study, the duration of debinding can also be reduced.

Characteristics of fuel cells under static and dynamic conditions

Modern internal combustion powertrains are the main source of propulsion for on-road and non-road vehicles. However, they are increasingly being replaced by electric or fuel cell-equipped alternative propulsion systems. The article presents a study of fuel cell characteristics operating under both static and dynamic conditions, with a 1.2 kW fuel cell set with a voltage converter and lead-acid batteries. In the conducted tests, the fuel cell stack's maximum efficiency reached 65%. Load tests (static and dynamic) have indicated higher fuel cell efficiencies when using hybrid operation with a DC/DC converter and battery.

Integrated Gas Diffusion Electrode with High Conductivity Obtained by Skin Electroplating for High Specific Power Density Fuel Cell.

Smaller volume/weight and higher output power/energy density are always the goals of electrochemistry energy devices. Here, a simple strategy is proposed to prepare an integrated gas diffusion electrode (GDE) with high conductivity through skin electroplating. The skin electroplating is the combination of magnetron sputtering and spatial confinement electroplating. The electroplated metal obtained by skin electroplating is uniformly, continuously, and tightly attached to the surface of carbon paper like a layer of skin. Uniform and continuous electroplating metal layer endows the integrated electrode excellent conductivity with the square resistance as low as 27mΩsq-1 . In application, the self-breathing fuel cell with 1cm2 active area can harvest ultrahigh volume specific power density (20.9kWL-1 ). Additionally, the weight of the fuel cell stack (23W) with the integrated electrode is only 20g, which is only 7% of the commercial stack with the same power. The mass specific power density reaches 1150Wkg-1 , which is 15 times of the commercial stack. Outstandingly, the stack can charge 4 mobile phones at the same time. More importantly, the skin electroplating provides an effective strategy to improve the specific power density of other energy devices including Zn-air batteries, Li-air batteries, and so on.

Prescriptive Lifetime Management for PEM fuel cell systems in transportation applications, Part I: State of the art and conceptual design

Proton exchange membrane (PEM) fuel cells represent a promising solution for a sustainable hydrogen-based mobility. Due to remaining challenges regarding costs and durability of PEM fuel cell systems, market activation programs as a precursor to market introduction are still required to accelerate the broad commercialization of PEM fuel cell systems in transportation applications. The recent shift by some original equipment manufacturers (OEMs) from passenger car (PC) and light-duty vehicle (LDV) applications to heavy-duty vehicle (HDV) applications is accompanied by higher lifetime and system power requirements that necessitate modified design and development approaches. Design-based approaches to increase the lifetime of PEM fuel cells usually concentrate on the use of advanced materials and the design of durable fuel cell stacks. Operation-based approaches aim to mitigate degradation through the development of advanced control strategies. However, the initial design of a PEM fuel cell system as well as the calibration of its control strategy to achieve a long service life is inevitably associated with a high degree of uncertainty. In addition, often challenging time-to-market specifications result in insufficient time for extensive durability testing, necessitating the use of accelerated stress tests (AST). Results of ASTs usually deviate to a greater or lesser extent from realistic driving conditions and exacerbate the issue of uncertainty regarding durability in field operation. Therefore, the coordinated development and deployment of on-board strategies for condition assessment, lifetime prediction and degradation mitigation are of huge importance to meet the high lifetime requirements in HDV applications.With this in mind, this paper presents an on-board Prescriptive Lifetime Management system that enables optimization-based post-prognostic decision-making to extend the service life of PEM fuel cell systems while considering the need to maximize system performance and efficiency. Based on the current state of the art, the requirements of the Prescriptive Lifetime Management are defined and its conceptual design as well as modeling and simulation framework are described.

A Review of Fuel Cell System Technology: From Fuel Cell Stack to System Integration

Review A Review of Fuel Cell System Technology: From Fuel Cell Stack to System Integration Weiqun Ren 1,*, Jun Shen 2, Xuebing Li 1, and Changqing Du 2 1 Dongfeng Commercial Vehicle Co. Ltd., 10 Dongfeng Avenue, Wuhan, China 2 Wuhan University of Technology, Wuhan, China * Correspondence: renweiqun@tsinghua.org.cn; Tel.: +86-139-1820-4209 Received: 14 October 2022 Accepted: 8 November 2022 Published: 18 December 2022 Abstract: The technology of hydrogen fuel cell vehicles (FCV) is the ultimate direction of clean energy vehicle development, and commercial vehicles are the most important application area for fuel cell commercialization. This paper summarizes the key components, technologies and development trends of the fuel cell stack, fuel cell system and vehicle integration at home and abroad, and points out that key materials (such as bipolar plates and membrane electrodes), key system components (such as air compressors and ejectors), high-power modular integration technologies, and fuel cell control technologies are the main factors influencing the commercialization of FCVs. Particularly, we put the main fouce on variable ejector or multi-stage ejector technology, integrated and optimized control technology, and multi-energy cooperative control technology due to their crucial roles in meeting the industrial development of FCVs in China. Furthermore, some guidance opinions are also provided for reference about the development and industrialization of FCVs.

Simulation to analyze operation strategy of combined cooling and power system using a high-temperature polymer electrolyte fuel cell for data centers

With the development of the information and communication technology (ICT) industry, the energy consumption of data centers is continuously increasing. High-temperature polymer electrolyte fuel cells (HT-PEFC) have a high operating temperature of 120 °C or higher; thus, the heat generated from fuel cells stack is effectively used as a heat source for a absorption refrigerator (AR) to generate cooling. The combined cooling and power (CCP) system is proposed to satisfy the energy demand of data centers that require both power and cooling. The CCP system comprises an HT-PEFC and a double-effect AR that recovers the wasted heat of the fuel cell stack. As a result of analyzing the electrical and cooling efficiency of the CCP system according to the fuel cell operating conditions, the overall efficiency increased to 95%, which was significantly higher than the existing system. Based on the simulation of the developed model, coefficient of performance (COP) and cooling capacity depending on the temperature changes of chilled water and cooling water were calculated within the stack temperature range of 150–180 °C, and the COP changed from 1.1 to 1.58 depending on the conditions. The developed CCP system model can be used to plan strategies for flexible fuel cell operation according to the power and cooling demands required in the data center.

An improved energy management strategy for fuel cell/battery/supercapacitor system using a novel hybrid jellyfish/particle swarm/BAT optimizers

In this paper, a fuel cell (FC) hybrid emergency system is presented. It contains fuel cells, batteries, and supercapacitors which are effective for different conveyance applications. Abbreviating the hydrogen consumption and incrementing the lifetime of power sources are the key factors of each energy management strategy (EMS). An incipient proposed EMS depending on an optimized proportional-integral (PI) controller is presented considering FC efficiency to ensure the operation of the FC stack within its maximum efficiency region and reduce the stress on it which in turn leads to reducing its hydrogen consumption. Regarding tunning the PI controller gains (Kp,Ki), a proposed hybrid metaheuristic optimization technique named JSPSOBAT has been presented which merges jellyfish (JS) optimizer, particle swarm optimizer (PSO) and BAT optimizer to achieve the balance between exploration and exploitation phases. To firstly validate the effectiveness of the JSPSOBAT technique, a comparative study with other single and hybrid metaheuristic optimization techniques is presented by testing on 50 complex benchmark functions. Then, the JSPSOBAT is used to select the controller gains of the proposed PI controller. A 30 min load profile of a More Electric Aircraft (MEA) is used. The performance of the proposed EMS using the proposed optimization technique is compared with other EMS such as state machine control strategy, classical PI control strategy, equivalent consumption minimization strategy, external energy maximization strategy, and the results show that the proposed technique produces the best performance.

Thermoeconomic comparison of a molten carbonate fuel cell and a solid oxide fuel cell system coupled with a micro gas turbine as hybrid plants

This study presents a comparative evaluation of Molten Carbonate Fuel Cell (MCFC) and Solid Oxide Fuel cell (SOFC) stacks coupled with a micro gas turbine (MGT). For the analysis, it is assumed that the fuel supply to the stacks is constant in all the analyzed conditions. The components of the system have been sized using the first law of thermodynamics to meet the thermal conditions required to maintain fuel cell stack operation, while an exergetic analysis has been implemented in order to assess the components in terms of irreversibilities. Furthermore, an economic analysis to estimate the Levelized Cost of Electricity (LCOE) has been carried out to indicate the most feasible option between the two analyzed systems. The capacity of the fuel cell stacks is 500kWdc operating at 350 kPa and 600 °C/650 °C. The results indicate that MCFC stacks are more efficient than SOFC stacks, but are considerably more expensive. Nevertheless, the SOFC/MGT system has a global efficiency higher than that of the MCFC/MGT; also its Total Capital Investment (TCI) is 2.5–3.5 times lower, thus making the SOFC/MGT coupling more attractive. The only product considered coming out from the systems to determine the LCOE is electricity. The LCOE for the SOFC/MGT system is 0.339–0.402$/kWh and for the MCFC/MGT is 0.875–0.897$/kWh, which for both configurations is still higher than the current electricity prices. One aspect that increases the investment and consequently the LCOE is the high cost of the stacks and their replacements which is around 19 % and 10 % of the total Purchased Equipment Cost (PEC) for MCFC and SOFC stacks, respectively.

Lifetime prediction method of proton exchange membrane fuel cells based on current degradation law

Lifetime evaluation and prediction of proton exchange membrane fuel cells (PEMFCs) are essential for the lifetime extension and commercialization of fuel cells. Under the background that the accelerated stress test (AST) is difficult to evaluate the lifetime accurately, and the actual road test is time-consuming and costly, it is necessary to propose a quick lifetime prediction method of fuel cells. In this study, the current degradation law is analyzed based on the first-order kinetic model, and the lifetime prediction method based on the current degradation law is proposed. Moreover, the scale factor k is proposed to completely describe the fuel cell degradation due to complex degradation causes, and its calculation and selection methods are discussed. Finally, the accuracy of the proposed method is verified by the experimental results of single cells and fuel cell stacks, and the maximum relative error is less than 5% when the fuel cells conform to the first-order kinetic model. The lifetime prediction method of PEMFCs based on current degradation law improves the utilization of degradation information in current density, which is a feasible way for automotive fuel cell lifetime evaluation and prediction.