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In this paper, the mechanism of proton exchange membrane fuel cell (PEMFC) cathode cycling is discussed and the high potential suppression control problem for fuel cell vehicles is investigated by using cathode cycling. Firstly, a rigorous single-cell experimental investigation is performed to reveal the impact mechanism of cathode recirculation on the internal polarization processes of PEMFC. Results show that an increase in the recirculation ratio leads to an increase in the polarization impedance in the low and medium frequency regions but decreases the ohmic impedance. Consequently, when the recirculation ratio increases to 1, the voltage drop rates are 2.2%, 3%, 4.6%, 5.8%, and 7% as the current density varies from 0 to 0.2 A/cm2, respectively, and the ohmic impedance decreases by 28.1%. On the basis, the optimal control scheme for high potential suppression based on cathode circulation in vehicular PEMFC system is proposed. The performance comparison of different control method is carried out on a software-in-the-loop testing platform. The results show that, for the same control objective, the model predictive control (T-S MPC) method is 55.5% and 16.7% lower than the proportional integral (PI) controller and the Takagi-Sugeno linear quadratic Gaussian (T-S LQG) in terms of controller input cost. On the contrary, the cumulative error of voltage tracking is reduced by 62% and 30.4% and the voltage response against disturbances is improved by 9.7% and 42.8%. Overall, the T-S MPC achieves the optimal control effect with less control effort. • An insight into the mechanism of cathode recirculation affecting PEMFC performance. • Cathode recirculation reduces ORR reaction rate and oxygen diffusion rate. • The T-S MPC provides optimal closed-loop control of high potential suppression. [ABSTRACT FROM AUTHOR]

Polymer-carbon composite bipolar plates (PCCBP) are accepted over graphite bipolar plates (BP) for their use in proton exchange membrane fuel cell (PEMFC), specially in hydrogen fuel cell-powered electric vehicles. This study developed a novel copper fiber-filled PCCBP with epoxy resin as the binder and natural flake graphite (NFG), carbon black (CB), and Cu fiber as filler materials. The fabrication is done by compression molding. Both electrical conductivity and flexural strength increased with the addition of Cu fiber. The composite BP fabricated with 8 vol % Cu fiber, 10 vol % CB, and 42 vol % NFG exhibited electrical conductivity of 169 S/cm, flexural strength of 43 MPa, thermal conductivity of 17 W m−1 K−1 and corrosion current density of 0.972 μA/cm2. The composite also showed acceptable results for contact angle, density and thermal stability tests. This research paper provides insights into further developments of the metal-based PCCBP. • Novel Cu fiber-filled composite bipolar plates were developed for PEM fuel cells. • Effect of content of epoxy resin, carbon black, and copper fiber was investigated. • Enhancement of electrical conductivity and flexural strength achieved concurrently. • Provides insights into future developments of the metal-based PCCBP. [ABSTRACT FROM AUTHOR]

This paper presents the development and implementation of a system supervisory controller in a hydrogen-based fuel cell electric vehicle. The controller's primary function is to ensure the safe control of the fuel cell system processes while facilitating coordination among various subsystems, including the balance of plant subsystems, vehicle control unit, diagnosis unit, and powertrain. The supervisory controller comprises of three primary parts: a State Machine, an Optimal Setpoint Generator, and a Power Limit Calculator. The State Machine, which serves as the central part of the supervisory controller, coordinates the fuel cell system's different operational states, including the complex processes of start-up and shutdown. To maximize the fuel cell system's efficiency and minimize the stack's degradation, the Optimal Setpoint Generator produces the subsystem's setpoints by solving an optimization problem and considering the manufacturer's requirements. The Power Limit Calculator assesses the stack's power output capability and calculates the current setpoint for the DC/DC converter. It then provides this data to the Energy Management System (EMS), which oversees the distribution of power between the fuel cell system and the batteries. The proposed fuel cell system supervisory controller is verified using the Worldwide Harmonized Light Vehicles Test Cycles (WLTC) in a real-world car. The designed control structure is implemented in a prototype hydrogen-based electric car at both PowerCell and CEVT facilities under the framework of the INN-BALANCE Horizon 2020 European project. • State machine-based supervisory controller for fuel cell system is designed. • The designed control structure is implemented in a prototype hydrogen-based vehicle. • The controller comprises: State Machine, Setpoint Generator, Power Limit Calculator. • The proposed control structure handles the startup and shutdown process of PEMFC. • Minimizing stack degradation by implementing a fuel cell power limit calculator. [ABSTRACT FROM AUTHOR]

The hydrogen pump is an important component in the hydrogen circulation system of fuel cells. Excessive pulsation at the outlet of the pump is challenging when the Roots hydrogen pump is used, which has a negative impact on the operation performance. To reduce the impact of excessive fluctuations in the hydrogen circulation system, a new structure of reflow grooves is proposed in this paper, which connects the different chambers and adjusts the pressure using a diversion method. The internal flow of the two pumps was studied for comparison, using a three-dimensional simulation model established by Computational Fluid Dynamics (CFD) method. Results showed that the reflow grooves reduce the exhaust pressure and mass flow pulsations, which has a positive effect on the pressure stabilization of the hydrogen circulation system and the anode inlet pressure of the fuel cell stack, contributing to the long durability and stability of the fuel cell stack. [Display omitted] • A novel reflow structure is proposed for the Roots hydrogen pump. • The internal flow of the pump is simulated by the dynamic grid method. • The gas pressure variation in one compression in the Roots pump was analysed. • The reductions in flow fluctuations at different rotational speeds are compared. • Pressure fluctuation is supressed at high rotation speed by the reflow structure. [ABSTRACT FROM AUTHOR]

An in-depth understanding of the local mass transport process is essential for precisely regulating the catalyst layer structure in fuel cells. The ionomer on the Pt surface in the catalyst plays a crucial role in the local transport of oxygen and protons. While most models assume that Pt is completely covered by ionomer, experiments have indicated that Pt is partially covered by ionomer in some cause. In this paper, an improved local mass transport model is proposed to investigate the effect of ionomer coverage on internal mass transport process and fuel cell performance. The results show that the current density first increases and then decreases as the ionomer coverage rises from 10% to 90% under 0.6 V. The optimal performance is achieved with a coverage of 40%. Oxygen is more easily transported in water, while ionomer is a better proton conductor. Variations in ionomer coverage lead to different distances for oxygen and proton transfer, which have an important effect on reactant concentration. Furthermore, further study reveals that the current density is greatest at the interface between water and ionomer. Increasing the interface can effectively reduce the comprehensive transport distance of reactants in ionomer and water to improve performance, which is more pronounced than increasing the oxygen transfer coefficient in the ionomer. Overall, this study provides new ideas for the design of high-performance catalyst layers. • An improved fine-structure model of local mass transport in CCL is developed. • Simulate the effect of local oxygen and proton transport on cell performance. • The best cell performance is obtained with an ionomer coverage of 40% under 0.6 V. • Increasing the ionomer/water interface can significantly improve cell performance. • Increasing interface is more effective than enhancing oxygen diffusion in ionomer. [ABSTRACT FROM AUTHOR]

The fuel cell airpath multivariable control problem of optimally coordinating the electric compressor motor and the back-pressure valve to achieve efficient and safe conditions, for both steady state and transient operation, has not been completely addressed in the literature. This paper proposes a nonlinear model predictive control strategy, implemented via the Garrett Motion proprietary NMPC toolbox, to regulate the oxygen stoichiometry and the cathode pressure of an automotive fuel cell airpath system, while avoiding compressor surge and air starvation. The controller set-points are optimized, using the nonlinear model, to achieve the maximum system power as a function of the operating stack condition. The effectiveness and robustness of the proposed control strategy have been validated by means of a simulated World harmonized Light-duty vehicles Test Cycle (WLTC), under both state feedback and model parameters uncertainties. [Display omitted] • MPC ensures compressor surge and oxygen starvation avoidance under severe dynamic scenarios. • Controller robustness assessed via a WLTC regulatory cycle under noisy and uncertain conditions. • Fuel efficiency is not significantly sensitive with respect to different controller calibrations. [ABSTRACT FROM AUTHOR]

The number of working points and response speed are two essential characteristics of proton exchange membrane fuel cell (PEMFC). The improper setting of the number of working points and response speed may reduce the life of PEMFC and increase the hydrogen consumption of the vehicle. This paper explores the impact of the response speed as well as the working points of the PEMFC on the hydrogen consumption in the real-system level. In this paper a dynamic model of the PEMFC system is established and verified by experiments. The model is able to reflect the dynamic response process of PEMFC under a series different number of working points and different response speed. Based on the proposed model, the influence of working points and the response speed of PEMFC on the hydrogen consumption in the vehicle under different driving cycles is analyzed and summarized, for the first time, in the open literature. The results highlight that the hydrogen consumption will decreases in both cases that with the increase of working point number and increase of response speed. However, the reduction range of hydrogen consumption trends to smaller and may reach to an optimal level considering the trade-off between the hydrogen saving and the other costs, for example the control cost. Also, with a more complex driving cycle, the working points and response speed have a greater the impact on the hydrogen consumption in the vehicle applications. • A dynamic response model of PEMFC considering working points number and response speed is established. • PEMFC dynamic response model is developed and enhanced by experiments. • Discover the influence of working points number and response speeds of PEMFC on hydrogen consumption. [ABSTRACT FROM AUTHOR]

To explore a new method for the selection of power battery capacity range considering the synergistic decay of dual power source lifespan under the operating lifespan cycle of fuel cell vehicle (FCV). Based on the dual power source decay model and the proposed power-following energy management strategy (EMS) based on low-pass filtering, this paper analyses the influence of control parameters (proton exchange membrane fuel cell (PEMFC) response speed, filter order) and design parameters (fuel cell rated power, power battery capacity) on the dual power source. The governing law is the power source decay rate, and based on this law, the synergy point of dual power source decay under variable control parameters and different power battery capacities is fitted, and the power battery capacity allowing dual power sources to synergistically decay under variable control parameters is summarized. The results show that under this strategy, when the capacity range of the power battery is 20–143 Ah, changing the control parameters in real time can make the dual power sources synergistically attenuate. Based on this capacity range, the PEMFC response speed and filter order corresponding to the dual power source decay synergy point obtained under the power battery capacity matching selection method can enable the dual power source synergistic decay to be verified by hardware-in-the-loop (HIL) simulation. The results show that at the end of the simulation, the dual power source decay rates can be synergistic. • Analyze the effect of control and design parameters on power source decay rates. • Exploring the synergy point of FCV dual power source decay. • Summarize the battery capacity range that dual power sources can synergistic decay. [ABSTRACT FROM AUTHOR]

Proton exchange membrane fuel cell (PEMFC) has advantages of zero emission, fast response and high-power density. There are still obstacles such as manufacturing cost, life span, infrastructure construction and subzero temperature star-up restricting commercialization of PEMFC. The low-temperature start-up is one of them that needs to be solved in the field of fuel cell vehicle. This paper presents research progresses involving PEMFC degradation caused by the low-temperature start-up. Degradation phenomena and mechanism under component-level caused by repeated freezing start, influencing factors and mitigation strategies are summarized and reviewed. Conclusions are made that frequent ice freezing and melting causes the membrane electrode assembly damaged irreversibly, the quality of cold start and low temperature influence the degradation strongly and purge after shutdown, better materials and optimal fuel cell structure design are helpful to reduce the impact of cold start on fuel cell performances. It is suggested that future work should be focused on optimizing strategies of the shutdown purge, promoting the quality of cold start, enhancing properties of the materials, improving internal structure design of stack and developing low-temperature attenuation models. • Degradation phenomena and mechanism under component-level are presented. • Some influencing factors are analyzed and concluded. • Degradation mitigation strategies are summarized and reviewed. [ABSTRACT FROM AUTHOR]

An effective online fault diagnosis system is of great significance to improve the reliability of fuel cell vehicles. In this paper, a fault diagnosis model for proton exchange membrane fuel cells is proposed. Firstly, the tests of electrochemical impedance spectroscopy under different fault types (flooding, drying, air starvation) and fault degrees (minor, moderate, severe) are carried out, and each polarization loss of the fuel cell is denoted by an equivalent circuit model (ECM). Then, the parameters of the ECM are identified by the proposed random mutation differential evolution algorithm. Furthermore, the parameters identified under different fault conditions are used to train and test a probabilistic neural network-based fault diagnosis model. The fault diagnosis model achieves diagnosis accuracies of 100% for the fault type and 96.67% for the fault degree. By setting operating conditions with different fault degrees, the fault diagnosis model proposed in this paper can realize the fault type and fault degree diagnosis, effectively avoiding the misjudgment of fault types, and is effective for improving the reliability of the fuel cell system. [Display omitted] • A RMDE algorithm is proposed to realize the impedance parameter identification. • A fault diagnosis model based on the probabilistic neural network is developed. • The diagnosis accuracies for fault type and fault degree reach 100% and 96.67%. [ABSTRACT FROM AUTHOR]

In the state-of-the-art high-power self-humidifying proton exchange membrane fuel cell (PEMFC) systems for vehicles, the high potential and low water production at idle or low load conditions strongly cause corrosion and decay of key materials and thus reduce durability. Therefore, the control technology of system-level durability requires an innovative design. Cathode recirculation is beneficial in alleviating the above unfavorable factors from the perspective of regulating oxygen and vapor partial pressure. This paper presents a pioneering study on the dynamics and control of cathode recirculation in vehicle high-power self-humidifying PEMFC system under low load conditions. First, a control-oriented dynamic model of the vehicle PEMFC system with a cathode recirculation loop is developed and the steady-state and dynamic performance is verified with experimental data from a 120 kW system. Active control of the intake component is achieved by re-feeding the reacted cathode gas to the air compressor outlet through a recirculation pump. On this basis, a high-potential controller based on oxygen partial pressure regulation is designed in combination with the dynamics of cathode recirculation. Results show that the designed dynamic fuzzy logic segmented proportional integral derivative controller with feedforward compensation achieves the optimal high-potential control effect by managing the oxygen partial pressure under variable low load conditions. It not only has excellent anti-disturbance ability but also effectively reduces the dynamic response time, transient overshoot, and steady-state error to satisfy the rapid and stable voltage output. Finally, the concomitant effect of humidification brought by the implementation of the optimal high-potential controller is analyzed, and the results show that the proton membrane is completely humidified. • Originally explore dynamic and control issues of cathode recirculation in vehicle PEMFC system. • A novel control model of PEMFC system with cathode recirculation is established and validated by experiments. • Active control of the oxygen partial pressure is achieved through a cathode recirculation pump. • Fuzzy logic piecewise PID controller with feedforward compensation obtains the optimal high-potential control effect. [ABSTRACT FROM AUTHOR]

The performance evaluation of 1.26 kW fuel cell fed electric vehicle system with reconfigured Quadratic Boost Converter along with the neural network based maximum power point tracking algorithm is presented in this paper. The acceptance of EV in modern society is relevant for the creation of pollution free environment. The main reason for creation of excessive pollution is transportation by the mode of roadways, with the own internal combustion engines by using crude oil as primary energy source. In this paper, a 1.26 kW Proton Exchange Membrane Fuel Cell (PEMFC) fed electric vehicle is designed in MATLAB/Simulink environment. To integrate PEMFC to brushless DC (BLDC) motor are configured Quadratic Boost Converter is designed for high static converter voltage gain. The performance of the proposed EV system is analysed with perturb and observer method and neural network based MPPT control techniques and obtained results are compared at different fuel cell input temperature conditions with respect to different time periods. • Designed a high voltage gain Reconfigured Quadratic Boost Converter for fuel cell. • Developed a new MPPT controller for PEMFC. • Various high gain converters available in literature are discussed for fuel cell. • The basic mathematical modeling of PEMFC and RQB Converter are reported. • Proposed system is studied for various temperature conditions with different MPPT. [ABSTRACT FROM AUTHOR]

In order to make proton exchange membrane fuel cell vehicles more marketable, not only should costs be reduced, but service life should also be further increased. Important factors determining the expected service life are the deformation and the stress distribution within the carbon paper g as d iffusion l ayer (GDL), on which the rib structure of the b i p olar p lates (BPP) has a significant impact. Against this background, a new analytical method is firstly developed to predict the deformation and stress distribution within the GDL, due to compression by the ribs, with high accuracy and low computing resources. Based on the analytical method, a new parabolic rib geometry is then proposed, which can significantly reduce the maximum normal and shear stresses occurring within the GDL, thus reducing the possibility of its mechanical damage. The optimized rib design provides guidance for designing and processing commercial fuel cell BPPs. • New analytical method (AM) to analyze deformation and stresses in PEM fuel cell GDL. • AM results show high agreement with FEM simulations while being significantly faster. • AM can predict normal and shear stress distribution for diverse BPP rib structures. • Proposal of new parabolic rib structure for stress reduction to prevent cell damage. • Reduction of maximum normal stress within GDL by >35% and shear stress by >60%. [Display omitted] [ABSTRACT FROM AUTHOR]

Fuel cell electric vehicles are a promising alternative on the way to emission-free mobility. However, there is still a great deal of uncertainty as to how this change can be implemented technologically. Despite various research and development activities on fuel cells in the past two decades, a real breakthrough of fuel cell technology has not yet been reached. The aim of this paper is therefore to identify barriers to a commercialized production of PEM fuel cell stacks. For this purpose, a comprehensive expert study is performed, consisting of a qualitative, exploratory and a quantitative, hypothesis-confirming step. As a result, technical and non-technical barriers are examined and described in this paper. A cost estimation of today's actual manufacturing cost is presented as identified in the study. Conclusively, future research topics and needs for action are derived. • An expert study is performed to evaluate barriers to fuel cell commercialization. • Organizational, economical, and technical barriers are identified. • Production challenges are seen considerably more hindering than product challenges. • For a large-scale production, great uncertainty of the production technology exists. • Cost assessment indicates today's actual manufacturing cost benchmark at 245 €/kW. [ABSTRACT FROM AUTHOR]

The hydrogen proton exchange membrane (PEM) fuel cells are promising to utilize fuel cells in electric vehicle (EV) applications. However, hydrogen PEM fuel cells are still encountering challenges regarding their functionality and degradation mechanism. Therefore, this paper aims to study the performance of a 3.2 kW hydrogen PEM fuel cell under accelerated operation conditions, including varying fuel pressure at a level of 0.1–0.5 bar, variable loading, and short-circuit contingencies. We will also present the results on the degradation estimation mechanism of four fuel cells working at different operational conditions, including high-to-low voltage range and high-to-low temperature variations. These experiments examine over 180 days of continuous fuel cell working cycle. We have observed that the drop in the fuel cells' efficiency is at around 7.2% when varying the stack voltage and up to 14.7% when the fuel cell's temperature is not controlled and remained at 95 °C. [Display omitted] • Performance of 3.2 kW PEM Fuel cell used for EV application is investigated. • The fuel cell output characteristics at short-circuit and purging routines is discussed. • The degradation mechanism of the fuel cell is examined using data captured over 180 days. • A statistical threshold is used to compare and find the probability factor of degradation for the considered fuel cell. [ABSTRACT FROM AUTHOR]

The thermal management of a proton exchange membrane fuel cell (PEMFC) is crucial for fuel cell vehicles. This paper presents a new simulation model for the water-cooled PEMFC stacks for automotive vehicles and cooling systems. The cooling system model considers both the cooling of the stack and cooling of the compressed air through the intercooler. Theoretical analysis was carried out to calculate the heat dissipation requirements for the cooling system. The case study results show that more than 99.0% of heat dissipation requirement is for thermal management of the PEMFC stack; more than 98.5% of cooling water will be distributed to the stack cooling loop. It is also demonstrated that controlling cooling water flow rate and stack inlet cooling water temperature could effectively satisfy thermal management constraints. These thermal management constraints are differences in stack inlet and outlet cooling water temperature, stack temperature, fan power consumption, and pump power consumption. • Thermal management of water-cooled PEMFC stack for automotive vehicles. • Cooling system model includes cooling of compressed air through the intercooler. • Cooling water distribution to the PEMFC stack and the intercooler investigated. • Regulations of stack inlet cooling water temperature and cooling water flow rate. • Fan and water pump power consumptions considered. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to build the first Energy and Life Cycle Analysis (LCA) comparison between buses with internal combustion engine currently used in the city of Rosario, Province of Santa Fe, Argentina, and some technological alternatives and their variants focusing on buses with an electrical engine powered by compressed hydrogen that feet fuel cells of polymer electrolyte membrane (PEM). This LCA comprehend raw material extraction up to its consumption as fuel. Specifically, hydrogen production considering different production processes from renewable sources called "green hydrogen" (Velazquez Abad and Dodds, 2020) [ 1 ] and non-renewable sources called "grey hydrogen" (Velazquez Abad and Dodds, 2020) [ 1 ]. Renewable sources for hydrogen production are rapid cut densified poplar energy plantation, post-industrial wood residues such as chips pallets, and maize silage. For non-renewable hydrogen production sources are the local electrical power grid from water electrolysis and natural gas from the steam methane reforming process. Buses whose fuel would be renewable hydrogen, produced near the City of Rosario, Province of Santa Fe, Argentina, meet one of the main criteria of sustainability biofuels of the European Union (EU) taken into account Renewable Energy Directive (RED) 2009/28 [ 2 ] and EU RED Directive 2018/2001 [ 3 ] that need significant reduction on net greenhouse gases (GHG) from biomass origin row material respect fossil fuels. At least 70% of GHG would be avoided from its main fossil counterpart of the intern combustion engine (ICE), in the worst and current scenario of the emission factor of the electrical grid of Argentina in the point of use that is about 0.40 kg CO 2eq /kWh with energy and environmental load of 100% in the allocation factor in the hydrogen production stage of the LCA analysis. • Significant GHG emissions avoided by using hydrogen in fuel cell buses. • At least 80% of energy consumption in hydrogen life cycle is due to the hydrogen production stage. • Hydrogen fuel cell vehicles are a sustainable alternative in the decarbonization of transport. • Biomass raw material is very competitive as one option to decarbonize transport. • Biogas reforming technology is 47% less energy demanding than solid biomass gasification. [ABSTRACT FROM AUTHOR]

With the acceleration of the development process of hydrogen fuel cell electric vehicles (HFCEV), it has become very important to maximize the energy stored in the vehicle and to use the vehicle with high efficiency. This paper puts forward how to cooperate with a proton exchange membrane fuel cell (PEMFC) as the primary energy source, a lithium-ion battery (LiB) and a supercapacitor (SCAP) as the energy storage technology. Furthermore, this paper examines the effect of two new control strategies developed for HFCEV in different road models on the vehicle fuel economy and life cycle of the system components. Both control strategies applied to the system can be easily applied to the different HFCEVs with minor changes due to the simplicity of their structure and parameters. The simulation results of the study have indicated that the impact of control strategies created in different road conditions on the power of energy sources, the life cycle of system components, system efficiency and fuel economy parameters of HFCEV. Image 1 • New control strategies developed for a hydrogen fuel cell vehicle. • A vehicle with PEM fuel cell, lithium-ion battery and supercapacitor technologies. • The power sharing between energy storage technologies. • The hydrogen fuel saving in the hydrogen fuel cell vehicles. • Extending the life cycle of system components in the hydrogen fuel cell vehicles. [ABSTRACT FROM AUTHOR]

The present work focusses on measuring the permeability across gas diffusion layers (GDLs) first in a dedicated cell and later in PEM fuel cell configuration with varying bi-polar plate designs. Eight carbon paper-based GDLs with and without the microporous layer (MPL), have been tested. An in-house designed dedicated cell allowed measuring pressure drop depending on flow rate, for i) through-plane and ii) in-plane direction. Further, transport measurements were conducted in 25 cm2 bi-polar plates (BPs) in fuel cell configuration having single or multiple serpentine channels, by stacking the GDL inside. The results show that gas permeability in the dedicated cell for through-plane and in-plane can be estimated by using Darcy's law. However, for BPs, the flow is affected additionally by inertial contribution (Darcy-Forchheimer). Finally, the efficiency allowed by selected GDLs installed in a fuel cell under operation shows a relationship between the equivalent permeability and the fuel cell performance. • Measured through- and in-plane permeability of GDL in a specially dedicated cell. • Measured the equivalent permeability of GDLs in bipolar plates of PEM fuel cells. • The equivalent permeability of GDL greatly differs from those obtained in a dedicated cell. • Inertial flow in the GDL stacked between the bipolar plates is of appreciable significance. • Relationship between equivalent permeability and fuel cell performance. [ABSTRACT FROM AUTHOR]

This research paper mainly deals with the realistic simulation of hydrogen fuel cell vehicles and the development of a lifecycle assessment (LCA) tool to calculate and compare the environmental impacts of hydrogen fuel cell passenger vehicles with conventional vehicles. Since fuel cell vehicles are equipped with regenerative braking, they have strong potential to recover an ample portion of the energy being wasted in the braking system. Thus, the driving cycle can significantly affect the performance of fuel cell vehicles. In order to investigate the effect of driving patterns, several driving patterns are considered, and both vehicle fuel economy and lifecycle emissions are calculated and compared. Fuel cell degradation, on the other hand, is another major problem fuel cell vehicles face. This is mainly caused by the starts/stops, acceleration/deceleration, membrane humidity variation and a high load of the engine. When the vehicle operates on various driving patterns, the fuel cell will degrade which eventually affects the fuel economy. The effect of fuel cell degradation is also investigated for these driving patterns, and the results are compared. The results showed that the highway driving cycle has the lowest total lifecycle emission compared to New York city driving cycle, the city of Surrey (CoS) driving cycle, and the UDDS driving cycles. The results also indicate that fuel cell degradation undesirably affected the average fuel economy of the vehicle for about 23%. • Developing a customized LCA tool for comparison of Hydrogen vehicle with gasoline. • To consider the vehicle specification and real world driving cycle. • To see the effect of fuel cell degradation on lifecycle emission. • To see the effect of driving patterns on both fuel economy and emission. [ABSTRACT FROM AUTHOR]

In the previous researches, researchers mainly focus on the single cell which is far away from the practical application. In this paper, shut-down process is studied in a 5-cell stack with segment technology. In the unprotected group, the hydrogen/air boundary is observed, and the output voltage performance degrades greatly after 300 start-stop cycles. A 2-phase auxiliary load strategy is proposed to avoid the hydrogen/air boundary. The lifetime is extended. But a serious local starvation is observed during the shut-down process. And corrosion happened in the inlet region. To avoid the starvation, the second strategy is designed, which combines 2-phase auxiliary and air purge (2-phase load& air purge strategy). With the new strategy, the degradation of the stack after 1500 cycles is acceptable, and the carbon corrosion in the inlet is effectively reduced. It could conclude that the hydrogen/air boundary is the main cause of the degradation of fuel cell during an unprotected shut-down process. And a strategy only with auxiliary load may suffer from the local starvation. The purge process can avoid the vacuum effect in the fuel cell caused by the auxiliary load. Therefore, adding an air purge during the shut-down process is promising in vehicle fuel cell. Image 1 • Using stack segment cell technology to optimize shut-down strategy. • H2/air boundary in different cell is observed. • Local starvation caused by auxiliary load may damage the inlet part. • 2-phase load& air purge strategy shortens H2/air boundary duration. • 2-phase load& air purge strategy also avoids local starvation. [ABSTRACT FROM AUTHOR]

Unmanned vehicles are increasing the performance of monitoring and surveillance in several applications. Endurance is a key issue in these systems, in particular in electric vehicles, powered at present mainly by batteries. Hybrid power systems based on batteries and fuel cells have the potential to achieve high energy density and specific energy, increasing also the life time and safe operating conditions of the power system. The objective of this research is to analyze the performance of a passive hybrid power system, designed and developed to be integrated into an existing Unmanned Ground Vehicle (UGV). The proposed solution is based on six LiPo cells, connected in series, and a 200 W PEM fuel cell stack, directly connected in parallel to the battery without any limitation to its charge. The paper presents the characterization of the system behavior, and shows the main results in terms of performance and energy management. • Hybrid power systems based on batteries and fuel cells for unmanned vehicles. • Passive hybrid power system, with direct coupling of fuel cell and battery. • Evaluation according to real load profiles of an unmanned ground vehicle (UGV). • Good performance during the long-term test (>7 hours). [ABSTRACT FROM AUTHOR]

Abstract Hydrogen refuelling stations are important for achieving sustainable hydrogen economy in low carbon transport and fuel cell electric vehicles. The solution presented in this paper provides us with a technology for producing carbon dioxide free hydrogen, which is an approach that goes beyond the existing large-scale hydrogen production technologies that use fossil fuel reforming. Hence, the main goal of this work was to design a hydrogen refuelling station to secure the autonomy of a hydrogen powered bicycle. The bicycle hydrogen system is equipped with a proton exchange membrane fuel cell stack of 300 W, a DC/DC converter, and a metal hydride storage tank of 350 NL of hydrogen. The hydrogen power system was made of readily available commercial components. The hydrogen station was designed as an off-grid system in which the installed proton exchange membrane electrolyzer is supplied with electric energy by direct conversion using photovoltaic cells. With the hydrogen flow rate of 2000 cc min−1 the hydrogen station is expected to supply at least 5 bicycles to be used in 20 km long city tourist routes. Highlights • Design of autonomous HRS is registered under Original Registration 1999 Act. • The HRS is expected to supply 5 bicycles in 20 km long city tourist routes. • The bicycle travelled 66 km with 4.5 g of H 2 stored in the storage tank of 30 bars. • The average consumption was 0.0682 g of H 2 per kilometre. • Presented solar HRS and H 2 bicycle are expected to boost H 2 urban mobility. [ABSTRACT FROM AUTHOR]

The demand for clean power source which can be used to run the various types of vehicles on the road is increasing on a daily basis due to the fact that high emissions released from internal combustion engine play a significant role in air pollution and climate change. Fuel cell devices, particularly Proton Exchange Membrane (PEM) type, are strong candidates to replace the internal combustion engines in the transport industry. The PEMFC technology still has many challenges including high cost, low durability and hydrogen storage problems which limit the wide-world commercialization of this technology. In this paper, the fuel cell cost, durability and performances challenges which are associated with using of fuel cell technology for transport applications are detailed and reviewed. Recent developments that deal with the proposed challenges are reported. Furthermore, problems of hydrogen infrastructure and hydrogen storage in the fuel cell vehicle are discussed. [ABSTRACT FROM AUTHOR]

This paper proposes an energy flow model and an optimal energy management strategy based on mean values for maximizing driving mileage of a fuel cell bus (FCB), which is powered by a polymer electrolyte membrane (PEM) fuel cell system and a lithium battery. Firstly, an energy flow model describing the relations between vehicle performance and power flow parameters is quantitatively established. An optimization problem for maximizing driving mileage on a predetermined route is defined, and an analytical solution with clear physical meanings is derived. Next, a practical real-time supervisory Energy Management strategy basing on Mean Values (EMMV) is proposed. The strategy, which doesn't require a priori knowledge of the driving trip, is then compared with several well-known strategies, e.g. charge depleting and charge-sustaining (CDCS), Blended, dynamic programming (DP), and Pontryagin's Minimum Principle (PMP). Simulation results show that, the proposed strategy achieves a near-optimal effect, and converges after one driving cycle on a predetermined bus route. Finally, on-road testing is carried out. The proposed strategy achieves an average endurance mileage on a real bus route of 162 km with a usable battery state of charge (SOC) of 90% and 20 kg hydrogen gas for a fully loaded fuel cell city bus. [ABSTRACT FROM AUTHOR]

In this paper, a semi-empirical model has been proposed for online identification in order to improve the performances of Fuel Cell Vehicles (FCV). The Adaptive Recursive Least Square (ARLS) method has been considered to update the semi-empirical model parameters online to cope with Fuel Cell System (FCS) parameter variations. After introducing a literature review of the semi-empirical model for online identification to show its importance. A Matlab/Simulink model has been designed to define the initial parameters of the ARLS algorithm for the online identification in real time. Then, an experimental test bench has been performed to verify the ARLS algorithm in real time on a Proton Exchange Membrane Fuel Cell (PEMFC). In order to simplify the semi-empirical model, an extensive ANalysis Of VAriance (ANOVA) technique has been used to evaluate the impact of each model parameter. It has been confirmed that the ARLS algorithm is suitable to take into account the operating parameters that changes the PEMFC performance. The simulation using ANOVA results has shown that a parameter with relative low impact (mass transport) is very relevant for the energy management. Therefore, the proposed study can be used for the control and energy management of the Hydrogen Research Institute FCV taking into account the influence of operating conditions. [ABSTRACT FROM AUTHOR]

In the face of growing environmental pollution, developing a PEMFC driving shunting locomotive is a great challenge in China for environmental protection and energy saving, it combines the environmental advantages of an electric locomotive with the lower infrastructure costs of a diesel electric locomotive. In this paper, through innovation of the power system using PEMFC, an experiment prototype of a PEMFC shunting locomotive has been developed which will reduce the effects on the environment. The performance of the fuel cell power plant and the integrated locomotive are experimentally investigated. It is the first locomotive to use a PEMFC power plant in China. Staring from October 2012, we started to test the PEMFC locomotive on the test rail-line in Chengdu, Sichuan. The achieved encouraging results can provide fundamental data for further modification of the locomotive powered by individual PEMFC stack or even development of hybrid ones powered by PEMFC and other power sources in China. [ABSTRACT FROM AUTHOR]

Abstract: A proton electrolyte membrane (PEM) fuel cell system and a Li-ion battery (LIB) are two power sources in a fuel cell electric vehicle (FCEV). The fuel cell system is composed of a fuel cell stack and subsystems for air/hydrogen supply and cooling water. The operation procedure of the fuel cell system can be generally separated into several processes, e.g. starting up, normal/abnormal working and shutting down. In this paper, a multi-mode real-time control strategy for a FCEV is proposed. The strategy is established based on three typical processes (starting up, normal working, shutting down) of the fuel cell system, taking the fuel economy and system durability into consideration. The strategy is applied into a platform vehicle for the 12th 5-year project of “the next generation technologies of fuel cell city buses”. Experiments of the “China city bus typical cycle” on a test bench for the bus were carried out. Results show that, the fuel economy is 7.6kg (100km)−1 in the battery charge-sustaining status. In a practical situation, a total driving mileage of more than 270km can be achieved. Cycle testing also showed that, the degradation rate of the fuel cell was reduced to half of the original level. No performance degradation of the LIB system was observed in the cycling test. [Copyright &y& Elsevier]

Abstract: With the requirements for reducing emissions and improving fuel economy, new markets have become attractive for automotive companies that are developing electric, hybrid, and plug-in vehicles using new technologies candidates to be implemented in the next generations of vehicles. Most of all, hybrid vehicles are attracting interest due to great potential to achieve higher fuel economy and a longer range with respect to pure electric mode but often this solution is not petroleum free. Within a national project CNR TAE Institute is involved in the development of a zero emission hybrid electric city bus based on PEM fuel cell technology able to increase the range at least 30% with respect to the same vehicle in pure electric configuration. Design, control and preliminary results are reported in this paper. [Copyright &y& Elsevier]

Abstract: Although electric-powered vehicles have developed rapidly in recent years, with significant progress in the lithium power battery industry, the Fuel Cell Electric Vehicle (FCEV) is still a competitive choice for a clean transportation solution, because of its extended driving range, zero emissions, and fast fuel recharging capability. In particular the fuel cell hybrid bus used for city traffic is the FCEV type most likely to be commercialized. Demonstration programs for a fuel cell bus fleet have been operated for a few years in China. It is necessary to develop comprehensive diagnostic tools to increase the reliability of these systems, because fuel cell city buses serve large numbers of passengers using public transportation. This paper presents a diagnostic analysis and implementation study based on the Principal Component Analysis (PCA) method for the fuel cell system. This diagnostic system was successfully implemented for detecting a fuel cell stack sensor network failure in the fuel cell bus fleet at the Shanghai Expo in 2010. [Copyright &y& Elsevier]

Abstract: Fuel cell hybrid vehicles'' sustained development and commercialization are contingent on the reliability and durability of the fuel cell engines. In August 2008, official trial of the three proton-exchange membrane (PEM) fuel cell hybrid city buses commenced in a commercial-operation urban-route in Beijing for one year. In this paper, data from the performance analysis of the automotive fuel cells used in those city buses are presented and analyzed. The durability and reliability of the fuel cell engines under realistic conditions were evaluated by analyzing the standard deviation of the single-cell fuel cell voltages and by estimating the voltage vs. current characteristics obtained using the recursive least squares fitting method. After studying the degradation status by analyzing fitted results from the measured data, it is concluded that the fuel cell engines'' performance meets the standard imposed by the driving conditions of the Beijing urban-routes, but that their performance degradation necessitates maintenance in order to ensure normal operation. [Copyright &y& Elsevier]

Abstract: This paper presents an experimental assessment of fuel cell hybrid propulsion systems for scooters based on a modular 1.2kW PEM fuel cell. The tests of the hybrid system are carried out using a programmable electronic load. Different configurations of the fuel cell/battery and the fuel cell/supercapacitor hybrid systems are explored. Both systems demonstrate their ability to deliver the requested load satisfactorily. The distributions of the fuel cell power delivery, although different between the two systems, are within the region where the fuel cell efficiency is approximately constant. As a result, the rates of fuel consumption show no discernable difference between the two systems for all three driving cycles considered. In addition to the fuel consumption, considerations including bus voltage, cost and packaging issues suggest that the supercapacitor has advantages over the battery for the use as secondary energy storage in fuel cell hybrid propulsion system for scooters. [Copyright &y& Elsevier]

Abstract: The work presented in this paper examines the use of pure hydrogen fuelled high temperature polymer electrolyte membrane (HTPEM) fuel cell stacks in an electrical car, charging a Li-ion battery pack. The car is equipped with two branches of two series coupled 1kW fuel cell stacks which are connected directly parallel to the battery pack during operation. This enables efficient charging of the batteries for increased driving range. With no power electronics used, the fuel cell stacks follow the battery pack voltage, and charge the batteries passively. This saves the electrical and economical losses related to these components and their added system complexity. The new car battery pack consists of 23 Li-ion battery cells and the charging and discharging are monitored by a battery management system (BMS) which ensures safe operating conditions for the batteries. The direct connection of the fuel cell stacks to the batteries can only be made if the stacks are carefully dimensioned to the battery voltage. The experimental results of stationary fuel cell charging are presented, showing stable and efficient operation. [Copyright &y& Elsevier]