Air mass flow and pressure optimisation of a PEM fuel cell range extender system

In order to eliminate the local CO₂ emissions from vehicles and to combat the associated climate change, the classic internal combustion engine can be replaced by an electric motor. The two most advantageous variants for the necessary electrical energy storage in the vehicle are currently the purely electrochemical storage in batteries and the chemical storage in hydrogen with subsequent conversion into electrical energy by means of a fuel cell stack. The two variants can also be combined in a battery electric vehicle with a fuel cell range extender, so that the vehicle can be refuelled either purely electrically or using hydrogen. The air compressor, a key component of a PEM fuel cell system, can be operated at different air excess and pressure ratios, which influence the stack as well as the system efficiency. To asses the steady state behaviour of a PEM fuel cell range extender system, a system test bench utilising a commercially available 30 kW stack (96 cells, 409 cm² cell area) was developed. The influences of the operating parameters (air excess ratio 1.3 to 1.7, stack temperature 20 °C–60 °C, air compressor pressure ratio up to 1.67, load point 122 mA/cm² to 978 mA/cm²) on the fuel cell stack voltage level (constant ambient relative humidity of 45%) and the corresponding system efficiency were measured by utilising current, voltage, mass flow, temperature and pressure sensors. A fuel cell stack model was presented, which correlates closely with the experimental data (0.861% relative error). The air supply components were modelled utilising a surface fit. Subsequently, the system efficiency of the validated model was optimised by varying the air mass flow and air pressure. It is shown that higher air pressures and lower air excess ratios increase the system efficiency at high loads. The maximum achieved system efficiency is 55.21% at the lowest continuous load point and 43.74% at the highest continuous load point. Future work can utilise the test bench or the validated model for component design studies to further improve the system efficiency.     

Study of nonlinear control schemes for an automotive traction PEM fuel cell system

To be practical in automotive traction applications, fuel cell systems must provide power output levels of performance that rival that of typical internal combustion engines. In so doing, transient behavior is one of the keys for success of fuel cell systems in vehicles. The focus of this paper is on the air/fuel supply subsystem in tracking an optimum variable pressurization and air flow for maximum system efficiency during load transients. The control-oriented model developed for this study considers electrochemistry, thermodynamics, and fluid flow principles for a 13-state, nonlinear model of a pressurized fuel cell system. For control purposes, a model reduction is performed, and several multi-variable control designs are examined. The first technique uses an observer-based linear optimum control which combines a feed-forward approach based on the steady-state plant inverse response, coupled to a multi-variable LQR feedback control. An extension of that approach, for control in the full nonlinear range of operation, leads to the second technique, nonlinear gain-scheduled control. Some enhancements were applied to overcome the fast variations in the scheduling variable. Finally, a rule-based, output feedback control, implemented with fuzzy logic, is coupled with a nonlinear feed-forward approach, and is examined under the same conditions applied to the first two techniques. The control designs developed are compared in simulation studies to investigate robustness to disturbance, time delay, and actuator limitations.     

Fuzzy control based engine sizing optimization for a fuel cell/battery hybrid mini-bus

The fuel cell/battery hybrid vehicle has been focused for the alternative engine of the existing internal-combustion engine due to the following advantages of the fuel cell and the battery. Firstly, the fuel cell is highly efficient and eco-friendly. Secondly, the battery has the fast response for the changeable power demand. However, the competitive efficiency of the hybrid fuel cell vehicle is necessary to successfully alternate the conventional vehicles with the fuel cell hybrid vehicle. The most relevant factor which affects the overall efficiency of the hybrid fuel cell vehicle is the relative engine sizing between the fuel cell and the battery. Therefore the design method to optimize the engine sizing of the fuel cell hybrid vehicle has been proposed. The target system is the fuel cell/battery hybrid mini-bus and its power distribution is controlled based on the fuzzy logic. The optimal engine sizes are determined based on the simulator developed in this paper. The simulator includes the several models for the fuel cell, the battery, and the major balance of plants. After the engine sizing, the system efficiency and the stability of the power distribution are verified based on the well-known driving schedule. Consequently, the optimally designed mini-bus shows good performance.     

Two new control strategies: For hydrogen fuel saving and extend the life cycle in the hydrogen fuel cell vehicles

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.     

The effects of driving patterns and PEM fuel cell degradation on the lifecycle assessment of hydrogen fuel cell vehicles

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%.     

车用燃料电池空气供给系统的净化与增压

近年来随着燃料电池汽车相关技术的迅速发展,消除空气中的杂质气体(尤其是内燃机汽车排放的各种污染物)对车用燃料电池阴极性能的影响亟待研究解决。文章简要论述了车用燃料电池空气供给系统的净化原理和装置结构,并认为采用废气涡轮增压装置有助于解决空气传输阻力增加的问题。     

Economic energy management strategy design and simulation for a dual-stack fuel cell electric vehicle

This paper presents the design and simulation validation of two energy management strategies for dual-stack fuel cell electric vehicles. With growing concerns about environmental issues and the fossil energy crisis, finding alternative methods for vehicle propulsion is necessary. Proton exchange membrane (PEM) fuel cell systems are now considered to be one of the most promising alternative energy sources. In this work, the challenge of further improving the fuel economy and extending the driving range of a fuel cell vehicle is addressed by a dual-stack fuel cell system with specific energy management strategies. An efficiency optimization strategy and an instantaneous optimization strategy are proposed. Simulation validation for each strategy is conducted based on a dual-stack fuel cell electric vehicle model which follows the new European driving cycle (NEDC). Simulation results show that a dual-stack fuel cell system with proposed energy management strategies can significantly improve the fuel economy of a fuel cell vehicle and thus lengthen the driving range while being able to keep the start-stop frequency of the fuel cell stack within a reasonable range.     

Development and demonstration flight of a fuel cell system for high-altitude balloons

Proton exchange membrane fuel cell offers higher energy density than the existing battery technologies for high-energy applications, and it is a promising power source for various industries including aerospace vehicles. We have been developing and testing a non-external humidified fuel cell system for high-altitude balloons, which require simple, light, and easy-to-operate power systems. This system consists of three major subsystems—a fuel cell stack, a reactant supply subsystem, and an electrical control subsystem. Ground performance testing in a vacuum chamber simulating the high-altitude vacuum condition was performed before the flight. Then, a demonstration flight of the fuel cell system was launched using a large balloon for verifying its performance under practical high-altitude conditions. Cell voltage variations synchronized with oxygen pressure spikes were observed that were probably caused by condensed product water plugging the flow passages of the back pressure regulator. Flight results indicated that the fuel cell system operated better when water was expelled as vapor, rather than in the liquid form. In addition, a back pressure regulator should be installed to avoid the accumulation of water droplets for realizing a stable performance.     

Modeling a hydrogen pressure regulator in a fuel cell system with Joule–Thomson effect

Fuel cell vehicles offer significant sustainability benefits by eliminating tailpipe emissions, increasing powertrain efficiency, and utilizing hydrogen that can be supplied from various sources including renewables. A pressure regulator in the hydrogen storage system on a fuel cell vehicle is an important component to ensure that the hydrogen delivery to the fuel cell stack meets the pressure and temperature requirements. A validated model of the regulator can be used to support the product design and optimization of the operating strategy. In this work, a pressure regulator model has been developed to capture the hydrogen discharge behaviors from the compressed hydrogen tank to the fuel cell stack. The focus of the model is to develop the pressure and temperature relationship at the regulator outlet given the inlet conditions from the storage tank. Besides the ideal-gas based derivation for pressure response, the model has used a constant-enthalpy approach to capture the hydrogen temperature increase associated with the pressure drop due to the Joule–Thomson effect. The model was validated with various testing data including hysteresis and dynamic flow conditions, showing satisfactory agreement. The validated model was then used for parametric studies. The modeling results concluded that the regulator inlet temperature has the strongest influence on raising the outlet temperature, while the regulator inlet pressure is an important factor although secondary to the inlet temperature. The comprehensive regulator modeling developed in this work provides the foundation for assessing and optimizing a key dynamic component in the hydrogen storage system.     

Experimental investigation of fuel cell dynamic response and control

An experimental study of the dynamic response of a commercial fuel cell system is presented in this work. The primary goal of the research is an examination of the feasibility for using fuel cells in a load-following mode for vehicular applications, where load-following implies that the fuel cell system provides the power necessary for transient responses without the use of additional energy storage elements, such as batteries or super-capacitors. The dynamic response of fuel cell systems used in the load-following mode may have implications for safe and efficient operation of vehicles. To that end, a DC–DC converter was used to port the power output of the fuel cell to a resistive load using a pulse-width-modulating circuit. Frequency responses of the system were evaluated at a variety of DC offsets and AC amplitudes of the PWM duty cycle from 1 out to 400 Hz. Open-loop transient responses are then evaluated using transitions from 10% to 90% duty cycle levels, followed by dwells at the 90% level and then transitions back to the 10% level. A classical proportional–integral controller was then developed and used to close the loop around the system, with the result that the fuel cell system was driven to track the same transient. The controller was then used to drive the fuel cell system according to a reference power signal, which was a scaled-down copy of the simulated power output from an internal combustion engine powering a conventional automobile through the Federal Urban Driving Schedule (FUDS). The results showed that the fuel cell system is capable of tracking transient signals with sufficient fidelity such that it should be applicable for use in a load-following mode for vehicular applications. The results also highlight important issues that must be addressed in considering vehicular applications of fuel cells, such as the power conditioning circuit efficiency and the effect of stack heating on the system response.     

Analysis of the control strategies for fuel saving in the hydrogen fuel cell vehicles

A hydrogen fuel cell vehicle requires fuel cells, batteries, supercapacitors, controllers and smart control units with their control strategies. The controller ensures that a control strategy predicated on the data taken from the traction motor and energy storage systems is created. The smart control unit compares the fuel cell nominal output power with the vehicle power demand, calculates the parameters and continually adjusts the variables. The control strategies that can be developed for these units will enable us to overcome the technological challenges for hydrogen fuel cell vehicles in the near future. This study presents the best hydrogen fuel cell vehicle configurations and control strategies for safe, low cost and high efficiency by comparing control strategies in the literature for fuel economy.     

Efficiencies of hydrogen storage systems onboard fuel cell vehicles

Energy efficiency, vehicle weight, driving range, and fuel economy are compared among fuel cell vehicles (FCV) with different types of fuel storage and battery-powered electric vehicles. Three options for onboard fuel storage are examined and compared in order to evaluate the most energy efficient option of storing fuel in fuel cell vehicles: compressed hydrogen gas storage, metal hydride storage, and onboard reformer of methanol. Solar energy is considered the primary source for fair comparison of efficiencies for true zero emission vehicles. Component efficiencies are from the literature. The battery powered electric vehicle has the highest efficiency of conversion from solar energy for a driving range of 300 miles. Among the fuel cell vehicles, the most efficient is the vehicle with onboard compressed hydrogen storage. The compressed gas FCV is also the leader in four other categories: vehicle weight for a given range, driving range for a given weight, efficiency starting with fossil fuels, and miles per gallon equivalent (about equal to a hybrid electric) on urban and highway driving cycles.     

Comparative study of different fuel cell technologies

Fuel cells generate electricity and heat during electrochemical reaction which happens between the oxygen and hydrogen to form the water. Fuel cell technology is a promising way to provide energy for rural areas where there is no access to the public grid or where there is a huge cost of wiring and transferring electricity. In addition, applications with essential secure electrical energy requirement such as uninterruptible power supplies (UPS), power generation stations and distributed systems can employ fuel cells as their source of energy.The current paper includes a comparative study of basic design, working principle, applications, advantages and disadvantages of various technologies available for fuel cells. In addition, techno-economic features of hydrogen fuel cell vehicles (FCV) and internal combustion engine vehicles (ICEV) are compared. The results indicate that fuel cell systems have simple design, high reliability, noiseless operation, high efficiency and less environmental impact. The aim of this paper is to serve as a convenient reference for fuel cell power generation reviews.     

The fuel cell electric vehicles: The highlight review

Transportation sector is the important sector and consumed the most fossil fuel in the world. Since COVID-19 started in 2019, this sector had become the world connector because every country relies on logistics. The transportation sector does not only deal with the human transportation but also relates to logistics. Research in every country has searched for alternative transportation to replace internal combustion engines using fossil fuel, one of the most prominent choices is fuel cells. Fuel cells can use hydrogen as fuel. Hydrogen can be fed to the fuel cells to provide electric power to drive vehicles, no greenhouse gas emission and no direct combustion required. The fuel cells have been developed widely as the 21st century energy-conservation devices for mobile, stationary, and especially vehicles. The fuel cell electric vehicles using hydrogen as fuel were also called hydrogen fuel cell vehicles or hydrogen electric vehicles. The fuel cells were misconceived by several people that they were batteries, but the fuel cells could provide electric power continuously if their fuel was provided continuously. The batteries could provide electric power as their only capacities, when all ions are released, no power could be provided. Because the fuel cell vehicles play important roles for our future transportation, the overall review for these vehicles is significantly interesting. This overall review can provide general and technical information, variety of readers; vehicle users, manufacturers, and scientists, can perceive and understand the fuel cell vehicles within this review. The readers can realize how important the fuel cell technologies are and support research around the world to drive the fuel cell vehicles to be the leading vehicles in our sustainable developing world.     

Dynamic simulation and lifecycle assessment of hydrogen fuel cell electric vehicles considering various hydrogen production methods

In this research study, a real model of a hydrogen fuel cell vehicle is simulated using Simcenter Amesim software. The software used for vehicle simulation enabled dynamic simulation, resulting in more precise simulation. Furthermore, considering that fuel cell degradation is one of the significant challenges confronting fuel cell vehicle manufacturers, we examined the impact of fuel cell degradation on the performance of hydrogen vehicles. According to the findings, a hydrogen vehicle with a degraded fuel cell consumes 14.3% more fuel than a fresh fuel cell hydrogen vehicle. A comprehensive life cycle assessment (LCA) is also performed for the designed hydrogen vehicle. The results of the hydrogen vehicle life cycle assessment are compared with a gasoline vehicle to fully understand the effect of hydrogen vehicles in reducing air emissions. The methods considered for hydrogen production included natural gas reforming, electrolysis, and thermochemical water splitting method. Furthermore, because the source of electricity used for electrolysis has a significant impact on the life cycle emission of a hydrogen vehicle, three different power sources were considered in this assessment. Finally, while a hydrogen vehicle with a degraded fuel cell emits lower carbon dioxide (CO₂) than a gasoline vehicle, the emitted CO₂ from this vehicle using hydrogen from electrolysis is approximately 25% higher than that of a new hydrogen vehicle.     

Research progress on performance of fuel cell system utilized in vehicle

The application of fuel cells was an important approach for vehicle industry to deal with the challenges of Energy shortage and environment pollution caused by traditional power machines. Fuel cells, which generate power and torque with zero emissions and high efficiency, are considered as an promising future power machine for vehicles. This paper reviewed previous research model and method for fuel cell, effect of state parameters and structural parameters on the performance of fuel cell，power density and life cycle of fuel cell systems in recent years，Prospected development and application of fuel cell system in the future.     

An energy matching method for battery electric vehicle and hydrogen fuel cell vehicle based on source energy consumption rate

The smart cities development requires reducing energy consumption and using as much renewable energy as possible, so the widespread use of new energy vehicles is a very important measure. In this work, for the energy system configuration and energy efficiency balance of new energy vehicles, we propose an energy matching method to study its energy efficiency from the view point for energy life cycle. Nowadays, new energy vehicles mainly include battery electric vehicles (BEV) and hydrogen fuel cell vehicles (HFCEV). Firstly, we proposed the Source to Range (STR) model. Then, based on STR model, we used energy efficiency analysis chart to visually represent the conversion, delivery and consumption of the vehicle energy life cycle. Furthermore, we proposed a Source Energy Consumption Rate (SECR), which is used to evaluate the vehicles energy efficiency. Finally, based on STR model, we obtained the dividing line of the same SECR for new energy vehicles and equivalent fuel vehicles, which provides constraints on the vehicle energy system design. The results show that STR model can provide an effective tool for energy matching and energy efficiency analysis of new energy vehicles, and has a reference for product development of new energy vehicles.     

Coordination control strategy for the air management of heavy vehicle fuel cell engine

Air supply system is an important subsystem in the fuel cell engine with strongly non-linear and coupling interactions. There are strong coupling problems between air flow and pressure in the air supply system, such as the air compressor and electronic throttle opening. This paper introduces a novel coordination control strategy for the air supply system of high power fuel cell engine in heavy truck. It consists of feed-forward and internal model decoupling control (IMC) with tracking an optimized working line of centrifugal air compressor. The strategy can maintain good control effect for model matching and model mismatching with robustness. The working efficiency of the centrifugal air compressor could be significantly increased and avoid the phenomenon of surge by the coordination control strategy. At the same time, the output current of fuel cell engine can meet the load requirement which has the short response time and good follow effect.     

Abating transport GHG emissions by hydrogen fuel cell vehicles: Chances for the developing world

Fuel cell vehicles, as the most promising clean vehicle technology for the future, represent the major chances for the developing world to avoid high-carbon lock-in in the transportation sector. In this paper, by taking China as an example, the unique advantages for China to deploy fuel cell vehicles are reviewed. Subsequently, this paper analyzes the greenhouse gas (GHG) emissions from 19 fuel cell vehicle utilization pathways by using the life cycle assessment approach. The results show that with the current grid mix in China, hydrogen from water electrolysis has the highest GHG emissions, at 3.10 kgCO₂/km, while by-product hydrogen from the chlor-alkali industry has the lowest level, at 0.08 kgCO₂/km. Regarding hydrogen storage and transportation, a combination of gas-hydrogen road transportation and single compression in the refueling station has the lowest GHG emissions. Regarding vehicle operation, GHG emissions from indirect methanol fuel cell are proved to be lower than those from direct hydrogen fuel cells. It is recommended that although fuel cell vehicles are promising for the developing world in reducing GHG emissions, the vehicle technology and hydrogen production issues should be well addressed to ensure the life-cycle low-carbon performance.     

Variable structure battery-based fuel cell hybrid power system and its incremental fuzzy logic energy management strategy

A hybrid power system consists of a fuel cell and an energy storage device like a battery and/or a supercapacitor possessing high energy and power density that beneficially drives electric vehicle motor. The structures of the fuel cell-based power system are complicated and costly, and in energy management strategies (EMSs), the fuel cell's characteristics are usually neglected. In this study, a variable structure battery (VSB) scheme is proposed to enhance the hybrid power system, and an incremental fuzzy logic method is developed by considering the efficiency and power change rate of fuel cell to balance the power system load. The principle of VSB is firstly introduced and validated by discharge and charge experiments. Subsequently, parameters matching of the fuel cell hybrid power system according to the proposed VSB are designed and modeled. To protect the fuel cell as well as ensure the efficiency, a fuzzy logic EMS is formulated via setting the fuel cell operating in a high efficiency and generating an incremental power output within the affordable power slope. The comparison between a traditional deterministic rules-based EMS and the designed fuzzy logic was implemented by numerical simulation in three different operation conditions: NEDC, UDDS, and user-defined driving cycle. The results indicated that the incremental fuzzy logic EMS smoothed the fuel cell power and kept the high efficiency. The proposed VSB and incremental fuzzy logic EMS may have a potential application in fuel cell vehicles.