Road testing of a three-wheeler driven by a 5 kW PEM fuel cell in the absence and presence of batteries

The road testing and demonstration of a three-wheeler vehicle driven by a 5 kW proton exchange membrane fuel cell (PEMFC) was carried out in the absence and presence of lead acid batteries. Prior to integrating the PEMFC module and batteries in the three-wheeler, they were tested and demonstrated separately. The PEMFC module had a very fast response as the load was manually or, especially, automatically changed and it could supply a continuous power when the reactant was supplied continuously. In contrast, the 5 kW lead acid batteries alone could supply power for no longer than 300 s. In the presence of both the PEMFC module and batteries, when the drawing power was in the range of the PEMFC module capacity the propulsion motor gained its energy from the PEMFC module only, whilst the stack power output at all conditions was greater than the setting power of approximately 400 W. After integrating the PEMFC module and batteries into the three-wheeler, both energy sources were found to power the vehicle effectively. The motor power as well as the stack power changed as a linear proportion to the throttle. The motor consumed more power in case of high speed driving, take off or hill climbing, while it used only 0.354 kW in the absence of throttle. The hybrid system can achieve a maximum speed in this three-wheeler of around 24.9 km/h with a hydrogen consumption of 11 g H₂/km (71 g H₂/kWh) and an operating cost of 1.99 USD/km. The thermodynamic efficiency of the vehicle was 42.9%.     

Optimization of PEMFC system operating conditions based on neural network and PSO to achieve the best system performance

PEMFC system is a complex new clean power system. Based on MATLAB/Simulink, this paper develops a system-level dynamic model of PEMFC, including the gas supply system, hydrogen supply system, hydrothermal management system, and electric stack. The neural network fits the electric stack model to the simulation data. The effects of different operating conditions on the PEMFC stack power and system efficiency are analyzed. Combining the power of the reactor and the system efficiency to define the integrated performance index, the particle swarm optimization (PSO) algorithm is introduced to optimize the power density and system efficiency of the PEMFC with multiple objectives. The final optimal operating point increases the power density and system efficiency by 1.33% and 12.8%, respectively, which maximizes the output performance and reduces the parasitic power.     

The development of a PEMFC hybrid power electric vehicle with automatic sodium borohydride hydrogen generation

This paper describes the development of a hybrid Proton Exchange Membrane Fuel Cell (PEMFC) electric vehicle consisting of a 3 kW PEMFC, PV arrays, secondary battery sets, and a chemical hydrogen generation system. We first integrate a hybrid PEMFC electric vehicle and design power management strategies. The on-board hydrogen generation system can provide sufficient hydrogen for continuous operation of the PEMFC, and the performance tests demonstrate the effectiveness of the integrated system in providing sustainable power for driving. We then use Matlab/SimPowerSystem? to develop a simulation model and adjust the model parameters using experimental data. The results indicated that the model can effectively predict system responses and can be used for performance evaluation. We also use the simulation model to estimate the mileage and costs of the developed electric vehicle, and we discuss the impacts of component sizes on system costs and travelling ranges.     

Modeling and thermal management of proton exchange membrane fuel cell for fuel cell/battery hybrid automotive vehicle

The proton exchange membrane fuel cell (PEMFC) stack is a key component in the fuel cell/battery hybrid vehicle. Thermal management and optimized control of the PEMFC under real driving cycle remains a challenging issue. This paper presents a new hybrid vehicle model, including simulations of diver behavior, vehicle dynamic, vehicle control unit, energy control unit, PEMFC stack, cooling system, battery, DC/DC converter, and motor. The stack model had been validated against experimental results. The aim is to model and analyze the characteristics of the 30 kW PEMFC stack regulated by its cooling system under actual driving conditions. Under actual driving cycles (0–65 kW/h), 33%–50% of the total energy becomes stack heat; the heat dissipation requirements of the PEMFC stack are high and increase at high speed and acceleration. A PID control is proposed; the cooling water flow rate is adjusted; the control succeeded in stabilizing the stack temperature at 350 K at actual driving conditions. Constant and relative lower inlet cooling water temperature (340 K) improves the regulation ability of the PID control. The hybrid vehicle model can provide a theoretical basis for the thermal management of the PEMFC stack in complex vehicle driving conditions.     

A model of PEMFC-battery system to evaluate inner operating status and energy consumption under different energy management strategies

A hybrid system with jointed battery and PEMFC is popular and of great potential in New Energy Vehicle (NEV) application. However, reliability and efficiency remain to be improved for commercial products. To reflect the complicated physics inside the proton exchange membrane fuel cell (PEMFC), the PEMFC model consisting of inner muti-physics process and other accessories was built, then a complete hybrid system was established when a matched battery, DC/DC, regenerative braking were taken into consideration. Based on the above model, the stack state and system performance under standard cycle for heavy duty vehicle-CWTVC were obtained. According to the simulation results, fuel cell states such as pressure, water content and voltage suffers severe oscillation with external load, especially in the highway cycle. Membrane electrode assembly (MEA) suffers from pressure impact with average value of more than 24 kPa in highway cycle. In the aspect of relative humidity, the PEMFC stack is most threatened in road cycle. As for the hybrid system, its efficiency and state of charge (SOC) fluctuation perform worst in urban cycle and road cycle respectively, while its highest efficiency occurs in road test. Operating mode of fuel cell has influence on hybrid system. When 3-level mode of fuel cell output was applied, the efficiency increased to its peak value at medium level of 28 kW and then declined gradually. H₂ consumption had an opposite trend compared to efficiency. In the aspect of battery SOC, it declines in operating process and its fluctuations decreases when medium level got bigger. The 3-level mode and 4-level mode were compared using this model. It can be concluded that although 3-level mode performs slightly better in hybrid system efficiency, H₂ consumption, pressure impact, it does not have absolute advantage over 4-level mode in other indicators.     

Fuel cell system with sodium borohydride as hydrogen source for unmanned aerial vehicles

In this study, we design and fabricate a fuel cell system for application as a power source in unmanned aerial vehicles (UAVs). The fuel cell system consists of a fuel cell stack, hydrogen generator, and hybrid power management system. PEMFC stack with an output power of 100 W is prepared and tested to decide the efficient operating conditions; the stack must be operated in the dead-end mode with purge in order to ensure prolonged stack performance. A hydrogen generator is fabricated to supply gaseous hydrogen to the stack. Sodium borohydride (NaBH₄) is used as the hydrogen source in the present study. Co/Al₂O₃ catalyst is prepared for the hydrolysis of the alkaline NaBH₄ solution at room temperature. The fabricated Co catalyst is comparable to the Ru catalyst. The UAV consumes more power in the takeoff mode than in the cruising mode. A hybrid power management system using an auxiliary battery is developed and evaluated for efficient energy management. Hybrid power from both the fuel cell and battery powers takeoff and turning flight operations, while the fuel cell supplies steady power during the cruising flight. The capabilities of the fuel-cell UAVs for long endurance flights are validated by successful flight tests.     

Numerical analysis of an energy storage system based on a metal hydride hydrogen tank and a lithium-ion battery pack for a plug-in fuel cell electric scooter

This work investigates on the performance of a hybrid energy storage system made of a metal hydride tank for hydrogen storage and a lithium-ion battery pack, specifically conceived to replace the conventional battery pack in a plug-in fuel cell electric scooter. The concept behind this solution is to take advantage of the endothermic hydrogen desorption in metal hydrides to provide cooling to the battery pack during operation.The analysis is conducted numerically by means of a finite element model developed in order to assess the thermal management capabilities of the proposed solution under realistic operating conditions.The results show that the hybrid energy storage system is effectively capable of passively controlling the temperature of the battery pack, while enhancing at the same time the on-board storage energy density. The maximum temperature rise experienced by the battery pack is around 12 °C when the thermal management is provided by the hydrogen desorption in metal hydrides, against a value above 30 °C obtained for the same case without thermal management. Moreover, the hybrid energy storage system provides the 16% of the total mass of hydrogen requested by the fuel cell stack during operation, which corresponds to a significant enhancement of the hydrogen storage capability on-board of the vehicle.     

Optimal design of a novel nested-nozzle ejector for PEMFC's hydrogen supply and recirculation system

The ejector-based hydrogen supply and recirculation system (HSRS) for a Proton Exchange Membrane Fuel Cell (PEMFC) system has the advantages of compact size and zero power consumption, compared with the HSRS using a recirculation pump. However, the conventional ejector with a single venturi nozzle can only function within a narrow power range of the PEMFC system due to its restricted primary inlet pressure. This study proposed a novel ejector design with nested nozzles to solve this problem. The key geometric parameters, including the nozzle diameters of a large nozzle (BN), a small nozzle (SN), and the axial distance between two nozzles, were optimized using CFD simulations to obtain the maximum entrainment capability. The BN mode is responsible for the stack's higher load operations, while the SN mode supports the lower power operations. Additionally, a bypass was used parallel to the nested-nozzle ejector in the HSRS to extend the ejector operating range further. The consistent CFD simulation and testing results of the nested-nozzle ejector showed effective hydrogen entrainment capability between 9% and 100% of power output for a 150 kW PEMFC stack. Moreover, the new nested-nozzle ejector HSRS showed much-reduced anode inlet pressure fluctuation compared to the HSRS using two conventional ejectors.     

Performance evaluation of a fuel processing system based on membrane reactors technology integrated with a PEMFC stack

The development of fuel cells is promised to enable the distributed generation of electricity in the near future. However, the infrastructure for production and distribution of hydrogen, the fuel of choice for fuel cells, is currently lacking. Efficient production of hydrogen from fuels that have existing infrastructure (e.g., natural gas, gasoline or LPG) would remove a major drawback to use fuel cells for distributed power generation.The aim of this paper is to define the better operating conditions of an innovative hydrogen generation system (the fuel processing system, FP) based on LPG steam reforming, equipped with a membrane shift reactor, and integrated with a PEMFC (Proton Exchange Membrane Fuel Cell) stack of 5 kWel.With respect to the conventional hydrogen generation systems, the use of membrane reactors (MRs) technology allows to increase the hydrogen generation and to simplify the FP-PEMFC plant, because the CO removal system, needed to reduce the CO content at levels required by the PEMFC, is avoided.Therefore, in order to identify the optimal operating conditions of the FP-PEMFC system, a sensitivity analysis on the fuel processing system has been carried out by varying the main operating parameters of both the reforming reactor and the membrane water gas shift reactor. The sensitivity analysis has been performed by means of a thermochemical model properly developed.Results show that the thermal efficiency of the fuel processing system is maximize (82.4%, referred to the HHV of fuels) at a reforming temperature of 800 °C, a reforming pressure of 8 bar, and an S/C molar ratio equal to 6. In the nominal operating condition of the PEMFC stack, the FP-PEMFC system efficiency is 36.1% (39.0% respect to the LHV).     

Optimal energy management strategy of fuel-cell battery hybrid electric mining truck to achieve minimum lifecycle operation costs

Proton exchange membrane fuel cell (PEMFC) electric vehicle is an effective solution for improving fuel efficiency and onboard emissions, taking advantage of the high energy density and short refuelling time. However, the higher cost and short life of the PEMFC system and battery in an electric vehicle prohibit the fuel cell electric vehicle (FCEV) from becoming the mainstream transportation solution. The fuel efficiency-oriented energy management strategy (EMS) cannot guarantee the improvement of total operating costs. This paper proposes an EMS to minimize the overall operation costs of FCEVs, including the cost of hydrogen fuel, as well as the cost associated with the degradations of the PEMFC system and battery energy storage system (ESS). Based on the PEMFC and battery performance degradation models, their remaining useful life (RUL) models are introduced. The control parameters of the EMS are then optimized using a meta-model based global optimization algorithm. This study presents a new optimal control method for a large mining truck operating on a real closed-road operation cycle, using the combined energy efficiency and performance degradation cost measures of the PEMFC system and lithium-ion battery ESS. Simulation results showed that the proposed EMS could improve the total operating costs and the life of the FCEV.     

Energetic and exergetic analysis of a biomass-fueled CCHP system integrated with proton exchange membrane fuel cell

As a high-efficiency and eco-friendly way of energy conversion, fuel cell has received much attention in recent years. A novel residential combined cooling, heating and power (CCHP) system, consisting of a biomass gasifier, a proton exchange membrane fuel cell (PEMFC) stack, an absorption chiller and auxiliary equipment, is proposed. Based on the established thermodynamic models, the effects of operating parameters, biomass materials type and moisture content on the system performance are closely investigated. Overall system performance is then compared under four different operating modes. From the viewpoints of energy utilization and CO₂ emissions, the CCHP mode has the best performance with corresponding energy efficiency of 57.41% and CO₂ emission index of 0.516 ton/MWh. Exergy analysis results suggest that the optimization and transformation on the gasifier and PEMFC stack should be encouraged. Energy and exergy assessments in this research provide pragmatic guidance to the performance improvement of the integrated CCHP systems with PEMFC. This research also achieves a reasonable combination of efficient cogeneration, green hydrogen production and full recovery of low grade waste heat.     

Automotive fuel cell stack and system efficiency and fuel consumption based on vehicle testing on a chassis dynamometer at minus 18 °C to positive 35 °C temperatures

This paper presents an in-depth laboratory technology assessment of a 2016 Toyota Mirai Fuel Cell (FC) vehicle based on chassis dynamometer testing. The 114.6 kW FC stack has a high dynamic response, which makes this powertrain a FC-dominant hybrid electric vehicle. The measured peak efficiency is 66.0% FC stack and 63.7% FC system with an idle hydrogen flow rate of 4.39 g/hr. The high FC system efficiencies at low loads match typical vehicle power spectrums, resulting in a high average vehicle efficiency of 62% compared to 45% and 23% for a hybrid electric vehicle and a conventional vehicle, respectively. An energy breakdown accounts for the FC stack losses, FC system losses, air compressor loads, and heater loads for different drive cycles and different thermal conditions. The cold-start North American city drive cycle (UDDS) energy consumption values are, respectively, 758, 581, 226, and 321 Wh/km at ambient conditions of −18 °C, −7 °C, 25 °C and 35 °C with 850 W/m² of solar loading. The FC system shutdown and startup processes at temperatures below the freezing point contribute to the increased hydrogen consumption. The raw test data files are available for download, thus providing the research community with a public reference data on a modern production automotive FC system.     

Dynamic behaviour of Li batteries in hydrogen fuel cell power trains

A Li ion polymer battery pack for road vehicles (48 V, 20 Ah) was tested by charging/discharging tests at different current values, in order to evaluate its performance in comparison with a conventional Pb acid battery pack. The comparative analysis was also performed integrating the two storage systems in a hydrogen fuel cell power train for moped applications. The propulsion system comprised a fuel cell generator based on a 2.5 kW polymeric electrolyte membrane (PEM) stack, fuelled with compressed hydrogen, an electric drive of 1.8 kW as nominal power, of the same typology of that installed on commercial electric scooters (brushless electric machine and controlled bidirectional inverter). The power train was characterized making use of a test bench able to simulate the vehicle behaviour and road characteristics on driving cycles with different acceleration/deceleration rates and lengths. The power flows between fuel cell system, electric energy storage system and electric drive during the different cycles were analyzed, evidencing the effect of high battery currents on the vehicle driving range. The use of Li batteries in the fuel cell power train, adopting a range extender configuration, determined a hydrogen consumption lower than the correspondent Pb battery/fuel cell hybrid vehicle, with a major flexibility in the power management.     

Experimental investigation of self-regulating capability of open-cathode PEMFC under different fan working conditions

Self-regulation capability of the open-cathode PEMFC generally means that the stack itself can adjust its state to response to different operating conditions to achieve better performance when the external control strategy remains unchanged. In this paper, self-regulating capability of the stack are analyzed when its cooling fan works under blow or suction mode at different voltages. The result of output voltage shows that the stack achieves better self-regulation when the fan operates at 8.5 V in both blow mode and suction mode. Analysis of impedance spectra reveals that the stack can realize self-regulating function by adjusting activation resistance and ohmic resistance, and the cathode activation resistance is dominant. Furthermore, the result of a cycle load test indicates that the stack can better reflect the self-regulating capability in fan suction mode than in blow mode, and the stack can achieve better water and heat regulation in suction mode. Finally, according to the air velocity distribution and temperature change, it is found that self-regulating capability in suction mode play a better role due to more uniform heat remove. A suitable fan operating voltage and mode are critical for the self-regulating capability of the open-cathode PEMFC stack to maintain a water-heat balance.     

Uncertainty analysis and robust control of fuel delivery systems considering nitrogen crossover phenomenon

In this paper, the fuel delivery subsystem (FDS) with hydrogen recirculation and anode bleeding is applied in proton exchange membrane fuel cell (PEMFC) system, which is utilized to supply hydrogen to the anode of stack and recirculate fuel back to the supply line. As the diffusion of nitrogen from cathode to anode is inevitable in a real PEMFC during long-term operation. To prevent system performance decline due to nitrogen accumulation. Therefore, this paper firstly develops a control-oriented nonlinear dynamic FDS model involving gas diffusion. Additionally, the FDS is very sensitive to operating environment, uncontrolled operation conditions may cause stack degradation. Specifically, a method based on Monte Carlo simulation is proposed to identify the key parameter boundaries. Then the gas distribution in FDS due to nitrogen crossover is analyzed in detail. After this, a hybrid robust methodology based on sliding mode algorithm is also proposed to maintain adequate hydrogen pressure supply, suitable hydrogen and nitrogen content in the system in presence of nitrogen crossover and renewed uncertainties. Finally, the performance of the presented controller is compared with nonlinear PID (NPID) control and nonlinear multi-input-multi-output (NMIMO) control through a hardware-in-the-loop test bench. Experimental results show that the hybrid controller is accurate and suitable for control purpose, the nitrogen content is restricted to the given range and the variation of output voltage is limited to the desired boundaries, the feasibility and effectiveness are validated.     

Experimental investigation on the dynamic performance of a hybrid PEM fuel cell/battery system for lightweight electric vehicle application

A hybrid system combining a 2 kW air-blowing proton exchange membrane fuel cell (PEMFC) stack and a lead–acid battery pack is developed for a lightweight cruising vehicle. The dynamic performances of this PEMFC system with and without the assistance of the batteries are systematically investigated in a series of laboratory and road tests. The stack current and voltage have timely dynamic responses to the load variations. Particularly, the current overshoot and voltage undershoot both happen during the step-up load tests. These phenomena are closely related to the charge double-layer effect and the mass transfer mechanisms such as the water and gas transport and distribution in the fuel cell. When the external load is beyond the range of the fuel cell system, the battery immediately participates in power output with a higher transient discharging current especially in the accelerating and climbing processes. The DC–DC converter exhibits a satisfying performance in adaptive modulation. It helps rectify the voltage output in a rigid manner and prevent the fuel cell system from being overloaded. The dynamic responses of other operating parameters such as the anodic operating pressure and the inlet and outlet temperatures are also investigated. The results show that such a hybrid system is able to dynamically satisfy the vehicular power demand.     

Fuel-cell sharing for a distributed hybrid power system

This paper investigates the benefits of sharing a proton exchange membrane fuel cell (PEMFC) in a distributed hybrid power system. The PEMFC is usually used as backup power in stationary hybrid power systems; however, in that scenario, it might be working only 2% of the time while incurring 20% of the system expenses. Therefore, this paper examines the potential of sharing a PEMFC among multiple power systems. We develop a distributed hybrid power system that comprises several immovable power stations and a fuel-cell vehicle (FCV). Each power station is equipped with solar panels and batteries, while the FCV contains a PEMFC module and can move among the stations to provide sustainable power as needed. We propose power management strategies and show that the total system costs can be significantly reduced by 10.83% and 17.89% when sharing one FCV between three and twelve power stations, respectively. We also design experiments to demonstrate the feasibility of the proposed distributed hybrid power system. In the future, the developed model can be extended to provide further cost reductions by optimizing distributed hybrid power systems with multiple FCVs.     

Hybrid polymer electrolyte membrane fuel cell–lithium‐ion battery powertrain testing platform – hybrid fuel cell electric vehicle emulator

A testing and validation platform for hybrid fuel cell (FC)–lithium‐ion battery (LIB) powertrain systems is investigated. The hybrid FC electric vehicle emulator enables testing of hybrid system components and complete hybrid power modules up to 25 kW for application in electric light‐duty vehicles, light electric vehicles and so forth. A hybrid system comprising a 10‐kW_el low‐temperature polymer electrolyte membrane FC stack and an 11.5‐kWh LIB pack is installed. The system supplies power to a 20‐kW permanent magnet synchronous motor and a 25‐kW alternating current asynchronous, electrically programmable dynamometer is used to simulate the vehicle load during testing at dynamic drive cycle. The steady‐state performance tests of the direct current (DC) motor, DC/DC converter, low‐temperature polymer electrolyte membrane FC stack and LIB are performed as well as dynamic tests of the complete hybrid system. The Economic Commission for Europe driving cycle is selected as a reference cycle to validate the investigated hybrid FC–LIB powertrain. An efficiency of 83% and 95% is measured for electric motor and DC/DC converter, respectively. An average stack efficiency of 50% is achieved. An average hydrogen consumption of 3.9 g * km^?1 is reached during the Economic Commission for Europe driving cycle test. Copyright © 2017 John Wiley & Sons, Ltd.     

车用PEMFC氢气系统建模及其排放特性研究

建立基于尾氢再循环的车用PEMFC氢气系统的集总参数模型和质子交换膜燃料电池堆的二维CFD模型,瞬态模拟研究额定功率工况下尾氢排放对系统及电堆工作特性的影响。结果表明：排放过程中,阳极进气压力和进气流量等参数出现显著的波动现象,且波动幅度和波动时间与排放持续时间存在直接关系;电堆性能在排放过程中有所下降,排放结束后能迅速恢复到排放前的水平;阳极内部的水气分布在排放过程中得到明显改善。     

Simulation analysis of hydrogen recirculation rates of fuel cells and the efficiency of combined heat and power

The objective of this study was to simulate a proton-electrolyte membrane fuel cell (PEMFC) system, namely a PEMFC stack, an anode gas supply subsystem, an anode gas-recovery subsystem, a cathode gas supply subsystem, and a tail gas exhaustion subsystem. In addition, this paper presents an analysis of the efficiency of combined heat and power (CHP) systems. MATLAB and Simulink were employed for dynamic simulation and statistical analysis. The rates of active and the passive anode hydrogen recirculation were considered to elucidate the mechanism of hydrogen circulation. When recovery involved diverse recovery mechanisms, the recirculation rate was affected by the pressure at the hydrogen outlet of the PEMFC system. The greater the pressure was at that outlet, the higher the recovery rate was. In the hydrogen recovery system, when the temperature of the hydrogen supply end remained the same, increasing the temperature of the gas supply end increased the efficiency of the fuel cells; fixing the flow of the hydrogen supply end and increasing the temperature of the hydrogen supply end increased the efficiency of the PEMFC system. A calculation of the efficiency of the recovery system indicated that the thermal efficiency of the fuel cells exceeded 35%, the power generation efficiency exceeded 45%, and the efficiency of the CHP system exceeded 80%.