Commercial vehicle auxiliary loads powered by PEM fuel cell

The commercial vehicles are in leadership in emission production for on-road vehicles. This high rate of emission is released in highly populated areas where diesel driven internal combustion engines are running in inefficient operating ranges. Except the propulsion, the internal combustion engine is powering the auxiliary devices such as refrigerator unit, etc. The auxiliary units are significant contributor to the overall pollutant production. In this paper the auxiliary load power supply for refrigerator unit is shifted from internal combustion engine to PEM fuel cell. The decrease in CO₂ accumulated emissions was estimated by simulation model containing vehicle model (tire, brake, differential, gearbox and driver model), diesel engine model and auxiliary power demand model. Four stroke diesel engine was modeled and investigated. For this investigation the fully filled truck was used for simulating 100% weight load. The gross weight is 7500 kg.The novelty of the approach is the simulation performed on realistic combination of city and urban road cycle. The focus was on modelling the realistic truck driving cycle in order to correctly predict emission and fuel consumption reduction. Since initial investigation are performed on constant load demand of fuel cell, simplified model of PEMFC was applied. PEM fuel cell stack was designed in order to meet the demands of auxiliary consumers. The H₂ consumption and size of hydrogen tank was estimated based on assumed 8-h daily drive. Finally, the migration of power supply for auxiliary units on commercial vehicle from internal combustion engine showed potential of fuel savings and CO₂ reduction of up to 9% for a given case on this specific test cycle.     

Exergetic environmental assessment of life cycle emissions for various automobiles and fuels

This paper examines material emissions produced during thirteen fuel life cycles for automobiles, on mass and exergy bases. The masses of fuel life cycle emissions are compared with the chemical exergies of these emissions. For the emissions data used, the chemical exergy results suggest that compressed natural gas use in motor vehicles produces emissions that are the most out of equilibrium with the natural environment, relative to all other fuel life cycle paths considered. It is also shown that diesel use in grid-independent hybrid electric vehicles has the lowest chemical exergies of emissions of all thirteen fuel-vehicle combinations under consideration, suggesting a lower degree of potential environmental impact. The exergy methodology presented for assessing the potential for environmental impact may help in the development and design of transportation technologies that are more environmentally benign than those presently used.     

Technical feasibility assessment of a PEM fuel cell refrigerator system

PEM Fuel Cells (PEMFCs), fueled by hydrogen, are electrochemical devices that convert hydrogen to useful power and two by-products: heat and water. They cover an important part of power applications namely in the transportation area, and in other practical applications that are either stationary or portable. In particular, the domestic refrigerator is one of the daily and indispensable applications but with a high-energy demand due to the high running time cycles. This work is a technical assessment of the feasibility of building a coupled “PEM Fuel Cell – Refrigerator” system. Real technical data for the refrigerator are collected, processed and evaluated. The obtained results show reasonable flows consumption rates. In fact, the refrigerator requires a flow rate of 1.607 slpm of hydrogen and 8 slpm of air at a pressure of respectively 3 atm and 1 atm. The water is produced at a rate of 1.285 10⁻³ slpm. The annual amount of hydrogen consumed by the refrigerator is estimated to 28, 47 kg. The energy provided to the refrigerator is about 130 W and the energy needed by the air compressor is 28, 24 W. A technical solution is suggested at the end of this work to reduce the start and stop cycles of the fuel cell.     

PEM fuel cell electrodes

The design of electrodes for polymer electrolyte membrane fuel cells (PEMFC) is a delicate balancing of transport media. Conductance of gas, electrons, and protons must be optimized to provide efficient transport to and from the electrochemical reactions. This is accomplished through careful consideration of the volume of conducting media required by each phase and the distribution of the respective conducting network. In addition, the issue of electrode flooding cannot be neglected in the electrode design process. This review is a survey of recent literature with the objective to identify common components, designs and assembly methods for PEMFC electrodes. We provide an overview of fabrication methods that have been shown to produce effective electrodes and those that we have deemed to have high future potential. The relative performances of the electrodes are characterized to facilitate comparison between design methodologies.     

Speed controlling of the PEM fuel cell powered BLDC motor with FOPI optimized by MSA

In this study, Brushless DC (BLDC) motor, which is commonly used as a drive element in the unmanned aerial vehicle (UAV), electric vehicles, and mobile robots today, is powered by hydrogen technologies as environmentally friendly and controlled by a fractional-order PI (FOPI) controller structure. Proton Exchange Membrane (PEM) electrolyzer, PEM Fuel Cell (PEMFC), storage tank, BLDC motor, and motor driver system are modeled and integrated into the Simulink environment in MATLAB. PEM electrolyzer that is energized from the AC grid via the AC/DC converter generates the hydrogen. This generated hydrogen is stored in the storage tank and used by PEMFC to energize to the BLDC motor. The model of the BLDC motor is controlled by using a closed-loop FOPI controller for the variable speed and torque reference values. Parameters of the FOPI are determined by Moth Swarm Algorithm (MSA) optimization method. It is observed from the results that the PEMFC powered FOPI controlled BLDC motor operates stably at high performance for different speed and torque values as expected from the modern drive systems. Furthermore, it is seen that the required energy for the BLDC motor is provided by the PEMFC-PEM electrolyzer system without interruption and the FOPI controlled BLDC motor successfully follows the reference speed values for the different torque values.     

车用燃料生命周期评估

以国际标准化组织的生命周期评价标准为依据,确定了车用燃料生命周期评估的系统边界和评价指标,给出了模型主要的计算公式,并进行了国外车用燃料全生命周期的能源消耗和排放评价。     

Energetic life cycle assessment of fuel cell powertrain systems and alternative fuels in Germany

By means of energetic life cycle assessment, innovative fuel cell (FC) powertrain systems and the respective fuels are examined and compared with conventional systems. The basis for this research is process chain analyses for the supply of conventional and alternative fuels at the point of consumption in Germany, e.g. compressed natural gas, methanol or hydrogen. To complete the integrated view, the use of these fuels in vehicles with internal combustion engines and FCs is examined. Within the scope of this study, special attention is paid to a system breakdown and energetic assessment of the FC powertrain. For the purpose of a full life cycle assessment, energy requirements and CO₂-emissions for the production, maintenance and disposal of the vehicles are included.     

A PEM fuel cell model for cold-start simulations

In this paper, a transient multiphase multi-dimensional PEM fuel cell model has been developed in the mixed-domain framework for elucidating the fundamental physics of fuel cell cold start. Cold-start operations of a PEM fuel cell at a subfreezing boundary temperature of −20 °C under both constant current and constant cell voltage conditions have been numerically examined. Numerical results indicate that the water vapor concentration inside the cathode gas channel affects ice formation in the cathode catalyst layer and thus the cold-start process of the fuel cell. This conclusion demonstrates that high gas flow rates in the cathode gas channel could increase fuel cell cold-start time and benefit the cold-start process. It is shown that the membrane plays a significant role during the cold-start process of a PEM fuel cell by absorbing the product water and becoming hydrated. The time evolutions of ice formation, current density and water content distributions during fuel cell cold-start processes have also been discussed in detail.     

Development,analysis and assessment of fuel cell and photovoltaic powered vehicles

This paper deals with a new hybridly powered photovoltaic- PEM fuel cell – Li-ion battery and ammonia electrolyte cell integrated system (system 2) for vehicle application and is compared to another system (system 1) that is consisting of a PEM fuel cell, photovoltaic and Li-ion battery. The paper aims to investigate the effect of adding photovoltaic to both systems and the amount of hydrogen consumption/production that could be saved/generated if it is implemented in both systems. These two systems are analyzed and assessed both energetically and exergetically. Utilizing photovoltaic arrays in system 1 is able to recover 177.78 g of hydrogen through 1 h of continuous driving at vehicle output power of 98.32 kW, which is approximately 3.55% of the hydrogen storage tank used in the proposed systems. While, using the same photovoltaics arrays, system 2 succeeds to produce 313.86 g of hydrogen utilizing the ammonia electrolyzer system 2 appeared to be more promising as it works even if the car is not in operation mode. Moreover, the hydrogen produced from the ammonia electrolyzer can be stored onboard, and the liquefied ammonia can be used as a potential source for feeding PEM fuel cell with hydrogen. Furthermore, the effects of changing various system parameters on energy and exergy efficiencies of the overall system are investigated.     

Onboard fuel processor for PEM fuel cell vehicles

To lower vehicle greenhouse gas emissions, many automotive companies are exploring fuel cell technologies, which combine hydrogen and oxygen to produce electricity and water. While hydrogen storage and infrastructure remain issues, Renault and Nuvera Fuel Cells are developing an onboard fuel processor, which can convert a variety of fuels into hydrogen to power these fuel cell vehicles.The fuel processor is now small enough and powerful enough for use on a vehicle. The catalysts and heat exchangers occupy 80 l and can be packaged with balance of plant controls components in a 150-l volume designed to fit under the vehicle. Recent systems can operate on gasoline, ethanol, and methanol with fuel inputs up to 200 kWth and hydrogen efficiencies above 77%. The startup time is now less than 4 min to lower the CO in the hydrogen stream to the target value for the fuel cell.     

Development and preliminary testing of a unitized regenerative fuel cell based on PEM technology

Results related to the development and testing of a unitized regenerative fuel cell (URFC) based on proton-exchange membrane (PEM) technology are reported. A URFC is an electrochemical device which can operate either as an electrolyser for the production of hydrogen and oxygen (water electrolysis mode) or as a H₂/O₂ fuel cell for the production of electricity and heat (fuel cell mode). The URFC stack described in this paper is made of seven electrochemical cells (256 cм² active area each). The nominal electric power consumption in electrolysis mode is of 1.5 kW and the nominal electric power production in fuel cell mode is 0.5 kW. A mean cell voltage of 1.74 V has been measured during water electrolysis at 0.5 A cm⁻² (85% efficiency based on the thermoneutral voltage of the water splitting reaction) and a mean cell voltage of 0.55 V has been measured during fuel cell operation at the same current density (37% electric efficiency based on the thermoneutral voltage). Preliminary stability tests are satisfactory. Further tests are scheduled to assess the potentialities of the stack on the long term.     

Design and evaluation of hybrid propulsion ship powered by fuel cell and bottoming cycle

Fuel cells are a promising power source in the electric propulsion systems for zero-emission vessels. The electric efficiency of fuel cells can be increased to 55% practically, but significant amounts of remaining energy from the electrochemical reaction are wasted as heat. This article proposes a hybrid propulsion system for ships that utilizes both the electric energy and thermal energy generated by fuel cells. The electric power capacity of fuel cells and the steam generation capacity of recovered heat from fuel cell systems are calculated, and then the propulsion power of the hybrid system is simulated by MATLAB Simulink. The overall energy efficiency of the proposed ship propulsion system is compared with that of conventional systems by comparing fuel consumption rate. Simulation results indicate that the proposed hybrid propulsion system can increase energy efficiency by 22.5% by additional utilization of the recovered heat from fuel cells.     

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%.     

A review: Exergy analysis of PEM and PEM fuel cell based CHP systems

In recent years, growing attention has been given to new alternative energy sources and exergy analysis since fossil fuels cause emissions that have some negative impacts on earth such as global warming, greenhouse effect etc. New power generation systems have been developed in order to reduce or eliminate these impacts as possible. So that, new alternative energy systems have been taken place instead of fossil fuel based systems with nearly zero emission levels. One of them is solid polymer electrolyte or proton exchange membrane (PEM) fuel cell. Although it has significant advantages, there are some disadvantages such as cost, and hydrogen is not a fuel that can be easily obtained. For these reasons, efficiency of a PEM fuel cell has a great significance. Energy efficiency of a system is the most important parameter for utilization. But, energy analysis does not always show the capacity to do work potential of energy of a system. Exergy analysis must be investigated for a system in order to see available work of the system. Because of disadvantages of the PEM fuel cell, exergy analysis has quite importance. In this paper PEM fuel cell and exergy analysis of PEM fuel cell are combined and investigated. A detailed review of the past and recent research activities has been documented. The review focuses on exergy analysis of both PEM fuel cells and PEM based combined heat and power (CHP) systems at different operating parameters. It is concluded that there are a lot of parameters which effects the exergy efficiencies of systems.     

Constructal PEM fuel cell stack design

This paper describes a structured procedure to optimize the internal structure (relative sizes, spacings), single cells thickness, and external shape (aspect ratios) of a polymer electrolyte membrane fuel cell (PEMFC) stack so that net power is maximized. The constructal design starts from the smallest (elemental) level of a fuel cell stack (the single PEMFC), which is modeled as a unidirectional flow system, proceeding to the pressure drops experienced in the headers and gas channels of the single cells in the stack. The polarization curve, total and net power, and efficiencies are obtained as functions of temperature, pressure, geometry and operating parameters. The optimization is subjected to fixed stack total volume. There are two levels of optimization: (i) the internal structure, which accounts for the relative thicknesses of two reaction and diffusion layers and the membrane space, together with the single cells thickness, and (ii) the external shape, which accounts for the external aspect ratios of the PEMFC stack. The flow components are distributed optimally through the available volume so that the PEMFC stack net power is maximized. Numerical results show that the optimized single cells internal structure and stack external shape are “robust” with respect to changes in stoichiometric ratios, membrane water content, and total stack volume. The optimized internal structure and single cells thickness, and the stack external shape are results of an optimal balance between electrical power output and pumping power required to supply fuel and oxidant to the fuel cell through the stack headers and single-cell gas channels. It is shown that the twice maximized stack net power increases monotonically with total volume raised to the power 3/4, similarly to metabolic rate and body size in animal design.     

A comprehensive assessment on the durability of gas diffusion electrode materials in PEM fuel cell stack

Polymer electrolyte membrane (PEM) fuel cell is the most promising among the various types of fuel cells. Though it has found its applications in numerous fields, the cost and durability are key barriers impeding the commercialization of PEM fuel cell stack. The crucial and expensive component involved in it is the gas diffusion electrode (GDE) and its degradation, which limits the performance and life of the fuel cell stack. A critical analysis and comprehensive understanding of the structural and functional properties of various materials involved in the GDE can help us to address the related durability and cost issues. This paper reviews the key GDE components, and in specific, the root causes influencing the durability. It also envisages the role of novel materials and provides a critical recommendation to improve the GDE durability.     

A simple model of a high temperature PEM fuel cell

We develop a simple analytical model of a high temperature hydrogen fuel cell with proton exchange membrane. The model is validated against experimental results obtained in our group. The model is pseudo two dimensional, steady-state and isothermal, it accounts for the crossover of reactant gases through the membrane and it can be solved analytically. The role of the crossover is considered in detail.     

Economic comparison of fuel cell powered forklifts to battery powered forklifts

This paper presents an economic comparison of fuel cell powered forklifts to various types of battery powered forklifts. The total costs of ownership of each technology is calculated and compared over their economic lifetimes and at varying workloads to determine the economic costs or benefits associated with each technology. The study is novel compared to the previous literature in that all data sources are referenced, it includes a model that is scalable by facility workload, and it includes the economic costs of hydrogen storage and charging infrastructure. Results show that fuel cell forklifts are more expensive to purchase and operate that battery powered forklifts for the types of facilities considered in this analysis. Fast charge forklifts are shown to be economically advantaged at high workloads relative to conventional battery-swapping forklifts.     

Microcontroller-based emulation of a PEM fuel cell

This paper proposes an accurate and easy-to-implement emulator which is able to track the characteristic curve of a Proton Exchange Membrane Fuel Cell (PEMFC). Such an emulator is based on a low-cost microcontroller , isolated voltage and current sensors. The proposed emulator takes advantages of the flexibility and robustness. The sensed voltage and current provide to the microcontroller the accurate information to compute the output voltage of an actual PEMFC. The obtained voltage is sent to a digital-to-analog converter in order to command the continuous control voltage. The simplified electrochemistry model is presented and validated through simulation and then corroborated via experimentation. The proposed emulator is subjected to two load conditions: fixed load resistor and power electronic converter. The employed power converter is controlled by a variable duty cycle which is adjusted to a value at which the power extracted from the emulator is maximum.