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Technical Paper

Instantaneous Optimization Energy Management for Extended-Range Electric Vehicle Based on Minimum Loss Power Algorithm

2013-09-08
2013-24-0073
Most of the existing energy management strategies for Extended-Range Electric Vehicles (E-REVs) are heuristic, which restricts coordination between the battery and the Range Extender. This paper presents an instantaneous optimization energy management strategy based on the Minimum Loss Power Algorithm (MLPA) for a fuel cell E-REV. An instantaneous loss power function of power train system is constructed by considering the charge and discharge efficiency of the battery, together with the working efficiency of the fuel cell Range Extender. The battery working mode and operating points of the fuel cell Range Extender are decided by an instantaneous optimization module (an artificial neural network) that aims to minimize the loss power function at each time step.
Technical Paper

Improvement on Energy Efficiency of the Spark Ignition System

2017-03-28
2017-01-0678
Future clean combustion engines tend to increase the cylinder charge to achieve better fuel economy and lower exhaust emissions. The increase of the cylinder charge is often associated with either excessive air admission or exhaust gas recirculation, which leads to unfavorable ignition conditions at the ignition point. Advanced ignition methods and systems have progressed rapidly in recent years in order to suffice the current and future engine development, and a simple increase of energy of the inductive ignition system does not often provide the desired results from a cost-benefit point of view. Proper design of the ignition system circuit is required to achieve certain spark performances.
Technical Paper

Experimental and Numerical Study on Combustion Characteristics of Hydrogen-Argon Jet in a Hot Vitiated Co-flow

2018-04-03
2018-01-1139
This paper presents a study of the Hydrogen/Argon lifted flames in a hot vitiated co-flow. The effects of the dilution of argon in central fuel, the volume fraction of argon in the central fuel, co-flow temperature and the velocity of the central jet on the flame lift-off length were studied, and the numerical simulation with PDF model were analyzed as well. The results could provide theoretical supports for the research of the hydrogen fueled argon cycle engine which is a potential way not only to increase the indicated thermal efficiency of internal combustion engine but also realize the zero emission. The result shows that at the same boundary condition the central jet of H2+Ar has a lower lift-off length than the central jet of H2+N2. By the numerical simulation, the jet flame of H2+Ar has a higher maximum temperature and maximum OH concentration. It indicated that the dilution of argon could promote the combustion reaction.
Technical Paper

Research on Control Algorithm of Air Supply System for High-Pressure PEMFC Engine

2019-04-02
2019-01-0379
The Proton Exchange Membrane Fuel Cell (PEMFC) is the most widely used engine in fuel cell vehicles. For PEMFC, whether the supply of oxygen for cathode is adequate or not is a critical factor for its net output power and service life, and the proper control of air supply mass flow and pressure can effectively improve its system performance and efficiency. At present, fuel cells need to reduce the mass and volume and increase the power density. Therefore, it is necessary to increase the air supply pressure for PEMFC. But at the same time, many auxiliary devices are appended to the system to provide high-pressure air, such as air compressor, intercooler, and back pressure valve, which make the control of the entire air supply system very complicated. So an excellent control algorithm is needed.
Technical Paper

Development of Hardware and Software for On-Board Hydrogen System

2019-04-02
2019-01-0377
The fuel cell engine is considered to be the ultimate technical direction for the development of vehicle power. The on-board hydrogen supply system is important in fuel cell system. However, the on-board hydrogen supply system is diversified, and the management is mostly integrated in the engine controller. Thus, the fuel cell engine controller is excessive coupled with design of on-board hydrogen supply system. In order to improve the portability and compatibility of the fuel cell engine controller, an independent controller of the on-board hydrogen supply system is designed. Meanwhile, the hardware and software are developed to control 35Mpa gaseous hydrogen storage system. After being tested in a high-pressure environment, the controller can detect temperature, pressure and ambient hydrogen concentration of the hydrogen supply system. Simultaneously, it can drive and control the hydrogen cylinder valve.
Technical Paper

DC/DC Modeling and Current Harmonic Analysis in Fuel Cell Hybrid Power System

2019-04-02
2019-01-0375
Fuel cells directly convert the energy stored in hydrogen into electrical energy through an electrochemical reaction, and the only reaction product is water, which can improve the energy efficiency and reduce the pollution caused by fossil fuels. The fuel cell hybrid power system used in vehicles usually consists of a fuel cell stack and a power battery module, and the DC/DC converter is the key component to connect them together. The current ripples caused by the system have been confirmed to have detrimental effects on the fuel cell’s reliability and lifespan. In addition, it is one of the key factors that reduce the system efficiency. So, it is necessary to analyze the current ripple in the system and maintain it at a low level. In this paper, a brief review on the different kinds of converters used in vehicles has been made. Then, with the help of MATLAB/SIMULINK, a simulation model of the hybrid power system based on 4-phase interleaved parallel topology is established.
Technical Paper

Real-Time Testing Technology of Powertrain System in Proton Exchange Membrane Fuel Cell Electric Vehicles: A Review

2019-04-02
2019-01-0371
The proton exchange membrane fuel cell (PEMFC) vehicle is one kind of new energy vehicle with fuel cell as power source, which has environmental friendliness, high power density and quick refueling. However, the productlization testing in powertrain system, especially for subsystems and key parts, is one of the critical technical challenges, which restricts the industry development and large-scale commercialization of fuel cell electric vehicles (FCEVs). In this paper, comprehensive testing requirement and latest testing technologies were reviewed, the development status and directions of testing technologies in FCEV powertrain system were presented. Based on comprehensive analysis, X-in-the-Loop (XiL) testing technology was proposed, and it is quite helpful to improve Real-time testing performance and functions for FCEV powertrain system. Furthermore, real-time and reliability as the two key factors for the XiL application was deeply analyzed and discussed.
Technical Paper

Voltage and Voltage Consistency Attenuation Law of the Fuel Cell Stack Based on the Durability Cycle Condition

2019-04-02
2019-01-0386
Based on the durability cycle test of fuel cell stack and the characteristics of cyclic working conditions, this paper defines the characteristic current point and studies the attenuation rule of the fuel cell stack voltage over time under the characteristic current point. The results show that the voltage of the fuel cell stack appears to be linear downward under the characteristic current point. and the voltage attenuation rate of the fuel cell stack increases quadratically with the increase of the current density in addition to the open-circuit voltage point. Then the coefficient of variation is introduced in statistics as the index to characterize the voltage consistency attenuation of the fuel cell stack, and its variation rule is explored. The results show that the voltage consistency of vehicle fuel cell stack decreases seriously with the increase of running time under the condition of durable cycling.
Technical Paper

A Lattice Boltzmann Simulation of Gas Purge in Flow Channel with Real GDL Surface Characteristics for Proton Exchange Membrane Fuel Cell

2019-04-02
2019-01-0389
Gas purge is considered as an essential shutdown process for a PEMFC (Proton Exchange Membrane Fuel Cell), especially in subfreezing temperature. The water flooding phenomenon inside fuel cell flow channel have a marked impact on performance in normal operating condition. In addition, the residual water freezes in the subzero temperature, thus blocking the mass transfer from flow channel to porous media. Therefore, the gas purge course is of primary importance for improvement of performance and durability. The water droplet residing in the flow channel can be purged out due to shearing force of gas. In fact, the flow channel is not completely flat due to surface roughness of gas diffusion layer (GDL), meaning the water droplet may climb over obstacles. Moreover, the water droplet may block the flow channel and then be sheared into films on the surface of GDL.
Technical Paper

Experiments of Methanol-Gasoline SI Engine Performance and Simulation of Flexible Fuel Characteristic Field

2018-04-03
2018-01-0927
Due to the oil crisis and the requirements of energy saving and emission reduction, the research of alternative energy sources for sustainable development has made good progress. Methanol has proven to be a very suitable alternative clean fuel. Compared with gasoline, methanol has a wide range of source and the higher oxygen content and octane number and combustion efficiency, which are beneficial for the engine performance. The effect of different proportions of methanol-gasoline mixed fuel on the performance of SI engine was studied experimentally (lower proportion and higher proportion). It was found that the engine power performance, fuel economy and exhaust emissions were related to the methanol ratio under different operating conditions. In order to adapt to different operating conditions to improve the performance of methanol-gasoline engine, an on-board flexible fuel mixed system was proposed.
Technical Paper

Powertrain System Durability in Proton Exchange Membrane Fuel Cell Electric Vehicles: A Review

2018-04-03
2018-01-1303
On account of environmental friendliness, high energy conversion efficiency and high power density, the proton exchange membrane fuel cell (PEMFC) has been used for automotive application for years. However, its durability in powertrain system is one of technical challenges, which restricts the large-scale commercialization of fuel cell electric vehicles (FCEV). In addition to the complex aging mechanism of PEMFC, the durability and energy relationship of key components in powertrain system, including battery and DC/DC converter, have a crucial impact on the vehicle performance, which have not been thoroughly analyzed. Nowadays, most researchers have explored the causes of components degradation from models or experiments and tried to carry out the life expectancy. Nevertheless, it is in need of system-level researches on durability against the actual automotive application.
Technical Paper

Simulation Analysis of Environmental Adaptability of High Pressure Fuel Cell Engine Air Supply System

2018-04-03
2018-01-1306
High pressure fuel cell engine, namely high pressure fuel cell system for automobiles, is the core power plant of fuel cell vehicle. Among many categories of fuel cells, proton exchange membrane fuel cell (PEMFC) is the most widely used one for automotive applications, with the characteristic of high power density, fast response and moderate working conditions. The cathode oxygen supply in PEMFC is one of the most important factors which affects its output power and operational lifespan. Reasonable regulation of air supply process flow and pressure can effectively improve system’s performance and efficiency. In this paper, a mathematical model of the air supply system and a model of altitude and environmental pressure are established in MATLAB \ Simulink by mechanism modeling method. Then the modules of the air supply system are integrated to supply air to the 85 KW PEMFC stack model.
Technical Paper

Effect of Clamping Load on the Performance and Contact Pressure of PEMFC Stack

2018-04-03
2018-01-1310
In the assembling process of proton exchange membrane fuel cell (PEMFC) stack, the clamping load is known to have direct effect on the contact pressure of interfaces. Compression on the membrane electrode assembly (MEA) results in change in gas diffusion layer (GDL), porosity and electrical resistance, thus affecting the performance, durability and reliability of the PEMFC stack. In this paper, the relation between clamping load and performance of PEMFC stack was obtained by experimental study, and the influence of clamping load on the contact pressure of MEAs was analyzed by finite element analysis. The performance test rig was established and the approach of polarization curve testing was introduced. Both the effect of magnitude and distribution of the bolt torques on the performance were taken into account. The finite element model was adopted to figure out the magnitude and uniformity of contact pressure of MEAs, which provides a new angle to understand the experimental results.
Technical Paper

A Progress Review on Gas Purge for Enhancing Cold Start Performance in PEM Fuel Cell

2018-04-03
2018-01-1312
Cold start capability is one of remaining major challenges in realizing PEMFC (Proton Exchange Membrane Fuel Cell) technology for automotive applications. Gas purge is a common and integral shutdown procedure of a PEMFC automotive in subzero temperature. A dryer membrane electrode assembly (MEA) can store more water before it gets saturated and ice starts to penetrate in the open pores of porous media, thus enhancing cold start capability of a PEMFC. Therefore, gas purge is always performed prior to fuel cell shutdown to minimize residual water in a PEMFC. In the hope of improving effectiveness of purge in a PEMFC vehicle, two important purge parameters are evaluated including purge time and energy requirement. In practice, an optimized gas purge protocol should be developed with minimal parasitic energy, short purge duration and no degradation of components. To conclude, the cold start capability and performance can be consolidated by proper design of gas purge strategies.
Technical Paper

Performance Prediction of Automotive Fuel Cell Stack with Genetic Algorithm-BP Neural Network

2018-04-03
2018-01-1313
Fuel cell vehicle commercialization and mass production are challenged by the durability of fuel cells. In order to research the durability of fuel cell stack, it is necessary to carry out the related durability test. The performance prediction of fuel cell stack can be based on a short time durability test result to accurately predict the performance of the fuel cell stack, so it can ensure the timeliness of the test results and reduce the cost of test. In this paper, genetic algorithm-BP neural network (GA-BPNN) is proposed to modeling automotive fuel cell stack to predict the performance of it. Based on the strong global searching ability of genetic algorithm, the initial weights and threshold selection of neural networks are optimized to solve the shortcoming that the random selection of the initial weights and thresholds of BP neural network which can easily lead to the local optimal value.
Technical Paper

Vibration Analysis of Series-parallel Hybrid Powertrain System under Typical Working Condition and Modes

2018-04-03
2018-01-1291
Powertrain system of series-parallel hybrid vehicle contains multiple excitation sources like engine, motor and generator. The reduction of noise and vibration is quite difficult during multiplex working modes or the switch of modes. Aiming at Series-parallel hybrid powertrain system which contains engine, motor and planetary gear subsystems, this paper considered a typical working condition which is based on the power control strategy and established the torsional vibration mechanical model of hybrid powertrain system. The inherent characteristics and transient vibration response of the electric mode, hybrid mode and parking charging mode were studied and it was discovered that the repetitive frequency of the powertrain system under the three working modes is the same which is only related to inertia and meshing stiffness of planetary gear system. The non-repetitive frequency and corresponding vibration modes under the electric mode and parking charging mode are both close.
Technical Paper

Combined Technologies for Efficiency Improvement on a 1.0 L Turbocharged GDI Engine

2019-04-02
2019-01-0233
The CO2 reduction request for automotive industry promotes the efforts on the engine thermal efficiency improvement. The goal of this research is to improve the thermal efficiency on an extremely downsized 3-cylinder 1.0 L turbocharged gasoline direct injection engine. Effects of compression ratio, exhaust gas recirculation (EGR), valve timing and viscosity of oil on fuel economy were studied. The results show that increasing compression ratio, from 9.6 to 12, can improve fuel economy at relative low load (below 12 bar BMEP), but has a negative effect at high load due to increased knock intensity. EGR can significantly reduce the pumping loss at low load, optimize combustion phase and reduce exhaust gas temperature. Therefore, the fuel consumption is reduced at all test points. The average brake thermal efficiency (BTE) benefit percentage is 3.47% with 9.6 compression ratio and 5.33 % with 12 compression ratio.
Technical Paper

Simulation Investigation of Working Process and Emissions on GDI Engine Fueled with Hydrous Ethanol Gasoline Blends

2019-04-02
2019-01-0219
Compared with ordinary gasoline, using ethanol gasoline blends as fuel of Internal Combustion Engine is beneficial for the performance of power, economy and emission of engine. However, the fuel ethanol blended in ethanol gasoline blends currently is usually anhydrous ethanol, which requires dewatering implementer in production process, and the cost is high. Therefore, the production cost can be significantly reduced by replacement of anhydrous ethanol with hydrous ethanol while exerting the advantage of ethanol gasoline blends. In this study, computation fluid dynamics (CFD) software CONVERGE is employed to establish a simulation model of an actual gasoline direct injection (GDI) engine, and investigate the effect of burning hydrous ethanol gasoline blends and different injection strategy on combustion process and emission, and the validity of the model was validated by experiments.
Technical Paper

Defrost Efficiency Analysis of PMMA Rear Window

2016-04-05
2016-01-0511
As a potential material for lightweight vehicle, polymethyl methacrylate (PMMA) has proven to perform well in optical behavior and weather resistance. However, the application in automotive glazing has seldom been studied. This paper investigates the defrost performance of PMMA rear window using both numerical and experimental methods. The finite element analysis (FEA) results were found to be in good agreement with the experimental data. Based on the validated finite element model, we further optimized the defrost efficiency by changing the arrangement of heating lines. The results demonstrated the frost layer on the vision-related region of PMMA rear window can melt within 30 minutes, which meets the requirement of defrost efficiency.
Technical Paper

Effect of Road-Induced Vibration on Gas-Tightness of Vehicular Fuel Cell Stack

2016-04-05
2016-01-1186
The vehicular fuel cell stack is unavoidably impacted by the vibration in the real-world usage due to the road unevenness. However, effects of vibration on stacks have yet to be completely understood. In this work, the mechanical integrity and gas-tightness of the stack were investigated through a strengthen road vibration test with a duration of 200 h. The excitation signals applied in the vibration test were simulated by the acceleration of the stack, which were previously measured in a vehicle vibration test. The load signals of the vehicle vibration test were iterated through a road simulator from vehicle acceleration signals which were originally sampled in the proving ground. Frequency sweep test was conducted before and after the vibration test. During the vibration test, mechanical structure inspection and pressure maintaining test of the stack were conducted at regular intervals.
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