氢燃料在汽车上的应用探讨

分析汽油－氢发动机、燃氢发动机及氢燃料电池的特点,并结合目前世界各国对氢燃料在汽车上的应用的研究状况,对氢燃料在汽车上的应用进行了展望。     

控制燃氢发动机不正常燃烧的研究

氢作为一种可再生的能源,可以缓解日益枯竭的石油资源。目前,氢作为发动机燃料的研究已经获得一定成果。但是,燃氢极易造成发动机的爆燃,避免爆燃和回火是发动机尤其是氢燃料发动机要考虑的最重要的问题,在分析和试验的基础上,为降低爆燃和回火提供了参考。     

氢及混氢燃料发动机研究进展与发展趋势

目前,氢燃料发动机发展迅速,本文总结了国内外在此领域的发展现状,分析了目前存在早燃、回火、功率密度低、储运难、NOx排放高等问题,重点介绍了汽油混氢的可行性与研究现状,并指出了未来先进氢燃料发动机的发展方向.     

火花点火发动机燃烧室沉积物未燃碳氢排放的理论与实验研究

本从实验和理论两个方面来系统地研究火花点火式发动机燃烧室沉积物处未燃碳氢排放浓度随冷却水温，发动机转速，节气门开度和点火提前角等运转参数的变化规律，对发动机缸内沉积物未燃碳氢的生成过程和缸内，排气系统中未燃碳氢的氧化过程进行了模拟，对缸内沉积物未燃碳氢生成过程进行了详细的研究，找出了影响燃烧室沉积物处未燃碳室氢生成量的关键因素。此外还分析了燃烧室中沉积对发动机性能的影响。     

稀燃天然气掺氢发动机的热效率与排放特性

为了分析在天然气中掺入不同体积比的氢气对发动机经济性和排放性的影响,在一台6缸火花点火天然气发动机上开展了体积掺氢比在不同工况下对热效率和排放特性影响的试验研究.结果显示掺氢可以拓宽发动机的稀燃极限,提高燃烧速度,使得最佳转矩点火提前角(MBT)相对推迟;在点火提前角不变的情况下掺氢对热效率没有明显优势,而且会使NOx排放升高.而在MBT时,掺氢可以一定程度上提高发动机的指示热效率,降低未燃CH4和CO的排放,改善NOx与未燃碳氢(主要为CH4)的trade-off关系.掺氢的优势还体现在可以让发动机高效的工作在更稀的情况下,从而有利于降低NOx的排放和传热损失.     

增压稀燃天然气掺氢发动机排放特性

为了研究20%掺氢比的增压稀燃天然气掺氢(HCNG)发动机的排放特性,通过对发动机进行了空燃比和点火提前角调整试验、ETC循环测试试验和加装氧化型催化器试验,获得了20%HCNG发动机的排放规律.CH4排放随着空燃比的增大先减少后增加;CO排放在高于理论空燃比后骤减;Nox排放随着空燃比的增大先增加后减少,在空燃比19～21 左右达到最大值,1600～1800r/min时最低.CO、Nox随着点火提前角的增大而增加;CH4随着点火提前角的增大略有增加,并且点火提前角越大,对CH4排放的影响越小.加装催化器后,CO、CH4的转化效率均＞90%.试验结果表明:增压稀燃和氧化型催化器相结合是天然气掺氢发动机节能减排的有效方案.     

氢燃料在汽车上的应用

本文作者结合自己在氢发动机方面的研究结果，分析了氢在汽车上应用时的特点，总结了汽车燃用氢时所在的问题及解决方法。并介绍了目前世界各国在此方面的研究情况。     

氢燃料在汽车上的应用

本文作者结合自己在氢发动机方面的研究结果,分析了氢在汽车上应用时的特点,总结了汽车燃用氢时所存在的问题及解决方法。并介绍了目前世界各国在此方面的研究情况。     

基于小波变换对氢发动机异常燃烧的研究

利用缸内压力研究氢发动机的异常燃烧.分别对氢发动机正常燃烧和早燃压力信号进行了小波变换,通过分析比较其频带分布特点,计算出不同尺度上小波能量,以此作为基础构造特征向量,进行异常燃烧诊断,结果表明小波变换可以有效地诊断氢发动机的异常燃烧现象.     

氢动力车研究与发展现状

评述了氢动力车的研究与发展现状，主要介绍了氢燃料的特性、燃氢车发动机的特点，随车贮氢技术以及氢动力车的最近发展动态。     

Techno-economic analysis of photovoltaic-hydrogen refueling station case study: A transport company Tunis-Tunisia

This paper sheds the light on the future of green hydrogen in Tunisia. So, a detailed economic assessment and evaluation of the Levelized Hydrogen Cost (LHC) and the Net Profit (NP) of a Photovoltaic (PV) Hydrogen Refueling Station (HRS) are presented and discussed. Tunisia is characterized by its high PV potential which makes the production of electricity from solar energy an effective alternative source. However, due to the regulations and issues related to the connection of medium PV scale to the power grid, the energy produced from renewable sources (RS) is still less than 3% of the total produced electricity. On the other hand, the price of hydrocarbon fuels is still increasing. The gap between production and total demand in hydrocarbons has created a deficit in the primary energy balance. Therefore, the production of hydrogen from solar energy for refueling Fuel Cell Vehicles (FCV)s consists of a promising solution to boost the development of the country, reduce hydrocarbon fuels consumption, and protect the environment. The sizing of a small PV-HRS to produce 150 kg of hydrogen per day shows the necessity to install PV systems with a total Direct Current (DC) capacity of 1.89 MWp. The Initial Cost (IC) analysis shows that while the PV system cost represents 48.5% of the total IC, the IC of electrolysers represents 41%. The storage system cost is approximately equal to 3.2% of the total IC. The LHC is equal to 3.32€/kg with a total IC of 2.34 million €.     

A Taguchi-fuzzy based multi-objective optimization study on the soot-NOx-BTHE characteristics of an existing CI engine under dual fuel operation with hydrogen

The present energy situation and the concerns about global warming has stirred active research interest in non-conventional and alternative fuel resources to reduce the emission and the unabated fossil fuel dependency footprint, particularly for transportation, power generation and agricultural sectors. Among various alternatives, hydrogen has been extensively studied and concluded to be a viable and promising alternative fuel option on existing IC engine platforms in bridging the contemporary gap to the long term fuel cell based power train roadmap. Further, with the advent of EPA Tier 4 interim and final emission mandates the limits of the regulated emissions are challenging the practical limits of current engine design and calibration strategies. With a compliance directive of a substantial reduction in Soot and NOx emission levels simultaneously than its immediately preceding directives, engine manufacturers are being increasingly challenged to meet the paradox of curtailing particulate matter and NOx emissions on one hand and maintaining consumer expectations of increased thermal efficiency on the other. In this respect, various studies on the application of hydrogen as a dual fuel in existing IC engines offer the motivation to explore the potential in exploiting the inherent superior combustion characteristics of hydrogen as an in situ solution to the emission and performance trade-off challenges of conventional diesel combustion. In the present study, an experimental investigation was carried out existing CI engine with hydrogen as a dual fuel. A Timed Manifold Injection (TMI) system was adopted to analyze the effect of durations of hydrogen induced on the performance and emission characteristics as compared to baseline diesel operation. Previous studies have already clearly established the virtues of hydrogen in mitigating the emission footprint of conventional diesel operation along with improved performance characteristics. However, with the penalty of increased NOx emissions with hydrogen participation, a definite study specifically addressing the NOx-Soot-BTHE trade-off vantage achievable on existing CI engines under the purview of existing emission mandates is yet to be addressed. Based on an experimental investigation, the present study employs offline calibration techniques centered on the rationale of the fuzzy logic based Taguchi analysis to investigate the optimal soot-NOx-BTHE trade-off regime of operation based on different hydrogen injection strategies.     

Analytical model for a techno-economic assessment of green hydrogen production in photovoltaic power station case study Salalah city-Oman

Hydrogen energy will play a credible role to reduce gas emissions in the transportation sector, the storage of energy, and other industrial applications. Moreover, the hydrogen produced from renewable energy sources allows to minimize greenhouse gas and increase the net profit of energy projects. This paper discusses the feasibility of the conversion of solar energy into hydrogen in a Photovoltaic Hydrogen Station (PVHS) in the south of Oman. Then, the sizing of different equipment and hydrogen production estimation in a 5 MWp PVHS is presented. The analysis of the investment cost (IC), the Net Profit (NP), and the Levelized Hydrogen Energy Cost (LHEC) are discussed to investigate the benefit of the project. The energy generated from the PV system and the produced hydrogen is calculated through an analytical model. The PVHS consists of 5 MWp PV panels connected to electrolyzers through maximum power point-controlled converters. The electrolyzers convert the electrical energy and the water into hydrogen. The hydrogen compressed and stored in special tanks can be used later in many industrial applications. The system produces about 90 910 kg of hydrogen per year with an IC of 5 301 760 €. The calculated LHEC is equal to 6.2 €/kg at an interest rate of 2%. The analysis has shown promising green hydrogen production projects in Oman.     

Measuring the relative efficiency of hydrogen energy technologies for implementing the hydrogen economy: An integrated fuzzy AHP/DEA approach

To provide and improve national energy security and low-carbon green energy economy, as a government-supported research institute related to developing new and renewable energy technologies, including energy efficiency, Korea Institute of Energy Research (KIER) needs to establish a long-term strategic energy technology roadmap (ETRM) in the hydrogen economy sector for sustainable economic development. In this paper, we establish a strategic ETRM for hydrogen energy technologies in the hydrogen economy considering five criteria: economic impact (EI), commercial potential (CP), inner capacity (IC), technical spin-off (TS), and development cost (DC). As an extended research, we apply the integrated two-stage multi-criteria decision-making approach, including the hybrid fuzzy analytic hierarchy process (AHP) and data envelopment analysis (DEA) model, to assess the relative efficiency of hydrogen energy technologies in order to scientifically implement the hydrogen economy. Fuzzy AHP reflects the vagueness of human thought with interval values, and allocates the relative importance and weights of four criteria: EI, CP, IC, and TS. The DEA approach measures the relative efficiency of hydrogen energy technologies for the hydrogen economy with a ratio of outputs over inputs.The result of measuring the relative efficiency of hydrogen energy technologies focuses on 4 hydrogen technologies out of 13 hydrogen energy technologies. KIER has to focus on developing 4 strategic hydrogen energy technologies from economic view point in the first phase with limited resources. In addition, if energy policy makers consider as some candidates for strategic hydrogen technologies of the other 9 hydrogen energy technology, the performance and productivity of 9 hydrogen energy technologies should be increased and the input values of them have to be decreased.With a scientific decision-making approach, we can assess the relative efficiency of hydrogen energy technologies efficiently and allocate limited research and development (R&D) resources effectively for well-focused R&D.     

Multi-dimensional modeling of mixture preparation in a direct injection engine fueled with gaseous hydrogen

With the recent advances of direct injection (DI) technology, introducing hydrogen into the combustion chamber through DI is being considered as a viable approach to circumvent backfire and pre-ignition encountered in early generations of hydrogen engines. As part of a broader vision to develop a robust numerical model to study hydrogen spark ignition (SI) combustion in internal combustion (IC) engines, the present numerical investigation focuses on mixture preparation in a hydrogen DI SI engine. This study is carried out with a single hole injector with gaseous hydrogen injected at 100 bar injection pressure. Simulations are carried out for high and low tumble configurations and validated against optical data acquired from planar laser induced fluorescence (PLIF) measurements. Varying mesh configurations are investigated for the impact on in-cylinder mixture distribution. A particular emphasis is placed on the effect of nozzle geometry and mesh orientation near the wall. Overall, the computational model is found to predict the mixture distribution in the combustion cylinder reasonably well. The results showed that the alignment of mesh with the flow direction is important to achieve good agreement between numerical analysis and optical measurement data.     

Environmental and sustainability aspects of hydrogen and fuel cell systems

Discussed in this paper are current environmental problems, potential solutions to these problems, possible future hydrogen energy‐utilization patterns for better environment and sustainable development through life cycle assessment (LCA), and how the principles of thermodynamics via exergy can be beneficially used to evaluate hydrogen and fuel cell systems and their role in sustainable development. Throughout the paper current and future perspectives of hydrogen and fuel cell systems based on exergetic, LCA and sustainability aspects development are considered. The results will likely be useful to scientists, researchers and engineers as well as policy and decision makers. Two case studies on the LCA aspects of hydrogen and fuel cell systems are presented to highlight the importance of the hydrogen and fuel cell systems and show that these can help achieve better environment and sustainability. Copyright © 2006 John Wiley & Sons, Ltd.     

Optimization of injection system for a medium-speed four-stroke spark-ignition marine hydrogen engine

In order to avoid the abnormal combustion in high-power hydrogen engine, a 3D CFD numerical model of a direct-injection spark-ignition hydrogen engine was built up based on a large-bore medium-speed four-stroke marine diesel engine using CONVERGE software. To obtain the influence of injection parameters on mixture homogeneity, a dimension reduction optimization method was proposed. The results revealed that the turbulence intensity and the penetration distance varied with the injection parameters, determined the level of mixture homogeneity. The performance comparison between the hydrogen engine and prototype diesel engine showed a great potential of hydrogen in internal combustion (IC) engines.     

Effect of Co loading on the hydrogen storage characteristics of hollow glass microspheres (HGMs)

The use of hydrogen as a fuel either direct combustion in an IC engine or for power generation in fuel cells continues to be a topic of significant interest. Developing and popularizing fuel cells for vehicular or other stationary applications depends upon the availability of safe and reliable hydrogen storage method. The greatest challenge as of now in this regard is the production of a light weight, nontoxic and easily transportable material which can store hydrogen. World-wide research is being conducted on developing newer materials for hydrogen storage. Hollow glass microspheres (HGMs) can be considered to be a potential hydrogen carrier which can store and deliver hydrogen for energy release applications. In this paper, we are reporting the preparation and characterization of cobalt loaded HGMs from amber glass powder for hydrogen storage applications. The feed glass powder with different percentage of cobalt loading was prepared by soaking and drying the feed glass powder in required amount of cobalt nitrate hexahydrate solution. Further, the dried feed glass powder was flame spheroidised to get cobalt loaded HGMs. Characterizations of all the HGMs samples were done using SEM, FTIR and XRD techniques. Hydrogen adsorptions on all the samples were done for 10 bar pressure at room temperature and 200 °C for 5 h. The results showed that the hydrogen adsorption capacity on these samples increased with increase in cobalt wt% from 0.2 to 2.0%. The hydrogen storage capacity of HACo2 was found to 2.32 wt% for 10 bar pressure at 200 °C.     

A novel method for determining effects of fire damage on the safety of the Type I pressure hydrogen storage tanks

Consumption of the fossil fuels causes greenhouse gas effect and environmental pollution, which are two basic problems of our age. As a result of this problem, clean and renewable alternative energy sources are beginning to replace fossil fuels. Nowadays, the use of hydrogen energy, which is one of the clean energy, is increasing in transportation and industrial areas. Increasing of hydrogen energy usage, scientists are attempting to solve the many safety problems (such as fire, burst, impact and hydrogen embrittlement) that can occur during the storage and consumption of hydrogen energy. In this study, during the event of fire, the safety of metallic Type I pressure hydrogen storage tanks is investigated by using a novel approach. In this new approach, the mechanical strength drops of the tank materials that is related with temperature rising are added to the safety calculations. In the study, 6061 T6 aluminum and SS 316L stainless steel alloys were used as hydrogen tank material. The safety of hydrogen tanks modelled using these alloys was investigated under different temperature conditions (22, 100, 200 and 300 °C) and internal pressure (15, 20 and 25 MPa).     

Effect of hydrogen enrichment on performance,combustion, and emission of a methanol fueled SI engine

The study of potentially high rated alternative fuel (Methanol) for the IC engines is an exciting topic in the recent research advancement. However, the study of combination of methanol and hydrogen is considered to address both economic and environmental needs. Hydrogen with best combustion characteristics will compensate for the drawbacks of methanol as a fuel. In the present investigation hydrogen enrichment to methanol has shown a significant enhancement in performance and combustion; the overall emission has reduced substantially. The experiments for a different set of trials, including hydrogen enrichment ranging between 5% and 20% with 2.5% increment, the engine is operated with wide-open throttle (WOT) condition for different speeds. The increase in enrichment of hydrogen has shown a rise in BTE, BP, and a reduced BSEC value. The percentage increase in BTE is between 20 and 30%, and an increase in hydrogen beyond 12.5% would affect the volumetric efficiency, and thus performance declines after that. The exhaust emissions have a huge impact on hydrogen enrichment; CO, HC, and CO₂ emission are reduced by 30–40%; however, an increase in cylinder temperature due to rapid combustion slightly increases the NO_x emission. Thus hydrogen enriched methanol operating at higher compression ratio can improve the overall engine characteristics significantly.