大缸径气体机和双燃料发动机燃油喷射系统

介绍了大缸径气体机概念和类型;着重介绍了几种基于共轨技术的不同双燃料发动机喷射系统喷油器的设计特点和效果。指出:这种共轨技术是未来产品开发的基石,并有助于实现燃气发动机市场的多样性发展。     

Combustion and emission characteristics of a hydrogen-diesel dual-fuel engine

Hydrogen generated from renewable sources is an eco-friendly fuel that can be used in automotive industry or for energy generation purposes. Hydrogen is a high-energy content gas and its carbonless chemical structure can provide significant benefits of high thermal efficiency and near zero or very low carbon emissions when combusted with other fuels.In this study, the implementation of hydrogen fuel was tested at low and medium operating loads in a heavy-duty hydrogen-diesel dual-fuel engine. The paper provides a detailed experimental analysis of the effects of hydrogen energy share ratio and various combustion strategies such as exhaust gas recirculation, diesel injection pressure and diesel injection patterns.At low load conditions, engine operation with an H₂ energy share ratio of up to 98% was achieved without any engine operation implications. This condition provided a simultaneous reduction of carbon and NOx emission of over 90% while soot emissions were dropped by 85% compared to the conventional diesel-only operation. At medium load, the increased NOx emission due to the high energy content of hydrogen fuel was found to be the primary challenge.     

The utilization of hydrogen in hydrogen/diesel dual fuel engine

A hydrogen fueled internal combustion engine has great advantages on exhaust emissions including carbon dioxide (CO₂) emission in comparison with a conventional engine fueling fossil fuel. In addition, if it is compared with a hydrogen fuel cell, the hydrogen engine has some advantages on price, power density, and required purity of hydrogen. Therefore, they expect that hydrogen will be utilized for several applications, especially for a combined heat and power (CHP) system which currently uses diesel or natural gas as a fuel.A final goal of this study is to develop combustion technologies of hydrogen in an internal combustion engine with high efficiency and clean emission. This study especially focuses on a diesel dual fuel (DDF) combustion technology. The DDF combustion technology uses two different fuels. One of them is diesel fuel, and the other one is hydrogen in this study. Because the DDF engine is not customized for hydrogen which has significant flammability, it is concerned that serious problems occur in the hydrogen DDF engine such as abnormal combustion, worse emission and thermal efficiency.In this study, a single cylinder diesel engine is used with gas injectors at an intake port to evaluate performance swung the hydrogen DDF engine with changing conditions of amount of hydrogen injected, engine speed, and engine loads. The engine experiments show that the hydrogen DDF operation could achieve higher thermal efficiency than a conventional diesel operation at relatively high engine load conditions. However, it is also shown that pre-ignition with relatively high input energy fraction of hydrogen occurred before diesel fuel injection and its ignition. Therefore, such abnormal combustion limited amount of hydrogen injected. Fire-deck temperature was measured to investigate causal relationship between fire-deck temperature and occurrence of pre-ignition with changing operative conditions of the hydrogen DDF engine.     

缸内直喷天然气低速船机压力振荡抑制方法数值研究

基于计算流体力学(CFD)软件CONVERGE建立了大型低速2冲程柴油引燃缸内直喷天然气船用发动机燃烧仿真模型。首先通过试验结果对模型进行了验证,进而开展了天然气高压喷射模式(high pressure direct injection,HPDI)下米勒循环和天然气两次喷射策略对发动机压力振荡的抑制效果研究。结果表明,推迟排气门关闭时刻,整体燃烧压力降低,燃烧相位推迟,发生剧烈压力振荡的时刻也推迟。排气门关闭时刻推迟较小时压力振荡强度降低,但过度推迟反而提高缸内压力振荡的强度,这主要是缸内热力学状态变化和燃料自燃特性相互作用的结果。通过调整预喷射量,可以降低燃烧前形成的可燃混合气量,从而影响燃烧过程中预混合燃烧比例,可以有效抑制压力振荡.但会导致输出功率降低及能耗增大。相比预喷射量,喷射间隔对缸内压力振荡的影响较小,但过大喷射间隔会影响燃烧相位,导致功率损失严重。合理的喷射策略可以在抑制压力振荡的同时保证功率输出。     

船用天然气-柴油双燃料发动机燃烧仿真计算

基于数值模拟计算方法,对淄柴6230型中速船用柴油机燃用天然气的燃烧系统进行优化。结果表明：在压缩比为11～14时,功率和热效率随压缩比递增且趋势不变,但受最高燃烧压力的限制,最佳压缩比取12.5。适当增大过量空气系数和提前喷油时刻都有助于NOx排放的减少,最低NOx排放可达0.817 g/（kW·h）,但当过量空气系数超过2.0、喷油时刻早于-20°时燃烧会急剧恶化。引燃油量对燃烧过程影响较小,在研究范围内,指示热效率增幅仅为0.85%,但过富的喷油量会造成额外的NOx和HC排放,因此取1%为最佳喷油量。     

F6L912Q柴油天然气双燃料发动机电控系统设计

电控天然气多点顺序喷射能使双燃料发动机的综合性能得到提高。结合F6L912Q发动机的特点,设计了以Motorola公司M68HC11E2单片机为核心的电控系统硬件部分,并用模块化设计方法设计了系统控制软件。实验结果证明该系统方案可行。     

LNG柴油双燃料发动机多点顺序喷射试验研究

为将纯柴油发动机改造为LNG/柴油双燃料多点顺序喷射发动机,在不改变原型机结构前提下设计了一套天然气供给系统。为验证该供气系满足否满足原型机在额定工况下的需求,设计了进气道喷射模拟试验台。试验验证表明:该天然气供给系统能够满足发动机在额定工况下燃气供应量及喷射控制的需求,且整套系统能够根据发动机不同工况调整天然气的喷射量。试验结果可为发动机在双燃料模式下运行提供前期数据支撑。     

LGIP主机及其LPG供液系统的设计与开发

以新开发的6G60ME-C9.5-LGIP发动机为对象,介绍了 LGIP主机的结构设计、装配和性能调试等.从主机对供液系统的要求,供液系统工艺方案,LPG储罐选型,供液系统压力模拟计算四个方面,重点介绍了 LGIP主机供液系统设计与开发.     

Investigation on the effect of injection schedule and EGR in hydrogen energy share using common rail direct injection dual fuel engine

In this research work, four different diesel injection schedules have been experimented at a BMEP of 2 bar (Low load) in hydrogen diesel dual fuel (HDDF) mode, which are namely single pulse, double pulse phase-1, double pulse phase-2 and multi-pulse. The maximum possible hydrogen energy shares (HES) for single pulse, double pulse phase-1, double pulse phase-2 and multi-pulse injection schedules were 73.99%, 48.98%, 34.46% and 24.39% respectively. Over the injection schedules, double pulse phase-2 improved the brake thermal efficiency (BTE) from 19.50% (single pulse) to 21.61% with a penalty in NO emission. On the other hand, multi-pulse moderately increased the BTE with significant reduction in NO beside rise in smoke emission. At a BMEP of 5 bar (Medium load) operation, there was a considerable reduction in NO emission at maximum range of HES level with 18.21% of EGR, moreover the engine stability was improved with minor increase in smoke emission.     

采用电控燃油喷射柴油机提高DF7型调车机车经济性和环保性能

柴油机采用电控燃油系统,可以有效地提高部分负荷工况下工作的经济性,降低有害气体的排放。调车机车装用电喷柴油机,效果尤为显著。     

高压共轨柴油机喷射系统参数优化方法研究

提出了基于代理模型的高压共轨柴油机喷射系统参数优化方法。首先通过试验数据对CFD软件中的喷雾燃烧模型进行了校核和验证,然后利用中心复合法进行试验设计,并用CFD软件进行仿真计算试验,由此建立响应面代理模型,最后对此模型进行全局寻优,得出了最优的喷射系统参数。     

Multi objective optimization of performance parameters of a single cylinder diesel engine with hydrogen as a dual fuel using pareto-based genetic algorithm

The present experimental investigation attempts to explore the performance characteristics of an existing single-cylinder four-stroke compression-ignition engine operated in dual-fuel mode with hydrogen as an alternative fuel. Experimental investigation was conceded with the engine being subjected to different loads at a predefined flow rate of hydrogen induction. A Timed Manifold Injection (TMI) system has been developed to vary the injection timing and the durations. The optimized timing for the injection of hydrogen was 10⁰ CA after top dead center (ATDC). From the study it was observed that hydrogen with diesel results in increased brake thermal efficiency (BTHE) by 15.7% at 40% full load, volumetric efficiency (Vol. Eff.) by 78.5% at full load condition compared to baseline diesel operation. Hydrogen enrichment registered a maximum reduction of 41.4% in specific fuel consumption (SFC) of diesel at 20% full load. A pareto-optimal front was then obtained using nondominated sorting genetic algorithm (NSGA). Analysis of the front was done to identify the separate regions for Brake specific energy consumption (BSEC), Brake thermal efficiency (BTHE) and Volumetric efficiency (Vol. Eff.). Designed experiments were then conducted in these focused regions to verify the optimization results and to identify the region– specific characteristics of the process.     

中速大功率双燃料船用发动机关键技术研究

以某型船用中速柴油机为基础,开展船用双燃料发动机关键技术研究。基于国内外先进柴油机及双燃料发动机技术,成功研发出具有自主知识产权的中速大功率双燃料发动机。配机试验表明:所研制的双燃料发动机功率和柴油机相当,NO_x 及CO₂排放明显降低;其动力性、总体经济性和排放性均优于纯柴油发动机。     

柴油/CNG双燃料发动机开发及其性能分析

在CA6113BZS-60柴油机的基础上,设计开发了CA6113BN-01柴油／CNG双燃料发动机,并对开发的双燃料发动机进行了动力性能和经济性能的实验与分析．结果表明,开发的混合器混合和机械控制引燃柴油量及由进气管压力调节控制天然气量的双燃料发动机,具有全负荷速度特性扭矩储备大及各种负荷下天然气替代率变化较小,综合柴油替代率高,结构简单和成本低等优点,并具有良好的动力性能和经济性能指标,操作性好,可随时恢复纯柴油运行并能够基本保持原柴油机的性能．     

某双燃料发动机的连杆CAE分析及优化设计

针对某型号天然气/柴油双燃料发动机,在其连杆的设计和开发过程中,运用ABAQUS和FEMFAT软件对连杆进行CAE分析,原设计连杆接触分析显示接触开度不满足安全要求。为此对连杆进行优化设计,优化后的连杆CAE分析表明:连杆杆身与大端接触面采用弧形设计能有效解决连杆接触开度问题,且优化后的连杆变形、接触应力及高周疲劳(high cycle fatigue,HCF)强度都在许用范围之内,满足设计安全需要。这一结论可为提高双燃料发动机的设计安全性提供有效的科学方法和可靠的理论依据,并为后续连杆装机验证提供有力的理论支撑。