氢发动机喷氢控制算法设计

在分析喷氢正时和喷氢量对氢发动机工作性能影响的基础上，设计了喷氢控制算法，并基于Pareto秩和决策偏好相结合的全自动标定算法，进行了喷氢提前角和喷氢脉宽电控系统的软硬件设计。实现了随工况变化动态寻优，使氢发动机动力性、经济性与排放等综合性能达到优化的目标。     

氢发动机排气污染及NOx排放优化控制

研究了在汽油中加入氢气后混合燃料发动机的排放特性,给出了氢汽油混合燃料可以全面改善汽油机的废气排放,然后进行了高压喷射型氢发动机的两个主要运转参数(点火提前角和喷氢提前角)对NOx排放影响的研究。试验表明点火提前角、喷氢提前角对NOx排放量有很大影响。在建立以点火提前角、喷氢提前角、喷氢量为控制变量,以动力性或经济性为性能指标泛函,且排放不超标等为约束条件的氢发动机最优控制模型的基础上,提出了分别以径向基(RBF)网络、模糊神经网络(FNN)求解最优控制模型的新方法,进行了仿真计算和试验数据的对比研究。研究结果给出了两种网络均可以成功取代传统MAP而满足要求。其中以模糊神经网络所用时间较短。     

氢燃料发动机性能参数的研究

针对氢作为发动机燃料的优越性以及氢燃料发动机的特点、技术发展趋势进行了简要概括,并在此基础上,结合实验研究,对压缩比、当量比、过量空气系数对氢燃料发动机性能的影响进行了分析研究.     

氢发动机电控喷氢系统的设计

将奇瑞SQR480汽油机改装为氢发动机,开发了以Microchip公司PIC16F877单片机为核心的多点进气道内顺序喷射的电控喷氢系统.采用高速开关型数字电磁阀作为电控系统的执行元件,运用PWM驱动方式来控制实际的喷氢量.采用模块化方法设计了系统控制软件,开发了卖时监控系统.仿真结果表明:该系统能较好地实现对喷氢量的控制.     

氢燃料发动机的应用

叙述了氢燃料发动机的特点，结构和工作原理，以及氢燃料的储存及燃烧特性。给出了一些氢燃料发动机的排放试验数据，并与使用其它燃料时进行了比较。主要从发动机的新能源和排放污染等方面，探讨推广氢燃料发动机的必要性及其应用可行性。     

氢-汽油双燃料发动机电控喷氢-喷油系统的设计

把嘉陵600汽油燃料摩托发动机改装为汽油-氢气双燃料发动机,开发了以freescale公司MC9S12XS128单片机为核心的单点进气道喷射的电控喷氢系统。采用智能化芯片MC33810对高速开关型数字电磁阀进行控制,采用输出比较对喷氢量和喷油量进行控制。使用定时监控系统并运用模块化的方法来对系统的软件进行设计。试验结果证明,这套系统能够很好地实现对喷油和喷氢量的控制。     

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。     

点火提前角对氢发动机性能的影响及智能控制技术

进行了进气管喷射的氢发动机点火提前角对发动机性能影响的研究，试验指出了点火提前角对氢发动机动力性，经济性和排放性能有较大影响。建立了模糊神经网络控制系统对点火提前角进行优化控制，建立了一个改进的模糊神经网络系统代替传统的试验方法来求解氢发动机的最佳点火提前角(MAP)。仿真和试验结果的对比研究给出该方法具有较高的运行精度。     

氢发动机性能的改进

本文论述了氢发动机的最新研究成果，着重描述了氢的储存和混合气形成及点火等技术问题，并提出了相应的措施。试验表明，采用氢的高压喷射、火花点火，并调整最佳点火正时，就能获得良好的经济和动力性能     

最佳过量空气系数优化控制氢发动机性能的建模实现

进行了进气管直接喷射式氢发动机中过量空气系数对其性能影响的研究,分析了过量空气系数对输出功率、氢燃料消耗率和NOx排放量的影响,试验表明过量空气系数对氢发动机性能有较大影响.基于神经网络在逼近动态系统输入和输出之间非线性关系的优势,运用BP神经网络对过量空气系数与输出功率和氢燃料消耗率的关系建模,仿真和试验结果的对比研究表明：模型能准确地得出各工况所需的最佳过量空气系数,可为优化控制氢发动机性能提供理论支持.     

Parametric study of instantaneous heat transfer based on multidimensional model in direct-injection hydrogen-fueled engine

This paper presents a parametric study on instantaneous heat transfer of a direct-injection hydrogen-fueled engine using a multidimensional model. A simplified single-step mechanism was considered for estimating the reaction rate of hydrogen oxidation. The modified wall-function was used for resolving the near-wall transport. An arbitrary Lagrangian–Eulerian algorithm was adopted for solving the governing equations. Experimental measurements were implemented to verify the developed model. They show that the instantaneous heat-transfer model is sufficiently accurate. The influence of engine speed, equivalence ratio, and the start of injection timing were investigated. The flow fields appeared to have greater size vectors and coarser distribution with an increase of engine speed. A heterogeneous distribution was obtained for an ultra-lean mixture condition (φ ≤ 0.5), which decreased with an increase of equivalence ratio. There was no pronounced influence of the start of injection on the flow field pattern and mixture homogeneity. Thermal field analysis was used to demonstrate trends in the instantaneous heat transfer. It was observed that there was a crucial distinction between the lean and ultra-lean mixtures as well as the engine speed. Furthermore, a non-uniform behavior was found for the impact of the equivalence ratio on temperature distribution. It is clear that the developed models are powerful tools for estimating the heat transfer of the hydrogen-fueled engine. The developed predictive correlation is highly accurate in predicting the heat transfer of the hydrogen-fueled engine, focusing on the equivalence ratio as a governing variable.     

Optimization of fuel injection timing and ignition timing of hydrogen fueled SI engine based on DOE-MPGA

For the port injection hydrogen-fueled spark ignition (SI) engine modified from the Jialing JH600 gasoline engine, the hydrogen injection timing and ignition timing of the hydrogen SI engine are comprehensively optimized on the AVL-FIRE software based on the combination of design of experiment (DOE) and multiple population genetic algorithm (MPGA). Firstly, the effects of hydrogen injection timing and ignition timing on the performance of the hydrogen engine are investigated through the full factors design of experiment scheme, and then the optimum intervals of them are determined respectively. Secondly, the uniform design of experiments scheme is arranged, and the regression functions of indicated power, indicated thermal efficiency and emissions of the hydrogen engine under different working conditions are fitted. Then, the comprehensive optimization model is constructed. Finally, the optimum hydrogen injection timing and ignition timing of the hydrogen engine under different working conditions are solved based on MPGA. The results show that, compared with the standard genetic algorithm (SGA), the MPGA has faster convergence speed and higher convergence accuracy. In addition, as the load increases from low to high, the optimum hydrogen injection timing is advanced and the rate of variation increases from 0.6% to 1.1%, the optimum ignition timing is delayed and the rate of variation decreases from 29.1% to 17.8%.     

氢内燃机的改装设计与控制研究

介绍了一款基于奇瑞480发动机改造而成的纯氢内燃机。该机采用氢气进气歧管多点顺序喷射,各缸顺序无分电器点火方式,同时改装了曲轴箱通风阀,加装了电子节气门、电控EGR阀等部件。采用江奎科技发动机电控单元快速开发平台UECU,开发出氢内燃机电控单元。对氢内燃机的控制策略进行了研究,实现了底层软件、应用层软件以及故障诊断软件的模块化;采用K线通讯模式,开发出了氢内燃机的监控与调试软件,对氢内燃机进行性能的标定试验,成功实现了氢内燃机的起动和转速PID控制,同时优化控制参数改善回火与抑制早燃现象。     

Use of hydrogen in dual-fuel diesel engines

Hydrogen is a promising future energy carrier due to its potential for production from renewable resources. It can be used in existing compression ignition diesel engines in a dual-fuel mode with little modification. Hydrogen's unique physiochemical properties, such as higher calorific value, flame speed, and diffusivity in air, can effectively improve the performance and combustion characteristics of diesel engines. As a carbon-free fuel, hydrogen can also mitigate harmful emissions from diesel engines, including carbon monoxide, unburned hydrocarbons, particulate matter, soot, and smoke. However, hydrogen-fueled diesel engines suffer from knocking combustion and higher nitrogen oxide emissions. This paper comprehensively reviews the effects of hydrogen or hydrogen-containing gaseous fuels (i.e., syngas and hydroxy gas) on the behavior of dual-fuel diesel engines. The opportunities and limitations of using hydrogen in diesel engines are discussed thoroughly. It is not possible for hydrogen to improve all the performance indicators and exhaust emissions of diesel engines simultaneously. However, reformulating pilot fuel by additives, blending hydrogen with other gaseous fuels, adjusting engine parameters, optimizing operating conditions, modifying engine structure, using hydroxy gas, and employing exhaust gas catalysts could pave the way for realizing safe, efficient, and economical hydrogen-fueled diesel engines. Future work should focus on preventing knocking combustion and nitrogen oxide emissions in hydrogen-fueled diesel engines by adjusting the hydrogen inclusion rate in real time.     

An investigation on the causes of cycle variation in direct injection hydrogen fueled engines

To achieve hydrogen power system with high performance and stable operation, cycle variation of hydrogen-fueled engine with direct injection was evaluated with several variables such as engine speed, injection timing, air–fuel equivalence ratio and spark timing. And the cause of cycle variation was analyzed by using coefficient of variation in combustion period defined in this study. The results showed that the cycle variation of hydrogen-fueled engine is mainly dependent on the early combustion period.     

Research on optimal calibration technology for hydrogen-fueled engine based on nonlinear programming theory

To analyze and resolve the contradiction of abnormal combustion and improving hydrogen-fueled engine power is the key for promoting the progress of hydrogen-fueled engine research. Optimal control is the most valuable technology for resolving this contradiction. In this paper, the optimal model of hydrogen-fueled engine for multi-variable, multi-objective, multi-constraint under the whole operating conditions was established. The technology was a combination of nonlinear programming theory and optimal calibration algorithm of genetic algorithm. Calibration process can be adjusted dynamically to match with the working conditions of engine by weighted function. It implements the unity of comprehensive performance optimization and individual optimization, and not only simplifies calibration process but also improves calibration speed. Furthermore, a new method that accurately and quickly calibrates MAP under the conditions of multi-variable, multi-goal and multi-constraint is provided to effectively resolve the contradiction of the abnormal combustion and improving hydrogen-fueled engine power.     

Idle performance of a hydrogen rotary engine at different excess air ratios

Rotary engine has flat chamber and longs for fuel with high flame speed and small quenching distance. Hydrogen has many excellent characteristics that are suitable for the rotary engine. In this paper, the performance of a rotary engine fueled with pure hydrogen at different excess air ratios was experimentally investigated. The investigation was carried out on a single-rotor hydrogen-fueled rotary engine equipped with port fuel injection system. An online electronic control module was used to govern the hydrogen injection duration and excess air ratio. In this study, the engine was operating at the idle speed of 3000 rpm and different excess air ratios varied from 0.993 to 1.283. The test results demonstrated that the fuel energy flow rate of the hydrogen rotary engine and engine stability were reduced with the increase of excess air ratio. When the excess air ratio increased from 0.993 to 1.283, the hydrogen energy flow rate was decreased from 14.91 to 11.55 MJ/h. Both the flame development and propagation periods were increased with excess air ratio. CO emission was negligible, but HC, CO₂ and NOx emissions were still detected due to the evaporation and possible burning of the lubrication-used gasoline, and oxidation reaction of nitrogen of the intake air.     

Hydrogen fueled spark ignition engine with electronically controlled manifold injection: An experimental study

In this work, a single cylinder conventional spark ignition engine was converted to operate with hydrogen using the timed manifold fuel injection technique. A solenoid operated gas injector was used to inject hydrogen into the inlet manifold at the specified time. A dedicated electronic circuit developed for this work was used to control the injection timing and duration. The spark timing was set to minimum advance for best torque (MBT). The engine was operated at the wide-open throttle condition. For comparison of results, the same engine was also run on gasoline.The performance and emission characteristics with hydrogen and gasoline are compared. From the results, it is found that there is a reduction of about 20% in the peak power output of the engine when operating with hydrogen. The brake thermal efficiency with hydrogen is about 2% greater than that of gasoline. A lean limit equivalence ratio of about 0.3 could be attained with hydrogen as compared to 0.83 with gasoline. CO, CO₂ and HC emissions were negligible with hydrogen operation. However, for hydrogen operation, NO_x emission was four times higher than that of gasoline at full load power. The best ignition timing for hydrogen was much retarded when compared to gasoline. The effect of hydrogen injection pressure was also studied and no specific changes were observed. The effect of operating speed was also studied.     

Research on the hydrogen injection strategy of a direct injection natural gas/hydrogen rotary engine considering apex seal leakage

The purpose of the present paper is to investigate the hydrogen injection strategy on the combustion performance of a natural gas/hydrogen rotary engine. Considering that apex seal leakage (ASL) is an inevitable problem in the actual working process of a rotary engine, the action of ASL cannot be ignored for an in-depth study of its combustion performance. Therefore, in this paper, a 3D dynamic simulation model that put the effect of ASL into consideration was established. Furthermore, based on the established 3D model, the combustion process of a natural gas/hydrogen rotary engine under various hydrogen injection angle (HIA) and hydrogen injection timing (HIT) was investigated. The results indicated that the hydrogen jet flow first impacted on the rotor wall after entering the cylinder, and then diffused under the action of the vortexes in the cylinder. Therefore, the HIA and HIT could change the hydrogen distribution by changing the hydrogen impact location and the intensities of the vortexes in the cylinder. In addition, the ideal hydrogen distribution at the ignition timing which could improve the combustion efficiency was given. That is, under the premise of ensuring minimized hydrogen leakage, the hydrogen should mainly distribute in the middle and the front of the cylinder, and a high hydrogen concentration is maintained near the spark plug.