Application of low carbon alternative fuels for engines has been well-known as an attractive approach to reduce greenhouse gas emissions. In recent years, additional efforts have been made on the research and development of alternative fuel engines that run on natural gas, methanol, hydrogen and ammonia, because they provide more potential to achieve strict emission targets. However, a technical challenge for these alternative fuel engines is whether a qualified fuel delivery system is available. Blending is perhaps the most convenient method to burn alternative fuel. A popular blending fuel is the mixture of gasoline and 10% ethanol (E10) for use in passenger vehicles. In this case, no change is needed for the fuel delivery system. In other cases including using methanol as an alternative, the components of fuel delivery system require materials modification to prevent corrosion. High-pressure direct injection of methanol is preferred for heavy-duty engines because compression ignition exhibits high thermal efficiency. In this case, the conventional fuel delivery system needs more modifications. For example, a higher flow capacity is needed for increased flow rate due to the lower energy density. Additional cooling elements are needed to prevent vaporization. A special coating should also be applied to the surface of the pump plunger and control valve to improve the lubricity because those components are made of the anticorrosive material. For natural gas, an effective combustion mode is so called dual—fuel mode. There, natural gas introduced from the intake port and mixed with air homogenously is ignited by injecting a small amount of diesel fuel when the piston approaches the end of compression stroke. More recently, a more advanced fuel delivery system has been developed, which uses one injector for diesel fuel and another for natural gas (or alternatively a co-axial injector with inner nozzle hole for diesel fuel and outer nozzle holes for natural gas). It has been reported that diesel fuel injected for ignition can be reduced to 5% of total fuel with using this new system. This dual-fuel mode has been used for methanol and ammonia fuel, and could be the next main-stream for alternative fuel engines.

柴油机颗粒物捕集器(DPF)热再生发生时,其内部温度受DPF碳载量、排气温度和排气流量等影响,在特殊运行工况下具有较强非受控特性.为避免非受控再生引起的DPF失效风险,确保安全和可靠再生,通过降怠速(DTI)再生方式探讨了一种确定DPF安全再生温度的试验方法,得到安全再生温度曲线.针对DPF热再生过程中温度控制的大滞后特性,研究了一种采用发动机排气温度和排气流量作为增益补偿的优化热再生温度控制结构,并进行了控制算法的仿真分析和整车道路试验验证.结果表明:再生过程中对实际排气温度控制的超调量小于3％,稳态控制误差小于20℃,为促进DPF的安全和高效率再生提供了参考.

通过建立柴油机氮氧化物(NOx)排放、碳烟排放预估模型和柴油机颗粒物过滤器(DPF)内碳烟颗粒的催化氧化反应模型,探讨了一种基于质量平衡的DPF碳烟负载量在线预估方法.欧盟驾驶循环(NEDC)测试工况的排放试验结果表明,柴油机NOx和碳烟排放预估模型计算结果与试验结果的误差分别为5.1％和3.9％.在车辆实际道路行驶工况进行了DPF碳烟颗粒加载试验,结果表明,试验过程中对DPF碳烟负载量的在线预估值与试验结果的最大偏差为0.48 g/L,平均偏差为0.17 g/L,模型的平均预测误差为2.1％.本研究为热再生时机的准确判断提供了有效参考.

In order to meet the worldwide increasingly stringent particulate matter (PM) and particulate number (PN) emission limits, the diesel particulate filter (DPF) is widely used today and has been considered to be an indispensable feature of modern diesel engines. To estimate the soot loading amount in the DPF accurately and in real-time is a key function of realizing systematic and efficient applications of diesel engines, as starting the thermal regeneration of DPF too early or too late will lead to either fuel economy penalty or system reliability issues. In this work, an open-loop and on-line approach to estimating the DPF soot loading on the basis of soot mass balance is developed and experimentally investigated, through establishing and combining prediction models of the NOx and soot emissions out of the engine and a model of the catalytic soot oxidation characteristics of passive regeneration in the DPF. The emission testing results under the New European Driving Cycle (NEDC) show that the prediction errors of the engine-out NOx and soot emission models are 5.1% and 3.9%, respectively. Tests and validations of the soot mass loading model are carried out under on-vehicle driving. The experimental results show that the maximum estimation error of the model is 0.48g/L and the average error is 0.17g/L. It shows that the model estimation error is less than 6%, which is conducive to promoting safe and reliable DPF regeneration and contributes to the DPF management and applications in real-world operation.

The China V emission standard for light duty vehicles, starting to be effective from January 1, 2018, is the first time to set particulate number (PN) emission limits. This necessitates diesel particulate filters (DPFs) to be equipped for diesel powered pick-up trucks. A DPF soot load estimation model based on the DPF pressure drop is established to support the regeneration time selection and DPF applications and management. The accuracy of the model is validated through the engine dynamometer testing and on-vehicle road tests.

To accurately estimate the amount of soot in the diesel particulate filters (DPFs) is critical to maintain DPF integrity while minimizing the fuel penalty. A mass balance based soot load estimation model is developed by use of the engine-out soot emission and DPF passive regeneration characteristics. Calibration mapping and the mapping result are described and discussed. Experimental validation is carried out in both engine test cell and vehicle road tests. Results show that after calibration mapping in a systematic way, the proposed mass balance based model has achieved an accuracy of +/-1g/L, which indicates a considerable potential to contribute to the DPF applications and management.

Electronic control assembly pump(ECAP)assembles mechanical hydraulic and electrical magnetic,and is a new electronic unit pump(EUP)fuel injection system which satisfies requirement of emission and fuel economy of diesel.The low pressure system pressure dynamic characteristic influences the coherence of each cylinder cyclic injection performance on the high pressure system.Experiment shows that the low pressure system fuel pressure always has the pulsating cycle fluctuation in operation,the fluctuation range is from minimum 0 MPa to maximum 2 MPa,the fluctuation amplitude improves with the increase of injection duration,and pressure dynamic characteristic has little difference at different measurement position.Pressure time history curve and injection cylinders have the corresponding relationship.Fourier analysis shows that the influence of high pressure system on low pressure system mainly focuses on the multiple frequency part of datum frequency as working cylinders increase.Wavelet transform shows that low pressure signal simultaneously moves towards low frequency and high frequency of the wavelet transform signal as injection cylinders increase.To analyze the influence of low pressure fluctuation on high pressure injection characteristic,the numerical study is conducted using the AMESim software.Simulation result shows fuel pressures at low pressure system and high pressure system are cyclic fluctuation.Cyclic fuel injection quantity at each cylinder has little difference,the fluctuation range is 1.5 mm3,and mean square deviation is within 0.5 mm3.

In this study,the validation of AMESim simulation model to injection parameters is made by comparing with experiment.The influence of the parameters such as fluctuation of supply fuel pressure,cam velocity,piston matching clearance,maximum control current,anchor residual clearance,valve matching clearance,valve lift,injector opening pressure,injector flow coefficient,injector needle lift on cycle fuel injection quantity fluctuation is analyzed in details with the simulation model.Quantitative influence of different parameters on cycle fuel injection quantity fluctuation,they are,the influence percentage of injector characteristic parameters from 44% to 34%,valve characteristic parameters from 20% to 35%,piston characteristic parameters from 32% to 19%,and low pressure supply characteristic parameters form 4% to 12% at cam speed from 500 r/min to 1 300 r/min.Based on experimental design method considering the interaction,the correlation of different factors with cycle fuel injection quantity is analyzed and the correlation coefficient of different factors with cycle fuel injection quantity is provided.The results show that both single parameter factor and parameter's interaction factor have the correlation with fuel injection quantity.

A new diesel electronic fuel injection system——electronic compound pump is developed for Chinese market. This system is same to electronic unit pump regarding working principle, and similar with the mechanical in-line pump in term of the geometric size and the mechanical connection. It is shown that this system can provide high injection pressure, excellent injection profile, flexible and precise control of injection timing and injection quantity. The test results on engines indicate that this system is an ideal solution to meet the national III emission legislation.

WIT Electronic Fuel System Co.,Ltd.has developed a new fuel injector,the Electronic In-line Pump(EIP) system,designed to meet China’s diesel engine emission and fuel economy regulations.It can be used on marine diesel engines and commercial vehicle engines through different EIP systems.A numerical model of the EIP system was built in the AMESim environment for the purpose of creating a design tool for engine application and system optimization.The model was used to predict key injection characteristics under different operating conditions,such as injection pressure,injection rate,and injection duration.To validate these predictions,experimental tests were conducted under the conditions that were modeled.The results were quite encouraging and in agreement with model predictions.Additional experiments were conducted to study the injection characteristics of the EIP system.These results show that injection pressure and injection quantity are insensitive to injection timing variations,this is due to the design of the constant velocity cam profile.Finally,injection quantity and pressure vs.pulse width at different cam speeds are presented,an important injection characteristic for EIP system calibration.

Electronically controlled assembly pump(ECAP) is a hydraulic and electro-magnetic driving assembling product,and is an electronic unit pump(EUP) fuel injection system that meets emission regulation and fuel economy.By the comparison between the numerical simulation and experiments,it is concluded that the AMESim simulated model can precisely estimate the fuel injection system parameters under all operating conditions.Comparative analysis at various pump pressure,injector pressure and fuel injection quantity showed that the ECAP characteristic maps including fuel injection timing,fuel injection quantity and fuel injection pressure were obtained.NOx of 4.74 g/(kW·h) and PM of 0.085 g/(kW·h) were obtained in Yuchai 4110 diesel engine,and this meets the Euro Ⅲ ESC emission regulation.

A new technique which is based on optoacoustic phenomena has been developed for measuring in-cylinder gas temperature and turbulent diffusivity. In the experiments, a high energy Nd:YAG pulsed laser beam was focused to cause local ionization of air at a point in the combustion chamber. This initiates a shock wave and creates a hot spot. The local temperature and turbulent diffusivity are determined by monitoring the shock propagation and the hot spot growth, respectively, with a schlieren photography system. In order to assess the validity and accuracy of the measurements, the technique was also applied to a turbulent jet. The temperature measurements were found to be accurate to within 3%. Results from the turbulent jet measurements also showed that the growth rate of the hot spot diameter can be used to estimate the turbulent diffusivity.... I.C. Engines, Diesel, Temperature measurement, Optics, Schlieren.

This paper introduces a new combustion system for D.I. diesel engine ― CSCS system, with which a new structural pintle injector and a combustion bowl with squish lip are used and no intake swirl is needed. The injection and spray characteristics of the new injector include the uniform peripheral distribution of spray and the good atomization quality of spray as well as the higher fuel injection rate. The schlieren photograph and the DDM spray model are applied to study fuel - air mixing and combustion processes of the new combustion system