博格华纳力推涡轮增压新技术

对于国IV阶段的EGR和SCR两种排放方案,其中EGR方案要求增压器涡端流量偏小一些,以得到较高的涡前压力来驱动EGR阀;但基本上,放气阀式增压器都能满足EGR和SCR两种排放方案。而在国V或国VI阶段,需要有较高的压比和EGR率,普通的放气阀式增压器很难达到。基于以上要求,博格华纳中国也正在积极地引入国外成熟的新技术,如非对称流道增压器、可变截面增压器VTG、两级增压增压器R2S和变流道增压器VTV等先进增压器技术。博格华纳可变截面涡轮增压器可变截面涡轮增压器在柴油发动机中应用的较多。涡轮增压系统的心脏是可调涡流截面的导流叶片。这些     

文丘里管废气再循环系统对涡轮增压柴油机性能影响的研究

加装文丘里管的高压废气再循环(Exhaust gas re-circulation,EGR)进气系统,在兼顾柴油机经济性、动力性的前提下,研究该进气系统对NO_x排放的影响。根据一款柴油机的基本结构建立柴油机一维仿真计算模型和燃烧室的三维仿真计算模型。在对模型进行标定和对柴油机原机性能仿真计算的基础上,为进气系统引入文丘里管装置并对其结构参数进行优化设计。应用所建立的一维和三维柴油机模型,对文丘里管EGR系统柴油机的经济性、NO_x和Soot排放特性进行仿真计算研究,并对计算结果进行试验验证。研究结果表明,优化设计的文丘里管EGR系统可使柴油机在欧洲稳态循环(European steady state cycle,ESC)各工况下实现较为理想的EGR率,并在不明显影响柴油机燃油经济性的前提下,使NO_x排放量下降了约28.4%。文丘里管进气系统可以实现较为理想的高压EGR循环,在柴油机ESC工况下(怠速除外)能够达到较为理想的EGR率。     

LP⁃EGR和电增压协同技术对汽油机性能的影响

在一款采用废气涡轮增压的直喷汽油机上,进行了电动增压器和低压废气再循环(Low pressure exhaust gas recirculation, LP-EGR)技术组合对发动机经济性、NO_x排放特性以及动力性、EGR率瞬态响应特性影响的试验研究。结果表明:电增压工作时,低速外特性EGR率可达到25%,使得1 250～2 000 r/min外特性的燃烧相位提前,油耗相对于电增压不工作时下降8.5%～10%,同时NO_x排放显著降低;而在部分负荷工况下,电增压的泵吸作用使得最大EGR率大于30%,取得了油耗和NO_x排放同时改善的综合效果,且最高油耗下降率可达10.8%;此外电增压工作时,1 500 r/min下负荷从0.2 MPa增大到1.5 MPa的瞬态响应时间缩短2/3;当发动机定转速加大负荷运行时,电增压工作时进气歧管目标EGR率的建立时间可缩短1.3 s,有效优化了发动机加速过程的运转控制参数。     

博格华纳由可变截面涡轮增压器向电子涡轮增压器发展

正随着中国汽车产业政策日趋严格的排放法规颁布,发动机必须配置涡轮增压器以到达排放标准,而且消费者选用配有涡轮增压器的汽车,在降低油耗的同时可以增加驾驶乐趣。目前,涡轮增压器在我国乘用车上的渗透率不到30%,而在欧洲,这一比例已经达到了八成以上。据预测,到2019年,中国涡轮增压器市场的总需求将达到60%以上。现在,涡轮增压器的技术趋势就是从普通的废气旁通阀涡轮增压向可变截面和两级增压过渡。其中,博格华纳的     

工程机械用涡轮增压柴油机及其排放控制与节能

阐述了工程机械柴油机废气涡轮增压器的作用、结构及工作原理;涡轮增压与排放控制技术;涡轮增压及中冷技术对排放的影响;分析了工程机械用柴油机涡轮增压技术的应用现状和发展趋势。     

汽油机涡轮增压与废气排放控制

涡轮增压技术与废气排放控制系统的结合,使汽油机的动力性能和燃油经济性能提高到一个新水平,废气涡轮增压技术在提高汽油机动力性能的同时,可以降低排放废气温度,降低排气噪音,改善燃油经济性,减少排放污染。结合目前采用废气涡轮增压技术的小排量汽车日益增多,维修中时常遇到涡轮增压器与废气排放系统相关联的故障,要解决这类问题就必须清楚其工作原理。     

柴油机废气再循环系统控制器的设计研究

根据增压柴油机废气再循环(EGR)系统的要求,采用动态矩阵控制(DMC)算法设计EGR系统控制器.通过仿真系统试验证实了所设计的控制器可以应用于柴油机EGR系统,并能够使EGR系统有效降低柴油机氮氧化物(NOx)的排放.     

柴油机废气再循环系统控制器的设计研究

根据增压柴油机废气再循环(EGR)系统的要求,采用动态矩阵控制(DMC)算法设计EGR系统控制器.通过仿真系统试验证实了所设计的控制器可以应用于柴油机EGR系统,并能够使EGR系统有效降低柴油机氮氧化物(NOx)的排放.     

电动增压器对废气涡轮增压器影响的试验研究

利用交流电动增压器串联于增压中冷公交车增压气路中消除加速烟度。利用电动增压器可瞬间增大增压柴油机自由加速时进入柴油机缸内的新鲜空气,同时增大废气涡轮增压器的角加速度,提高其动态响应,改善柴油机的低速性能。通过不同压气机型号电动增压器流量特性与工作电流特性试验以及道路试验的试验数据,证明增大电动增压器压气机叶轮直径可增大进气流量,更大幅度地提高废气涡轮增压器的动态响应。引入压气机特性参数数学表达式,分析电动增压器辅助增压时,对废气涡轮增压器的影响以及对其动态响应的影响。电动增压器可增大柴油机自由加速时废气涡轮增压器的角加速度,且电动增压器的质量流量越大,角加速度增大越明显。而质量流量越大,电动增压器消耗的功率越大。利用压气机叶轮直径为90 mm的电动增压器可将原机自由加速烟度降低54%左右。     

柴油机EGR瞬态参数采集处理与诊断系统

基于PCL-818HG型总线数据采集卡和S3C2410型高性能低功耗微处理器,开发了一种便携式柴油机废气再循环(exhaust gas recycle,简称EGR)瞬态参数的采集与诊断系统.运用DASYLab和Linux软件编写接口、标定与诊断程序,实现了对柴油机EGR系统的位移、压力、温度和转速等信号实时采集、处理与诊断等功能.依据柴油机瞬态测试循环法进行增压柴油机废气再循环系统的EGR阀自诊断、EGR率过大诊断和瞬态响应特性等试验.结果表明,该系统性能可靠、处理能力强、诊断精度高,能满足增压柴油机EGR性能瞬态参数的采集与诊断要求.     

甲醇裂解气-柴油混合燃料对柴油机排放的影响

为研究甲醇裂解气-柴油混合燃料对柴油机排放的影响,设计了一种集成式尾气裂解甲醇反应器和进气共轨系统,将YC6A220型柴油机改装成燃烧由甲醇裂解而成的氢富气与柴油混合燃料的柴油机。实验研究表明,改装后的柴油机在中、高负荷运行时可以使NOx、HC和碳烟大幅度降低,且随着甲醇裂解气掺烧量的增加,各排放物质的减少量增加。     

纳米WS2车用机油添加剂在柴油发动机中的应用效果研究

通过柴油发动机台架实验和行车实验,分析了不同工况下自制纳米WS2车用机油添加剂在柴油发动机中的应用效果。结果表明,在FC2000柴油发动机台架上应用时,纳米WS2车用机油添加剂在不同转速和不同负载下均能在一定程度上降低发动机油耗率,减少发动机尾气中NOx含量和颗粒物含量,并且当发动机转速为1 700r/min,负载为70N.m时,节油率最高为9.95%,颗粒物减排率最高为49.3%,而当发动机处于低速、高速、低载和高载等工况时,NOx减排率较高,最高达到36%;在柴油机大客车上应用时,纳米WS2车用机油添加剂使其耗油量下降约14.4%,并能在一定程度上降低发动机的运行噪声,使发动机的有害气体(NOx)排放减少34.8%～51%。综合表明纳米WS2车用机油添加剂具有良好的节能减排效果。     

Performance and emission studies on an agriculture engine on neat Jatropha oil

Diesel engines have proven their utility in the transportation, agriculture, and power sectors in India. They are also potential sources of decentralized energy generation for rural electrification. Concerns on the long-term availability of petroleum diesel and the stringent environmental norms have mandated the search for a renewable alternative to diesel fuel to address these problems. Vegetable oils have been considered good alternatives to diesel in the past couple of years. However, there are many issues related to the use of vegetable oils in diesel engine. Jatropha curcas has been promoted in India as a sustainable substitute to diesel fuel. This study aims to develop a dual fuel engine test rig for evaluating the potential suitability of Jatropha oil as diesel fuel and for determining the performance and emission characteristics of an engine with Jatropha oil. The experimental results suggest that engine performance using Jatropha oil is slightly inferior to that of diesel fuel. The thermal efficiency of the engine was lower, while the brake-specific fuel consumption was higher with Jatropha oil compared with diesel fuel. The levels of nitrogen oxides (NOx) from Jatropha oil during the entire duration of the experiment were lower than those of diesel fuel. The reduction of NOx was found to be an important characteristic of Jatropha oil as NOx emission is the most harmful gaseous emission from engines; as such, its reduction is always the goal of engine researchers and makers. During the entire experiment, carbon monoxide (CO), hydrocarbon (HC), and carbon dioxide (CO₂) emissions in the case of using Jatropha oil were higher than when diesel fuel was used. The higher density and viscosity of Jatropha oil causes lower thermal efficiency and higher brakespecific fuel consumption. The performance and emission characteristics found in this study are significant for the study of replacing diesel fuel from fossils with Jatropha oil in rural India, where the availability of diesel has always been a problem.     

EFFECTS OF COOLED EXTERNAL EXHAUST GAS RECIRCULATION ON DIESEL HOMOGENEOUS CHARGE COMPRESSION IGNITION ENGINE

The effects of cooled external exhaust gas recirculation (EGR) on the combustion and emission performance of diesel fuel homogeneous charge compression ignition (HCCI) are studied. Homogeneous mixture is formed by injecting fuel in-cylinder in the negative valve overlap (NVO) period. So, the HCCI combustion which has low NOx and smoke emission is achieved. Cooled external EGR can delay the start of combustion effectively, which is very useful for high cetane fuel (diesel) HCCI, because these fuels can easily self-ignition, which makes the start of combustion more early. External EGR can avoid the knock combustion of HCCI at high load which means that the EGR can expand the high load limit. HCCI maintains low smoke emission at various EGR rate and various load compared with conventional diesel engine because there is no fuel-rich area in cylinder..     

电动EGR在柴油发动机上的标定策略研究

废气再循环是一种简单有效的降低氮氧化物的方法。介绍了柴油机电控EGR的匹配与标定,探讨了空气系统的大闭环进气量控制和小闭环EGR阀位置控制方式。结果表明通过这种控制匹配方式能够比较好地实现空气系统的静态稳定性和动态跟随性,并能够满足柴油机欧IV排放对空气系统的要求。     

Investigation of the effects of steam injection on the emissions and performance of a diesel engine using waste chicken oil methyl ester

The use of biodiesel-blended fuels in diesel engines improves the engine performance parameters and the partial recovery of incomplete combustion products, while also increasing the level of NOx emissions. In this study; biodiesel obtained through the transesterification of waste chicken frying oil was mixed with diesel fuel (90% diesel + 10% biodiesel-B10), and was then used as fuel in a direct injection diesel engine. To reduce the increased NOx emissions caused by the use of B10 fuel, the steam injection method (which is one of the NOx reduction methods) was applied. Steam was injected into the intake manifold at different ratios (5%-S5, 10%-S10 and 15%-S15) and at the time of the induction stroke with the aid of an electronically controlled system. Based on the study results, it was observed that steam injection into the engine using B10 fuel improved both the engine performance and the exhaust emission parameters. It was determined that the S15 steam injection ratio resulted in the best engine performance and emissions parameters. In comparison to STD fuel; the highest increase observed at the S15 steam injection ratio in the effective engine power was 2.2%, while the highest decrease in the specific fuel consumption was 3.4%, the highest increase in the effective efficiency was 3.5%, and the highest decrease in NOx emissions was 13.7%.

     

Numerical Analysis of Nozzle Clearance's Effect on Turbine Performance

Variable nozzle turbine (VNT) has become a popular variable geometry turbine (VGT) technology for the diesel engine application. Nozzle clearance, which can’t be avoided on the hub and shroud side of the VNT turbine due to the pivoting stators, can lead to turbine performance deterioration. However, its mechanism is still not clear. In this paper, numerical investigation, which is validated by experiment, is carried out to study the mechanism of the nozzle clearance’s effect on the turbine performance. Firstly, performance of the mixed flow turbine with fixed nozzle clearances tested on flow bench. Performance of the tested turbine with the same nozzle clearance is numerically simulated. The numerical result agrees well with the test data, which proves correct of the numerical method. Then the turbine performance with different nozzle clearances is numerically analyzed. The research showed that with nozzle clearance, flow loss in the nozzle increases at first and it reaches the maximum value when the clearance ratio is 5%. Flow at the exit of the nozzle becomes less uniform with nozzle clearance. The negative incidence angle of the rotor also increases with nozzle clearance and leads to more incidence angle loss in the rotor. The low energy fluid formed in the nozzle due to the nozzle clearance migrates from hub to shroud side in the rotor, which is another main reason for the rotor’s performance degradation. The present research exposed the mechanism of the dramatically decrease of the turbine performance with nozzle clearance: (a) The loss associated with the nozzle leakage increases with the nozzle clearance; (b) The flow loss grows up quickly in the rotor due to the incidence angle loss and migration of the low energy fluid from hub to shroud side.     

COMPOSITIVE EMISSION CONTROL SYSTEM OF GASOLINE VEHICLE

The working principle of a kind of compositive emission control system is inquired into, which includes exhaust heater, secondary air supplement, exhaust gas recirculation (EGR), thermal reactor and catalytic converter, etc. The purification effect of CO, HC and NOx emission of the gasoline spark ignite (S.I.) engine is studied. The entire vehicle driving cycle tests based on the national emission standard and a series of the gasoline engine-testing bench tests including full load characteristic experiment, load characteristic experiment and idle speed experiment are done. The results show that the system has a very good emission control effect to CO, HC and NOx of gasoline engine. The construction of the system is very simple and can be mounted on the exhaust pipe conveniently without any alteration of the vehicle-use gasoline engine.     

Emission characteristics of exhaust gases and nanoparticles from a diesel engine with biodiesel-diesel blended fuel (BD20)

This experimental study sought to investigate the characteristics of the exhaust emissions, and nanoparticle size distribution of particulate matter (PM) emitted from diesel engines fueled with 20% biodiesel-diesel blended fuel (BD20). The study also investigated the conversion efficiency of the warm-up catalytic converter (WCC). The emission characteristics of HC, CO, NOx and nano-sized PM were also observed according to engine operating conditions with and without exhaust gas recirculation (EGR). The study revealed that the maximum torque achievable with the biodieseldiesel blended fuel was slightly lower than that achievable with neat diesel fuel at high-load conditions. Smoke was decreased by more than 20% in all 13 modes. While the CO and THC emissions of BD20 slightly decreased, the NOx emission of BD20 increased by 3.7%. Measured using the scanning mobility particle sizer (SMPS), the total number and total mass of the nanoparticles in the size range between 10.6nm and 385nm were reduced by about 10% and 25%, respectively, when going from D100 to BD20. The particle number and mass for both fuels were reduced by about 43% when going from with EGR to without EGR. When EGR was applied in the engine system, the particle number and mass were reduced by 24%, and 16%, respectively, when going from D100 to BD20.