电喷汽油机燃用乙醇汽油的仿真研究

对吉利MR479Q型发动机建立一维仿真模型,并利用该模型进行了电喷汽油机燃用乙醇汽油的仿真研究。研究发现,在不改变发动机的前提下,燃用含适当比例乙醇的乙醇汽油对发动机的动力性有少量的提升,但由于乙醇的低位热值远小于汽油,发动机的比油耗也随着掺醇比例的提高而提高。     

车用乙醇汽油对电喷汽油机性能影响的实验研究

在电控汽油机参数未作任何调整的情况下,实验研究了汽油机燃用乙醇汽油对发动机经济性和动力性的影响。研究表明：电控汽油机改燃乙醇汽油后,部分负荷时汽油机的功率和转矩有所降低,但全负荷时汽油机的动力输出不变;与普通汽油相比,乙醇汽油的燃油消耗率增加5％～10％,而且汽油机的经济区范围变窄;但能耗率会有所改善,在怠速工况下,乙醇汽油会降低汽油机的CO、HC和NOx排放;乙醇汽油对汽油机性能的影响与空燃比控制策略有关。     

电喷汽油机燃用微乳化E10含水乙醇汽油的试验研究

应用微乳化理论研制E10含水乙醇汽油乳化剂,在电喷发动机上进行燃用E10含水乙醇汽油对发动机动力性、经济性和排放性的影响试验研究.试验结果表明:基于HLB值理论配制的SPY乳化剂能较好地解决E10含水乙醇汽油的稳定性问题;发动机燃用E10含水乙醇汽油后,动力性略有降低,有效燃油消耗率略有升高,能源消耗率降低;怠速排放的CO、HC、NOx均下降,NOx下降幅度达到65％;多工况排放的CO、HC在低负荷略有降低,中高负荷时明显降低,CO降低9％ ～ 17％,HC降低4％～9％;NOx在中小负荷时降低12％左右,大负荷时改变不明显.     

电喷汽油机燃用低比例甲醇汽油的试验研究

在电喷汽油机上燃用低比例甲醇汽油混合燃料与燃用93#汽油进行对比试验研究。试验结果表明,汽油机燃用M15,M25混合燃料均比燃用93#汽油输出功率高,增幅为3．1％～7．7％;M15当量油耗率与93#汽油油耗率基本相等,M25当量油耗率降幅较为明显,最大降幅达16．8％;混合燃料有效热效率高于93#汽油;混合燃料比93#汽油CO放稍有降低,HC排放降低明显,NOx排放在中低负荷时有所改善,在大负荷时排放增加。     

汽油机燃用乳化汽油节能的试验研究

摘要本文以节油为目的,对不同含水量的乳化汽油进行了台架和行车试验,结果表明合理调整点火提前角和化油器主量孔开度,可以在动力性能大致不变的情况下,明显改善燃油经济性,降低NO_x排放.和燃用纯汽油时相比,节油率在7%以上,技术趋于成熟,操作简便,具有推广使用的价值.     

E20w含水乙醇汽油对电喷汽油机的性能及排放的影响

在汽油机台架试验中以SQR481F为研究对象,进行了燃用E20W含水乙醇汽油与93^#纯汽油的性能与排放对比试验。试验结果表明：在汽油机未做任何改动的情况下,汽油机燃用E20W含水乙醇汽油后,功率下降约4.7%-7.6%;在n=1500r/min、3500r/min、5500r/min时的有效燃油消耗率平均分别增加了5.84%、4.25%及4.36%;当量燃油消耗率下降了1%-6.59%,HC、CO的排放在小负荷时的改善效果不明显,仅为1%;在中大负荷时HC为10%左右,CO为6%-13%,NOx的排放得到了改善。     

电控汽油机燃用中低比例甲醇汽油的试验研究

因电控汽油机具有空燃比自适应控制功能,将中、低比例甲醇汽油用作汽油机的燃料时,电控系统可以将混合气的实际空燃比维持在理论空燃比附近,从而能够保持汽油机平稳运转。本文对电控发动机燃用M25和M50甲醇汽油的动力性、燃油经济性和排放进行了试验研究,结果表明发动机的动力性与燃用RON93汽油时基本相当,以比能耗为指标的燃料经济性有所提高,燃烧中的CO、HC和NOx生成量显著降低,三效催化转化器对燃用甲醇汽油时的CO和HC的转化效率较高,但因燃用甲醇汽油时排气温度较低导致对NOx的转化效率有所降低。     

汽油机燃用汽油-乙醇混合燃料的试验研究

本文针对摩托车汽油机燃用乙醇的应用研究，在汽油机结构不作变动的前提下，掺烧一定比例的工业乙醇，进行发动机台架试验。在节气门开度分别为25％、50％、75％及100％时，在不同转速和负荷下，对发动机的功率、扭矩、能耗率及排放性能进行了研究，并与原机进行比较。试验结果表明，燃用汽油一乙醇混合燃料可以提高发动机的动力性和经济性，有效改善排放特性。     

E10含水乙醇汽油对汽油机性能及排放的影响研究

采用自主研发的"复方两性乳化剂"进行了E10含水乙醇汽油(体积比为90%的90#汽油+10%的含水乙醇)稳定性研究。研究结果表明:乳化剂能有效改善含水乙醇汽油的稳定性,加入强化剂和防冻剂、提高乙醇浓度能够有效改善乳化含水乙醇汽油的低温稳定性。针对汽油机进行了燃用E10含水乙醇汽油混合燃料与原机的性能对比试验研究。试验结果表明:在未对汽油机作任何调整的情况下,燃用E10含水乙醇汽油混合燃料的动力性略低于原机。在经济性方面,燃油消耗率比原机有所上升,以热值计的当量燃油消耗率比原机有所改善。在尾气排放方面,燃用E10含水乙醇汽油时,CO排放在整个负荷范围内基本比原机低,CO排放得到改善;HC排放在整个负荷范围内都得到了改善,改善效果可达9%左右;NOx排放在低负荷时有所改善,随着负荷增加NOx排放变化不大。在怠速工况,CO、HC和NOx排放均获得改善。尾气排放产物在催化器中的转化效率与发动机工况有关。     

Experimental and theoretical investigation of using gasoline–ethanol blends in spark-ignition engines

The effects of ethanol addition to gasoline on an SI engine performance and exhaust emissions are investigated experimentally and theoretically. In the theoretical study, a quasi-dimensional SI engine cycle model, which was firstly developed for gasoline-fueled SI engines by author, has been adapted for SI engines running on gasoline–ethanol blends. Experimental applications have been carried out with the blends containing 1.5, 3, 4.5, 6, 7.5, 9, 10.5 and 12 vol% ethanol. Numerical applications have been performed up to 21 vol% ethanol. Engine was operated with each blend at 1500 rpm for compression ratios of 7.75 and 8.25 and at full throttle setting. Results obtained from both theoretical and experimental studies are compared graphically. Experimental results have shown that among the various blends, the blend of 7.5% ethanol was the most suitable one from the engine performance and CO emissions points of view. However, theoretical comparisons have shown that the blend containing 16.5% ethanol was the most suited blend for SI engines. Furthermore, it was demonstrated that the proposed SI engine cycle model has an ability of computing SI engine cycles when using ethanol and ethanol–gasoline blends and it can be used for further extensive parametric studies.     

Performance and exhaust emissions of a gasoline engine with ethanol blended gasoline fuels using artificial neural network

The purpose of this study is to experimentally analyse the performance and the pollutant emissions of a four-stroke SI engine operating on ethanol–gasoline blends of 0%, 5%, 10%, 15% and 20% with the aid of artificial neural network (ANN). The properties of bioethanol were measured based on American Society for Testing and Materials (ASTM) standards. The experimental results revealed that using ethanol–gasoline blended fuels increased the power and torque output of the engine marginally. For ethanol blends it was found that the brake specific fuel consumption (bsfc) was decreased while the brake thermal efficiency (η_b.th.) and the volumetric efficiency (η_v) were increased. The concentration of CO and HC emissions in the exhaust pipe were measured and found to be decreased when ethanol blends were introduced. This was due to the high oxygen percentage in the ethanol. In contrast, the concentration of CO₂ and NO_x was found to be increased when ethanol is introduced. An ANN model was developed to predict a correlation between brake power, torque, brake specific fuel consumption, brake thermal efficiency, volumetric efficiency and emission components using different gasoline–ethanol blends and speeds as inputs data. About 70% of the total experimental data were used for training purposes, while the 30% were used for testing. A standard Back-Propagation algorithm for the engine was used in this model. A multi layer perception network (MLP) was used for nonlinear mapping between the input and the output parameters. It was observed that the ANN model can predict engine performance and exhaust emissions with correlation coefficient (R) in the range of 0.97–1. Mean relative errors (MRE) values were in the range of 0.46–5.57%, while root mean square errors (RMSE) were found to be very low. This study demonstrates that ANN approach can be used to accurately predict the SI engine performance and emissions.     

油品差异对汽车发动机性能影响的试验研究

国内外汽车用油存在较大差异,为了让国产车更好地满足国外市场需求,以我国出口汽车使用的甲基叔丁基醚（MTBE）（体积分数为10%）混合汽油、乙醇体积分数为20%（E20）的含水乙醇汽油和我国92号汽油为对象,基于某排量为2.0 T的汽油发动机台架试验,进行了三种油品对发动机性能影响的分析及验证。通过试验结果对比发现,使用MTBE混合汽油和E20含水乙醇汽油的动力性均低于92号汽油。在经济性方面,E20含水乙醇汽油略低于92号汽油,而MTBE混合汽油能使燃料消耗下降7%左右。在排放性方面,使用E20含水乙醇汽油和MTBE混合汽油对CO、HC的排放都有显著的改善效果,而在低转速、低负荷时对NO_x的排放有一定改善,随着转速和负荷的上升,E20含水乙醇汽油对NO_x的排放改善不明显,使用MTBE混合汽油时NO_x的排放反而变差。     

The effects of ethanol–unleaded gasoline blends on engine performance and exhaust emissions in a spark-ignition engine

Alcohols have been used as a fuel for engines since 19th century. Among the various alcohols, ethanol is known as the most suited renewable, bio-based and ecofriendly fuel for spark-ignition (SI) engines. The most attractive properties of ethanol as an SI engine fuel are that it can be produced from renewable energy sources such as sugar, cane, cassava, many types of waste biomass materials, corn and barley. In addition, ethanol has higher evaporation heat, octane number and flammability temperature therefore it has positive influence on engine performance and reduces exhaust emissions. In this study, the effects of unleaded gasoline (E0) and unleaded gasoline–ethanol blends (E50 and E85) on engine performance and pollutant emissions were investigated experimentally in a single cylinder four-stroke spark-ignition engine at two compression ratios (10:1 and 11:1). The engine speed was changed from 1500 to 5000 rpm at wide open throttle (WOT). The results of the engine test showed that ethanol addition to unleaded gasoline increase the engine torque, power and fuel consumption and reduce carbon monoxide (CO), nitrogen oxides (NO_x) and hydrocarbon (HC) emissions. It was also found that ethanol–gasoline blends allow increasing compression ratio (CR) without knock occurrence.     

Experimental and numerical investigation of effects of CNG and gasoline fuels on engine performance and emissions in a dual sequential spark ignition engine

Compared to widening usage of CNG in commercial gasoline engines, insufficient but increasing number of studies have appeared in open literature during last decades while engine characteristics need to be quantified in exact numbers for each specific fuel converted engine. In this study, a dual sequential spark ignition engine (Honda L13A4 i-DSI) is tested separately either with gasoline or CNG at wide open throttle. This specific engine has unique features of dual sequential ignition with variable timing, asymmetrical combustion chamber, and diagonally positioned dual spark-plug. Thus, the engine led some important engine technologies of VTEC and VVT. Tests are performed by varying the engine speed from 1500 rpm to 4000 rpm with an increment of 500 rpm. The engine’s maximum torque speed of 2800 rpm is also tested. For gasoline and CNG fuels, engine performance (brake torque, brake power, brake specific fuel consumption, brake mean effective pressure), emissions (O₂, CO₂, CO, HC, NO_x, and lambda), and the exhaust gas temperature are evaluated. In addition, numerical engine analyses are performed by constructing a 1-D model for the entire test rig and the engine by using Ricardo-Wave software. In the 1-D engine model, same test parameters are analyzed, and same test outputs are calculated. Thus, the test and the 1-D engine model are employed to quantify the effects of gasoline and CNG fuels on the engine performance and emissions for a unique engine. In general, all test and model results show similar and close trends. Results for the tested commercial engine show that CNG operation decreases the brake torque (12.7%), the brake power (12.4%), the brake mean effective pressure (12.8%), the brake specific fuel consumption (16.5%), the CO₂ emission (12.1%), the CO emission (89.7%). The HC emission for CNG is much lower than gasoline. The O₂ emission for CNG is approximately 55.4% higher than gasoline. The NO_x emission for CNG at high speeds is higher than gasoline. The variation percentages are the averages of the considered speed range from 1500 rpm to 4000 rpm.     

Reduction of smoke and nitrogen oxides of a partial HCCI engine using premixed gasoline and ethanol with air

This paper investigates the combustion and emissions characteristics for a partial homogeneous charge compression ignition (HCCI) engine by injecting gasoline and ethanol into the intake port of a diesel engine with diesel fuel injected in cylinder. The experiments were conducted on a diesel engine at premixed ratio (0, 10, 20, and 30) with injection timings (0–65° BTDC), under engine speeds (1200, 1500, and 1800 rpm) and loads (10 and 20 N m). The experimental results are compared with the numerical results and found to be reasonable. The results show that the injection timing of auxiliary fuels obtains less smoke concentration at 25° BTDC than at other crank angles. The diesel engine with premixed gasoline and ethanol can reduce emissions effectively; in particular, premixed ethanol affects the emissions reduction more than premixed gasoline does. The temperature contours and velocity fields in engine cylinder from the numerical calculation are also varied with engine load for various auxiliary fuels.     

乙醇汽油沉积物生成与喷雾特性试验研究

为研究乙醇汽油在缸内直喷汽油机中的积碳生成问题及喷雾特性,选取5孔直喷喷嘴为研究对象,通过试验模拟缸内积碳生成环境,制备得到积碳喷油器。基于高速摄像技术和定容弹,对未积碳喷油器和积碳喷油器进行喷雾试验,得到5孔直喷喷嘴的喷雾图像,利用MATLAB程序对喷雾图像进行可视化处理。针对喷雾中可能出现的闪急沸腾现象,研究燃料温度与背景压力对乙醇汽油喷雾闪沸的影响,结果表明:乙醇汽油的使用会加重直喷喷嘴的积碳问题,导致喷嘴的喷油量减小,雾化质量恶化。     

Low-speed pre-ignition and super-knock in boosted spark-ignition engines: A review

The introduction of downsized, turbocharged Gasoline Direct Injection (GDI) engines in the automotive market has led to a rapid increase in research on Low-speed Pre-ignition (LSPI) and super-knock as abnormal combustion phenomena within the last decade. The former is characterized as an early ignition of the fuel–air mixture, primarily initiated by an oil–fuel droplet or detached deposit. Meanwhile, super-knock is an occasional development from pre-ignition to high intensity knocking through detonation, which is either initiated by a shock wave interacting with a propagating reaction and cylinder surfaces or inside a hotspot with a suitable heat release and reactivity gradient. The phenomenon can be divided into four stages, including LSPI precursor initiation, establishment and propagation of a pre-ignited flame, autoignition of end-gases and development to a detonation. LSPI and super-knock are rare phenomena, difficult to observe optically in engines, and differences in methodologies and setups between steady-state experiments can lead to discrepancies in results. Experimental research has included more detailed approaches using glow plug-equipped engines, constant volume combustion chambers and rapid compression machines. In addition, the improved availability of mechanisms for fuel and lubricant surrogates has allowed researchers to model the oil–fuel interaction at the cylinder walls, evaporation and autoignition of oil–fuel droplets and regimes for different propagation modes of an autoignition reaction wave. This paper presents a comprehensive review of the underlying phenomena behind LSPI and its development to super-knock. Furthermore, it presents the methodology in experimental research and draws conclusions for mitigating strategies based on studies involving fuel, oil and engine parameters. Finally, it discusses the prerequisites for LSPI from oil–fuel droplets and the future needs of research as original equipment manufacturers (OEM) and lubricant industry have already adopted some proven solutions to their products.     

汽油发动机稀薄燃烧NOx后处理系统试验研究

在一台1.5 L涡轮增压缸内直喷汽油发动机上,使用不同的三效催化反应器(three-way catalytic,TWC)、稀燃NOx捕集器(lean NOx trap,LNT)、被动选择性催化还原器(passive selective catalytic reduction,PSCR)等排气后处理组合,研究了汽油发动机...     

Cold-start hydrocarbon emissions in port-injected gasoline engines

An analysis is made of the sources of the high engine-out hydrocarbon (HC) emissions during cold starting of port-injected gasoline engines. A cycle-by-cycle analysis of the different parameters, which affect engine-out HC emissions, is made during the startup process. The contribution of each cylinder of a four-stroke V6, 3.3 l production engine in the total HC emissions is investigated. The HC emissions were measured in the exhaust port using a fast response flame ionization detector (FID). The effect of the initial startup position of the piston and valves in the cycle on combustion and HC emissions is examined. The mass of fuel injected, burned and emitted was calculated for each of the first 120 cycles. Different approaches to reduce engine-out and tailpipe HC emissions during cold-start are discussed.