乙醇燃料HCCI-SI双燃烧模式发动机性能的试验研究

第26卷第1期西华大学学报·自然科学版2007年1月Vol 26, No. 1Journal of Xihua University. Natural Sciencejan 200文章编号:1673-159X(2007)01-0001-04乙醇燃料 HCCI-SI双燃烧模式发动机性能的试验研究郭英男1,彭亚平1,谭满志1,刘爽1,李华,张人杰1,李孟华2(1.吉林大学汽车学院,吉林长春130025;2.中国人民解放军总装备部车船军代局驻一汽代表室,吉林长春130011)摘要:在一台改进的单缸发动机上实现了乙醇火花点火燃烧和均质压燃两种燃烧方式。通过进气预热的方法得到了乙醇HCCI燃烧方式的工作区,并定义了燃烧的爆震边界和失火边界。研究结果表明,在采用进气预热的方式下,仅靠空气稀释,乙醇燃料的HCCl燃烧工作上限最大达到了SI工作方式下的50%。在乙醇HCCI燃烧的工作区域内,与SI燃烧方式相比,混合气很稀,因此缸内温度低,NOx的排放降低幅度最大可达58%以上。随着负荷的越小,混合气变得更稀缸内燃烧温度进一步降低,NOκ的降低幅度越大。但在整个负荷变化范围内CO和HC的排放都比较高关键词:乙醇;双燃烧模式;性能;排放中图分类号:U473.1+4;U464.11+4文献标识码:A0 Introductionmisfire in the light load and too rich charge wouldAlong with the development of economy, the lead to knocking in the heavy load. Hence, it'sproblems of energy conservation and environmental difficult for the engine to operate HCCI in full loadprotection have become more and more important. One of the solutions is that the engine operates HCCIThe engine, the main power source, consumes mostin medium load and operates SI in other loads[12-14Jof the petroleum resource. So how to improve theThe ethanol hCCi combustion has been achievedenergy utilization and decrease exhaust emission is the in a dual mode engine with fast-thermo managementmaInchallenge confronted by the related researchers. system and the combustion mode transition betweenHomogeneous charge compression ignition is a new HCCI and SI has been realized. The performances ofcombustion mode which combines the corresponding dual combustion modes engine have beenadvantages of combustion in the conventional gasolengine 'and diesel engine 1-4. The combustible 1 Experimental Apparatuses and Methodcharge in this new combustion mode is homogeneous 1.1 Engineand the NOx and soot emissions are little as cylinderIn order to realize the dual combustion modes incombustion temperature is low. The thermal this engine, the modifications on the compressionefficiency is high and the cycle-by-cycle variation is ratio and fuel supply system were carried out; thesmall. This combustion can be achieved in the engine ignition system and cylinder pressure acquisitionfueled with various fuels, including aether, natural system were added in this enginegas, gasoline, diesel, methanol, ethanol and soFor the ethanol with high octane value, theon(5-10. The investigation results obtained until now compression ratio in HCCI may be quite high.Butindicate that the combustion of this new mode mainly too high compression ratio would result in knock in SIdepends on the chemical kinetics of the charge, the mode, so the compression ratio of this engine wascombustion is almost simultaneous, there is no direct optimized and chosen to 11means to control the combustion rate[]. One of theIn order to control the fuel amount injected intomethods to control the combustion rate is to utilize thelean charge; however, too lean charge would result in contiHH中国煤化工 pressure electronicCNMHGReceived date: 2006-11-01Foundation item: This project is supported by State key basic study development layout(No: 2001CB209206)Biography: GUO Ying-nan(1946-), Male, Professor, ph. D advisor. His research interests include internal combustion engine emissions controlengine combustion control and engine substitute fuel, etc西华大学学报·自然科学版2007年form the homogeneous charge. The mCu of thiscontrol system is 80196KC and the ethanol amount上hasinjected can be adjusted freely according to theexperimentsThe idler rotate speed of base engine is half ofHorita gas analyerthe crankshaft speed exactly, so the shaft of the idleris machined to install the ignition distributor to ensurethe engine can be ignited during the operation. Apark plug is installed in the hole originally for theFuel Injetion trigsdiesel fuel injector in the cylinder head. The ignitionFig 2 Experimental Set-uptimings for the different operation conditions werecalibrated1.2 Methodor the ethanol fuel, one of the methods toThe load is controlled by the fuel injected whenobtain HCCI is to preheat the intake charge; based on the engine operates in HCCI mode. The chargefast-thermo management system was becomes richer as the load increases and the knockingdeveloped. The maximum temperature can be up to may occur when fuel-air ratio is up to a certain value350t in full speed and load. There would be and this is the upper limit of HCCI. During theknocking when the engine operates SI if the intake experimental process, the combustion is monitored bycharge is still preheated, so some modifications have a resonance knock sensor. Compared to the normalbeen done in the intake system, as shown in Fig. 1. combustion, the maximum sensor output which is aThe hot air valve closes and the ambient temperature voltage signal increases greatly when there isair valve opens when the engine operates in SI mode knocking. The outputs of the sensor with andat the cold start condition and at the light and heavy without knocking are shown in Fig 3 at the engineload conditions, the hot air valve opens and the speed 1200rpm. It is able to distinguish the normalambient temperature air valve closes when the engine combustion and knocking according to the voltage andoperates in HCCI at the medium load. The engine in the upper limit of HCCI operation can be definedSI mode is throttled with a main throttlebased on the voltage output. Too lean charge wouldresult in misfire or unstable combustion when theFast-thermo management systemengine load decreases, thus, the lower limit of HCcItake chargoperation can be defined The engine operates in SImode at other loads and the HCCI operation regioncan be obtainedHot air valve itsThe engine operates in SI mode at cold start andstinn molewarm-up. The ambient temperature air valve opensMainand the hot air valve closes. during the warm-up, theelectric heater is turned on and when the coolingFig. I Engine intake systemThe cylinder pressure acquisition system is madewithout knockingup of AVL gm12d cylinder pressure on the cylinderhead, charge amplifier, LF-102. 4BM-COSE photo-中国煤化工electricity coder, high speed data acquisition card andcorresponding software. The engine speed and torqueCNMHere also recorded with another high speed card“"4V3synchronously when the cylinder pressure is recordedThe experimental set-up is shown in Fig. 2Fig 3 Sensor output with or without knocking第1期郭英男等:乙醇燃料H( CI-SI双燃烧模式发动机性能的试验研究water temperature exceeds 80t and the intaketemperature exceeds 220C, the ambient temperatureknock boundaryair valve closes the hot air valve opens, and the mainthrottle is wide open, the ignition spark is cut offthe engine operates in HCCI mode2 Results and discussion10.5%The operation regions of HCCI and SI modes aremisfire boundaryonfined by the engine speed, n, and the brake mean10001200140016001800200022002400effective pressure, Pe, as shown in Fig. 4. Themaximum load in HCCi modes is about 50% of that(b)be variation rate compared with SIFig5 Effective thermal efficiencies and brake fuel consumptionsin SI mode. The combustion mode transition can bereduction rate of Ethanol engine in HCCI operation regionachieved near the knocking boundary and misfireboundaryThe following Fig. 6, 7 and 8 show theemissions in HCCI mode and the corresponding← ter linecomparisons with the SI mode. The+ in thefigures denotes increase and the"-denotes decreaseSI Operation region→ KnockingCompared to SI mode, the conclusion can be drawnthat the NOx emission in HCCI mode is extra lowand the maximum reduction of NOx in HCCI mode isHCCI Operation region98%, but the emission of HC and CO is a little bitSI Operation regionhigh. As the engine load increases, the charge10001200140016001800200022002400richens, the cylinder temperature rises, the heatFig 4 Operation regions of HCCI and SI combustion modesreleased increases and the combustion accelerates theemissions of hc and co reduce, the nox emisThe variations of effective thermal efficiency, et, in increases. The charge used in HCCI mode isthe hcci operation and comparisons with SI in brake fuelconsumption,be, are shown in Fig.5,the“"” in thegure denotes decreasenock boundarybecomes richer and yet increases. The reason lies in thatthe richer the charge the higher the combustion rate andhence the cylinder temperature and the more oomplete thecombustion. It also can be observed that the net mainlydepends on the load and there is hardly any relationshipmisfire boundarybetweenne and engine speed. Compared with the SI10001200140016001800200022002400mode 6 is 9-30% lower in HCCI modeNOx specikncok boundary中国煤化工CNMHGn/r/m/n2000220024000001200140016001800200022002400b)NOx reduction percentage compared with SI modeFig 6 NOx specific emissions in HCCI operation region and the(a)ne in the HCCIcomparisons with SI mode西华大学学报·自然科学版2007年and the combustion temperature is low, hence the 3 Conclusionsemission of Co and HC are higher, especially in the(1)The ethanol combustion mode transitoperation conditions with lightl engine loadbetween hCCi and SI can be achieved with the fas(2) The maximum engine load in HCCI modepurely diluted by air is about 50% of that at the samepeed in si mode.(3)Compared with the SI mode, met in HCCImode is higher and the be decreases 9-30%. Themisfire boundaryNOx emission decreases greatly, the reduction can be10001200140016001800200022002400n/r/ninup to 58%-98%, but the emission of HC and CO(a)Co specific emissionincrease especially in the operation conditions of light0.6Referencesknock boundary[1]U.S. Department of Energy Efficiency and Renewable EnergyOffice of Transportation Technologies[Z]. Homogeneous Charge Copression Ignition(HCCI) Technology-A Report to the U. S. Congress[2]M. Christensen, B. Johansson, P. Amneus, F. Mauss. Super-charged Homogeneous Charge Compression Ignition[C]. SAE 980787misfire boundary10001200140016001800200022002400[3]S. Aceves, J. Martinez Frias, D. Flowers, J. Smith, A De-coupled Model of Detailed Fluid Mechanics for Prediction of Iso-Octane(b)CO reduction percentage compared with SI modeHCCI Combustion[C]. SAE paper 2001-01-3612,2001Fig. 7 CO specific emissions in HCCI operation region and the4]Najt, P. M. Foster, D E Compression Ignited Homocomparisons with SI modeCharge Combustion[C]. 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