The performance and emissions of modern automotive diesel engines are highly dependent on the application of pilot injection technology. This technology also appears well suited for application to low-temperature combustion strategies. In this study, the first results of a new quantitative planar laser-induced fluorescence equivalence ratio measurement technique of pilot injections inside an optically accessible diesel engine are presented using 1-methylnaphthalene as a tracer in a mixture of the diesel primary reference fuels, n-hexadecane (cetane) and 2,2,4,4,6,8,8-heptamethylnonane (iso-cetane). This combination overcomes the shortcomings of mismatched fuel volatility and density associated with commonly used toluene/n-heptane/iso-octane planar laser-induced fluorescence techniques. A tracer characterization in a flow cell and a calibration in the internal combustion engine are performed. The internal combustion engine measurements illustrate the mixture formation process for a pilot injection. Even at low injection mass of 3 mg, a strong penetration of the pilot is observed; fuel hits the piston bowl wall and is redirected upward to the cylinder head. Small amounts of fuel are also found to have penetrated into the bottom of the piston bowl. At top dead center, the pilot injection is still not completely homogeneously distributed in the piston bowl, and local equivalence ratios of Φ > 1 are found in the bowl.
EineckeSSchulzCSickV. Measurement of temperature, fuel concentration and equivalence ratio fields using tracer LIF in IC engine combustion. Appl Phys B2000; 71: 717–724.
2.
SchulzCSickV. Tracer-LIF diagnostics: quantitative measurement of fuel concentration, temperature and fuel/air ratio in practical combustion systems. Prog Energ Combust2005; 31: 76–121.
3.
LöfflerMBeyrauFLeipertzA. Acetone laser-induced fluorescence behavior for the simultaneous quantification of temperature and residual gas distribution in fired spark-ignition engines. Appl Optics2009; 49: 37–49.
4.
RothamerDASnyderJAHansonRKSteeperRR. Optimization of a tracer-based PLIF diagnostic for simultaneous imaging of EGR and temperature in IC engines. Appl Phys B2010; 99: 371–384.
5.
LuongMZhangRSchulzCSickV. Toluene laser-induced fluorescence for in-cylinder temperature imaging in internal combustion engines. Appl Phys B2008; 91: 669–675.
6.
DevillersRBruneauxGSchulzC. Investigation of toluene LIF at high pressure and high temperature in an optical engine. Appl Phys B2009; 96: 735–739.
7.
WilliamsBEwartPWangXStoneRMaHWalmsleyH. Quantitative planar laser-induced fluorescence imaging of multi-component fuel/air mixing in a firing gasoline-direct-injection engine: effects of residual exhaust gas on quantitative PLIF. Combust Flame2010; 157: 1866–1878.
8.
KochPLöfflerMWensingMLeipertzA. Study of the mixture formation processes inside a modern direct-injection gasoline engine. Int J Engine Res2010; 11: 455–471.
9.
TrostJZiganLLeipertzA. Quantitative vapor temperature imaging in DISI-sprays at elevated pressures and temperatures using two-line excitation laser-induced fluorescence. P Combust Inst2013; 34: 3645–3652.
10.
BerckmüllerMTaitNPLockettRDGreenhalghDAIshiiKUrataY. In-cylinder crank angle resolved imaging of fuel concentration in a firing spark-ignition-engine using planar laser-induced fluorescence. P Combust Inst1994; 25: 151–156.
11.
PetersenBMilesPCSahooD. Equivalence ratio distributions in a light-duty diesel engine operating under partially premixed conditions. SAE Int J Eng2012; 5: 526–537.
12.
TeaGBruneauxGKashdanJTSchulzC. Unburned gas temperature measurements in a surrogate diesel jet via two-color toluene-LIF imaging. P Combust Inst2011; 33: 783–790.
13.
MusculusMPBLachauxTPickettLMIdicheriaA. End-of-injection over-mixing unburned hydrocarbon emissions in low-temperature-combustion diesel engines. SAE technical paper 2007-01-0907, 2007.
14.
HottaYInayoshiMNakakitaKFujiwaraKSakataI. Achieving lower exhaust emissions and better performance in an HSDI diesel engine with multiple injection. SAE technical paper 2005-01-0928, 2005.
15.
RicaudJCLavoisierF. Optimizing the multiple injection settings on an HSDI diesel engine. In: THIESEL 2002, conference on thermo- and fluid dynamic processes in diesel engines, Valencia, 11–13 September 2002, pp.251–275.
16.
BadamiMMilloFD’AmatoD. Experimental investigation on soot and NOx formation in a DI common rail diesel engine with pilot injection. SAE technical paper 2001-01-0657, 2001.
17.
KastnerOAtzlerFMüllerAWeigandAWenzlawskiKZellbeckH. Multiple injection strategies and their effect on pollutant emission in passenger car diesel engines. In: THIESEL 2006, conference on thermo- and fluid dynamic processes in diesel engines, Valencia, 12–15 September 2006, pp.61–75.
18.
BadamiMMallamoFMilloFRossiEE. Experimental investigation on the effect of multiple injection strategies on emissions, noise and brake specific fuel consumption of an automotive direct injection common-rail diesel engine. Int J Engine Res2003; 4: 299–314.
19.
HasseCPetersN. Modelling of ignition mechanisms and pollutant formation in direct-injection diesel engines with multiple injections. Int J Engine Res2005; 6: 231–246.
20.
ParkCKookSBaeC. Effects of multiple injections in a HSDI diesel engine equipped with common rail injection system. SAE technical paper 2004-01-0127, 2004.
21.
CarlucciPFicarellaALaForgiaD. Effects on combustion and emissions of early and pilot fuel injections in diesel engines. Int J Engine Res2005; 6: 43–60.
22.
MendezSThirouardB. Using multiple injection strategies in diesel combustion: potential to improve emissions, noise and fuel economy trade-off in low CR engines. SAE technical paper 2008-01-1329, 2008.
23.
AnaselmiPKashdanJBressionGFerrero-LesurEThirouardBWalterB. Improving emissions, noise and fuel economy trade-off by using multiple injection strategies in diesel low temperature combustion (LTC) mode. SAE technical paper 2010-01-2162, 2010.
24.
VogelTWensingMLeipertzAIannuzziSLutzM. Influence of the fuel quantity on the spray formation and ignition under current engine relevant conditions. SAE technical paper 2011-01-1928, 2011.
25.
KastnerOAtzlerFJuvenelleCRotondiRWeigandA. Directly actuated piezo injector for advanced injection strategies towards cleaner diesel engines. In: 7th international symposium towards clean diesel engines, Aachen, 4–5 June 2009.
26.
CarlucciPFicarellaALaforgiaD. Effects of pilot injection parameters on combustion for common rail diesel engines. SAE technical paper 2003-01-0700, 2003.
27.
TerazawaYNakaiEKataokaMSakonoT. The new Mazda four-cylinder diesel engine. MTZ Worldwide2011; 72: 26–32.
28.
CataniaAd’AmbrosioSFinessoRSpessaECipollaGVassalloA. Combustion system optimization of a low compression-ratio PCCI diesel engine for light-duty application. SAE technical paper 2009-01-1464, 2009.
29.
KandaTKobayashiSMatsuiRSonoH. Study on euro IV combustion technologies for direct injection diesel engine. SAE technical paper 2004-01-0113, 2004.
30.
KitamuraTItoT. Mixing-controlled, low temperature diesel combustion with pressure modulated multiple-injection for HSDI diesel engine. SAE technical paper 2010-01-0609, 2010.
31.
EhleskogROchoterenaRLAnderssonS. Effects of multiple injections on engine-out emission levels including particulate mass from an HSDI diesel engine. SAE technical paper 2007-01-0910, 2007.
32.
KobanWKochJDHansonRKSchulzC. Oxygen quenching of toluene fluorescence at elevated temperatures. Appl Phy B2005; 80: 777–784.
33.
FuchsRKrenzerLGaubeJ. Excess properties of binary mixtures composed of a polar component and an alkane. Ber Bunsen Phys Chem1984; 88: 642–649.
34.
ShenSNagataI. Prediction of excess enthalpies of ketone-alkane systems from infinite dilution activity coefficients. Thermochim Acta1995; 258: 19–31.
35.
Le CozJ-FBaritaudT. Application of laser induced fluorescence for measuring the thickness of evaporating gasoline liquid films. In: Developments in laser techniques and applications to fluid mechanics: proceedings of the 7th international symposium, Lisbon, 11–14 July 1996, pp.115–131. Berlin/Heidelberg: Springer-Verlag.
36.
HanBSteeperR. Examination of iso-octane/ketone mixtures for quantitative LIF measurements in a DISI engine. SAE technical paper 2002-01-0837, 2002.
37.
HentschelWSchindlerK-PHaahtelaO. European diesel research IDEA: experimental results from DI diesel engine investigations. SAE technical paper 941954, 1994.
38.
ZhaoHLadommatosN. Optical diagnostics for in-cylinder mixture formation measurements in IC engines. Prog Energ Combust1998; 24: 297–336.
39.
KaiserSALongMB. Quantitative planar laser-induced fluorescence of naphthalenes as fuel tracers. P Combust Inst2005; 30: 1555–1563.
40.
OrainMBarangerPRossowBGrischF. Fluorescence spectroscopy of naphthalene at high temperatures and pressures: implications for fuel-concentration measurements. Appl Phys B2011; 102: 163–172.
41.
FaustSTeaGDreierTSchulzC. Temperature, pressure, and bath gas composition dependence of fluorescence spectra and fluorescence lifetimes of toluene and naphthalene. Appl Phys B2013; 110: 81–93.
42.
TrostJZiganLLeipertzASahooDMilesPC. Characterization of four different potential laser-induced fluorescence tracers for diesel engine application. Appl Optics2013; 52: 8001–8007.
43.
LeiningerJ-PLorantFMinotCBeharF. Mechanisms of 1-methylnaphthalene pyrolysis in a batch reactor. Energ Fuel2006; 20: 2518–2530.
44.
FLUIDAT® on the Net V 1.39/6.18—mass flow and physical property calculator, 2013, www.fluidat.com
45.
DavyMWilliamsPHanDSteeperR. Evaporation characteristics of the 3-pentanone–isooctane binary system. Exp Fluids2003; 35: 92–99.
46.
DaubertTEDannerRP. Physical and thermodynamic properties of pure chemicals: data compilation. Washington, DC: Taylor & Francis, 1989.
47.
WeastRC. CRC handbook of chemistry and physics. 70th ed.Boca Raton, FL: CRC Press, 1989.
48.
ColbanWFKimDMilesPCOhSOpatRKriegerR. A detailed comparison of emissions and combustion performance between optical and metal single-cylinder diesel engines at low temperature combustion conditions. SAE Int J Fuels Lubr2008; 1: 505–519.
49.
StaplesLRReitzRDHergartC. An experimental investigation into diesel engine size-scaling parameters. SAE Int J Eng2009; 2: 1068–1084.
50.
MilesPCRempelEwertBReitzRD. Squish-swirl and injection-swirl interaction in direct injection diesel engines. In: Proceedings of ICE 2003—6th international conference on engines for automobile, Capri-Naples, 14–19 September 2003.
