This paper demonstrates the use of laser induced breakdown spectroscopy (LIBS) as a diagnostic technique to obtain optical measurements of equivalence ratio in a sparkignited engine. Point measurements were obtained in the exhaust manifold of an automotive engine close to the exhaust port of a cylinder. The experimental apparatus was synchronized with the engine in order to obtain measurements in a fixed position during the cycle. Eighty-shot averaged measurements of equivalence ratio P, obtained in under 10 s, were shown to have ΔP = ±0.05 (95 per cent confidence interval). Single-shot measurements were hindered by noise in the signal, but it is shown that the statistical technique of principal component analysis can significantly improve the precision of the data and allows discrimination between measurements obtained in lean, stoichiometric, and rich conditions. The data presented represent one of the first applications of LIBS to optical measurements of the equivalence ratio in an engine, and considerable improvements are expected with further study.
SchutteM.FinkeH.GrunfeldG.Spatially-resolved air-fuel ratio and residual measurements by spontaneous raman scattering in a direct injection gasoline engineSAE Trans, J. Fuels Lubricants2000, 109, 942.
2.
EineckeS.SchultzC.SickV.Measurement of temperature, fuel concentration, and equivalence ratio fields using tracer LIF in IC engine combustionAppl. Phys B.2000, 71, 717–723.
3.
PhuocT. X.WhiteF. P.Laser-induced spark for measurements of the fuel-to-air ratio of a combustible mixtureFuel2002, 81, 1761–1765.
4.
FanslerT. D.DrakeM. C.StojkovicB.Local fuel concentration measurements in internal combustion engines using spark-emission spectroscopyAppl. Phys. B.2002, 75(4/5), 577–591.
5.
FanslerT. D.DrakeM. C.StojkovicB.Local fuel concentration, ignition, and combustion in a stratified charge spark-ignited direct-injection engine: Spectroscopic, imaging, and pressure-based measurementsInt. J. Engine Res.2003, 4(2), 61–87.
6.
FurlongE. R.MihalceaR. M.WebberM. E.Real-time adaptive combustion control using diode-laser absorption sensors In Proceedings of the Combustion Instisute, 1998, 27, 103–111.
7.
TongoniE.PalleschiV.CorsiM.Quantitative micro-analysis by laser-induced breakdown spectroscopy: A review of the experimental approachesSpectrochimica Acta B2002, 57, 1115–1130.
8.
SchechterI., Direct aerosol analysis by time resolved laser plasma spectroscopy - improvement by single shot measurementsAnalyt. Sci. Technol. (J. Korean Soc. Analyt. Sci.)1995, 8(4), 779–787.
9.
RadziemskiL. J.Review of selected analytical applications of laser plasmas and laser ablation, 1987–1994Microchem. J.1994, 50, 218–234.
10.
SneddonJ.LeeY.-I.Novel and recent applications of elemental determination by laser-induced breakdown spectrometryAnalyt. Lett.1999, 32(11), 2143–2162.
11.
BindhuC. V.HarilalS. S.TillackM. S.Energy absorption and propagation in laser-created sparksAppl. Spectrocscopy2004, 58(6), 719–726.
12.
YalcinS.CrosleyD. R.SmithG. P.Influence of ambient conditions on the laser air sparkAppl. Phys. B.1999, 68(1), 121–130.
13.
BuckleyS. G.JohnsenH. A.HenckenK. R.Laser-induced breakdown spectroscopy as a continuous emission monitor for toxic metals in thermal treatment facilitiesWaste Mgmt2000, 20, 455–462.
14.
BuckleyS. G.Laser-induced breakdown spectroscopy for toxic metal emission measurements: Experimental considerations and oxygen quenchingEnviron. Engng Sci.2005, 22(2), 195–204.
15.
FerioliF.PuzinauskasP. V.BuckleyS. G.Laser-induced breakdown spectroscopy for on-line engine equivalence ratio measurementsAppl. Spectroscopy2003, 57(9), 1183–1189.
16.
SturmV.NollR.Laser-induced breakdown spectroscopy of gas mixtures of air, CO2, N2, and C3H8 for simultaneous C, H, O, and N measurementAppl. Optics2003, 42(30), 6221–6225.
17.
FerioliF.BuckleyS. G.Measurements of hydrocarbons using laser-induced breakdown spectroscopyCombust. Flame2006, 144, 435–447.
18.
WinklerM. A.MuellerE.Determination of the air/fuel ratio of an SI engine during transients with a standard UEGO sensorSAE paper 2001-01-1955, 2001.
19.
WagnerR. M.DawC. S.GreenJ. B.Low order map of lean cyclic dispersion in premixed spark ignition enginesSAE paper 2001-01-3559, 2001.
20.
NodaM.DeguchiY.IwasakiS.Detection of carbon content in a high-temperature and high-pressure environment using laser-induced breakdown spectroscopySpectrochimica Acta B2002, 57(4), 701–709.
21.
ChenY. L.LewisJ. W.L.PariggerC., Spatial and temporal profiles of pulsed laser-induced air plasma emissionsJ. Quant. Spectrosc. Radiat. Transfer2000, 67(2), 91–103.
22.
PanneU.HaischC.ClaraM.Analysis of glass and glass melts during the vitrification process of fly and bottom ashes by laser-induced plasma spectroscopy. Part I: Normalization and plasma diagnosticsSpectrochimica Acta, B1998, 53, 1957.
23.
FisherB.JohnsenH.BuckleyS.Temporal gating for the optimization of laser-induced breakdown spectroscopy detection and analysis of toxic metalsAppl. Spectrocscopy2001, 55(10), 1312–1319.
24.
BulatovV.XuL.SchechterI.Spectroscopic imaging of laser-induced plasmaAnalyt. Chem.1996, 68(17), 2966–2973.
25.
FerioliF.PuzinauskasP. V.BuckleyS. G.LIBS for real-time equivalence ratio measurements in spark-ignited engines In Second International Conference on Laser-induced plasma spectroscopy, 2002, Orlando, FL.
26.
ZangA.TempelT.YuK.Experimental characterization of cavity-augmented supersonic mixing43rd AIAA Aerospace Sciences Meeting and Exhibit, 2005, Reno, NV.
27.
BrownS. D.Chemical systems under indirect observation: Latent properties and chemometricsAppl. Spectroscopy1995, 49(12), 14A.
