Factors Determing Ignition and Efficient Combustion in Modern Engines Operating on Gaseous Fuels332.The higher initial pressure increases the thermal efficiency of the ignition system.3.For the conventional ignition systems even with high secondary energy above 60 mjonlya small partmaximum15%of it is consumedby the charge.The maximum of thermal efficiencywas obtained at initial pressure 25 bars with value4.of13,5%forthesparkplugwiththinelectrodesandonly1%atambientpressureandtemperature.The spark plug with thin electrodes indicates higher thermal efficiency than the spark5.plug with normal electrodes. This is caused by small heat exchange with the electrodewalls.6.The energy losses consist of heat exchange, ionization energy (breakdown), radiationand others. The biggest of them are the heat transfer to the spark electrodes andradiation.7.On thebasisof CFD simulation oneproved thatnatureof mixturemotion (tumble orswirl)in the combustion chamber influences on propagation velocity of the ignitionkernel and combustionprocess.Ignition in CNG diesel engine can be caused by injection of small ignition dose of diesel8.oil.AuthordetailsWladyslaw MitianiecCracowUniversityof Technology,Cracow,PolandAcknowledgementThe author would like to acknowledge the financial support of the European Commission inintegrated project"NICE"(contract TIP3-CT-2004-506201).PersonallyIwould like toacknowledge the contribution of the Cracow University of Technology,particularly Prof.B.Sendyka for supervising during the project and Dr. M. Noga for his big input in theexperimental work.12.References[1] Heywood J (1988), Internal Combustion Engine Fundamentals, Mc Graw-Hill, NewYork[2] Look D.C., Sauer H.J (1986), Engineering Thermodynamics, PWS Engineering, Boston[3] Mitianiec W., Jaroszewski A. (1993),Mathematical models of physical processes insmall power combustion engines (in polish),Ossolineum, Wroclaw-Warszawa-Krakow[4] Ramos J.I (1989),Internal combustion modeling,Hemisphere Publishing Corporation,NewYork[5] Amsden A.A. et al (1989), KIVA-II -A Computer Program for Chemically ReactiveFlowswith Sprays, LosAlamosNational Lab.,LA-11560-MS
Factors Determing Ignition and Efficient Combustion in Modern Engines Operating on Gaseous Fuels 33 2. The higher initial pressure increases the thermal efficiency of the ignition system. 3. For the conventional ignition systems even with high secondary energy above 60 mJ only a small part maximum 15% of it is consumed by the charge. 4. The maximum of thermal efficiency was obtained at initial pressure 25 bars with value of 13, 5% for the spark plug with thin electrodes and only 1% at ambient pressure and temperature. 5. The spark plug with thin electrodes indicates higher thermal efficiency than the spark plug with normal electrodes. This is caused by small heat exchange with the electrode’ walls. 6. The energy losses consist of heat exchange, ionization energy (breakdown), radiation and others. The biggest of them are the heat transfer to the spark electrodes and radiation. 7. On the basis of CFD simulation one proved that nature of mixture motion (tumble or swirl) in the combustion chamber influences on propagation velocity of the ignition kernel and combustion process. 8. Ignition in CNG diesel engine can be caused by injection of small ignition dose of diesel oil. Author details Wladyslaw Mitianiec Cracow University of Technology, Cracow, Poland Acknowledgement The author would like to acknowledge the financial support of the European Commission in integrated project “NICE” (contract TIP3-CT-2004-506201). Personally I would like to acknowledge the contribution of the Cracow University of Technology, particularly Prof. B. Sendyka for supervising during the project and Dr. M. Noga for his big input in the experimental work. 12. References [1] Heywood J (1988), Internal Combustion Engine Fundamentals, Mc Graw-Hill, New York [2] Look D.C., Sauer H.J (1986), Engineering Thermodynamics, PWS Engineering, Boston [3] Mitianiec W., Jaroszewski A. (1993), Mathematical models of physical processes in small power combustion engines (in polish), Ossolineum, Wroclaw-Warszawa-Krakow [4] Ramos J.I (1989), Internal combustion modeling, Hemisphere Publishing Corporation, New York [5] Amsden A.A. et al (1989), KIVA-II - A Computer Program for Chemically Reactive Flows with Sprays, Los Alamos National Lab., LA-11560-MS
34 Internal Combustion Engines[6] Ballal D., Lefebvre A (1981), The Influence of Flow Parameters on Minimum IgnitionEnergyandQuenchingDistance,15thSymposiumonCombustion,Pp.1737-1746,TheCombustionInstitute,Pittsburgh[7] Eriksson L (1999), Spark Advance Modeling and Control, Linkoping University,dissertation No 580, Linkoping[8] Hires S.D., Tabaczynski R.J (1978), The Prediction of Ignition Delay and CombustionIntervalsforHomogeneousCharge,SparkIgnitionEngine,SAEPap.780232[9] Liu J.,Wang F., Lee L., Theiss N., Ronney P (2004), Gundersen M., Effect of DischargeEnergyand cavityGeometryonFlame Ignition byTransientPlasma,42ndAerospaceSciences Meeting, 6th Weakly lonized Gases Workshop,Reno, Nevada[10] Maly R, Vogel M (1979), Initiation and propagation of Flame Fronts in Lean CH4 - AirMixtures byaThreeModes of theIgnition Spark,Seventeenth SymphosiumonCombustion,Pp821-831,TheCombustion Institute,Pittsburgh[11] Sendyka B., Noga M (2007), Propagation of flame whirl at combustion of lean naturalgas charge in a chamber of cylindrical shape, Combustion Engines, 2007-SC2, BielskoBiala[12] Spadaccini L.J.,Tevelde J.A (1980), Autoignition Characteristic of Aircraft Fuels, NASAContractor Report Cr-159886[13] Thiele M, Selle S., Riedel U., Warnatz J.,Maas U (2000), Numerical simulation of sparkignition including ionization, Proceedings of the Combustion Institute, Volume 28, pp1177-1185[14] Vandebroek L.,Winter H., Berghmans J (2000), Numerical Study of the Auto-ignitionProcess in Gas Mixtures using Chemical Kinetics, K.U.Leuven, Dept. Of MechanicalEngineering, 2000[15] FEV (2004) information materials, Aachen
34 Internal Combustion Engines [6] Ballal D., Lefebvre A (1981), The Influence of Flow Parameters on Minimum Ignition Energy and Quenching Distance, 15th Symposium on Combustion, pp.1737-1746, The Combustion Institute, Pittsburgh [7] Eriksson L (1999), Spark Advance Modeling and Control, Linkoping University, dissertation No 580, Linkoping [8] Hires S.D., Tabaczyński R.J (1978), The Prediction of Ignition Delay and Combustion Intervals for Homogeneous Charge, Spark Ignition Engine, SAE Pap. 780232 [9] Liu J.,Wang F., Lee L., Theiss N., Ronney P (2004), Gundersen M., Effect of Discharge Energy and cavity Geometry on Flame Ignition by Transient Plasma, 42nd Aerospace Sciences Meeting, 6th Weakly Ionized Gases Workshop, Reno, Nevada [10] Maly R., Vogel M (1979), Initiation and propagation of Flame Fronts in Lean CH4 – Air Mixtures by a Three Modes of the Ignition Spark, Seventeenth Symphosium on Combustion, pp 821-831, The Combustion Institute, Pittsburgh [11] Sendyka B., Noga M (2007), Propagation of flame whirl at combustion of lean natural gas charge in a chamber of cylindrical shape, Combustion Engines, 2007-SC2, Bielsko Biała [12] Spadaccini L.J.,Tevelde J.A (1980), Autoignition Characteristic of Aircraft Fuels, NASA Contractor Report Cr-159886 [13] Thiele M., Selle S., Riedel U., Warnatz J.,Maas U (2000), Numerical simulation of spark ignition including ionization, Proceedings of the Combustion Institute, Volume 28, pp. 1177- 1185 [14] Vandebroek L.,Winter H., Berghmans J (2000), Numerical Study of the Auto-ignition Process in Gas Mixtures using Chemical Kinetics, K.U.Leuven, Dept. Of Mechanical Engineering, 2000 [15] FEV (2004) information materials, Aachen
Chapter2Fundamental StudiesontheChemical ChangesandItsCombustionPropertiesofHydrocarbonCompoundsbyOzoneInjectionYoshihitoYagyu, HideoNagata,NobuyaHayashi,HiroharuKawasakiTamikoOhshima,Yoshiaki Suda and Seiji BabaAdditional information is available at the end of the chapterhttp://dx.doi.org/10.5772/547061.IntroductionThepreventionofglobalwarmingcausedbyincreasingofCOzhasbeenhighinteresttothepublicand grows environmental awareness,and alsoeffectiveuseoffossilfuelespeciallyforavehicle with internal combustion engine, such as an automobile, a ship and an aircraft, hasbeen developed in several research field. Hydrogen for fuel cell, bio-diesel fuel (BDF),dimethyl ether (DME) and ethanol as alternative energy source for vehicle has been widelystudied (S. Verhelst&T. Wallner, 2009, M.Y. Kim et al., 2008, B. Kegl, 2011, T.MI Mahlia et al.,2012)andsomeofthemhavebeguntoexistatthemarketintherecentdecade.However,thesenew energy sources may take a long time until reaching at a real general use because of highinvestment not only for improving an infrastructure but retrofitting a system of vehicle.Effects of ozone addition on combustion of fuels were reported as original research works.Combustion of natural gas with ozone was studied, and reduction of concentration of cOandCnHmbyozoneinjectionwasobserved(M.Wilk&A.Magdziarz,2010).Ozoneinjectiontointernal compressionengineiseffectivetodecreaseintheemissionrateofNO,COandCH and an improvement of cetane number and fuel efficiency (T. Tachibana et al., 1997).Also there arepatent applications covering theinvention developed by the effect of ozoneinjection (Imagineering Inc.: JP 19-113570(A), Sun chemical Co., Ltd.: JP 7-301160, NissanMotor Co., Ltd.:JP 15-113570(A).Although the results of ozone injection were oftenreported, the mechanism of the phenomenon is still unclear.Discharge system forgenerating ozone was usually introduced before or directly in a cylinder, and then beforeexpansion stroke the excited oxygen species including ozone reacts on hydrocarboncompounds, such as petrol and light diesel oil.Previous reports are chiefly focused on the
Chapter 2 Fundamental Studies on the Chemical Changes and Its Combustion Properties of Hydrocarbon Compounds by Ozone Injection Yoshihito Yagyu, Hideo Nagata, Nobuya Hayashi, Hiroharu Kawasaki, Tamiko Ohshima, Yoshiaki Suda and Seiji Baba Additional information is available at the end of the chapter http://dx.doi.org/10.5772/54706 1. Introduction The prevention of global warming caused by increasing of CO2 has been high interest to the public and grows environmental awareness, and also effective use of fossil fuel especially for a vehicle with internal combustion engine, such as an automobile, a ship and an aircraft, has been developed in several research field. Hydrogen for fuel cell, bio-diesel fuel (BDF), dimethyl ether (DME) and ethanol as alternative energy source for vehicle has been widely studied (S. Verhelst&T. Wallner, 2009, M.Y. Kim et al., 2008, B. Kegl, 2011, T.M.I. Mahlia et al., 2012) and some of them have begun to exist at the market in the recent decade. However, these new energy sources may take a long time until reaching at a real general use because of high investment not only for improving an infrastructure but retrofitting a system of vehicle. Effects of ozone addition on combustion of fuels were reported as original research works. Combustion of natural gas with ozone was studied, and reduction of concentration of CO and CnHm by ozone injection was observed (M. Wilk&A. Magdziarz, 2010). Ozone injection to internal compression engine is effective to decrease in the emission rate of NO, CO and CH and an improvement of cetane number and fuel efficiency (T. Tachibana et al., 1997). Also there are patent applications covering the invention developed by the effect of ozone injection (Imagineering Inc.: JP 19-113570(A), Sun chemical Co., Ltd.: JP 7-301160, Nissan Motor Co., Ltd.: JP 15-113570(A)). Although the results of ozone injection were often reported, the mechanism of the phenomenon is still unclear. Discharge system for generating ozone was usually introduced before or directly in a cylinder, and then before expansion stroke the excited oxygen species including ozone reacts on hydrocarbon compounds, such as petrol and light diesel oil. Previous reports are chiefly focused on the
36 Internal Combustion Enginesphenomena/effects and are notmentioned.Wefocused on themeasurement of reactionproducts and investigated chemical changes among vapourised hydrocarbon compoundsand activated dry air or oxygen including ozone by exposing discharge in this paper.2. Material and method2.1.DischargereactorDischarge was generated on the surface of a grid pattern discharge element (size: 85mm x40mm, grid size: 5mm with 1mm in width of electrode) placed in the discharge reactor. Theelement was designed for generating surface discharge, and the discharge voltage wasgenerated by high AC voltage power supply (Logy Electric Co, LHV-13AC) and varyingfrom8.0kVto13.0kV(with approx.9kHz-11kHzin frequency).Ozoneconcentrationwasmeasured as a standard of active oxygen species and was generated between 0.62g/m3 to8.8g/m3 by dry air or pure oxygen.2.2.ReactorvesselandhydrocarboncompoundsPetrol and light diesel oil were used for reaction with dry air or oxygen exposed todischarge. We used commercially available petrol and light diesel oil in the test, and theoctane numberofpetrol and the cetane numberof light diesel oil areamong90 to92 andamong 53 to55 respectively.Hydrocarbon compounds as typified bypetrol and light dieseloil consist of a lot of chemical substances. Isooctane (2.2.4-trimethylpentane, CsHis), whichare one of the components of petrol and light diesel oil, are also applied as reactingsubstance of thetest.Thesehydrocarbon compoundswerevapourized inthe reactorvessel(Figure 1), and air or oxygen exposed to discharge was injected through inlet to investigatechemical reaction between active species and vapourised hydrocarbon compounds.Thecondition of the entire experiment was not controlled and was carried out under anatmosphericpressureandtemperaturearound23degreesCelsius.MixturegasHydrocarboncompoundsActiveDischargeFTIRCharcoalfilterreactorFigure1.Aschematicoftheexperimentalapparatus
36 Internal Combustion Engines phenomena/effects and are not mentioned. We focused on the measurement of reaction products and investigated chemical changes among vapourised hydrocarbon compounds and activated dry air or oxygen including ozone by exposing discharge in this paper. 2. Material and method 2.1. Discharge reactor Discharge was generated on the surface of a grid pattern discharge element (size: 85mm × 40mm, grid size: 5mm with 1mm in width of electrode) placed in the discharge reactor. The element was designed for generating surface discharge, and the discharge voltage was generated by high AC voltage power supply (Logy Electric Co., LHV-13AC) and varying from 8.0kV to 13.0kV (with approx. 9kHz~11kHz in frequency). Ozone concentration was measured as a standard of active oxygen species and was generated between 0.62g/m3 to 8.8g/m3 by dry air or pure oxygen. 2.2. Reactor vessel and hydrocarbon compounds Petrol and light diesel oil were used for reaction with dry air or oxygen exposed to discharge. We used commercially available petrol and light diesel oil in the test, and the octane number of petrol and the cetane number of light diesel oil are among 90 to 92 and among 53 to 55 respectively. Hydrocarbon compounds as typified by petrol and light diesel oil consist of a lot of chemical substances. Isooctane (2.2.4-trimethylpentane, C8H18), which are one of the components of petrol and light diesel oil, are also applied as reacting substance of the test. These hydrocarbon compounds were vapourized in the reactor vessel (Figure 1), and air or oxygen exposed to discharge was injected through inlet to investigate chemical reaction between active species and vapourised hydrocarbon compounds. The condition of the entire experiment was not controlled and was carried out under an atmospheric pressure and temperature around 23 degrees Celsius. Figure 1. A schematic of the experimental apparatus FTIR Active Charcoal filter Discharge reactor Mixture gas Air O2 Hydrocarbon compounds
Fundamental StudiesontheChemical Changes andIts CombustionProperties of Hydrocarbon Compounds by Ozone Injection 372.3.AnalysisofthemixturegasA compositionof the mixture gas of dry air exposedtodischarge and vapourisedhydrocarboncompoundswasdetectedbyFouriertransforminfraredspectroscopy(FTIRShimadzu corp.,FTIR-8900)and gas chromatography mass spectroscopy analysis (GC-MS,Shimadzu corp., GCMS-QP2010). Twenty-two meters reflective long-path distance gas cell(PikeTechnologies inc., PermanentlyAligned GasCell 162-2530)was installed to theFTIRfor detecting the detail of the gas.Wavenumber of the mixture gas was measured between4000cmto1000cmand theFTIRspectra of themixturegaswereaccumulated to40 times.Temperatureof thevapourizingchamberofGC (gas chromatography)was setupfrom30 to250 degrees Celsius with increasing10 degrees Celsius a minute,and entiremeasurementtimewas24minutes.Columnflowstayedconstanton2.43mLaminuteandcolumnpressure was kept 97.9kPa.Mass-to-charge ratio in MS (mass spectrometry) was detectedfrom35to250m/z.3.FTIRanalysisFirst of all of the investigations, dry air exposed to discharge and hydrocarbon compoundswas mixed in thetransparent bell jar (approximately 18L).FiftymL of commerciallyavailable petrol (octan number 90~92)was poured into the beaker,and it was placed in thecentreof thebell jar.Flowrateof the injectedgasto thebell jarwasconsistentlykepton12L/min,The vapourized hydrocarbon compounds became clouded immediately afterinjecting dry air exposed to the discharge, and it grew into a dense fume increasingly(Figure 2). It was suggested that active species in the gas decomposed a part of structure ofhydrocarboncompounds andwater molecules weregenerated.Thusthegenerationofcloudy mixture gas was probably caused by saturated water vapour.Figure 2. A picture of the bell jar with discharge (left) and without discharge (right)
Fundamental Studies on the Chemical Changes and Its Combustion Properties of Hydrocarbon Compounds by Ozone Injection 37 2.3. Analysis of the mixture gas A composition of the mixture gas of dry air exposed to discharge and vapourised hydrocarbon compounds was detected by Fourier transform infrared spectroscopy (FTIR, Shimadzu corp., FTIR-8900) and gas chromatography mass spectroscopy analysis (GC-MS, Shimadzu corp., GCMS-QP2010). Twenty-two meters reflective long-path distance gas cell (Pike Technologies inc., Permanently Aligned Gas Cell 162-2530) was installed to the FTIR for detecting the detail of the gas. Wavenumber of the mixture gas was measured between 4000cm-1 to 1000cm-1 and the FTIR spectra of the mixture gas were accumulated to 40 times. Temperature of the vapourizing chamber of GC (gas chromatography) was set up from 30 to 250 degrees Celsius with increasing 10 degrees Celsius a minute, and entire measurement time was 24 minutes. Column flow stayed constant on 2.43mL a minute and column pressure was kept 97.9kPa. Mass-to-charge ratio in MS (mass spectrometry) was detected from 35 to 250m/z. 3. FTIR analysis First of all of the investigations, dry air exposed to discharge and hydrocarbon compounds was mixed in the transparent bell jar (approximately 18L). Fifty mL of commercially available petrol (octan number 90 ~ 92) was poured into the beaker, and it was placed in the centre of the bell jar. Flow rate of the injected gas to the bell jar was consistently kept on 12L/min. The vapourized hydrocarbon compounds became clouded immediately after injecting dry air exposed to the discharge, and it grew into a dense fume increasingly (Figure 2). It was suggested that active species in the gas decomposed a part of structure of hydrocarbon compounds and water molecules were generated. Thus the generation of cloudy mixture gas was probably caused by saturated water vapour. Figure 2. A picture of the bell jar with discharge (left) and without discharge (right)