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Computational Optimization of Internal Combustion Engines Yu Shi Hai-Wen Ge Rolf D. Reitz • • Computational Optimization of Internal Combustion Engines 123 Dr. YuShi Prof.RolfD.Reitz Department of Chemical Engineering EngineResearch Center Massachusetts Instituteof Technology Universityof Wisconsin-Madison Bldg.66-264 1500EngineeringDr. 77Massachusetts Avenue Madison, WI53706 Cambridge,MA 02139 USA USA e-mail: [email protected] e-mail: [email protected] Dr. Hai-Wen Ge EngineResearch Center Universityof Wisconsin-Madison 1500EngineeringDr. Madison, WI53706 USA e-mail: [email protected] ISBN978-0-85729-618-4 e-ISBN978-0-85729-619-1 DOI10.1007/978-0-85729-619-1 SpringerLondonDordrechtHeidelbergNewYork BritishLibraryCataloguinginPublicationData AcataloguerecordforthisbookisavailablefromtheBritishLibrary (cid:2)Springer-VerlagLondonLimited2011 CONVEREGEisatrademarkofDeltathetaUKLimited,TheTechnocentre,PumaWay,Coventry,CV12TT,UK CONVERGEisatrademarkofConvergentScience,Inc.(Detailsinhttp://www.convergecfd.com/) ForteistrademarkofReactionDesign(Detailsinhttp://www.reactiondesign.com/)modeFRONTIERisatrademarkof ES.TEC.O.s.r.l.,AREAScienceParkPadriciano,99,Trieste,Italy,34012 OracleandJavaareregisteredtrademarksofOracleand/oritsaffiliates.Othernamesmaybetrademarksoftheir respectiveowners. Apartfromanyfairdealingforthepurposesofresearchorprivatestudy,orcriticismorreview,aspermittedunderthe Copyright,DesignsandPatentsAct1988,thispublicationmayonlybereproduced,storedortransmitted,inanyform orbyanymeans,withthepriorpermissioninwritingofthepublishers,orinthecaseofreprographicreproductionin accordancewiththetermsoflicensesissuedbytheCopyrightLicensingAgency.Enquiriesconcerningreproduction outsidethosetermsshouldbesenttothepublishers. Theuseofregisterednames,trademarks,etc.,inthispublicationdoesnotimply,evenintheabsenceofaspecific statement,thatsuchnamesareexemptfromtherelevantlawsandregulationsandthereforefreeforgeneraluse. Thepublishermakesnorepresentation,expressorimplied,withregardtotheaccuracyoftheinformationcontainedin thisbookandcannotacceptanylegalresponsibilityorliabilityforanyerrorsoromissionsthatmaybemade. Coverdesign:eStudioCalamarS.L. Printedonacid-freepaper SpringerispartofSpringerScience+BusinessMedia(www.springer.com) Preface Striking progress has been made in internal combustion engine design due to the development of computer models and optimization techniques. In this book we strive to document the state of the art in predictive IC engine modeling and optimization.Thefactthatthisisanimportanttopicforresearchanddevelopment is emphasized by society’s reliance on IC engines for transportation, commerce andpowergeneration. Indeed, theworldasweknow it wouldbe aquite different place were it not for the remarkable internal combustion engine! It drives all manner of utility devices (e.g., pumps, mowers, chain-saws, portable generators, etc.), as well as earth-moving equipment, tractors, propeller aircraft, ocean liners and ships, personal watercraft and motorcycles. However, its major application is powering the 600 million passenger cars and other vehicles on our roads today. 250millionvehicles(cars,buses,andtrucks)wereregisteredin2008intheUnited States alone. According to the International Organization of Motor Vehicle Manufacturers,about50millioncarsweremadeworld-widein2009,comparedto 40 million in 2000. Much of this dramatic increase comes from increased pros- perity in China, which became the world’s second-largest car market in 2010. A third of all cars are produced in the European Union, and about 50% of those are powered by diesel engines. Thus, IC engine research spans both gasoline and diesel powerplants. The world’s economic expansion has been powered by cheap oil. It has been argued that the increasein population from 1.9 billion inthe 1920s totoday’s 6.6 billion has been made possible, in part, by fossil fuel combustion and by the Ha- ber–Boschprocesstomakecropfertilizer.80%oftheroughly80billionbarrelsof crude oil consumed annually world-wide is used in IC engines for transportation. IntheUnitedStates,10millionbarrelsofoilareusedperdayinautomobilesand light-duty trucks, and 4 million barrels per day are used in diesel engines, with totaloilusageofabout2.5gallonsperdayperperson.Ofthis,62%isimportedoil, which at today’s $80/barrel, costs the US economy $1 billion/day. This cost is certain to increase as more-and-more economic development drives increased de- mand for automotive fuels world-wide. v vi Preface Associatedwithourmassiveoiluseistheaccompanyingannualemissionof37 billion tons of CO (6 tons each for each person in the world) and other pollutant 2 emissions, including nitric oxides (NOx) and particulates (soot). Pollutant emissions have serious environmental and health implications, and thus most govern- ments have imposed stringent vehicle emissions regulations that are continually being tightened further. In addition, CO emissions contribute to Green House 2 Gases (GHG), which some fear could lead to climate change with unpredictable consequences. Drastic reductions in fuel usage will be required to make appre- ciable changes in GHG trends. Today’s gasoline IC engine powered vehicle equipped with its 3-way catalyst foremissioncontrolconvertsonlyabout16%ofthechemicalenergyinthefuelto useful work—the rest is lost to the environment. The modern automotive diesel engine is 20 to 40% more efficient than its gasoline counterpart. However, mea- sures introduced to meet emissions mandates, such as the use of non-optimal fuel injectiontimings,largeamountsofExhaustGasRecirculation(EGR)orultra-high injectionpressures reduce dieselenginefuelefficiencies,andalsoincreaseengine expense.ManydieselenginemanufacturershaveelectedtouseSelectiveCatalytic Reduction (SCR) exhaust after-treatment for NOx reduction. However, with SCR thereisalsoafuelpenaltysinceareducingagentsuchasurea(carbamide)mustbe sprayedintotheexhauststreamatrates(andcost)ofabout1%ofthefuelflowrate forevery1g/kWhofNOxreductiondesired.SootcontrolisachievedusingDiesel Particulate Filters (DPF), which generally require periodic regeneration. This is achieved by adjusting the fuel-air mixture strength so as to increase exhaust temperatures to burn off the accumulated soot, which imposes as much as a 3% additional fuel penalty. From thesediscussions it is clear that new technologies are urgently needed to improve the efficiency of both gasoline and diesel engines. For further improvements, engines need to be optimized to balance emissions, fuel cost, and market competitiveness. As described in this book, this task can be efficiently attacked using state-of-the-art computational models and optimization methods. This has been made possible, in part, by dramatic increases in computer speeds that have increased 10,000-fold in the past 15 years. Engine development is now greatly facilitatedusingmulti-dimensionalComputationalFluidDynamic(CFD)toolsand optimization algorithms, supported by significantly reduced requirements for ex- perimental testing, which is extremely expensive. An additional enabling factor for engine CFD modeling has been the development of predictive models for the physical processes occurring in the combustion chamber. Many of these models are reviewed in this book, together with discussion of strategies to reduce computational cost and numerical inaccuracies. Exampleapplicationsarepresentedfortheoptimizationof2-strokespark-ignition gasoline and 4-stroke heavy- and light-duty diesel engines. The effects of design parameters including nozzle design, injection timing and pressure, swirl, EGR, engine size scaling, and piston bowl shape are considered, together with explo- ration of fuel effects for low temperature combustion strategies. It is also dem- onstrated how optimization results can be used in combination with regression Preface vii analysis to explore and explain the complex interactions between engine design parameters. The present example applications also demonstrate that current multi-dimen- sional CFD tools are mature enough to guide the development of more efficient and cleaner internal combustion engines. New low temperature combustion con- cepts, such as Homogeneous Charge Compression Ignition (HCCI), Premixed Charge Compression Ignition (PCCI) and Reactivity Controlled Compression Ignition (RCCI) offer the promise of dramatically improved engine efficiencies. For example, optimized dual fuel RCCI operation (port injection of gasoline togetherwithoptimizedin-cylindermultipledieselfuelinjections)wasdiscovered with computer simulations using the models and tools described in this book (Kokjohn et al. 2009). The computer simulations predicted high-efficiency, low- emissions operation with excellent combustion phasing control at high and low engine loads without excessive rates of pressure rise. Subsequent engine experi- mentshaveconfirmedthemodelpredictions,andhavedemonstratedthatUSEPA 2010 NOx and soot emissions mandates can be met in-cylinder without after- treatment,whileachievingupto57%grossindicatedthermalefficiency(Kokjohn et al. 2011). The adoption of RCCI combustion engines could improve fuel efficiencies by up to 20% over standard diesel operation, while also providing dramatic cost reductionsthroughtheeliminationoftheneedforexhaustafter-treatment.RCCIis applicable with a wide range offuels, including conventional gasoline and diesel, aswellasbiofuelssuchasethanolandbiodieselandtheirblends.Theimplications ofsuchimprovementsinfuelefficiencyareverysignificant.Forexample,ifRCCI were adopted to replace the relatively inefficient spark-ignition engine it is esti- mated that US transportation oil usage could be reduced by 34%, which equals 100% of the current US oil imports from Persian Gulf. If these efficiency improvements were combined with electric hybrid technologies in the vehicle, even greater reductions in oil usage would be possible. The ultimate goal of engine modeling is to guide designers to improve engine performanceandtoreducepollutantemissions.Thegoalofthisbookistoprovide an up-to-date reference to current developments and future directions in the field ofenginemodeling. We hopethatyouwillthinkthatwehave achieved thisgoal. Acknowledgments This book expands on recent computational optimization studies of internal combustion engines performed at the Engine Research Center of the University of Wisconsin-Madison. The present work would not have been possible without the solidresearchfoundationthatourERCcolleagueshavebuiltoverthepastdec-ades. Wewouldliketoexpressoursinceregratitude tothem.Duringthepreparationof this book, we also received valuable suggestions from our colleagues, Dr. Shiyou Yang, Dr. Yuxin Zhang and Mr. Yue Wang, towhom we are indebted. The work included in this book was supported financially by several govern- ment and industry research projects. We are grateful to the US Department of Energy, Caterpillar Inc., Ford Motor Company, General Motors, and Detroit DieselCompanyfortheirlongtermsupport.WealsothankDr.DavidWickmanof Wisconsin Engine Research Consultants for allowing use of the Kwickgrid software. ESTECO provided access to optimization software (modeFRONTIER), which facilitated some of the assessment studies in this book. We thank the Society of Automotive Engineers (SAE), American Society of Mechanical Engineers (ASME), American Chemical Society (ACS), SAGE Pub- lications Ltd., Elsevier, and Taylor & Francis for allowing us to use figures and other materials from previously published articles. We also thank Springer for inviting us to write and helping us to prepare this book. Finally, we very much appreciate our families for their love, encouragement, support, and their understanding in our lives, in our research work, and in the preparation of this book. December 31, 2010 Yu Shi Hai-Wen Ge Rolf D. Reitz ix

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using state-of-the-art computational models and optimization methods. This book expands on recent computational optimization studies of internal com .. Polycyclic aromatic hydrocarbon. PCA. Principal component analysis. PDF.