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`Air Pallllmfigm fmm
`
`Emgmeg
`
`Migrmafl Cgmbmflfimn
`
`
`
`Edited by
`
`ER-AN SEER
`
`PAICE 2032
`BMW v. Paice
`|PR2020-01299
`
`1
`
`PAICE 2032
`BMW v. Paice
`IPR2020-01299
`
`

`

`Handbook of
`
`Air Pollution from
`
`Internal Combustion Engines
`
`Pollutant Formation and Control
`
`2
`
`

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`This Page Intentionally Left Blank
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`3
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`

`Handbook of
`
`Air Pollution from
`
`internal Combustion Engines
`
`Pollutant Formation and Control
`
`Edited by
`
`Eran Sher
`
`@
`
`ACADEMIC PRESS
`
`Boston
`London
`
`San Diego New York
`Sydney Tokyo Toronto
`
`4
`
`

`

`This book is printed on acid-free paper.
`
`Copyright © 1998 by Academic Press.
`
`All rights reserved.
`
`No part of this publication may be reproduced or
`transmitted in any form or by any means. electronic
`
`or mechanical. including photocopy, recording, or
`any information storage and retrieval system, without
`
`permission in writing from the publisher.
`
`ACADEMIC PRESS
`
`525 B Street, Suite 1900. San Diego. CA 92101. USA
`
`130!) Boylston Street, Chestnut Hill. MA 02167, USA
`bttpflwwwapnetcom
`
`United Kingdom Edition published by
`ACADEMIC PRESS LIMITED
`
`24-28 Oval Road. London NW1 70X
`
`httpzlt'wwwhbuk/coukfap/
`
`ISBN: 0-12-639855-0
`
`Library of Congress Cataloging—in-Publication Data
`
`Handbook of air pollution from internal combustion engines : pollutant
`formation and control 1' edited by Eran Sher-
`p.
`cm.
`
`Includes bibliographical references and index.
`ISBN 0-12-639855-0 (alk. paper)
`1. Motor vehicles—Motors—Exhaust gas—Environmental aspects.
`2. Internal combustion engines—Environmental aspects.
`3. Air--
`Pollution.
`I. Sher, Eran.
`TD886.S.H36
`1998
`
`629.25’28—de21
`
`97-48256
`
`CIP
`
`Printed in the United States ot‘ America
`
`989900t11021P987654321
`
`5
`
`

`

`Dedication
`
`I owe my roots to Professor Chaim Elata of the Ben-Gurion University.
`
`Beer-Sheva, Israel,
`
`who taught me how to think.
`
`I owe my stem to the late Professor Rowland S. Benson of UMIST
`Manchester, England.
`who taught me how to observe.
`
`I owe my foliage to Professor James C. Keck of MIT, Cambridge.
`Massachusetts. USA,
`
`who taught me how to analyze.
`
`6
`
`

`

`This Page Intentionally Left Blank
`
`7
`
`

`

`Contents
`
`List of Contributors ..............................
`
`xiii
`
`Acknowledgments ...............................
`
`xix
`
`PART l
`
`OVERVIEW ....................................
`
`1. Motor Vehicle Emissions Control: Past
`Achievements, Future Prospects
`
`John B. Heywood Sun Jae Professor of Mechanical Engineering,
`
`Director: Sloan Automotive labo ratory. Massachusetts Institute of
`
`Technology, Massachusetts, United States
`
`1.1
`l .2
`
`Synopsis ......................................
`Introduction ...................................
`
`1.3 Motor Vehicles and Air Pollution ...................
`
`1.4
`
`1.5
`
`The Science of Pollutant Formation and Control ........
`
`Effectivcncszs of Current Emission Control Technology .
`
`.
`
`.
`
`1.6 Direct-Injection Engines, "No-Strokes. and Diesels ......
`
`1.7
`
`Future Prospects ................................
`References ....................................
`
`l
`
`3
`
`4
`4
`
`5
`
`9
`
`15
`
`17
`
`20
`23
`
`PART ll
`
`GLOBAL ASPECTS ..............................
`
`25
`
`2. Environment Aspects of Air Pollution
`
`Eran Sher Department of Mechanical Engineering, The Pearlstone
`
`CenterforAeronauticai Engineering Studies, Ben-Gurion University of
`
`the Negev, Beer Shelia, Israel
`2. 1
`Introduction ...................................
`
`27
`
`28
`
`vii
`
`8
`
`

`

`viii
`
`Contents
`
`2.2 Global Effects ..................................
`
`2.3
`
`Regional Effects ................................
`References ....................................
`
`3. Health Aspects of Air Pollution
`
`Rafaei 5. Care! Division of Community Medicine. Facnity of Hcaith
`
`Sciences. Soroka Medical Center: Beer-Shem, Isroei
`
`Anatomy and Physiology of the Respiratory System .....
`3.]
`3.2 Defense Mechanisms of the Lung ...................
`
`3.3 Ventilatoty Function Tests .........................
`3.4
`Principles of Inhalation Injuries .....................
`3.5 Airborne Pollutants Causing Cancer and other Diseases
`.
`.
`References ....................................
`
`4. Economic and Planning Aspects of Transportation
`Emissmn
`
`Paint: 0. Piaut Faculty of Architecture and Town Planning, Technion,
`Israel Institute of Technology. Haifa. Israel
`
`Steven E. Piotr! Graduate Schooi of Business Adtttittistration, Uttiversig'
`
`ofHaifa. Haifa. Israei
`4.1
`Introduction ...................................
`
`The Notion of Optimal Pollution Abatement and Control
`4.2
`4.3 Alternative Sets of Abatement. Policies for Mobile-
`
`_
`
`Source Emissions ...............................
`
`4.4 Administrative Methods of Pollution Emissions Control
`
`.
`
`.
`
`4.5
`4.6
`
`indirect Pricing Mechanisms .......................
`Conclusions ...................................
`
`References ....................................
`
`23
`
`35
`41
`
`42
`
`43
`52
`
`56
`58
`63
`64
`
`65
`
`66
`
`68
`
`T2
`
`7?
`
`82
`86
`
`87
`
`PART III
`
`
`
`SPARK-IGNITION ENGINES ......................
`
`91
`
`5.
`
`Introductory Chapter. Overview and the Role
`of Engines with Optical Access
`
`Richard Stone Department ofEngineerittg Science. University.’ of
`Oxford. Oxford. United Kingdom
`5.]
`Introduction ...................................
`
`5.2
`5.3
`5.4
`
`Engines with Optical Access .......................
`High-Speed Photography .........................
`Flame Front Detection ...........................
`
`5.5 Mixture Preparation and Combustion Diagnostics .......
`
`93
`
`94
`
`97
`98
`102
`
`105
`
`9
`
`

`

`Contents
`
`Some Applications of Engines with Optical Access ......
`5.6
`5.? Conclusions ...................................
`
`References ....................................
`
`6. Combustion-Related Emissions in 51 Engines
`
`Simone Hochgreb Department ofMechanical Engineering,
`
`Massachusetts institute of Technology, Massachusetts, United Stores
`6.]
`Introduction ...................................
`
`6.2 NOxFormation .................................
`6.3
`Carbon Monoxide ...............................
`
`6.4 HC Emissions ..................................
`
`6.5
`
`Summary .....................................
`References ....................................
`
`7. Pollution from Rotary Internal Combustion Engines
`
`Mark Dnlger Deparmenr of Mechanical Engineering, Ben-Gurion
`UniversiQL Beer-Sheen. Israel
`7.1
`Introduction ...................................
`
`12
`
`Sources of Hydrocarbon Emissions ..................
`References ....................................
`
`8. Control Technologies in Spark-Ignition Engines
`
`Brian E. Milton Nnjfield Professor of Mechanical Engineering, Head of
`School, School ofMechanical and Manofacmring Engineering. The
`University of New South Wales, Sydney. Australia
`8.1 Global and Local Emissions: A Brief Overview of the
`
`Problem ......................................
`
`8.2 Global Emissions from SI Engines ..................
`8.3
`Engine Control Factors for Local Emissions ...........
`8.4
`Transient Operation of Engines and the Effect on
`Emissions .....................................
`
`8.5
`
`Some Details of Control Systems ...................
`
`8.6 Developments for the Future .......................
`References ....................................
`
`1):
`
`112
`115
`
`l 15
`
`113
`
`119
`
`124
`135
`
`137
`
`163
`164
`
`171
`
`171
`
`115
`188
`
`139
`
`190
`
`205
`209
`
`210
`
`222
`
`246
`255
`
`PART IV
`
`COMPRESSION-IGNITION ENGINES ...............
`
`259
`
`9.
`
`Introduction
`
`Franz F. Piscltinger FEV Motorenrechnik GmbH and Co KG. Aachen,
`Germany
`9.1
`
`The Diesel Engine for Cars—Is There a Future? ........
`
`261
`
`262
`
`10
`
`10
`
`

`

`x
`
`Contents
`
`9.2
`9.3
`9.4
`
`State of Technology .............................
`Technology for the Future .........................
`Summary and Conclusions ........................
`
`10. Combustion-Related Emissions in C1 Engines
`
`J. Gary Hawley. Chrisl Brace, and Frank J. Wallace Department of
`
`Mechanical Engineering, University of Bath, Bath, United Kingdom
`
`Roy W. Horrocks Diesel Engine Poniertrain. Ford Motor Co. Ltd.
`
`Laindon. United Kingdom
`10.]
`Introduction ...................................
`
`10.2 Review of Current and Projected Emissions Concerns—
`General Considerations ...........................
`
`10.3 High—Speed DI Diesel Developments ................
`10.4 Overview of Emissions from C1 Engines ..............
`10.5 Current and Projected Global Emissions Legislative
`Requirements ..................................
`10.6 Advanced Emission Reduction Strategies for the Year 2000
`
`and Beyond ....................................
`
`10.7
`Steady—State and Transient Emissions ................
`10.8 Application of Computational Tools Toward Predicting and
`
`Reducing Emissions .............................
`
`10.9 Advance Engineering Project ......................
`References ....................................
`
`11. Control Technologies in Compression-Ignition
`Engines
`
`Stephen J. Charlton Director: Advanced Diesel Engine Technology,
`
`Cammins Engine Company, Inc, indiana, United States
`11.1
`Introduction ...................................
`
`11.2 Electronic Fuel Systems for Diesel Engines ............
`11.3 Basic Principles of Electronic Control for Diesel Engines .
`11.4 Electronic Hardware for Diesel Engine Control .........
`l 1.5 Exhaust Aftcrtrcatment ...........................
`
`References ....................................
`
`265
`
`269
`
`278
`
`280
`
`281
`
`283
`
`285
`
`288
`
`301
`
`306
`
`33?
`
`341
`
`350
`
`353
`
`358
`
`359
`
`365
`
`374
`
`390
`
`406
`
`4171
`
`PART V
`
`TWO-STROKE ENGINES ..........................
`
`421
`
`12.
`
`Introductory Chapter: From a Simple Engine to an
`Electrically Controlled Gasdynamic System
`
`FTZ Research rind Technology Association Zwickau.
`Come! C. Stan
`Westsaton institute of Zwickaa, Zwiekaa. Germany
`12.1
`Introduction ...................................
`
`423
`
`424
`
`11
`
`11
`
`

`

`Contents
`
`12.2 Pollution Formation .............................
`
`12.3 Methods of Mixture Preparation ....................
`12.4 Techniques to Reduce Pollution ....................
`
`l2.5 The Future of the Two-Stroke Engine ................
`References ....................................
`
`l3. Air Pollution from Small Two-Stroke Engines and
`Technologies to Control It
`
`Yuji Ikeda and Tsnyoshi Nairjima Department of Mechanical
`Engineering, Kobe Universiot Roklxio‘ai, Nada, Kobe, Japan
`
`Eran Sher Department of Mechanical Engineering, The Pearlstone
`Centerfor Aeronautical Engineering Studies. Ben-Gurion University,
`Beer-Sheva, Israel
`13. l
`Pollutant Formation .............................
`
`13.2 Pollutant Control ................................
`
`13.3
`
`.
`.
`Flow and Emission Diagnostics (Experimental Results)
`References ....................................
`
`14. Air Pollution from Large Two-Stroke Diesel Engines
`and Technologies to Control It
`
`Svend Henningsen MAN B&W Diesei A/S. R&D Department.
`Copenhagen, Denmark
`14. I
`Introduction ...................................
`
`14.2 Regulated Emissions .............................
`14.3 Exhaust Emissions ..............................
`
`14.4
`
`ExhaUSt Emission ControlTechnologies—NOX Reduction
`Techniques ....................................
`14-5 Exhaust Emission Control Technologies—Reduction of
`Other Pollutants ................................
`
`References ....................................
`
`xi
`
`426
`
`429
`
`433
`
`436
`
`442
`
`441
`
`442
`
`448
`
`456
`
`473
`
`477
`
`478
`
`479
`
`482
`
`494
`
`516
`
`530
`
`PART VI
`
`FUELS ........................................
`
`535
`
`15.
`
`Introductory Chapter: Fuel Effects
`
`David R. Blackmore Sheff Research and Technology Centre, Shell
`Research Ltd” Thornton, Chester, United Kingdom
`15.1 Historical Landmarks ............................
`
`15.2 Recent Developments ............................
`15.3 The Future ....................................
`
`[5.4
`
`In Conclusion ..................................
`
`537
`
`538
`
`541
`
`544
`
`545
`
`12
`
`12
`
`

`

`xii
`
`Contents
`
`16.
`
`Fuel Effects on Emissions
`
`Yoram Zvirin, Marcel Gunman and Leonid Tartakovsky Faculty of
`Mechanical Engineering, Technion. Haifit, Israel
`
`16.1 Background ...................................
`
`16.2 Gasolines (SI Engines) ...........................
`16.3 Diesel Fuels (CI Engines) .........................
`16.4 Alternative Fuels ................................
`
`References ....................................
`
`1 National Gasoline Specifications ........
`Appendix:
`Appendix: 2 National Specifications for Automotive
`Diesel Fuel ....................................
`
`Appendix: 3 US EPA Models for Calculation of Fuel
`Effects on Exhaust Emissions ......................
`
`547
`
`543
`
`550
`5?5
`603
`
`619
`
`624
`
`639
`
`645
`
`Index .........................................
`
`653
`
`13
`
`13
`
`

`

`List of Contributors
`
`PART I
`
`OVERVIEW
`
`1. Motor Vehicle Emissions Control: Past Achievements, Future Prospects
`
`Prof. John B. Heywood
`Dept. of Mechanical Engineering
`
`Massachusetts Institute of Technology
`
`Cambridge, MA 02139
`tel: 617-253-2243
`
`fax: 611253-598]
`
`e—mail: jheywood@mit.edu
`
`PART ll
`
`GLOBAL ASPECTS
`
`2. Environmental Aspects of Air Pollution
`
`Prof. Eran Sher
`
`Dept. of Mechanical Engineering
`Ben-Gurion University
`Beer-Sheva 84 105
`
`Israel
`
`tel: 972-7-646-1394
`
`fax: 972-7-647-2990
`
`e-mai]: sher®menix.bgu.ac.il
`
`3. Health Aspects of Air Pollution
`
`Prof. Rafael Carol
`
`Soroka Medical Center
`
`xi {'1'
`
`14
`
`14
`
`

`

`xiv
`
`List of Contributors
`
`Beer-Sheva, Israel
`tel: 9'72—"F-6494—663
`
`fax: 9?2—7—649—.3934
`
`e-mail: rearel@post.tau.ae.i|
`
`4. Economic and Planning Aspects of Transportation Emission
`
`Dr. Steven E. Plant
`
`Graduate School of Business Administration
`
`University of Haifa
`Haifa 31905. Israel
`tel: 972-4824—01 10
`
`fax: 972-4824—9194
`
`e-mail: rsec792 @uvm.haifa.ae.ii
`
`Dr. Pnina 0. Plant
`
`Faculty of Architecture and Town Planning
`Technion, Haifa, Israel
`
`PART III
`
`
`
`SPARK-[GNITION ENGINES
`
`Introductory Chapter: Overview and the Role of Engines
`5.
`with Optical Access
`
`Dr. Richard Stone
`
`Department of Engineering Science
`University of Oxford
`Oxford OX1 3P]
`
`United Kingdom
`tel: 44-1865-273—000
`
`fax: 44—1865—273—010
`
`e—mai]: richardstone@eng.ox.ac.uk
`
`6. Combustion-Related Emissions in SI Engines
`
`Prof. Simone Hochgrcb
`Dept. of Mechanical Engineering
`Massachusetts Institute of Technology
`Cambridge. MA 02139
`tel: 617-253-0912
`
`fax: GIT-2539453
`
`e—mail: simone® mit.edu
`
`7. Pollution from Rotor}r Internal Combustion Engines
`
`Dr. Mark Dulger
`Department of Mechanical Engineering
`
`15
`
`15
`
`

`

`XV
`
`List of Contributors
`
`Ben—Gurion University
`Beer~Sheva 84 105
`
`Israel
`
`tel: 972-7-646-1353
`
`fax: 912-7-647-2990
`
`e-mail: markd©menix.bgu.ac.il
`
`8. Control Technologies in Spark-Ignition Engines
`
`Prof. Brian Milton
`
`School of Mechanical and Manufacturing Engineering
`The University of New South Wales
`
`Barker Street, Gate [4
`
`Kensington, S ydney 2052
`Australia
`
`tel: 61~2-385-4088
`
`fax: 61-2-663—1222
`
`e-mail: milton@unsw.edu.au
`
`PART IV
`
`COMPRESSION-IGNITION ENGINES
`
`9.
`
`Introduction
`
`Prof. Dr. Franz Pischinger
`FEV Motorentechnik GmbH and Co. KG
`Neuenhofstrasse 181
`
`Aachen D—520?8
`
`Germany
`tel: 49—241—5689-10
`
`fax: 49-241-5689-224
`
`10. Combustion-Related Emissions in CI Engines
`
`Dr. Gary Hawley
`School of Mechanical Engineering
`University of Bath
`Bath, United Kingdom
`tel: 44—1225—826-860
`
`fax: 44—1'225—826—928
`
`e—mail: ensjgh®bath.ac.uk
`
`R. W. Horrocks
`
`Advanced Diesel Engines
`Research and Engineering Centre
`Ford Motor Company, Ltd.
`Laindon, United Kingdom
`
`16
`
`16
`
`

`

`xvi
`
`List of Contributors
`
`Frank Wallace and Chris Brace
`
`School of Mechanical Engineering
`University of Bath
`
`Bath. United Kingdom
`
`11. Control Technologies in Compression-Ignition Engines
`
`Dr. Stephen Charlton
`Direc tor, Advanced Diesel Engine Teehn ology
`
`Cummins Engine Company, Inc.
`Mail Code 50174
`
`1900 McKinley Avenue
`Columbus, Indiana 47201
`tel: 812—377—3788
`
`fax: 812-377—7226
`
`e—mail: 103173.622@eompuservetcom
`
`PART V
`
`TWO-STROKE ENGINES
`
`Introductory Chapter: From a Simple Engine to an Electrically
`12.
`Controlled Gasdynamic System
`
`Prof. Dr. Cornel Stan
`
`College of Technology and Economics
`Westsaxon Institute of Zwickau
`
`Germany
`tel: 49-3?5-536-[600
`
`fax: 49-3375-536-1193
`
`e-mail: comel.stan@fh-zwickau.de
`
`13. Air Pollution from Small Two-Stroke Engines and Technologies
`to Control [t
`
`Prof. Yuji Ikeda and Tsuyoshi Nakjma
`Department of Mechanical Engineering
`Kobe University
`Roklcodai, Nada
`
`Kobe. Japan
`lel: 81-78—803-1114
`
`fax: 81—78—84fi~2736
`
`e-mail: ikeda@mech.kobe—u.ac.jp
`
`Prof. Eran Sher
`
`Dept. of Mechanical Engineering
`Ben~Gurion University
`
`17
`
`17
`
`

`

`List of Contributors
`
`xvii
`
`Becr-Sheva 84 105
`
`Israel
`
`14. Air Pollution from Large Two-Stroke Diesel Engines
`and Technologies to Control It
`
`Dr. Svend Henningsen
`MAN and B&W Diesel A/S
`
`Copenhagen SV
`DK—2450
`
`Denmark
`
`tel: 453385-1100
`
`fax: 45—3385-1030
`
`e-Inail: svend.henningsenfcopenhagen@manbw.dk
`
`PART VI
`
`FUELS
`
`15.
`
`Introductory Chapter: Fuel Effects
`
`Dr. David Blackmore
`
`Research Centre
`
`Shell Research, Ltd.
`Thornton HO. 1
`
`Chester CH1 33H
`
`United Kingdom
`tel: 44-151-373—5768
`fax: 44-151-373—5674
`
`16. Fuel Effects on Emissions
`
`Prof. Yoram Zvirin
`
`Department of Mechanical Engineering
`Technion, Haifa 32000. Israel
`tel: 9T2—4—292-070
`
`fax: 972-4-324-533
`
`e-mail: meryzvi@1x.technion.ac.il
`
`18
`
`18
`
`

`

`This Page Intentionally Left Blank
`
`19
`
`

`

`Acknowledgments
`
`The editor wishes to acknowledge the following organizations for their support
`
`and cooperation: Ford Motor Co. Ltd, Advanced Diesel Engines Research and
`
`Engineering Centre, UK; FEV Motorentechnik GmbH & Co KG, Aachen,
`
`Germany; Cumrnins Engine Company, Inc., Advanced Diesel Engine Technology
`
`Columbus, Indiana. USA; MAN and B&W Diesel AIS, Copenhagen Denmark;
`Research Centre. Shell Research Ltd., Chester UK; and the Pearlstone Center for
`
`Aeronautical Studies, Ben—Gurion University, Israel.
`Academic Press and the editor would like to express their thanks to the fol-
`lowing reviewers and other helpful persons for their invaluable comments and
`
`suggestions: David Blackmore, Shell Research Ltd., Chester UK; Mark Dulger,
`Ben-Gurion University, Israel; Elbert Hendricks, The Technical University of
`
`Denmark, Lyngby, Denmark; Itzik Henig, Ford MotorCo., UK; Simone Hochgreb,
`MIT, Cambridge, Massachusetts, USA; Uri Regev, Ben-Gurion University, Israel;
`Zvi Ruder, Academic Press, Boston, Massachusetts, USA; Roger Sierens, Uni-
`versity of Gent, Gent, Belgium; Cornet Stan, Westsaxon Institute of Zwickau,
`Germany; Richard Stone, Oxford University, Oxford, UK; and Desmond Winter—
`bone, UMIST, Manchester, UK.
`
`The authors and editor wish to acknowledge the following publishers for their
`kind permission to reproduce figures from their publications: The Society of Au-
`tomotive Engineers, American Society of Mechanical Engineers, The Institution
`of Mechanical Engineers, Gordon and Breach Science Publishers, The Combus-
`tion Institute, Elscvicr Science Publishing Company, Edward Arnold Publishers,
`Macmillan Press, Automotive Matters International Ltd.. and TNO Road-Vehicles
`Research Institute.
`
`Special thanks are due to Elizabeth Voit. of Academic Press. and to Ian Vino-
`
`gradov and Ilai Sher for a careful preparation of some of the figures and illustrations
`in the handbook.
`
`Department of Mechanical Engineering
`
`The Peartstone Centerfor Aeronautical Studies
`
`Ben-Gurion University of the Negev. Beer-Shem. fsraef
`
`Eran Sher
`
`xix
`
`20
`
`20
`
`

`

`This Page Intentionally Left Blank
`
`21
`
`

`

`Handbook of
`
`Air Pollution from
`
`Internal Combustion Engines
`
`Pollutant Formation and Control
`
`22
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`22
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`PART I
`
`
`Overview
`
`1 Motor Vehicle Emissions Control: Past Achievements, Future Prospects
`
`John B. Heywood
`
`24
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`24
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`

`CHAPTER 6
`
`
`Combustion-Related
`
`Emissions in 51 Engines
`
`
`
`Simone Hochgreb
`Department of Mechanical Engineering, MIT} Massachusetts, USA
`
`
`
`6.1
`
`Introduction 119
`
`6.111 Main Regulated Pollutants: NO: , CO, HC, and Toxics
`6.1.2 Maximum Allowed Emission Levels
`120
`
`119
`
`6.1.3 Overview of Emission Sources
`
`121
`
`6.2
`
`N01 Formation 124
`
`6.2.] NO,‘ Production Mechanism 124
`
`6.2.2 Modeling NO Formation 126
`6.2.3 Effect of Operating Conditions on NO Formation
`6.2.4 Advanced Low-NO Engine Designs
`135
`Carbon Monoxide
`135
`
`130
`
`6.3
`
`6.3.1 Mechanism of C0 Formation
`
`135
`
`6.3.2 CO Formation Models
`
`135
`
`6.4
`
`HC Emissions
`
`137
`
`6.4.1 HC Sources
`
`139
`
`6.4.2 Effect of Operating Conditions on HC Emissions
`6.4.3
`Postflame Oxidation
`159
`
`156
`
`6.5
`
`Summary 163
`References
`164
`
`ISBN: 0-12—639855-0
`$25.00
`
`US
`
`Copyright (5‘; 1993 by Academic PMS
`All “girls of reproduction in any form reserved.
`
`26
`
`26
`
`

`

`6.]
`
`Introduction
`
`“9
`
`6.1
`
`-
`
`INTRODUCTION
`
`The design of spark—ignition (SI) engine systems has been increasingly constrained
`
`by the need to minimize vehicle pollutant emissions. Regulations requiring ever
`more stringent maximum emission levels have posed difficult challenges to the
`automotive industry. Significant engineering advances in combustion systems
`and emission control methods have led to major improvements in emissions per
`vehicle over the past 20 years. particularly in ambient carbon monoxide levels [1,
`2]. Owing to the increase in vehicle miles traveled. however, these improvements
`have not always translated into improved urban air quality.
`Emissions from properly operating modern Vehicles are at least one order
`of magnitude lower than original precontrol levels. Further reductions are being
`mandated. calling for better fueling and operation control. new catalytic materials.
`and innovative engineering solutions.
`In this chapter. the production mechanisms of combustion-related pollutants
`from four-stroke. spark-ignited engines are discussed. as well as techniques for
`minimizing sources upstream of the emissions aftertreatment process. This section
`offers an overview of the mechanisms leading to emissions in SI engines. Section
`6.2 describes the procoss of nitric oxide formation. and Section 6.3 discusses the
`origins of carbon monoxide. Sources of hydrocarbon emissions are examined in
`Section 6.4.
`
`6.l.l Main Regulated Pollutants: NO. , CO. HC, and Toxics
`
`The main pollutants of concern in the case of spark—ignition engines are nitric
`oxides (NO and N03 in general. but primarily N0 in spark-ignition engines}.
`carbon monoxide (CO). hydrocarbons (BC), and organic toxics (currently regu—
`lated toxics in the United States are benzene. acetaldehyde, formaldehyde. and
`1.3-butadiene). Nitric oxides, carbon monoxide. and toxic compounds have direct
`effects on human health. Nitric oxides and hydrocarbons contribute. in addition.
`to the formation of tropospheric ozone and smog. which lead to deleterious effects
`on visibility and human health. Particulate matter. a very important pollutant in
`the case of compression-ignition engines, is produced only in very small amounts
`in SI engines. However. concerns about health effects of small-size particulate
`matter (<2 um) have been increasing. and may lead to stricter standards.
`Nitric oxides and carbon monoxide are formed during the combustion pro-
`cess. leaving the engine with other combustion products. Hydrocarbons and toxics
`emissions, however, may originate both from the tailpipe in the form of unburned or
`partially burned fuel. as well as in the form of evaporative emissions from the fuel
`tank. fuel lines. and losses during the refueling process. Evaporative losses of HC
`are estimated to be about the same order of magnitude as the contribution from the
`
`27
`
`27
`
`

`

`120
`
`Chapter 6: Combustion-Related Emissions in 51 Engines
`
`
`
`Fig. 6.l.
`
`10
`
`3 ..
`
`
`
`g 6 l
`'U
`:I:
`5
`g
`
`4 I-
`
`2 l'
`
`+NO (glad)
`+ Exhaust HC (ghni)
`
`— N0 std (31ml)
`.
`.
`.
`. -HC std(g!mi)
`
`+C0 {simi}
`— — -CO std {glmi}
`
`100
`
`315'
`
`son
`%
`g
`
`40
`
`20
`
`.
`:
`'
`
`.
`
`'
`
`'
`
`:
`
`
`
`0
`I
`i o.."—' a; H I: '—‘
`_________
`1970
`1980
`1990
`2000
`2010
`
`a
`1960
`
`Year
`
`Evolution of aggregate light‘duty vehicle fleet emissions and associated uncertainties. as esti-
`mated by fleet aggregate simulations {symbols and lines:- and historical evolution of standards
`[lines]: [21.
`
`[n this chapter, however, only combustion-related (nonevaporative)
`exhaust [2].
`sources are considered.
`
`Enormous progress has been made in reducing tailpipe emissions since the
`introduction of catalytic converters 25 years ago (Figure 6.1). Emissions from
`properly operating modern vehicles are at least one order of magnitude lower than
`precontrol levels.
`
`6.1.2 Maximum Allowed Emission Levels
`
`Emissions standards are permanently evolving throughout the world, reflecting
`demands for air quality as well as expectations on the minimum technically feasi-
`ble emission levels. The state of California has led the way in lowering maximum
`allowable emission levels to address the severe air quality problems in southern
`California; however, many other countries have continuously moved to increas—
`ingly lower admissible levels.
`Maximum allowed emissions levels in the largest consumer markets (the
`United States, Eumpe, and Japan) govern manufacturers’ decisions in emission
`control implementation. Standards are defined relative to representative driving
`schedules in each region, so that absolute emission levels are not directly com-
`parable. The different schedules for passenger vehicle tests, as well as the cor-
`responding emission levels for spark-ignition engines are outlined in Figure 6.2
`and Table 6.1. These driving schedules, designed to represent a ”typical" driv-
`ing pattern, include a cold-start period, followed by moderate accelerations and
`
`28
`
`28
`
`

`

`12!
`
`6.]
`
`Introduction
`
`Fig.6.2.
`
`(ECE+EUDCJ
`
`uI
`
`
`I
`u
`II
`I
`
`I
`
`(EUROPE)
`
`namtumani
`[EOE]
`
`mmtm-umm}
`teuoci
`
`:12203
`:nmvkm Talaldurafion
`Langlh
`mmzmm Wmmam
`
`IONiMODEHOTCTCLE
`
`u‘
`
`II
`
`In
`
`an
`
`III
`
`III
`
`III
`
`II
`
`{JAPAN}
`
`HI I
`
`I a "
`
`I u a
`
`:ustcrn
`Length
`MSp-ndflOkrnt‘h
`
`:ama
`0mm
`AwngenpudfiZJM
`
`HI I
`
`
`
`
`II
`In
`mi"
`II
`
`Gold lllnsilnt
`PM (I)
`
`Dulcl Itlhlnd
`Phase {II}
`
`Hot Soak
`{9-11 min}
`
`Ho‘lWt
`Flue {III}
`
`(US)
`
`:17.8 km Tatum :18?“
`Length
`Hammad mam Ammlpmmtt Iii-Mi
`
`Driving schedules for emissions testing in Europe. Japan, and the United Slates.
`
`decelerations. The cold start period contributes a disproportionate fraction of the
`emissions (particularly hydrocarbons), as the catalytic converter requires tens of
`seconds to warm up and reach maximum removal efficiency. Therefore, much of
`the effort in designing effective emission controls has been targeted at the initial
`cold-start phase. This will become clear in the following discussions and in the
`description of emission control technology in Chapter 8.
`
`6.1.3 Overview of Emission Sources
`
`The origin of tailpipe (i.e., nonevaporative) emissions from spark-ignition engines
`is shown schematically in Figure 6.3. Nitric oxides and carbon monoxide are
`formed via oxidation of molecular nitrogen and fuel in the bulk gases, whereas
`
`29
`
`29
`
`

`

`122
`
`EU
`
`Chapter 6: Combustion—Related Emissions in SI Engines
`
`Table 6.I
`
`Emissions standards for passenger vehicles
`
`] 99311.0
`Gasoline
`
`1996
`
`2000“
`
`Test
`Emissions
`Units
`(:Diesel)
`Gasoline
`Diesel
`Gasoline
`Diesel
`
`
`EU
`
`HC—i—NO,1
`C0
`PM
`
`gfkm
`
`0.97
`2.72
`0.14
`
`0.5
`2.2
`—*
`
`0.7
`1 .0
`0.08
`
`0.31
`I .7"
`—
`
`05
`0.5
`0.04
`
`"For passenger cars (<6 passsengers. 2.5 tons gross weight}.
`
`”Deterioration factors for 80.000 km: Gasoline: 1.2: Diesel: HC+NO.¢:I.1. C0:l.l. PM:].2.
`
`“Proposed.
`
`Japan
`
`Vehicle"
`Test
`Emissions
`Units
`Mean”
`Max”
`
`
`Gasoline
`
`105 mode
`
`Diesel
`
`105 mode
`
`HC
`
`CO
`N0.
`
`BC
`
`CD
`NO;
`PM
`
`glkm
`
`gfkrn
`
`0.25
`
`2.]
`0.25
`
`0.4
`
`2.1
`0.5
`0.2
`
`0.39
`
`2.?
`0.48
`
`0.62
`
`2.7
`0.72
`0.34
`
`“Light-duty vehicles.
`
`l"Mean applies to imports, max to nonimpons.
`
`US
`
`Test”
`
`Emi ssions
`
`Units.
`
`US
`FTP
`
`HC
`NMHC
`
`gfmile
`
`CO
`
`N01
`
`PM
`
`Durability
`(miles)
`
`50.000
`50.000
`l00.000
`50.000
`100,000
`50,000
`[00.000
`50.000
`[00,000
`
`199l
`
`
`1994
`2003
`ULEV”
`
`0.41
`
`3.4
`
`[.0
`
`0.2
`
`0.4l
`0.25
`0.31
`3.4
`4.2
`0.4
`0.6
`0.08
`0.] 0
`
`0125
`
`1.7
`
`0.2
`0.03
`
`—
`0.040
`0.055
`I 7
`2.!
`0.2
`0.3
`—
`0.04
`
`" For light duty vehicles and trucks (<12 passsengcrs].
`
`”ULEV: ultralow vehicles emissions {California}. mandated manufacturers‘ fleet average.
`
`HC: hydrocarbons. N01: nitric oxides, PM: particulate matter. NMHC: nonmethane hydrocarbons.
`
`30
`
`30
`
`

`

`6.]
`
`introduction
`
`Fig. 6.3.
`
`hqtnd Incl
`
`rnlahc \ alvc
`deposits
`
`I23
`
`[IEVILIF‘
`
`quench __
`
`ml layer
`
`Rum. m- ul
`
`lu-llutalrl lutrlmllnn III almii.
`
`|f_"1I||.L'\i
`
`.-IIg_'IIIt'~
`
`unburned hydrocarbons are produced primarily around cold regions where the
`flame does not propagate.
`Nitric oxide (NO) is formed during combustion as the high flame temper—-
`atures break down molecular oxygen and nitrogen from the inducted air, which
`then recombine into NO (although nitric oxides are usually referred to as NO,“
`the level of N03 formed in spark-ignited engines is negligible). As will be shown,
`the production of N0 depends primarily on the peak temperatures achieved during
`combustion.
`
`Carbon monoxide (CO) results from the incomplete oxidation of the fuei lo
`carbon dioxide. Carbon monoxide formation increases steeply with decreasing
`air—fuel ratio, as not enough oxygen is available to completely oxidize the mixture.
`Excursions into fuel-rich operation during cold start and transients are responsible
`for the bulk of carbon monoxide emissions in modem engines.
`Unburned hydrocarbons (HC), unlike CO and NO, result from multiple pro-
`cesses in which fuel escapes the main combustion event during flame passage.
`As will be discussed in greater detail in the following sections, these processes
`include flame quenching near cold walls and within narrow gaps on the surfaces of
`the combustion chamber, absorption of fuel on layers such as lubricating oils and
`combustion chamber deposits. and the presence of liquid fuel, particularly during
`cold start. A large fraction of the hydrocarbons escaping combustion through one
`of these processes reenters the combustion chamber during the cycle, mixes with
`the burned gases, and is partially or completely oxidized before the exhaust gases
`leave the system. The so-called engine-our hydrocarbon emissions (i.e., emissions
`before catalytic converter treatment) are composed of the original fuel compounds,
`as well as partially oxidized hydrocarbons not originally present in the fuel.
`Figure 6.4 shows the typical behavior of exhaust emissions with air—fuel
`ratio in SI engines. The exhaust gases collected in the exhaust manifold then flow
`
`31
`
`31
`
`

`

`124
`
`Chapter 6: Combustion-Related Emissions in Si Engines
`
`
`
`Fig. 6.4.
`
`C0.C02.02[volume%)
`
`
`
`
`HC(100ppm)
`
`NO(I000ppm)
`
`Variation of exhaust emissions with relative air-fuel ratio {Harrington and Shisu [3]].
`
`through the catalytic converter, where most of the NO. CD, and HC is converted
`to molecular nitrogen, carbon dioxide, and water vapor.
`
`Nitric oxide concentrations peak around the lean side of the stoichiometric
`
`air-fuel ratio.* Since that is close to the point where the mixture temperature is hi gh-
`est. Carbon monoxide and HC levels increase at fuel—rich conditions due to the lack
`
`of oxygen and low temperatures. Clearly, one would like to operate under fuel-lean
`conditions from the point of view of minimizing emissions. However, the process
`of conversion of N0 back to nitrogen and oxygen in the catalytic converter requires
`the presence of hydrocarbons as reducing agents for best efficiency. The maximum
`air-fuel ratio is also limited by the occurrence of misfires. which lead to poor op-
`eration and high hydrocarbon emissions. Most engines are therefore designed to
`operate under stoichiometn'c conditions. The use of lean bum engines is currently
`limited by their inability to meet the strictest N0 emission levels, since there are
`at the moment no high-cfficiency NOx catalytic converters for fuel—lean operation.
`
`
`
`6.2
`
`NOx FORMATION
`
`6.2.l NO,‘ Production Mechanism
`
`The process of NOx formation during combustion has been extensively studied
`since the initial work by Zeldovich [4]. Although one generally refers to nitric
`
`is the theoretical proportion of air required for
`*The stoichiometric air—fuel ratio {AH-"1.,-
`complete conversion of fuel to carbon dioxide and water. The equivalence ratio (6 and relative air-fuel
`ratio A are defined as A. = ”45 = (AfF'JflAfFl‘u
`
`32
`
`32
`
`

`

`6.2 NO: Formation
`
`[25
`
`oxides, only NO is of relevance in spark-ignition engines operating under approx-
`imately stoichiometric conditions, while N03 is pmsent in a substantial amounts
`only in compression—ignition engines. N0 is formed in the hot burned gases dur—
`ing combustion. The formation rate is slow, relative to the overall combustion
`
`process. and the rates increase exponentially with burned gas temperatures. The
`major route to the formation of NO in a combustion system is the so-calied thermal
`route or the Zeldovich-Keck mechanism [4, 5]:
`
`N2+OHNO+N
`
`N+OzHN0+O
`
`N+0H+>N0+H
`
`(R1)
`
`(R2)
`
`(R3)
`
`The oxygen atoms present behind the. flame in the burned gases initiate the
`decomposition of molecular nitrogen to form N atoms. The activation energy of
`reaction R1 is of the order of 75 kcalfmol (Table 6.1), which is typically the rate-
`limiting step in the formation of N0 under most engine operating conditions. A
`smaller contribution arises from the forma