Heavy-Duty-, On- und Off-Highway-Motoren 2018: Zukünftige Herausforderungen 13. Internationale MTZ-Fachtagung Großmotoren [1. Aufl.] 978-3-658-25888-7;978-3-658-25889-4

Table of contents :
Front Matter ....Pages I-XVII
Why I love my diesel so much – … and nevertheless flirt with other drives (Werner Seifried, Marion Schmid)....Pages 1-14
How do you define the best powertrain solution for your off‑highway customers? (William Missions, Ben Dexter, Andy Skipton-Carter, Pascal Revereault, Matthew Maunder)....Pages 15-30
Next generation high-speed engines paving the road for the highest engine efficiency (Günter Figer, Kurt Schmidleitner, Thomas Kammerdiener, Mathias Schönbacher)....Pages 31-47
Efficiency improvements for commercial vehicles through dynamic electronic horizon (Gareth Milton, Fabien Fiquet, Anuradha Wijesinghem, Andy Noble, Peter Fussey)....Pages 49-64
Layout and integration of a range extender in a medium‑duty truck (Stefan Wedowski, Markus Ehrly, Korbinian Vogt, Farouk Odeim, Bastian Holderbaum, Christopher Marten et al.)....Pages 65-87
Improving the quality of in‑service emission compliance based on advanced statistical approaches (Daechul Jeong, Maurice Smeets, Henning Gero Petry, Markus Netterscheid, Imre Pörgye, Matthias Kötter et al.)....Pages 89-105
Emission simulation as a tool for the evaluation of future CV emission concepts (Heike Többen, Philipp Weinmann, Lisa Zimmermann, Markus Henzler)....Pages 107-121
DEUTZ G2.2 – the new 3-cylinder gas engine for non‑road mobile machinery (Heiner Bülte, Carsten Funke, Klaus-Peter Bark, Kai Tedsen)....Pages 123-133
A high efficiency lean-burn mono‑fuel heavy‑duty natural‑gas engine for achieving Euro VI emissions legislation and beyond – part 2 (André Barroso, Andrew Auld, James Manuelyan, Matthew Keenan, Paolo Ferrero Giacominetto, Rhys Pickett)....Pages 135-158
Improving fuel flexibility: new Jenbacher gas engine versions with high power density for gases with high carbon dioxide content (Stefan Prankl, Robert Böwing, Herbert Schaumberger, Robert Wilson, Dietmar Heintschel, Thomas Elsenbruch)....Pages 159-173
The effective use of ethanol for GHG emissions reduction in a dual‑fuel engine (Vinícius B. Pedrozo, I. May, T. Lanzanova, W. Guan, H. Zhao)....Pages 175-189
Real‑time capable combustion simulation of a dual‑fuel engine for hardware‑in‑the‑loop application (Stefan Kraft, M. Moser, C. Büskens, M. Echim)....Pages 191-206
Formulating to meet the lubrication challenges of modern gas engines to prolong oil life and maximize engine protection (Jonathan M. Hughes)....Pages 207-224
Integration of manufacturing aspects into the development of heavy-duty engine cast components (Johannes Heger, Götz Hartmann, Mathias Bodenburg)....Pages 225-237
Flow-optimized cooling gallery concept for laser welded steel pistons to enable reduction of oil flow (Daniel Hrdina, Weiping Yang, Geno Marinov, Adam Loch)....Pages 239-258
Development methodology for valves spindles and seat ring tailored for future large bore engines (Oliver Lehmann)....Pages 259-279
Combined LP / HP EGR system for HD diesel engines for optimum fuel consumption and lowest raw NOX emissions (Simon Schneider, Carsten Koolmann, Rainer Lutz, Jorge Curras-Guede)....Pages 281-296
Electrically assisted turbocharging – enhanced engine agility for off-highway applications (Rudi Rappsilber, J. Thiesemann, J. Kech)....Pages 297-313
Holistic design process for new commercial application engine concepts (Sören Franke, Uwe Parsche, Carsten Schreiter, Tom George)....Pages 315-333
Dynamic rate shaping – one diesel common-rail injector for all combustion strategies (David Needham, Dan Mellors, Tony Williams, Thomas Cawkwell, Simon Tullis)....Pages 335-357
The new Liebherr LI1 common-rail injector platform (Norbert Schöfbänker, Richard Pirkl, Dennis Herrmann, Verena Kögel)....Pages 359-375
Next generation of smart injectors for future diesel and dual-fuel applications (Andreas Lingens, Clemens Senghaas, Michael Willmann, Hartmut Schneider)....Pages 377-391
eWHR box approach: from component development to system testing in the real world and synergies with future drive train (Hannes Marlok, Jana Mertens, Michael Bucher, Klaus Irmler, Richard Brümmer)....Pages 393-410
Development of an ORC turbo pump for waste heat recovery from the coolant of an HD truck (Pascal Smague, Pierre Leduc, Philippe Pagnier, Gaël Leveque, Norman Holaind, Gabriel Henry et al.)....Pages 411-433
Challenges for the power pack system from the perspective of a global agricultural machinery producer (Thomas Böck)....Pages 435-443
Tagungsbericht (Marc Ziegler)....Pages 445-447

Citation preview

Proceedings

Wolfgang Siebenpfeiffer Hrsg.

Heavy-Duty-, On- und Off-HighwayMotoren 2018 Zukünftige Herausforderungen 13. Internationale MTZ-Fachtagung Großmotoren

Proceedings

Ein stetig steigender Fundus an Informationen ist heute notwendig, um die immer komplexer werdende Technik heutiger Kraftfahrzeuge zu verstehen. Funktionen, Arbeitsweise, Komponenten und Systeme entwickeln sich rasant. In immer schnelleren Zyklen verbreitet sich aktuelles Wissen gerade aus Konferenzen, Tagungen und Symposien in die Fachwelt. Den raschen Zugriff auf diese Informationen bietet diese Reihe Proceedings, die sich zur Aufgabe gestellt hat, das zum Verständnis topaktueller Technik rund um das Automobil erforderliche spezielle Wissen in der Systematik aus Konferenzen und Tagungen zusammen zu stellen und als Buch in Springer.com wie auch elektronisch in Springer Link und Springer Professional bereit zu stellen. Die Reihe wendet sich an Fahrzeug- und Motoreningenieure sowie Studierende, die aktuelles Fachwissen im Zusammenhang mit Fragestellungen ihres Arbeitsfeldes suchen. Professoren und Dozenten an Universitäten und Hochschulen mit Schwerpunkt Kraftfahrzeug- und Motorentechnik finden hier die Zusammenstellung von Veranstaltungen, die sie selber nicht besuchen konnten. Gutachtern, Forschern und Entwicklungsingenieuren in der Automobil- und Zulieferindustrie sowie Dienstleistern können die Proceedings wertvolle Antworten auf topaktuelle Fragen geben. Today, a steadily growing store of information is called for in order to understand the increasingly complex technologies used in modern automobiles. Functions, modes of operation, components and systems are rapidly evolving, while at the same time the latest expertise is disseminated directly from conferences, congresses and symposia to the professional world in ever-faster cycles. This series of proceedings offers rapid access to this information, gathering the specific knowledge needed to keep up with cutting-edge advances in automotive technologies, employing the same systematic approach used at conferences and congresses and presenting it in print (available at Springer.com) and electronic (at Springer Link and Springer Professional) formats. The series addresses the needs of automotive engineers, motor design engineers and students looking for the latest expertise in connection with key questions in their field, while professors and instructors working in the areas of automotive and motor design engineering will also find summaries of industry events they weren’t able to attend. The proceedings also offer valuable answers to the topical questions that concern assessors, researchers and developmental engineers in the automotive and supplier industry, as well as service providers.

Weitere Bände in der Reihe http://www.springer.com/series/13360

Wolfgang Siebenpfeiffer (Hrsg.)

Heavy-Duty-, On- und Off-Highway-Motoren 2018 Zukünftige Herausforderungen 13. Internationale MTZ-Fachtagung Großmotoren

Hrsg. Wolfgang Siebenpfeiffer Stuttgart, Deutschland

Ergänzendes Material zu diesem Buch finden Sie auf http://extras.springer.com. ISSN 2198-7432 ISSN 2198-7440  (electronic) Proceedings ISBN 978-3-658-25888-7 ISBN 978-3-658-25889-4  (eBook) https://doi.org/10.1007/978-3-658-25889-4 Die Deutsche Nationalbibliothek verzeichnet diese Publikation in der Deutschen National­ bibliografie; detaillierte bibliografische Daten sind im Internet über http://dnb.d-nb.de abrufbar. Springer Vieweg © Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2019 Das Werk einschließlich aller seiner Teile ist urheberrechtlich geschützt. Jede Verwertung, die nicht ausdrücklich vom Urheberrechtsgesetz zugelassen ist, bedarf der vorherigen Zustimmung des Verlags. Das gilt insbesondere für Vervielfältigungen, Bearbeitungen, Übersetzungen, Mikroverfilmungen und die Einspeicherung und Verarbeitung in elektronischen Systemen. Die Wiedergabe von allgemein beschreibenden Bezeichnungen, Marken, Unternehmensnamen etc. in diesem Werk bedeutet nicht, dass diese frei durch jedermann benutzt werden dürfen. Die Berechtigung zur Benutzung unterliegt, auch ohne gesonderten Hinweis hierzu, den Regeln des Markenrechts. Die Rechte des jeweiligen Zeicheninhabers sind zu beachten. Der Verlag, die Autoren und die Herausgeber gehen davon aus, dass die Angaben und Informa­ tionen in diesem Werk zum Zeitpunkt der Veröffentlichung vollständig und korrekt sind. Weder der Verlag, noch die Autoren oder die Herausgeber übernehmen, ausdrücklich oder implizit, Gewähr für den Inhalt des Werkes, etwaige Fehler oder Äußerungen. Der Verlag bleibt im Hinblick auf geografische Zuordnungen und Gebietsbezeichnungen in veröffentlichten Karten und Institutionsadressen neutral. Verantwortlich im Verlag: Markus Braun Springer Vieweg ist ein Imprint der eingetragenen Gesellschaft Springer Fachmedien Wiesbaden GmbH und ist ein Teil von Springer Nature Die Anschrift der Gesellschaft ist: Abraham-Lincoln-Str. 46, 65189 Wiesbaden, Germany

Vorwort

Die Hersteller von Großmotoren für mobile, stationäre und maritime Anwendungen sowie deren Zulieferer müssen zur Realisierung der stetig strenger werdenden Abgasgrenzwerte bis hin zu lokalen Null-Emissions-Anforderungen unterschiedlichste Antriebskonzepte verfolgen, um sowohl heutige als auch zukünftige Anforderungen verwirklichen zu können. „Zukünftige Herausforderungen“ lautet demzufolge auch das diesjährige Motto der jährlich stattfindenden MTZ-Fachtagung „Heavy-Duty-, On- und Off-Highway-Motoren“. Die erfolgreiche ATZlive-Veranstaltung bietet allen mit der Großmotorenentwicklung beschäftigen Ingenieuren die ideale Plattform, sich ausführlich über die aktuellen technischen Entwicklungen sowie zukünftige Trends zu informieren und im Expertenkreis zu diskutieren. Die Fachtagung hält Schritt mit den Entwicklungen im Motorenbereich: So werden in diesem Jahr beispielsweise erstmals mehrzügige Sessions angeboten, wodurch mehr Vorträge und neue Themenbereiche in den zwei Tagen angeboten werden können. Die Schwerpunkte im Jahr 2018 sind neue Diesel- und Gasmotoren, Schadstoffreduzierung, Powertrain-Konzepte für den On- und Off-Highway-Bereich, Einspritzung sowie die Komponentenentwicklung im Hinblick auf das System. Am Ende des ersten Tages lädt die DEUTZ AG zu einem Besuch ihres Motorenwerks in Köln-Porz ein. Eine begleitende Fachausstellung rundet das Programm ab. Nutzen Sie die Gelegenheit, Ihr Netzwerk zu erweitern und wertvolle Kontakte zu knüpfen. Hierfür bietet insbesondere auch die Abendveranstaltung am 6. November in lockerer Atmosphäre zahlreiche Möglichkeiten. Ich freue mich auf Ihre Teilnahme an der Tagung. Für den Wissenschaftlichen Beirat Wolfgang Siebenpfeiffer Herausgeber ATZ | MTZ | ATZelektronik V

Editorial

In order to comply with increasingly low emissions thresholds and in some cases to meet the requirement to produce no local emissions, the manufacturers of heavy-duty engines and their suppliers are adopting a wide range of different powertrain concepts with a focus on both current and future standards. For this reason, this year’s theme of the annual MTZ Conference ‘Heavy-Duty, On- and OffHighway Engines’ is ‘Future Challenges’. This successful ATZlive event is the ideal platform for engineers in the field of heavy-duty engine development to find out in detail about current technical developments and future trends. It also offers the opportunity to take part in discussions with other experts. The conference is keeping pace with developments in the field of engines. As a result, this year parallel sessions are being held for the first time, which allows us to offer more presentations and cover new subjects during the course of the two days. The key themes in 2018 are new diesel and gas engines, reducing emissions, powertrain concepts for on- and off-highway vehicles, fuel injection, and developing components in the context of an entire system. At the end of the first day DEUTZ AG has invited the conference participants to visit its engine plant in the Porz district of Cologne. In addition, the conference is accompanied by a technical exhibition. Don’t miss this chance to expand your network and make new and valuable contacts. The evening event on 6 November is the ideal opportunity for doing this in a relaxed atmosphere. I look forward to seeing you at the conference. On behalf of the Scientific Advisory Board Wolfgang Siebenpfeiffer Editor-in-Charge ATZ | MTZ | ATZelektronik

VII

Inhaltsverzeichnis

Why I love my diesel so much – … and nevertheless flirt with other drives Werner Seifried und Marion Schmid How do you define the best powertrain solution for your off‑highway ­customers? William Missions, Ben Dexter, Andy Skipton-Carter, Pascal Revereault und Matthew Maunder Next generation high-speed engines paving the road for the highest engine efficiency Dr. Günter Figer, Kurt Schmidleitner, Thomas Kammerdiener und Mathias Schönbacher Efficiency improvements for commercial vehicles through dynamic electronic horizon Dr. Gareth Milton, Fabien Fiquet, Anuradha Wijesinghe, Dr. Andy Noble und Dr. Peter Fussey Layout and integration of a range extender in a medium‑duty truck Stefan Wedowski, Markus Ehrly, Korbinian Vogt, Dr. Farouk Odeim Dr. Bastian Holderbaum, Christopher Marten und Johannes Moritz Maiterth Improving the quality of in‑service emission compliance based on advanced statistical approaches Daechul Jeong, Maurice Smeets, Henning Gero Petry, Markus Netterscheid, Imre Pörgye, Matthias Kötter und Sung-Yong Lee Emission simulation as a tool for the evaluation of future CV emission ­concepts Dr. Heike Többen, Philipp Weinmann, Lisa Zimmermann und Dr. Markus Henzler IX

X

Inhaltsverzeichnis

DEUTZ G2.2 – the new 3-cylinder gas engine for non‑road mobile ­machinery Dr. Heiner Bülte, Carsten Funke, Klaus-Peter Bark und Kai Tedsen A high efficiency lean-burn mono‑fuel heavy‑duty natural‑gas engine for achieving Euro VI emissions legislation and beyond – part 2 André Barroso, Andrew Auld, James Manuelyan, Matthew Keenan, Paolo Ferrero Giacominetto und Rhys Pickett Improving fuel flexibility: new Jenbacher gas engine versions with high power density for gases with high carbon dioxide content Stefan Prankl, Dr. Robert Böwing, Herbert Schaumberger, Robert Wilson, Dietmar Heintschel und Thomas Elsenbruch The effective use of ethanol for GHG emissions reduction in a dual‑fuel engine Dr. Vinícius B. Pedrozo, Dr. I. May, Dr. T. Lanzanova, W. Guan und Prof. H. Zhao Real‑time capable combustion simulation of a dual‑fuel engine for hardware‑in‑the‑loop application Stefan Kraft, Dr. M. Moser, Prof. Dr. C. Büskens und Dr. M. Echim Formulating to meet the lubrication challenges of modern gas engines to prolong oil life and maximize engine protection Dr. Jonathan M. Hughes Integration of manufacturing aspects into the development of heavy-duty engine cast components Johannes Heger, Götz Hartmann und Mathias Bodenburg Flow-optimized cooling gallery concept for laser welded steel pistons to enable reduction of oil flow Dr. Daniel Hrdina, Dr. Weiping Yang, Geno Marinov und Dr. Adam Loch Development methodology for valves spindles and seat ring tailored for future large bore engines Oliver Lehmann Combined LP / HP EGR system for HD diesel engines for optimum fuel consumption and lowest raw NOX emissions Dr. Simon Schneider, Carsten Koolmann, Rainer Lutz und Jorge Curras-Guede

Inhaltsverzeichnis

Electrically assisted turbocharging – enhanced engine agility for off-highway applications Rudi Rappsilber, J. Thiesemann und Dr. J. Kech Holistic design process for new commercial application engine concepts Sören Franke, Uwe Parsche, Carsten Schreiter und Tom George Dynamic rate shaping – one diesel common-rail injector for all combustion strategies David Needham, Dan Mellors, Tony Williams, Thomas Cawkwell und Simon Tullis The new Liebherr LI1 common-rail injector platform Norbert Schöfbänker, Richard Pirkl, Dennis Herrmann und Verena Kögel Next generation of smart injectors for future diesel and dual-fuel applications Dr. Andreas Lingens, Clemens Senghaas, Dr. Michael Willmann und Hartmut Schneider eWHR box approach: from component development to system testing in the real world and synergies with future drive train Hannes Marlok, Jana Mertens, Michael Bucher, Klaus Irmler und Richard Brümmer Development of an ORC turbo pump for waste heat recovery from the ­coolant of an HD truck Pascal Smague, Pierre Leduc, Philippe Pagnier, Gaël Leveque, Norman Holaind, Gabriel Henry und Arthur Leroux Challenges for the power pack system from the perspective of a global ­agricultural machinery producer Thomas Böck Tagungsbericht Marc Ziegler

XI

Autorenverzeichnis

Andrew Auld  Ricardo UK Ltd, Shoreham-by-Sea, Großbritannien Klaus-Peter Bark  DEUTZ AG, Köln, Deutschland Andre Barroso  Ricardo UK Ltd, Shoreham-by-Sea, Großbritannien Thomas Böck  CLAAS KGaA mbH, Harsewinkel, Frankreich Mathias Bodenburg  MAGMA GmbH, Aachen, Deutschland Dr. Robert Böwing  GE Jenbacher GmbH & Co OG, Jenbach, Österreich Richard Brümmer  MAHLE Behr GmbH & Co. KG, Stuttgart, Deutschland Michael Bucher  MAHLE Amovis GmbH, Stuttgart, Deutschland Dr. Heiner Bülte  DEUTZ AG, Köln, Deutschland Prof. Dr. C. Büskens  Universität Bremen, Bremen, Deutschland Thomas Cawkwell  Delphi Technologies Ltd, London, Großbritannien Jorge Curras-Guede  MAHLE Behr GmbH & Co. KG, Stuttgart, Deutschland Ben Dexter  Ricardo UK Ltd, Shoreham-by-Sea, Großbritannien Dr. M. Echim  Universität Bremen, Bremen, Deutschland Stefan Ehrly  FEV Europe GmbH, Aachen, Deutschland Thomas Elsenbruch  GE Jenbacher GmbH & Co OG, Jenbach, Österreich Günter Figer  AVL List GmbH, Graz, Österreich Fabien Fiquet  Ricardo Innovations, Shoreham-by-See, Großbritannien XIII

XIV

Autorenverzeichnis

Sören Franke  IAV GmbH, Berlin, Deutschland Carsten Funke  DEUTZ AG, Köln, Deutschland Dr. Peter Fussey  Ricardo UK Ltd, Shoreham-by-See, Großbritannien Tom George  IAV GmbH, Berlin, Deutschland Paolo Ferrero Giacominetto  Ricardo UK Ltd, Shoreham-by-Sea, Großbritannien W. Guan  Brunel University London, London, Großbritannien Dr. Götz Hartmann  MAGMA GmbH, Aachen, Deutschland Johannes Heger  Heger-Guss GmbH, Enkenbach-Alsenborg, Deutschland Dietmar Heintschel  GE Jenbacher GmbH & Co OG, Jenbach, Österreich Gabriel Henry  ENOGIA, Marseille, Frankreich Dr. Markus Henzler  Eberspächer Exhaust Technology GmbH & Co. KG, Esslingen, Deutschland Dennis Herrmann Liebherr-Components Deggendorf GmbH, Deggendorf, Deutschland Norman Holaind  ENOGIA, Marseille, Frankreich Dr. Bastian Holderbaum  FEV Europe GmbH, Aachen, Deutschland Dr. Daniel Hrdina  MAHLE GmbH, Stuttgart, Deutschland Dr. Jonathan M. Hughes  Infineum UK Ltd, Abingdon, Großbritannien Klaus Irmler  MAHLE Behr GmbH & Co. KG, Stuttgart, Deutschland Daechul Jeong  FEV Europe GmbH, Aachen, Deutschland Thomas Kammerdiener  AVL List GmbH, Graz, Österreich Dr. J. Kech  MTU Friedrichshafen GmbH, Friedrichshafen, Deutschland Matthew Keenan  Ricardo UK Ltd, Shoreham-by-Sea, Großbritannien Liebherr-Components Verena Kögel  ­Deutschland

Deggendorf

GmbH,

Deggendorf,

Carsten Koolmann  MAHLE International GmbH, Stuttgart, Deutschland Matthias Kötter  FEV Europe GmbH, Aachen, Deutschland

Autorenverzeichnis

Stefan Kraft  MAN Diesel & Turbo SE, Augsburg, Deutschland Dr. T. Lanzanova  Brunel University London, London, Großbritannien Pierre Leduc  IFP Energies nouvelles, Rueil-Malmaison, Frankreich Sung-Yong Lee  VKA RWTH Aachen University, Aachen, Deutschland Oliver Lehmann  Märkisches Werk GmbH, Großbodungen, Deutschland Arthur Leroux  ENOGIA, Marseille, Frankreich Gaël Leveque  ENOGIA, Marseille, Frankreich Andreas Lingens  Woodward L’Orange GmbH, Stuttgart, Deutschland Dr. Adam Loch  MAHLE International GmbH, Stuttgart, Deutschland Rainer Lutz  MAHLE Behr GmbH & Co. KG, Stuttgart, Deutschland Johannes Moritz Maiterth  RWTH Aachen University, Aachen, Deutschland James Manuelyan  Ricardo UK Ltd, Shoreham-by-Sea, Großbritannien Geno Marinov  MAHLE Powertrain GmbH, Stuttgart, Deutschland Hannes Marlok  MAHLE GmbH, Stuttgart, Deutschland Christopher Marten  RWTH Aachen University, Aachen, Deutschland Matthew Maunder  Ricardo UK Ltd, Shoreham-by-Sea, Großbritannien Dr. I. May  Brunel University London, London, Großbritannien Dan Mellors  Delphi Technologies Ltd, London, Großbritannien Jana Mertens  MAHLE Amovis GmbH, Stuttgart, Deutschland Dr. Gareth Milton  Ricardo Innovations, Shoreham-by-See, Großbritannien William Missions  Ricardo UK Ltd, Shoreham-by-Sea, Großbritannien Dr. M. Moser  MAN Diesel & Turbo SE, Augsburg, Deutschland David Needham  Delphi Technologies Ltd, London, Großbritannien Markus Netterscheid  FEV Europe GmbH, Aachen, Deutschland Dr. Andy Noble  Ricardo UK Ltd, Shoreham-by-See, Großbritannien Dr. Farouk Odeim  FEV Europe GmbH, Aachen, Deutschland

XV

XVI

Autorenverzeichnis

Philippe Pagnier  IFP Energies nouvelles, Rueil-Malmaison, Frankreich Uwe Parsche  IAV GmbH, Berlin, Deutschland Dr. Vinicius B. Pedrozo  Brunel University London, London, Großbritannien Henning Gero Petry  FEV Europe GmbH, Aachen, Deutschland Rhys Pickett  Ricardo UK Ltd, Shoreham-by-Sea, Großbritannien Richard Pirkl  Liebherr-Components Deutschland

Deggendorf

GmbH,

Deggendorf,

Imre Pörgye  FEV Europe GmbH, Aachen, Deutschland Stefan Prankl  GE Jenbacher GmbH & Co OG, Jenbach, Österreich Rudi Rappsilber  MTU Friedrichshafen GmbH, Friedrichshafen, Deutschland Pascal Revereault  Ricardo UK Ltd, Shoreham-by-Sea, Großbritannien Herbert Schaumberger  GE Jenbacher GmbH & Co OG, Jenbach, Österreich Marion Schmid  Liebherr-Hydraulikbagger GmbH, Kirchdorf/Iller, Deutschland Kurt Schmidleitner  AVL List GmbH, Graz, Österreich Dr. Simon Schneider  MAHLE International GmbH, Stuttgart, Deutschland Hartmut Schneider  Woodward L’Orange GmbH, Stuttgart, Deutschland Norbert Schöfbänker Liebherr-Components Deggendorf GmbH, Deggendorf, Deutschland Mathias Schönbacher  AVL List GmbH, Graz, Österreich Carsten Schreiter  IAV GmbH, Berlin, Deutschland Werner Seifried  Liebherr-Hydraulikbagger GmbH, Kirchdorf/Iller, Deutschland Clemens Senghaas  Woodward L’Orange GmbH, Stuttgart, Deutschland Andy Skipton-Carter  Ricardo UK Ltd, Shoreham-by-Sea, Großbritannien Pascal Smague  IFP Energies nouvelles, Rueil-Malmaison, Frankreich Maurice Smeets  FEV Europe GmbH, Aachen, Deutschland Kai Tedsen  DEUTZ AG, Köln, Deutschland

Autorenverzeichnis

XVII

J. Thiesemann  MTU Friedrichshafen GmbH, Friedrichshafen, Deutschland Heike Többen  Eberspächer Exhaust Technology GmbH & Co. KG, Esslingen, Deutschland Simon Tullis  Delphi Technologies Ltd, London, Großbritannien Korbinian Vogt  FEV Europe GmbH, Aachen, Deutschland Stefan Wedowski  FEV Europe GmbH, Aachen, Deutschland Philipp Weinmann  Eberspächer Exhaust Technology GmbH & Co. KG, Esslingen, Deutschland Anuradha Wijesinghe  Ricardo Innovations, Shoreham-by-See, Großbritannien Tony Williams  Delphi Technologies Ltd, London, Großbritannien Dr. Michael Willmann  Woodward L’Orange GmbH, Stuttgart, Deutschland Robert Wilson  GE Jenbacher GmbH & Co OG, Jenbach, Österreich Dr. Weiping Yang  MAHLE GmbH, Stuttgart, Deutschland Prof. H. Zhao  Brunel University London, London, Großbritannien Marc Ziegler  Springer Fachmedien Wiesbaden GmbH, Wiesbaden, Deutschland Lisa Zimmermann  Eberspächer Exhaust Technology GmbH & Co. KG, Esslingen, Deutschland

Why I love my diesel so much – … and nevertheless flirt with other drives Werner Seifried, Liebherr Hydraulikbagger GmbH, Kirchdorf / Iller Marion Schmid, Liebherr Hydraulikbagger GmbH, Kirchdorf / Iller

© Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2019 W. Siebenpfeiffer, Heavy-Duty-, On- und Off-Highway-Motoren 2018, Proceedings, https://doi.org/10.1007/978-3-658-25889-4_1

1

Why I love my diesel so much – … and nevertheless flirt with other drives

1 about the common understanding of non-road mobile machinery ….. To approach the subject we should take the time to look what is behind the term “nonroad mobile machinery (NRMM)”. According to1 nrmm.london “NRMM is described as any mobile machine, item of transportable industrial equipment, or vehicle – with or without bodywork – that is – not intended for carrying passengers or goods on the road – installed with a combustion engine – either an internal spark ignition (SI) petrol engine, or a compression ignition diesel engine” In addition, there are several other terms describing “heavy equipment” or “construction machinery”. Therefore Wikipedia2 refers “heavy equipment () to heavy-duty vehicles, specially designed for execution construction tasks, most frequently ones involving earthwork operations”. The Free Dictionary3 describes construction machinery as ”mechanized equipment designed to perform construction operations. Certain construction machines perform a series of operations in sequence to achieve a final objective”. Heavy machines are mostly related to different industries such as construction, mining and quarry, material handling, recycling, concrete handling, paving and asphalting, demolition or public and municipal works. Considering function and specialization degree, heavy machinery is separated in two major groups, which are either universal heavy machinery or specialized heavy machinery. Whereas ordinary excavators, dozers, loaders, tele handlers, cranes or dump trucks are allocated to universal heavy machinery, piling and drilling machines, concrete pumps or mixers, material handlers, underground mining machines or pavers are categorized to specialized heavy machinery. [see Figure 1] The CECE position paper4 described a characteristic of construction equipment sector is that manufacturers develop and produce thousands of applications. Many of them are used in niche markets with sales of less than one hundred units per year, often even down to series of less than 10 units per year.

1 2 3 4

2

NRMM Wikipedia The Free Dictionary CECE Position on the NRMM Regulation

Why I love my diesel so much – … and nevertheless flirt with other drives

Figure 1: universal heavy machinery vs. specialized heavy machinery

To complete the picture at the example of the earthmoving sector a detailed look shows the wide range of the available machines5, [see Figure 2]: ● from micro excavators of about 0,9t machine weight and about 7kW diesel engine power, which are used very often by gardening and landscaping companies ● via mobile excavators of 20t machine weight and about 120kW diesel engine power, used in urban construction sites or general building tasks ● up to crawler excavators with a machine weight of 800t and 3.000 kW engine power. Machines of that size are used in worldwide mining applications, mining sites are situated round the world from Australia up to the Himalayan mountains in Tibet

Figure 2: great diversity within the application excavator

2 about the worldwide applications of mobile machinery ….. Incredible and unique – that is how the planet Earth presents itself. People live on nearly every spot in the world. Depending on the specific place, a different kind of infrastructure requests a different kind of mobile machines. Therefore, regarding an application very often specific characteristics have to be considered. [see Figure 3]

5 AVL International Commercial Powertrain Conference

3

Why I love my diesel so much – … and nevertheless flirt with other drives

application

location

tunneling

mining

particularity

comment

robustness

Tibet

height

5.375 m underground mining

ventilation

road construction

Siberia

temperature

max. – 50°

slag handling

steelworks

temperature

slag temperature 800 – 1.200 °

slope

slope up to 100 %

embankment construction

recycling

sorting station

dust

material handling

harbour

seawater

urban construction site

cities

narrowness

Figure 3: environmental conditions

4

tail radius 1.850 mm

Why I love my diesel so much – … and nevertheless flirt with other drives

3 about the specific expectations on mobile machinery ….. 3.1 whose expectations ….. Because of their special purpose in every days life the usage of NRMM is accepted and it can´t be imagined without them. We suppose things as given, which were formed with the help of mobile machinery. Later on we need them for regular maintenance of the things we created. Examples are infrastructural constructions such as roads, bridges or buildings. Even for the daily supply of our society NRMM are integral parts. Machines in scrap handling, recycling companies, timber industries or harbor logistics enable operating sequences within the different processes. As diverse as the potential applications are as various are the groups which define systematic demands. Attention should be paid on the statements of following four groups, which will be examined for a better understanding in more detail: – Customer: “The customer is king” – this generally accepted saying clarifies that the customers demand ranks first – Boundary conditions: Every product operates in an environment, which per se is given and has to be dealt with successful – Society: Trends and developments are existing in all societies and everyone has to deal with them. Therefore, they have to be monitored carefully – OEM: Finally, the producers of non-road mobile machinery pursue objectives, which have to be considered in an overall context

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Why I love my diesel so much – … and nevertheless flirt with other drives

3.2 which expectations ….. Since the four described groups vary considerably, it is quite exciting to look at the expectations, which are from their point of view quite relevant. From the NRMM customers point of view the following arguments are the most important: – availability / performance /easy serviceing / total cost of ownership (TCO) / durability and reliability In addition, boundary conditions include for the most part laws and standards: – noise regulation / international and national emission laws / national and regional immission laws / type of operating energy, sources of energy, fuels Trends in society get more and more important, they are as – low (no) emissions / sustainability, CO2 neutrality The OEM´s objectives mainly define the basics of defining, designing, producing and selling the machines: – global solutions / legislation / durability and reliability / availability / performance / easy serviceing / total cost of ownership (TCO) A consolidation of the information shows, that there are quite some expectations, which are important not only for one group.[see Figure 4]

Figure 4: specific expectations on mobile machinery

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Why I love my diesel so much – … and nevertheless flirt with other drives

3.3 which expectations on diesel engines ….. As a consequence of the market driven, widely varying expectations of mobile machinery, the conclusion for the used diesel engines is equally diverse as expected. In the further elaboration the following fields of activity have been identified to be worth taken in detailed consideration – – – – – –

total cost of ownership / TCO availability easy serviceing legislation performance durability / reliability

Just to get an idea of the specific demands depending on diesel engines, Figure 5 gives a closer insight into the different fields and the corresponding arguments.

Figure 5: specific expectations on diesel engines

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Why I love my diesel so much – … and nevertheless flirt with other drives

4 about future modular concepts ….. 4.1 Liebherr modular concept of mobile excavators ….. If you keep up with the current discussion about particulate matter, nitrogen oxide or carbon dioxide in the media, the situation seems to be pretty straightforward with the culprit having been identified clearly and unambiguously. His name is „diesel engine“, his job is “the propulsion of passenger vehicles, utility vehicles, locomotives and nonroad mobile machinery“. As shown in the previous elaboration the requirements on the OEM´s will continuously rise. Therefore, it will be necessary to develop new design concepts, which will allow the external customer variance and the internal variance as well with a controllable level of complexity on the same time. But how to handle up to eight national different emission legislations or other national regulations such as occupational safety regulations? This allows only one final conclusion: a strictly modular based machine concept. According to the preceding principles as a first step a cross-functional product architecture team developed guidelines, how to handle with future machine concepts concerning interface management, BOM concepts and other general requirements e.g. PLM-, assembly- or purchase-based. The team defined during the second step so called “systems” like driver´s stand, undercarriage or power pack. An execution of the described approach can be seen in Figure 6. It shows the A 918 compact of Liebherr, a wheel based excavator weighing 18t with an installed diesel engine power of 115kW and based on the platform PL01. A detailed look at the right and rear side with dismantled coverings shows the system power pack including exhaust aftertreatment.

Figure 6: Liebherr modular machine concept

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Why I love my diesel so much – … and nevertheless flirt with other drives

To be optimally prepared for the already up to eight national different emission legislations (EU, USA, Russia, China, India, Brazil, Japan, rest of the world) this concept allows the realization of the necessary diesel-technology independent from the rest of the machine. Figure 7 illustrates in detail the section power pack (right side of the machine), in which the diesel engine in his different specifications including cooling system and hydraulic pumps is located. It also shows the localization of the exhaust aftertreatment system (rear side of the machine) including all different characteristics.

Figure 7: Liebherr modular machine concept / diesel engine

4.2 Liebherr modular concept of diesel engines and exhaust aftertreatment systems ….. The OEM´s point of view is very often a machines point of view, e.g. a manufacturers opinions of excavators, wheel loaders or dozers requirements vary widely. As an example, Figure 9 points out duty cycles of three different machines, which can lead to only one conclusion: a single EATS-Strategy for each machine type is necessary.

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Why I love my diesel so much – … and nevertheless flirt with other drives

Figure 9: examples for duty cycles of NRMM

Because this is not an exception but the standard a supplier of diesel engines has to deal with regularly, he has to fulfil all the OEM´s demands completely at the same time. Liebherr modular concept of common rail injection systems, exhaust aftertreatment systems and diesel engines to realize the NRMM´s goals in their entirety is explained in Figure 10.

Figure 10: Liebherr modular engine concept

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Why I love my diesel so much – … and nevertheless flirt with other drives

5 about the flirt with others, visions of the future ….. Metropolitan areas, where about 35% of people live6 , are compared to other areas in Germany characterized by various human activities (industry, trade, transport) and therefore most harmed by air pollution and outdoor noise. Therefore, the reduction of NOx-, particle-, CO2- and noise-emissions is a No.1 topic on all agendas. According to7 considered in isolation the share of mobile machinery responsible for NOx-emission in Germany is about 20% whereas road transport stands for 80%. A detailed look on the contribution of construction machinery within the NRMM figures out a total of 6%. In addition mobile machinery stands for 48% of particle emissions (road transport 52%), construction machinery in turn represent 10% of the total amount. Figure 11 outlines the explained connections in detail.

Figure 11: comparison NOX- and particle emissions of road transport and mobile machinery in Germany

Nevertheless especially in urban areas combustion processes affect the local air quality quite a lot, simultaneously concerned persons feel the outdoor noise of construction machinery and construction sites as a heavy burden. Diesel engines do have an efficiency of 25% to 40% meanwhile electric engines achieve up to 95%. Considering the CO2-emissions of electricity generation (well to wheel) of the conventional electricity mix the CO2- amount can be reduced approx. 50%, if the electricity is based completely on renewable sources it can be reduced even up to 100%. A comparison at the example of a mobile excavator equipped with a diesel-hydraulic system to an electro-hydraulic system in Germany results best case in following:

6 Umweltbundesamt 7 Schriftenreihe der Forschungsvereinigung Bau- und Baustoffmaschinen e.V.

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Why I love my diesel so much – … and nevertheless flirt with other drives

– at an average diesel consumption of 7l/hour and 1.000 operating hours/year the energy saving potential per excavator per year is approx. 7.000l/year – therefore CO2 reduction potential per excavator could be about 6,9t (tank to wheel) respectively 18,5t (well to wheel) This forecast corresponds in general to8, a by the VDMA instructed study which led concerning non-road mobile machinery to following results: – while fuel consumption reduction through hybridization is limited for tractors, excavators and wheel loaders show significant fuel economy benefit – in terms of payback periods of add-on costs small and large excavators as well as large wheel loaders are most suitable for hybridization – driven by substantial fuel economy benefits hybrid electric applications are expected to gain significant market shares in excavators Coming back to where we started, OEM´s of mobile machinery can´t ignore social discussions as well as political tendencies and will offer suitable solutions – but only in useful applications with sustainable concepts. As shown in Figure 11 Liebherr expanded the description of the modular concept PL01 by integrating an electrical drive. The electric engine replaces the diesel engine whereas the control cabinet is situated at the location of the former fuel tank.

Figure 11: Liebherr modular machine concept / electric engine

8 VDMA

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Why I love my diesel so much – … and nevertheless flirt with other drives

Power to X – many brilliant ideas or rumors about disruptive solutions for the future are circulating around. Studies like9 forecast, that depending on the calculated scenario the share of energy sources will change within the EU transport sector from nowadays nearly 100% single-use of fossil fuels to a nearly irrelevant share in 2050. In addition, the use of electricity, H2, methane and renewable liquid fuels will increase dramatically whereas no energy will dominate the others, tendency is leading towards a multi-use with renewable liquid fuels as a favorite. There is still a lot of guardedness concerning new alternative solutions; very often the reasons for the missing acceptance are very easily explained: advanced fuels are more expensive and high initial costs as well as other acceptance issues for battery mobility can be expected. Even if e-hydrogen and e-fuels are actually more expensive than fossil fuels, they seem to be the most cost-efficient solutions for renewable fuels in the future. At this point we´ve come to a full circle, where the non-road mobile machinery cannot undock from other industries. Even if the requirements are much more diverse, the number of applications is much higher and the demands for the installed technologies are more challenging, the OEM´s have to integrate them some day in their products. As a final consequence, future driveline concepts will be rather different than today.

6 conclusion ….. Finally the following key statements have been identified: – the upcoming challenges on NRMM will be more and more diverse and cannot be covered by only one technology – the future of the non-road mobile machinery and of the diesel engine is consistently modular – it becomes more and more clear, that there will be not just one drive concept, one type or one source of drive anymore. For that, the required conditions will be too different in future – anticipated energy sources will change from nearly single-use of fossil fuels to an energy mix – already existing small lot sizes will continue to be under pressure

9 German Energy Agency

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Why I love my diesel so much – … and nevertheless flirt with other drives

REFERENCES 1

NRMM: https://nrmm.london/content/what-non-road-mobile-machinery

2

Wikipedia: https://en.wikipedia.org/wiki/Heavy_equipment

3

The Free Dictionary: https://encyclopedia2.thefreedictionary.com/Construction+Machinery

4

CECE Position on the NRMM Regulation, January 19th, 2015, CECE position paper

5

Energy efficiency of construction machines – a contribution to CO2 reduction, 7th AVL International Commercial Powertrain Conference, May 22nd – 23rd, 2013, Graz, Werner Seifried

6

Umweltbundesamt: https://www.umweltbundesamt.de/daten/luft/luftbelastungin-ballungsraeumen#textpart-1

7

Schriftenreihe der Forschungsvereinigung Bau- und Baustoffmaschinen e.V., Studie Nr. 48, Juli 2015, Gefährdung durch Feinstaubemissionen von Baumaschinen

8

VDMA 2018, Studie „Antrieb im Wandel: Die Elektrifizierung des Antriebsstrangs von Fahrzeugen und ihre Auswirkung auf den Maschinen- und Anlagenbau und die Zulieferindustrie“

9

German Energy Agency (DENA), 11/2017, „The potential of electricity-based fuels for low-emission transport in the EU”

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How do you define the best powertrain solution for your off‑highway customers? William Missions – Chief Engineer, Commercial Vehicle and Off-Highway Market Sector Ben Dexter – Engineer Andy Skipton-Carter – Head of Commercial Vehicle and Off-Highway Market Sector, Europe Pascal Revereault – Principal Engineer, Simulation Matthew Maunder – Technical Specialist Ricardo UK Ltd

© Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2019 W. Siebenpfeiffer, Heavy-Duty-, On- und Off-Highway-Motoren 2018, Proceedings, https://doi.org/10.1007/978-3-658-25889-4_2

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How do you define the best powertrain solution for your off‑highway customers?

Introduction The optimum powertrain configuration for future machines will vary from BEV to improved efficiency ICE and everything in between including mild and full hybrid systems. The best solution will be the one that delivers the lowest costs (total cost of ownership and capital cost) while meeting customer performance goals, and legislative and ethical requirements for emissions including pollutants and greenhouse gases. Selecting the “right” powertrain for a given machine, application or user is becoming increasingly complex and more advanced analysis methodologies are required. Ricardo has developed an approach for efficient powertrain down-selection through utilisation of a hierarchy of simulation tools. This paper provides a simulation-based approach to define the best solution for a range of off-highway machines and highlights the importance of the machine duty cycle. An example of how this initial simulation can be developed to provide detailed simulation to refine and specify the powertrain arrangement is included.

Approach & Results The first step in the hierarchical approach is a “Cycle and Engine Operating Residency Analysis” or “CEORA”. This initial basic analysis assesses the feasibility of powertrain hybridisation, with engine downsizing, based on the operating regime of the engine. If the Cycle and Engine Operating Residency Analysis, indicates an opportunity for hybridisation then the next level of analysis is “Hybrid Powertrain Architect Assessment tool” or “HyPAA”. HyPAA provides the ability to simulate the alternative powertrain architectures and evaluate different size subsystems (e.g. engine, battery, motor). The simulation considers the operating cycle of the machine and provides a prediction of both fuel consumption and NOX emissions for each configuration. The final and most detailed analytical step utilises the latest in simulation software and Integrated Model Based Development (IMBD) methodology to enable system control strategy development and calibration, and hardware optimisation. The following describes case studies applying the three steps of the hierarchical methodology.

Step 1: Cycle and Engine Operating Residency Analysis (CEORA) Two case studies are used to illustrate the Cycle and Engine Operating Residency Analysis. The first is a mini-excavator (4 tonne) currently fitted with a 22kW three-cylinder

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How do you define the best powertrain solution for your off‑highway customers?

naturally aspirated diesel engine. The second is a skid-steer loader (3 tonne) currently fitted with a 55kW four-cylinder turbocharged diesel engine. In both cases, typical duty cycles (Figure 1 and Figure 2 respectively) of 20 minutes duration were extracted from United States Environmental Protection Agency (EPA) website [1] and scaled according to power and speed data for the engines in question. These EPA duty cycles are derived from data collected on machines operating in the field and are therefore appropriate examples for the study. The scaled duty cycles were presented on residency plots (Figure 3 and Figure 4 respectively) that indicate the proportion of time spent at each speed/load point.

Normalised Speed and Torque [%]

Excavator 120

100 80 60 40

20 0

0

120

240

360

480

600

Time [s]

720

840

960

1080

1200

Figure 1: EPA Duty Cycle (normalised) - Excavator

Normalised Speed and Torque [%]

Skid Steer Loader Typical Operation 1 120

100 80 60 40

20 0

0

120

240

360

480

600

Time [s]

720

840

960

1080

1200

Figure 2: EPA Duty Cycle (normalised) - Skid Steer Loader

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How do you define the best powertrain solution for your off‑highway customers?

Figure 3: Cycle and Engine Operating Residency Analysis (CEORA) - 22kW Excavator

Figure 4: Cycle and Engine Operating Residency Analysis (CEORA) - 55kW Skid Steer Loader

Mini Excavator For the 22kW excavator, the analysis highlighted that the machine spends most time operating either at high power or at idle: 70% of the duty cycle’s duration is spent

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How do you define the best powertrain solution for your off‑highway customers?

above 15kW power output (68% of maximum power), and 23% of the duty cycle’s duration is spent ‘idling’ below 1kW power output. The opportunity for downsizing the engine and utilising a hybrid system to provide additional torque when required is not available, because there is insufficient opportunity to use spare engine power to recharge the battery during the working cycle. If the battery state of charge (SoC) could not be maintained through the cycle, then the machine would suffer reduced maximum power. However, stop-start functionality could be considered to reduce idle operation and improve fuel consumption.

Skid Steer Loader A similar analysis of the 55kW Skid Steer Loader revealed that the machine spends most of its time operating at moderate or low power: 85% of the duty cycle’s duration is spent below 50% power (27.5kW). Therefore, there is opportunity to downsize the engine and still have sufficient spare engine power to charge a battery to provide electrical torque assist whenever required by the cycle. If the engine were downsized to 3-cylinder 42kW (i.e. three quarters of current engine displacement and power), the remaining 13kW could be provided by a low-cost 48V hybrid electric system. The engine alone could still supply sufficient power for approximately 95% of the duty cycle, with power “topped-up” electrically when necessary. With this configuration, up to approximately 55% of the duty cycle could be achieved without the combustion engine running: 32% in pure electric mode, operating under battery power, and 23% shut down instead of idling. Further, more detailed, simulation would be required to confirm the system high level specification and determine the best strategy for operation of the engine and electric motor to maintain battery SoC throughout the cycle. Downsizing and electrification of the powertrain could enable operation of the engine at a more efficient point and therefore achieve improvements in total fuel consumption and emissions. The cost of the hybrid system may be offset by the reduced cost of the engine and aftertreatment as well as reduced fuel costs. The Step 1 analysis has demonstrated that a more detailed simulation and cost analysis is justified.

Step 2: Hybrid Powertrain Architecture Assessment (HyPAA) Following Cycle and Engine Operating Residency Analysis (CEORA) for the Skid Steer Loader, the HyPAA tool was used to simulate various powertrain architectures and quantify the possible fuel consumption and NOX emission benefits from hybridisation. The principle is articulated around engine load levelling, whereby the energy storage system present on the vehicle is used to smooth out the demands on the engine, hence

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How do you define the best powertrain solution for your off‑highway customers?

maintaining a relatively constant load on the engine, ideally at near optimum BSFC conditions.

Figure 5: Engine Load Levelling

CEORA indicated that a Skid Steer Loader application was suitable for HyPAA analysis. In this step the performance of the powertrain architecture was assessed using four drive cycles from the United States Environmental Protection Agency website [1]. As per step 1, these are normalised for the specific engine rating; in this case the baseline 55kW. Note: Both the CEORA and HyPAA approaches can be run using any duty cycle; the EPA cycles were used as typical examples.

Figure 6: Skid Steer Loader Typical Duty Cycle 1 - EPA Duty Cycle (normalised)

Testbed mapping data from the baseline 55kW engine was used to generate BSFC and tailpipe NOX emission maps.

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How do you define the best powertrain solution for your off‑highway customers?

Fuel consumption and NOX emissions for each point on the duty cycle were then calculated by the model, and from this, cumulative duty cycle fuel consumption and NOX emissions were estimated. A key assumption made during this level of analysis is that fuel consumption and NOX calculations are based on steady-state mapping data only. Any effects of transient operation would be included in the next level of analysis. As observed during the Step 1 analysis, the Skid Steer Loader Typical Duty Cycle 1 infrequently uses 100% of the available engine power (55kW). The downsized and hybridised powertrain must be able to at least match the work required over the cycle, and as CEORA indicated a 3-cylinder 42kW engine was appropriate for this application. A 13kW 48V hybrid-electric boost system was used, to ensure the 55kW maximum power demand could still be met by the powertrain. Once the 42kW downsized engine had been selected, a BSFC map was generated, and two fuel-efficient operating points were identified: One “low demand” point (30kW) and one “high demand” point (36kW). Note: The number of operating points may differ between applications as tuning of the engine may be possible to further optimise this. Based on this, a strategy was defined for operation of the engine within the hybridised powertrain, at four key points: ● Idle ● “Low demand” fuel efficient point (30kW) ● “High demand” fuel efficient point (36kW) ● Rated power (42kW) The strategy is such that the engine is constrained to operate at the two defined, fuel efficient key points unless the duty cycle demand (factoring in electrical energy storage and usage) requires increased torque from the engine. If increased torque is required, then the model will operate the engine at the rated power point. The model aims to maintain the battery state of charge (SoC) at a defined level throughout the cycle; in this case an SoC of 50% was targeted. If the SoC decreases below 50%, the model runs the engine at the fuel efficient operating point greater than the required power. This allows the work demand to be met and surplus power to be used to re-charge the battery. If the SoC increases above 50%, the model runs the engine at the fuel efficient operating point less than the required power. The shortfall in demanded power is then met by the electric motor. Provided that the battery SoC is above 50%, and the work demand is below the rated power of the motor (13kW), then the work demand is met by the electric motor and the engine is switched off. In this case study, conservative conversion efficiencies of 70% energy storage and 80% energy usage were applied to the model, however this can be adjusted according to specific system capabilities. The following limitations of this strategy were applied to the model:

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How do you define the best powertrain solution for your off‑highway customers?

● The maximum charge rate of the battery limits the amount of surplus power from the engine that can be used to re-charge the battery. ● The model uses the power rating of the 48V system to limit the amount of power the electric motor can provide. If the maximum of 13kW, combined with the available engine power at the given fuel efficient operating point, is not sufficient to meet demand then the model moves the engine to the required operating point. The model strategy used in this case study is illustrated in Figure 7. The strategy can be quickly and easily adapted within the model to suit different powertrain configurations and applications.

Figure 7: HyPAA Operating Strategy Scenarios

The required engine operating conditions to meet the work demand of the duty cycle and maintain the battery SoC at approximately 50% are then used to predict the cycle fuel consumption and NOX emissions for the revised powertrain architecture using the maps of the 42kW engine. The same constraint of using steady-state only mapping data was also applied. The HyPAA model applied to the Skid Steer Loader Typical Duty Cycle 1 yields a fuel consumption saving of 4.5% during a single cycle when the downsized hybrid powertrain is used compared to the baseline 55kW engine (see Table 1).

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How do you define the best powertrain solution for your off‑highway customers?

Table 1: HyPAA Calculation of Fuel Consumption and NOX

Fuel Consumption (g) NOX Emissions (g)

Powertrain Architecture Baseline 55kW 42kW engine with 13kW, 48V hybrid engine system 1281 1226 15.0 15.4

Percentage change -4.5% +2.7%

Over the same cycle however, the model also yields a 2.7% increase in NOX emissions compared to the baseline 55kW engine. Both the baseline 55kW engine and the downsized 42kW hybrid are compliant to the same emissions standard (Tier 4 Final; 37kW ≤ P < 56kW), therefore this increase in predicted “real world” NOX does not indicate an engine non-compliance, but rather highlights a risk that real world performance can be negatively impacted if the correct powertrain assessment is not conducted. In this case the engine operating points were selected based on best BSFC only, rather than considering NOX impact, and so the result was anticipated. To illustrate an alternative approach, the simulation was repeated with the target to maintain total fuel consumption and minimise NOX. The results are shown in Table 2. Table 2: HyPAA Calculation of Fuel Consumption and NOX - Optimised for NOX

Fuel Consumption (g) NOX Emissions (g)

Powertrain Architecture Baseline 55kW 42kW engine with 13kW, 48V hybrid engine system 1281 1277 15.0 12.64

Percentage change -0.3% -15.7%

By altering the efficient operating points to a low region of the NO X emission map, a predicted 15.7% reduction in tailpipe NOX emissions can be achieved with no fuel consumption penalty. This demonstrates that it is possible to tune the HyPAA model to optimise for any parameter to suit the requirements and limitations of the powertrain application. Depending on the product requirements, the model could very simply be optimised for fuel consumption or NOX emissions, or a balance between the two, within the limitations of the engine capability. A next level of simulation, to also consider the optimisation of the engine and aftertreatment calibrations, is described in Step 3.

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How do you define the best powertrain solution for your off‑highway customers?

To further assess the robustness of proposed powertrain architecture for the Skid Steer Loader, the HyPAA approach was applied to two additional duty cycles from the United States Environmental Protection Agency website [1]. ● Skid Steer Loader Typical Duty Cycle 2 ● Skid Steer Loader High Speed Duty Cycle

Figure 8: Skid Steer Loader High Speed Duty Cycle - EPA Duty Cycle (normalised)

The results of the HyPAA calculation for the alternative duty cycles are shown in see Table 3. It can be seen that for both powertrain layouts the fuel consumption is dependent on the specific duty cycle; however, the selected hybrid system is predicted to yield fuel savings across a wide range of operating regimes. Table 3: HyPAA Calculation of Skid Steer Loader Fuel Consumption

Duty Cycle 2 Fuel Consumption (g) High Speed Cycle Fuel Consumption (g)

Powertrain Architecture 42kW engine with Baseline 55kW 13kW, 48V hybrid engine system

Percentage change

839

774

-7.7%

1389

1365

-1.7%

In this case study, the hybrid system architecture included stop-start functionality. If a particular application requirement prevented the use of stop-start, for example due to

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How do you define the best powertrain solution for your off‑highway customers?

cabin heating requirements or anti-ice, then the HyPAA model can be adapted to accommodate this. Due to the operating strategy of the model, there are extended periods of engine off operation whilst the electric motor meets the duty cycle work demand. If the engine was to be at idle condition during this period, the fuel consumption and particularly the NOX emissions would significantly increase. However, the model can accommodate the power usage of sub-systems such as auxiliary heaters to overcome this.

Step 3: Ricardo Integrated Model Based Development (IMBD) The analysis carried out in Step 2 allows a first order assessment of potential gains to be obtained from hybridisation of the powertrain. The mechanism described is articulated around the use of the electrical storage system to level out the engine load and power, either through electrical generation or re-use, and therefore encourage operation around best efficiency points. This process provides key information regarding the relative merits of different architectures or sets of system hardware, and as such is a key tool to perform technology selection screening at an early stage. As architecture and system definition becomes more mature, the focus of the modelling and simulation work shifts towards the optimisation of the complete machine, capturing all aspects of the machine that contribute directly or indirectly to vehicle fuel efficiency, and importantly, all interactions between the related systems. The first step consists in the identification of key vehicle attribute requirements and targets. In the case of vehicle efficiency optimisation, the process involved can be summarised as Figure 9:

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How do you define the best powertrain solution for your off‑highway customers?

Figure 9: Vehicle Efficiency Optimisation Process

For vehicle efficiency optimisation, the work focuses on managing the energy flows in the vehicle, whether of mechanical, thermal or electrical nature. This implies that the following domains are often represented during such activities: ● Engine: friction, airpath, calibration ● Transmission and driveline ● Hydraulics ● Vehicle ● Electrical system: electric engine charge compressors, electric waste heat recovery systems, driveline motors, batteries ● Thermal systems: engine coolant, engine oil, cabin ● Aftertreatment system ● Control system The build and exploitation of models capturing all these domains and interactions is non-trivial and requires suitable toolsets and processes. Over recent years, Ricardo has been active in consolidating and integrating its suite of models, leading to the

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How do you define the best powertrain solution for your off‑highway customers?

foundation of Ricardo Integrated Model Based Development (IMBD) platform. IMBD is now used to carry out multi-domain optimisation. The IMBD process and tools were applied on a recent project for a European OEM. The application was, in terms of architecture, similar to that described in the previous sections and consisted in a P0 parallel hybrid architecture with electrical charge compressor on the engine. As before, the P0 electric motor could either add or remove load from the engine, using a 48V battery as the storage and delivery medium. Finally, the duty cycles of relevance for the application included two low to medium load cycles, offering opportunities to move the engine operation to high efficiency areas. Beyond the standard analysis of fuel economy gains through the hybridisation of the powertrain, the particular focus of the study was to understand the further gains that could be realised through total system optimisation, and therefore inclusive of engine calibration parameters. An integrated model of the vehicle was defined and built according to the process depicted on Figure 9. The domains captured during the project are shown on Figure 10. The engine air system was simulated using Ricardo WAVE-RT; a fast running version of the standard WAVE 1-D engine performance simulation code. This enabled dynamic air-path modelling to be incorporated to the simulation, allowing the transient impact of the e-boost system to be captured. This was coupled to a stochastic process model (SPM) of the combustion system, to link the prediction of the engine response, both in terms of performance and emissions, to engine calibration parameters such as AFR or EGR targets. The instantaneous engine torque and speed were also passed to other submodels, and the turbine outlet temperature and mass flow used in the exhaust aftertreatment model to predict tailpipe emissions. The vehicle, transmission and hybrid components were simulated in Ricardo IGNITE. Finally, a MATLAB-based supervisory controller performed power request calculations and generated duty demand signals for all sub-models.

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How do you define the best powertrain solution for your off‑highway customers?

Whilst state-of-the-art toolchains enable optimisation of hybrid and aftertreatment calibration, they typically assume fixed engine calibration. The IMBD toolchain, however, is able to consider impacts of engine calibration simultaneously with all other optimisation parameters. This is particularly the case with the engine EGR strategy, whose calibration may now be performed synergistically with the hybrid and the exhaust aftertreatment systems.

Figure 10: IMBD model setup

Following the model build and validation against measured data (for the non-hybrid case), 17 key parameters were selected for optimisation. These covered engine calibration, aftertreatment control and hybrid control domains. A set of simulations covering the design space defined by those 17 parameters was generated using DoE techniques (Ricardo EfficientCal Toolbox). The test cases were then simulated, and the results compiled together to generate response surfaces for the key output variables. The optimiser was then used to generate Pareto trade-off curves to show the relationship between tailpipe NOX emissions and cycle fuel consumption, with a constraint applied to ensure battery SoC neutrality over the cycle. The IMBD-generated Pareto trade-off curve is illustrated in Error! Reference source not found., along with the Pareto curve obtained with a fixed engine calibration (hybrid & aftertreatment system optimisation only).

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How do you define the best powertrain solution for your off‑highway customers?

Figure 11: IMBD Optimisation of Engine Calibration

In this particular case, a potential reduction in fuel consumption of between 2 and 5% was predicted (on top of hybrid benefits already accrued). Considering that this is obtained at no additional cost in terms of vehicle hardware, these results highlight the very significant potential and key role that awaits total system optimisation in future product design and development. The work conducted in Steps 1 & 2 led to the general assessment of potential hybridisation benefits and has identified the benefits that can be achieved. Future steps will involve the use of higher fidelity and integrated models for more accurate predictions and complete system optimisation in a virtual environment.

Discussion & Conclusions In the off-highway machinery markets powertrains are becoming more complex, and electrification is a growing trend as more efficient and cleaner solutions are sought. Legislation is a driving factor; however, customer requirements for machine performance, as well as economic expectations, must also be considered. When considering the best powertrain for a given machine, there will be multiple “right” answers depending on how the machine will be used and the priority of desired attributes. With a complex mixture of possible technologies and demanding, and sometimes conflicting, customer requirements, the assessment of different powertrain options requires complex simulation. This is not always straightforward and can cost the product developers significant time and money. By employing a hierarchy of simulation methodologies, the powertrain architect can efficiently assess, down select, and optimise the systems:

15

How do you define the best powertrain solution for your off‑highway customers?

● Step1: A high-level analysis of the operating requirements can be used to identify if a powertrain is well matched to the duty cycle or whether opportunity exists to improve, for example through hybridisation. ● Step2: Simulation can then enable the system designer to configure and specify the powertrain and quantify the potential benefits or impacts to the total system performance. ● Step 3: As demonstrated in this report, optimisation of the hybrid system operating strategy is key to realise the greatest benefit. Advanced computer aided engineering tools can be employed to optimise and calibrate systems in a virtual environment. The case studies described in this report highlight the complexity of specifying a hybrid powertrain for off-highway machinery and illustrate that a “one-size-fits-all” solution does not exist. Electrified powertrains for off-highway applications will require a greater amount of application specific customisation than conventional ICE-only systems, not only to realise their full benefits, but also to avoid unintended performance degradation. OEMS will need modular solutions and a highly trained sales team (with the right tools) to make sure the customer buys what is right for them. The right system layout and calibration can yield performance and economic benefits. Providing minimised emissions and air quality impacts, as well as the lowest total cost of ownership (TCO). Further development of Ricardo HyPAA tool will involve integration of system cost models to enable simultaneous TCO evaluation.

References 1. “EPA Nonregulatory Nonroad Duty Cycles”, United States Environmental Protection Agency, https://www.epa.gov/moves/epa-nonregulatory-nonroad-duty-cycles, downloaded July 2018.

16

Next generation high-speed engines paving the road for the highest engine efficiency Dr. Günter Figer, Kurt Schmidleitner, Thomas Kammerdiener, Mathias Schönbacher, AVL List GmbH

© Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2019 W. Siebenpfeiffer, Heavy-Duty-, On- und Off-Highway-Motoren 2018, Proceedings, https://doi.org/10.1007/978-3-658-25889-4_3

1

Next generation high-speed engines paving the road for the highest engine efficiency

Abstract High-speed engines are set to be the main power source for decentralized power generation, commercial and high-performance marine, Oil&Gas service, Rail as well as for construction equipment (C&I). Considering the projection, that next generation highspeed engines will be operated much more in integrated systems and hybridized applications, the thermal efficiency of the combustion engine will still be in the main focus of new engine developments. The next generation of high-speed engines will find itself in a challenging competition. It will be measured against the high efficiency and power density of best-in-class medium speed engines, but under the conditions of a much smaller engines size, weight and cost. To unleash the highest engine efficiency combined with a high power density above 35 bar BMEP the peak firing pressures will be beyond 300 bar. There are numerous challenges down the road of designing engines operating at very high peak firing pressures, mainly addressing the cylinder head design, cylinder head cooling concept and the interaction of cylinder head design with fuel injectors or prechamber components. In this paper AVL is addressing some of these challenges from the design perspective and will give an insight to already realized solutions and an outlook of future potential.

Drivers for new engine generation Market drivers Worldwide growing demand for electrical power generation as well as an again increasing demand for marine propulsion, power sources for oil field services or construction equipment will drive Diesel- and gas engines market also in the future. Production numbers from 2018 show, that for engines above 500kW roughly 95% of power generation engines and about 75% of all marine engines – for propulsion as well as auxiliary power – were high-speed engines1 (>1200rpm), as shown in Figure 1. Over the last 10 years production numbers were stable and are furthermore forecasted to steadily increase over the next decade, as shown in Figure 2.

1 Power Systems Research (PSR); Market study for AVL; 2017

2

Next generation high-speed engines paving the road for the highest engine efficiency

Figure 1: Total Engine Production ≥0.5 MW

Figure 2: HS- Engines for Powergen, Marine Propulsion and Marine Auxiliary

The high-speed engine marked is hence particular attractive because of high production numbers and competition in this market segment is about to increase in the next couple of years. A new generation of high-speed engines is under development where fuel efficiency and power density are competing with larger medium speed engines but under the conditions of a much smaller engines size, weight and cost.

3

Next generation high-speed engines paving the road for the highest engine efficiency

Even if high-speed engines will be operated much more in integrated systems and hybridized applications in the future fuel efficiency of the combustion engine will stay in the focus of any new engine development as operational cost are utmost important to be competitive in the future. Another aspect regarding efficiency is linked to CO2 and greenhouse gas emissions. A centerpiece of the EU’s 2030 framework is a binding target to reduce greenhouse gas emissions by 40% below 1990 levels by 20302. Renewable energy and hence (bio-) gas engines will be inherently important to meet this target as the EU target for 2030 is at least a 27% share of renewable energy consumption. Decentralized power generation is a strongly increasing demand in view of the current electrification trend for low emission mobility and transportation. The trend for autonomous driving for all fields of applications like passenger cars, commercial vehicle and finally ships require numerous new datacenters with respective power demand. Mobile application will slowly adapt to gas engines as LNG infrastructure grows, but the Diesel engine will prevail for some time, especially for high power applications. Needless to say, that both diesel and gas engines are similarly important to cover the entire high-speed engine market requirements and fuel flexibility will play a role.

Product specifications and operator requirements One of the biggest challenges for high-speed engines is its wide and diverse area of applications. Each application has its own specific requirements regarding engine parameters in terms of power density, engine speed range and emission limits. The marine sector for instance includes propulsion engines with constant or variable speeds in the range of approximately 1200 rpm to 2100 rpm as well as auxiliary engines which mostly are operated at 60 Hz (1800rpm). Power density requirements are high particularly for yachts and pleasure boats combined with low load factors whereas for commercial marine applications the power density is more moderate, yet the load factors are high. Fuel efficiency is a topic which is relevant in areas with high operating hours especially in the segment of electric power generation with continuous service like for prime power (PRP) and continuous power generation (COP). Reliability is key for sensitive applications like mining and fracking.

2 2030 Energy Strategy; A policy framework for climate and energy in the period from 2020 to 2030 [COM(2014) 15]; https://ec.europa.eu/energy/en/topics/energy-strategy-and-energy-union/2030-energy-strategy

4

Next generation high-speed engines paving the road for the highest engine efficiency

Systems and applications are subject of a continuous process of improvement and change of boundary conditions, which are linked to higher efficiencies and power increase most of the time. A topic especially related to the combustion engine. With the increasing power density of new engine platforms and high cylinder numbers highspeed engines conveniently reach the power class of 3.0 to 5.0 MW, where they must compete the medium speed engines. In terms of installation space however or for a retrofit a medium speed engine is no alternative due to its unfavourable size. The success of a new high-speed engine platform is related to the conviction in three major areas – end-users key buying criteria, end-users cost effectiveness and last but not least the cost effectiveness for the manufacturer (OEM), see Figure 3. One of the key buying criteria’s is the time between overhaul (TBO). In terms of overhaul intervals, the medium speed engine sets the pace. Next generation of high-speed engines however, with highest power density and improved performance will meet TBO requirements of 24.000 hours. Lower power ratings though will have a higher TBO target, but this will be heavily depending on the specific application. Related to the buying criteria is the cost effectiveness for the end-user which is among others Capital Expenditure (CAPEX) and Operational Expenses (OPEX). Therefore, for instance a multi fuel capability is important. Looking at electric power generation, depending on the type of engine CAPEX and OPEX have different significance. For an emergency standby (ESP) a small CAPEX is important which implicates a Diesel engine, whereas for non-emergency use a small OPEX is significant which can be achieved with a Gas engine where the fuel price is much lower. To close a circle the requirements for the manufacturer are low costs in production. This can be achieved with parts communality, modularity and a specific design and strategy which allows to use low cost suppliers for certain applications.

5

Next generation high-speed engines paving the road for the highest engine efficiency

Figure 3: Product Requirements

Conceptual and thermodynamic considerations An extract of current developments of high-speed engines regarding power requirements is displayed in Figure 4. They reflect the wide field which is covered by this type of engines utilized in various applications. Low and moderate power densities are found in applications with high load factors such as for construction & industrial, marine commercial or continuous electric power generation. The highest specific power output is found in the marine sector for pleasure boats with 250 kW/cyl. Highest break mean effective pressures (BMEP) though are used for the electric power generation in emergency standby configuration. For this development the maximum operational peak firing pressure is approximately 250 bar.

6

Next generation high-speed engines paving the road for the highest engine efficiency

Figure 4: Benchmark Cylinder Power vs. BMEP

Although the aforementioned performance targets are already demanding the next question would be, what are the benefits of a further increased peak firing pressure limit. Two scenarios are obvious, an increase in power or an increase in engine efficiency. Figure 5 shows the current development in power output for electric power generation in standby configuration. With a specific power output of approximately 200 kW per cylinder, the 20-cylinder engine delivers over 4 MW in total power output at an operational peak firing pressure of around 250 bar. An increased capability in cylinder pressure could give the possibility to put the specific power output per cylinder to 260 kW. This allows a reduction of cylinder numbers from 20 to 16 and still have a total power output of nearly 4 MW. In addition to that the 20-cylinder engine with this configuration would have a power output over 5 MW.

Figure 5: Specific Power Increase with Down Numbering / Increased Power

7

Next generation high-speed engines paving the road for the highest engine efficiency

For the estimation of the potential in efficiency increase a 50 Hz electric power generation application was used as a baseline. The emission scenario Tier4 was assumed and the target emissions of 0.6 g/kWh NOx was achieved by using selective catalytic reduction (SCR) with a conversion rate over 90 %. In a first step the injection timing was advanced until an optimum centre of combustion, around 8-degree crank angle after firing top dead centre, is reached. In the investigated case the cylinder pressure rises above 260 bar. To see the final efficiency potential at 300 bar the compression ratio and the excess air ratio was used to further increase the cylinder pressure. The study reveals a potential in fuel consumption decrease of approximately 7 % while the benefit in total fluid consumption is thought to be around 5 % (assumption: reduction of 1g/kWh NOx correlates to an increase of 1 g/kWh BSFC equivalent), see Figure 6.

Figure 6: Efficiency Potential with Increased PFP

To access the abovementioned potentials, changes in the current state of the art design as well as for all major building blocks are necessary. – Exhaust Aftertreatment System (EAS): Most stringent emission application EAS will consist of a high efficient SCR in any case and a DPF for some applications. Higher engine efficiency by means of advanced combustion timing will additionally increase the EAS efficiency requirements. – Turbocharging: The increase of power and / or efficiency will imply two stage turbocharging. In combination with the use of an early intake valve closing (Miller timing) for NOx emission reduction the demand for high boost pressure will further increase.

8

Next generation high-speed engines paving the road for the highest engine efficiency

– Enhanced Valve Train Capabilities: Depending on the timing of the inlet valve closing a variability in the closing event is necessary to guarantee the cold start ability as well as to improve or keep the transient behaviour of the engine. – Fuel Injection System: Despite the requirements of high power ratings still the low load operation capabilities must not be compromised.

Design challenges Power cylinder unit (PCU) design: The thermodynamic requirements lead to increased thermo-mechanical loads on all components of the power unit. Above that the designer needs to consider following aspects in the planning phase of a new high-speed engine family of the involved components (see Figure 7). – Modular design with maximum part communalities for diesel and gas version across all applications – The wall heat losses of the diesel combustion are higher compared to the gas combustions due to the higher combustion temperatures – The heat impact to the components of the quiescent combustion systems is different for diesel and gas version. The piston bowl of the diesel piston shifts the thermal challenge towards the fire deck of the cylinder head, while the gas combustion system with its pre-chamber and open combustion chamber increases the heat impact on the piston top surface – Integration of gas-scavenged pre-chamber in the same space as for the diesel common rail injector – Provision for a controlled pre-chamber gas admission valve – Provision for cooled exhaust manifold (marine versions) – Consideration of 50%-50% glycol-water mixture, which represents the worst case in terms of heat coolant side heat transfer – Different valve seat angle for diesel and gas engine variant

9

Next generation high-speed engines paving the road for the highest engine efficiency

Figure 7: Power cylinder unit components

Some major differences and communalities between diesel version and gas version family are summarized in Table 1. Table 1: Modular family considerations of diesel and gas version Cylinder head cast part Cylinder head machining Intake and exhaust ports

Diesel Single head with 6 bolts CR-Injector plus fuel supply

Fuel injection

Quiescent (swirl 70 %Vol.

Figure 6: Validated engine operation range Figure 6 shows that the achievable maximum CO2 content depends on engine power. This limitation is caused by the exhaust gas temperature (component temperature limit) mainly. Furthermore, it was possible to start the engine under pre heated conditions with the chosen gas composition listed in Table 4 successfully. It was possible to develop a combustion concept tailored to gases with high CO2 content > 70 %Vol. Conclusion: Great progress has been made in making non-natural gas applications increasingly attractive for customers and meeting their requirements. The development efforts resulted in a new engine version of the Type 4 series designed for low BTU applications with equal power output to NG operation (20 bar BMEP) and a mechanical engine efficiency of 41,5 %. Table 6 shows the gas specification for this new engine version.

12

Improving fuel flexibility: new Jenbacher gas engine versions with high power density …

Table 6: New engine version gas specification (low BTU gas) Main Gas Content in %Vol

Target

Methane

CH4

30,4

Ethane

C2H6

1,1

Propane

C3H8

0,1

Butane

C4H10

0,1

Higher Hydro Carbons

C(5+)H(12+)

Inert Components

N2

0,1

Inert Components

CO2

68,2

LHV [kWh/Nm3]

3,25

MN Band w/o inerts

86

Summary and Outlook This publication describes the development of a combustion concept for the efficient usage of non-natural gases with high CO2 content. The development methodology combined an experience-based approach with reaction kinetic calculations and resulted in a tailor-made combustion system. The new combustion system enables robust engine performance in the corresponding non-natural gas applications with a high engine efficiency of 41,5 % and a high-power density up to 20 bar BMEP. This development step was facilitated by the interaction of in-house engine testing with non-natural gas and field testing of various engines running with landfill gas, bio gas and coal mine gas etc.. The development activities resulted in new Jenbacher gas engine versions for gases with high CO2 content. Customers benefit from higher power density, higher engine efficiency and reduced specific costs (no gas treatment, no NG admixing, high BMEP).

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Improving fuel flexibility: new Jenbacher gas engine versions with high power density …

Abbreviations and symbols A/F

- air/fuel

BMEP

- Brake mean effective pressure

°CA

- Degree crank angle

CHP

- Combined heat and power

IMEP

- Internal mean effective pressure

ITP

- Ignition timing point

MCE

- Multi cylinder engine

MN

- Methane number

NG

- Natural gas

NNG

- Non-natural gas

TC

- Turbo-charger

TKE

- Turbulent kinetic energy

14

Improving fuel flexibility: new Jenbacher gas engine versions with high power density …

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Fuchs J., Gebhardt A., Leitner A., Thalhauser J., Tinschmann G., Trapp C.: Technology Blocks for High Performance Direct Ignition Gas Engines, 7th International MTZ Conference, Heavy-Duty, On- and Off-Highway Engines 2012, Nuremberg

[2]

Prankl S., Trapp C., Böwing R., Zuschnig A., Schiestl S., Schneßl E., Wimmer A.: „Fortschritte bei Sondergasen – GE Gasmotoren mit hoher Leistung für wasserstoffund kohlenmonoxidreiche Gase“; 4. Rostocker Großmotorentagung, 15. - 16. September 2016, Rostock, Deutschland

[3]

Amplatz E., Schneider M., Trapp C.: „Verwendung von Sondergasen in stationären Gasmotoren“; Heavy-Duty, On- and Off-Highway Engines, MTZ Konferenz, 15. und 16. Nov. 2011, Kiel, Deutschland

[4]

Amplatz E., Schneider M., Trapp C.: „Sondergase aus Industrieprozessen – neue Ressourcen für Energieerzeugung mit Verbrennungsmotoren“; Tagung Gasfahrzeuge 2009, Stuttgart, Deutschland

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Schneßl E., Kogler G., Wimmer A.: „Großgasmotorenkonzepte für Gase mit extrem niedrigem Heizwert“; 6. Dessauer Gasmotoren-Konferenz, 26. und 27. März 2009, Dessau, Deutschland

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Schneßl E., Pirker G., Wimmer A.: „Optimierung von Brennverfahren für Sondergasanwendungen auf Basis Simulation und Versuch am Einzylinder-Forschungsmotor“; Heavy-Duty, On- and Off-Highway Engines, MTZ Konferenz, 17. und 18. Nov. 2009, Friedrichshafen, Deutschland

[7]

Trapp C., Böwing R., Zauner S., Amplatz E., Arnold G., Kopecek H., Wimmer A.,Schneßl E.: „Nutzung von Gichtgas im Großmotor mit Hilfe eines auf Zweigasbetrieb angepassten Regelungskonzeptes“; 3. Rostocker Großmotorentagung, 18. - 19. September 2014, Rostock, Deutschland

15

The effective use of ethanol for GHG emissions reduction in a dual‑fuel engine Dr Vinícius B. Pedrozo, Dr I. May, Dr T. Lanzanova, W. Guan, and Prof. H. Zhao

© Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2019 W. Siebenpfeiffer, Heavy-Duty-, On- und Off-Highway-Motoren 2018, Proceedings, https://doi.org/10.1007/978-3-658-25889-4_11

1

The effective use of ethanol for GHG emissions reduction in a dual‑fuel engine

Abstract Regulations have been established for the monitoring and reporting of greenhouse gas (GHG) emissions and fuel consumption from the transport sector, including heavy-duty vehicles. Low carbon fuels combined with new powertrain technologies have the potential to provide significant reductions in GHG emissions while decreasing the dependency on fossil fuels. In this study, advanced combustion control strategies have been used as means to improve upon the efficiency and emissions of a lean-burn ethanol-diesel dual-fuel engine. Experiments have been performed on a 2.0 dm3 single cylinder heavy-duty engine equipped with a high pressure common rail diesel injection system, port fuel injection of ethanol, and variable valve actuation (VVA). The VVA system allowed for the use of an intake valve re-opening during the exhaust stroke (2IVO) as well as late intake valve closing (LIVC). At low engine load, the combination of an early diesel injection and the 2IVO strategy helped increase the fuel conversion efficiency and control the exhaust emissions for a dual-fuel engine operation with an ethanol energy fraction of 56%. At high engine load, the LIVC strategy lowered the effective compression ratio and enabled a substantial increase in the maximum ethanol energy fraction from 25% to 79%. Compared to a baseline diesel-only operation, the optimised ethanol-diesel dual-fuel combustion demonstrated competitive levels of fuel conversion efficiency while simultaneously achieving up to 57% lower well-to-wheels GHG emissions.

1 Introduction In 2015, heavy-duty (HD) trucks and buses were responsible for approximately 25% of the GHG emissions from road transportation in the European Union (EU)1,2. This contribution is highlighted by the fact that these commercial vehicles represented only 2.4% of the total fleet in use while relying almost exclusively on diesel fuel3. GHG emissions, such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), are very likely to be the dominant cause for the increase in the global annual mean surface air temperature over the last 35 years4. A higher average surface air temperature can cause irreversible climate change and negatively affect the health of living organisms across the globe5. In an effort to reduce the transport sector’s impact on the environment, new HD vehicles produced in the EU will have their CO2 emissions and fuel consumption regulated starting 1 January 2019. Future proposals are targeting a 15% and 30% CO2 emissions reduction by 2025 and 2030 respectively, relative to a baseline 2019 model year6,7. HD vehicle manufacturers have lobbied that reductions of 7% by 2025 and 16% by 2030 would be more attainable targets8. Provisions have been established in the Commission Regulation (EU) 2017/2400 9, laying down the certification of HD vehicle components with an impact on CO2 emissions and fuel consumption. Both of these performance metrics will have to be calculated using the vehicle energy consumption calculation tool (VECTO), a dedicated simulation software2. The results will be declared on a tank-to-wheels (TTW) basis, representing the vehicle operation only7. Therefore, CO2 emissions will likely be reported in grams per thousand kilometre (g/t-km).

2

The effective use of ethanol for GHG emissions reduction in a dual‑fuel engine

Cost-effective technologies have been deployed in order to decrease the fuel consumption of HD vehicles and achieve CO2 mitigation targets. These technologies typically help to improve the efficiency of the internal combustion engine, transmission, exhaust after-treatment system, and aerodynamic design10. Additionally, low rolling resistance tyres and idle management are expected to be employed in the HD sector in order to help reduce CO2 emissions8,10–12. Alternatively, the introduction of low carbon fuels13, driver training and route optimisation10, as well as vehicle convoying and platooning systems8,14 have the potential to minimise CO2 emissions. In particular, the use of low carbon fuels such as sugar cane ethanol have demonstrated significant reductions of 14% to 57% in the well-to-wheels (WTW) CO2 equivalent (CO2eq) emissions relative to a diesel-only engine operation15. It is important to note that the WTW CO2eq emissions take into account the different global warming potentials of CH4 and N2O, and is therefore representative of the total GHG emissions associated with fuel production, distribution, and vehicle operation (per MJ of fuel). Displayed in Table 1 are the results of a theoretical analysis for the complete combustion of diesel and sugar cane ethanol. Well-to-tank (WTT) CO2eq emissions are the GHG emitted during the extraction or cultivation of raw materials, processing, transportation, and other processes necessary to physically get the fuel into the fuel tank16. TTW CO2eq emissions released during the combustion of sugar cane ethanol were excluded from the analysis as they are absorbed by the plants during photosynthesis17. As a result, the utilisation of bioethanol can obtain up to 72.2% lower WTW CO2eq emissions than diesel. This highlights the importance of the development of clean and high efficiency ethanol-based technologies in order to reduce fossil fuel dependency and meet CO2 emission targets in the short to medium term. Table 1 – Analysis of a theoretical complete combustion of diesel and sugar cane ethanol. Property Normalised fuel molecular composition Well-to-tank (WTT) CO2eq emissions Normalised fuel molar mass (‫ܯ‬௙௨௘௟ ) Mass of CO2 emissions per mole of fuel Mass of CO2 emissions per mass of fuel Lower heating value (‫ܸܪܮ‬௙௨௘௟ ) Tank-to-wheels (TTW) CO2 emissions TTW CO2 emissions reduction Tank-to-wheels (TTW) CO2eq emissions Well-to-wheels (WTW) CO2eq emissions WTW CO2eq emissions reduction

Diesel ‫ܪܥ‬ଵǤ଼ଶହ ܱ଴Ǥ଴଴ଵସ 15.4 gCO2eq/MJ16 13.87 g/mol 44.01 gCO2/mol 3.17 gCO2/g 42.9 MJ/kg 73.9 gCO2/MJ 73.9 gCO2eq/MJ 89.3 gCO2eq/MJ -

Sugar cane ethanol ‫ܪܥ‬ଷ ܱ଴Ǥହ 24.8 gCO2eq/MJ16 23.03 g/mol 44.01 gCO2/mol 1.91 gCO2/g 26.9 MJ/kg18 71.0 gCO2/MJ 3.9% 24.8 gCO2eq/MJ 72.2%

The dual-fuel combustion strategy is an effective means of using ethanol in HD diesel engines despite the need for a second fuel supply system19. However, the fuel conversion efficiency is

3

The effective use of ethanol for GHG emissions reduction in a dual‑fuel engine

usually reported to be lower than that of a diesel-only operation at low engine loads20–24. This is associated with the lower combustion efficiency of the dual-fuel mode at such conditions25. Moreover, the amount of ethanol injected and therefore the CO2 reduction is restricted to low percentages at high load conditions. This is a result of peak in-cylinder pressure (Pmax)26 and/or pressure rise rate (PRR) limitations27,28. Research and development work is needed to optimise the combustion process and overcome the challenges encountered by current dual-fuel engines. In this study, advanced combustion control strategies were experimentally explored in order to increase the efficiency, decrease the emissions, and maximise the use of ethanol on a single cylinder HD diesel engine equipped with a VVA system. The application of an early diesel injection and intake valve re-opening during the exhaust stroke (2IVO) was examined at a low engine load of 0.3 MPa net indicated mean effect pressure (IMEP). The effectiveness of late intake valve closing (LIVC) was investigated at a high engine load of 1.8 MPa IMEP. WTW CO2eq emissions for the optimised ethanol-diesel dual-fuel combustion were compared to those for the baseline dual-fuel and diesel-only operations.

2 Experimental setup A schematic diagram of the single cylinder HD engine experimental setup is depicted in Figure 1. An eddy current dynamometer was used to absorb the power produced by the engine. Fresh intake air was supplied to the engine via an external compressor with a closed loop control for the boost pressure. A throttle valve located upstream of a surge tank provided fine control over the intake manifold pressure. The fresh air mass flow rate was measured with a thermal mass flow meter. Another surge tank was installed in the exhaust manifold to damp out pressure fluctuations. An electronically controlled back pressure valve located downstream of the exhaust surge tank was used to set the required exhaust manifold pressure.

Figure 1 – Schematic diagram of the engine experimental setup.

4

The effective use of ethanol for GHG emissions reduction in a dual‑fuel engine

Base engine hardware specifications are outlined in Table 2. The combustion system consisted of a 4-valve swirl-oriented cylinder head and a stepped-lip piston bowl design. A lost-motion VVA system enabled the adjustment of the intake valve lift profile via a normally open high-speed solenoid valve assembly and a special intake cam design 29. Coolant and oil pumps were driven by separate electric motors. Engine coolant and oil temperatures were set to 353 ± 3 K. The oil pressure was held at 450 ± 10 kPa throughout the experiments. Table 2 – Single cylinder HD engine specifications. Parameter Displaced volume Bore/Stroke Connecting rod length Geometric compression ratio Pmax Diesel Injection System Ethanol Injection System

Value 2.026 dm3 129/155 mm 256 mm 16.8 18 MPa Bosch common rail, 25–220 MPa, 8 holes with a diameter of 0.176 mm, included spray angle of 150° PFI Marelli IWP069, 300 kPa (relative pressure), included spray angle of 15°

A high pressure common rail diesel injection system was controlled via a dedicated engine control unit (ECU) with the ability to support up to three injections per cycle. Two Coriolis flow meters were used to determine the diesel mass flow rate by measuring the total fuel supplied to and from the diesel high pressure pump and injector. Ethanol was injected through a port fuel injector (PFI) installed in the intake manifold. An inhouse injector driver controlled the injector pulse width, which was adjusted according to the desired ethanol energy fraction. The ethanol mass flow rate was measured using another Coriolis flow meter. Gaseous emissions such as CO2, carbon monoxide (CO), nitrogen oxides (NOx), and unburned hydrocarbon (HC) were measured with a Horiba MEXA-7170 DEGR emissions analyser. An AVL 415SE smoke meter was used to determine the concentration of black carbon containing soot, which was reported on a filter smoke number (FSN) basis. The in-cylinder pressure was measured by a piezoelectric pressure sensor coupled with a charge amplifier. Intake and exhaust manifold pressures were measured by two water-cooled piezoresistive absolute pressure sensors. Temperatures and pressures at relevant locations were measured by K-type thermocouples and pressure gauges, respectively. Two data acquisition (DAQ) cards and a personal computer were used to acquire the signals from the measurement devices. These data were displayed live by an in-house developed DAQ program and combustion analyser.

5

The effective use of ethanol for GHG emissions reduction in a dual‑fuel engine

3 Data analysis PRR was represented by the average of the maximum pressure variations of 200 cycles of cylinder pressure versus crank angle. Combustion and in-cylinder flow stability were monitored by the coefficient of variation of IMEP (COV_IMEP). The concentration of CO, NOx, and unburned HC in the exhaust stream were converted from parts per million (ppm) to net indicated specific emission30. Combustion efficiency calculations were based on the emissions products not fully oxidised during the combustion process except soot31. CO2 and WTW CO2eq emissions were calculated using the methodology described in Pedrozo et al.15. The ethanol energy fraction was defined as the ratio of the energy content of the ethanol to the total fuel energy supplied.

4 Test methodology The steady-state engine test conditions are summarised in Table 3. A PRR of 2.0 MPa/CAD and a Pmax of 18 MPa were considered as the upper bounds for calibration. Stable engine operation was quantified by COV_IMEP of less than 5%. The intake and exhaust manifold pressure set points were taken from a Euro V compliant multi-cylinder HD diesel engine in order to provide a sensible starting point. This was necessary because an external boosting device and a back pressure valve were used in place of a turbocharger. Table 3 – Testing conditions for the different engine operating modes. Parameter Engine load Engine speed Diesel injection pressure Intake air temperature Intake manifold pressure Exhaust manifold pressure Engine operating mode Ethanol energy fraction Diesel injection strategy

Low load operation 0.3 MPa IMEP 1200 rpm 50 MPa 292 K 103 kPa 104 kPa (1a) Diesel-only (2a) Dual-fuel (3a) Dual-fuel + 2IVO32 (1a) n/a (2a) 56% (3a) 56% (1a) single (2a) single (3a) early single32,33

High load operation 1.8 MPa IMEP 1200 rpm 155 MPa 324 K 260 kPa 270 kPa (1b) Diesel-only (2b) Dual-fuel (3b) Dual-fuel + LIVC31 (1b) n/a (2b) 25% (3b) 79% (1b) single (2b) single (3b) pre + main34

Engine testing was performed without external exhaust gas recirculation (EGR). Moreover, all comparisons were carried out for the cases that attained the highest fuel conversion efficiencies (given by the net indicated efficiencies) after the optimisation of the diesel injection timing.

6

The effective use of ethanol for GHG emissions reduction in a dual‑fuel engine

Diesel fuel was introduced using a single injection near firing top dead centre (TDC) for cases (1) and (2). However, the dual-fuel combustion case (3a) employed an early single injection at -40.8 CAD ATDC while case (3b) was achieved with a small pre-injection of 3 mm3 prior to the main diesel injection near TDC. These optimised diesel injection strategies helped improve upon engine-out emissions and performance. The fixed exhaust valve lift and variable intake valve lift used in this study are depicted in Figure 2. The VVA system allows for a 2IVO with the purpose of introducing internal EGR (iEGR) at low engine loads32 and enables a LIVC for reduced effective compression ratio (ECR) at high load conditions31. The main intake valve opening (IVO) and closing (IVC) were initially set at 354 ± 1 CAD ATDC and -153 ± 1 CAD ATDC, as determined at 0.5 mm valve lift.

Figure 2 – Overview of the fixed exhaust valve lift and variable intake valve lift curves.

At 0.3 MPa IMEP, case (3a)’s 2IVO had its opening and closing events set at 160 ± 1 CAD ATDC and 230 ± 1 CAD ATDC, respectively, yielding a maximum valve lift of approximately 2 mm at 195 ± 1 CAD ATDC. At 1.8 MPa IMEP, case (3b)’s LIVC strategy delayed the IVC to -107 ± 1 CAD ATDC, lowering the pressure-based ECR31 from 16.8 to 14.4.

5 Results and discussion 5.1 Combustion characteristics A comparison between (1) diesel-only, (2) dual-fuel, and (3) optimised dual-fuel combustion cases at two different engine loads is displayed in Figure 3. At 0.3 MPa IMEP, the dual-fuel combustion with a late single diesel injection (2a) led to a similar HRR profile to a diesel-only operation (1a). The low reactivity of the ethanol fuel decreased the peak heat release and yielded a longer combustion duration despite the use of a slightly more advanced diesel start of injection. Alternatively, the use of an early diesel injection in case (3a) enhanced the combustion process via a more progressive and probably sequential combustion from high to low reactivity regions25,35. Moreover, the use of a 2IVO allowed for hot residuals (e.g. iEGR) to be pushed into

7

The effective use of ethanol for GHG emissions reduction in a dual‑fuel engine

the intake port and re-inducted into the cylinder during the intake stroke36. This effectively increases the in-cylinder gas temperature and helps improve upon the fuel conversion efficiency32.

Figure 3 – In-cylinder pressure, HRR, and diesel injector current signal for the different engine operating modes at 0.3 and 1.8 MPa IMEP.

At 1.8 MPa IMEP, compression ignition of the ethanol fuel occurred prior to the start of the diesel injection in case (2b) and is highlighted by the first peak heat release. The maximum ethanol energy fraction was limited to 25% due to PRR and Pmax limitations at an ECR of 16.831. The application of the LIVC in case (3b) lowered the ECR to 14.4 as a result of a delay in the initiation of the compression process. This strategy is commonly known as Miller cycle37,38 and is an effective means of reducing the in-cylinder gas temperature and delaying the autoignition process of the premixed ethanol fuel. The introduction of a pre-injection prior to the main diesel injection helped shorten the ignition delay of the diesel fuel and decrease the levels of PRR, enabling the use of a high ethanol energy fraction of 79%31.

5.2 Engine-out emissions and fuel/air equivalence ratio Depicted in Figure 4 are the engine-out emissions and global fuel/air equivalence ratio (Φ) for the different engine operating modes at 0.3 and 1.8 MPa IMEP. At low engine load, cases (1a) and (2a) yielded approximately the same levels of NOx emissions of 10 g/kWh due to the similar HRR and possibly comparable peak combustion temperatures. Nevertheless, the use of an ethanol energy fraction of 56% in the dual-fuel case helped decrease the smoke, as less diesel fuel was available for soot formation. The relatively lower amount of diesel, however, reduced the incylinder charge reactivity and increased the unburned HC and CO emissions. Low load dual-fuel

8

8

The effective use of ethanol for GHG emissions reduction in a dual‑fuel engine

combustion modelling performed by Kokjohn et al.39 showed that the majority of late cycle unburned HC is located near the cylinder liner, and that the bulk of the CO resides near the centre of the combustion chamber.

Figure 4 – Engine-out emissions and global fuel/air equivalence ratio (Φ) for the different engine operating modes at 0.3 and 1.8 MPa IMEP.

The optimised dual-fuel case (3a) attained considerably lower NOx emissions (0.25 g/kWh) and smoke (0.046 FSN) than the other low load cases (1a) and (2a). This was a result of the longer ignition delay and hence better mixture preparation achieved with the early diesel injection, which minimised the formation and combustion of locally fuel rich diesel mixtures. Moreover, the introduction of iEGR via a 2IVO possibly helped improve the ethanol evaporation process and

9

The effective use of ethanol for GHG emissions reduction in a dual‑fuel engine

minimise unburned HC emissions32. However, the relatively lower peak combustion temperatures of this alternative dual-fuel mode were ineffective at reducing CO emissions. At 1.8 MPa IMEP, the dual-fuel cases (2b) and (3b) decreased NOx emissions from 17.3 g/kWh in a diesel-only operation (1b) to 13.5 g/kWh and 7.6 g/kWh, respectively. This represented a significant improvement and was primarily attributed to the fact that less diesel was burned during the mixing-controlled combustion phase. The lower local combustion temperatures, however, increased the levels of smoke from 0.016 FSN in case (1b) up to 0.048 FSN in case (3b) with LIVC due to the reduced soot oxidation during and after the combustion process. High load dual-fuel combustion yielded significantly lower levels of CO and unburned HC than the low load dual-fuel operation due to the increase in combustion temperatures and relatively higher global fuel/air equivalence ratio (Φ). Nevertheless, CO and unburned HC increased when elevating the ethanol energy fraction from 25% in case (2b) to 79% in case (3b), as more premixed fuel was likely trapped in the crevice volumes of the stock diesel piston39.

5.3 Engine performance and CO2 emissions The engine performance and calculated CO2 emissions for diesel-only (1), dual-fuel (2), and optimised dual-fuel (3) combustion cases at two different engine loads are presented in Figure 5. At 0.3 MPa IMEP, the diesel-only mode (1a) achieved higher fuel conversion efficiency and consequently lower calculated CO2 emissions than the dual-fuel cases (2a) and (3a). Lower combustion efficiencies decreased the fuel conversion efficiency and elevated the engine-out CO2 emissions from these dual-fuel engine operating modes. The use of an early single diesel injection combined with a 2IVO in case (3a) effectively curbed unburned HC emissions when compared to case (2a), increasing the combustion efficiency from 85.9% to 91.4% and the fuel conversion efficiency from 34% to 38.5%. At 1.8 MPa IMEP, the highest fuel conversion efficiency of 47.5% was attained by case (2b) while operating with an ethanol energy fraction of 25%. This represented a relative increase of 2.9% in the fuel conversion efficiency in comparison with a 46.1% achieved by the diesel-only case (1b). Alternatively, case (3b) with LIVC and an ethanol energy fraction of 79% increased the fuel conversion efficiency by 1.6% to 46.9% when compared to case (1b). These improvements were attained despite the reductions in combustion efficiency and were attributed to lower heat transfer losses. This is supported by the decrease in NOx emissions (see Figure 4), which indicates the presence of lower combustion temperatures. Finally, higher fuel conversion efficiencies combined with the use of a high ethanol energy fraction reduced the calculated CO2 emissions from the dual-fuel mode (3b) by 4.8% when compared to the diesel-only case (1b).

10

The effective use of ethanol for GHG emissions reduction in a dual‑fuel engine

Figure 5 – Engine performance and calculated CO2 emissions15 for the different engine operating modes at 0.3 and 1.8 MPa IMEP.

5.4 Overall engine efficiency and WTW CO2eq emissions Higher engine-out NOx emissions can increase the consumption of aqueous urea solution in the aftertreatment system of a HD vehicle, which effectively translates into higher engine running costs. In this subsection, the amount of aqueous urea solution required to meet the Euro VI NOx limit of 0.4 g/kWh was estimated and added to the overall engine efficiency calculation15. Furthermore, a theoretical analysis was carried out to determine the levels of GHG emissions for the different engine operating modes. These were given by the WTW CO2eq emissions15. The results for the two engine loads are depicted in Figure 6. At 0.3 MPa IMEP, the optimised dual-fuel combustion (3a) curbed NOx emissions and eliminated the need for aqueous urea solution. This increased the overall engine efficiency from 31% in the baseline dual-fuel mode (2a) to 38.5% in case (3a). The improved performance is competitive for a low load engine operation, particularly when compared to an overall engine efficiency of 41.4% for the diesel-only mode (1a). Moreover, dual-fuel modes (2a) and (3a) enabled reductions of approximately 40% in WTW CO2eq emissions in comparison with the diesel-only case (1a). This was mainly attributed to the use of sugarcane ethanol in place of diesel, as the CO2 emissions emitted during bioethanol combustion can be disregarded40,41. The dual-fuel mode (3a) yielded no improvement in WTW CO2eq emissions relative to case (2a) as the ethanol energy fraction was held constant at 56%.

11

The effective use of ethanol for GHG emissions reduction in a dual‑fuel engine

Figure 6 – Estimated aqueous urea solution consumption, overall engine efficiency, and WTW CO2eq emissions for the different engine operating modes at 0.3 and 1.8 MPa IMEP.

At 1.8 MPa IMEP, dual-fuel modes (2b) and (3b) achieved lower NOx emissions and higher fuel conversion efficiency than the diesel-only combustion (1b). This reduced the consumption of aqueous urea solution and significantly increased the overall engine efficiency from 39.4% in case (1b) to 43.7% in case (3b). Moreover, lower engine-out CO2 emissions combined with less diesel injected in the dual-fuel modes decreased the WTW CO2eq emissions by up to 57% when compared to the diesel-only operation (1b). Overall, the results demonstrated the potential of the ethanol-diesel dual-fuel technology and advanced combustion control strategies to help combat climate change and achieve a more sustainable energy source for the HD sector.

6 Conclusions In this study, experiments were performed on a HD engine operating at a constant speed of 1200 rpm and two loads of 0.3 and 1.8 MPa IMEP. The objectives were to overcome the challenges encountered by current lean-burn dual-fuel engines and demonstrate effective means of utilising ethanol to reduce pollutant and GHG emissions. At 0.3 MPa IMEP, the optimisation of the combustion process was focused on achieving higher combustion efficiency via an intake valve reopening during the exhaust stroke (2IVO). At 1.8 MPa IMEP, the investigation aimed at maximising the amount of ethanol injected through the application of a late intake valve closing (LIVC). The primary findings can be summarised as follows:

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The effective use of ethanol for GHG emissions reduction in a dual‑fuel engine

1. At the low engine load, the combination of an early diesel injection and a 2IVO strategy helped to increase the combustion efficiency and control the exhaust emissions. As a result, this optimised dual-fuel mode attained relatively higher fuel conversion efficiency than the baseline dual-fuel case (38.5% vs. 34%) and, more importantly, up to 40% lower WTW CO2eq emissions than a diesel-only engine operation. 2. At the high load condition, the LIVC strategy lowered the effective compression ratio and enabled a dual-fuel combustion with an ethanol energy fraction of up to 79%, which is more than three times higher than the 25% used in the conventional dual-fuel operation. Fuel conversion efficiency was increased by 1.6% to 46.9% and WTW CO2eq emissions were reduced by 57% when compared to a diesel-only operation. 3. Advanced combustion control strategies, such as 2IVO and LIVC, have demonstrated potential to improve upon the overall engine efficiency and emissions of a lean-burn ethanol-diesel dual-fuel engine, helping to make a transition to a low carbon HD sector.

Acknowledgments V.B. Pedrozo would like to acknowledge CAPES Foundation (Brazil) for supporting his PhD study at Brunel University London under the supervision of Prof. Hua Zhao.

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Duty Natural Gas/Diesel Engine. SAE Tech. Pap. (2016). doi:10.4271/2016-01-0790 Goldsworthy, L. Fumigation of a heavy duty common rail marine diesel engine with ethanol-water mixtures. Exp. Therm. Fluid Sci. 47, 48–59 (2013). Benajes, J., García, A., Monsalve-Serrano, J., Balloul, I. & Pradel, G. An assessment of the dual-mode reactivity controlled compression ignition/conventional diesel combustion capabilities in a EURO VI medium-duty diesel engine fueled with an intermediate ethanol-gasoline blend and biodiesel. Energy Convers. Manag. 123, 381–391 (2016). Schwoerer, J., Kumar, K., Ruggiero, B. & Swanbon, B. Lost-Motion VVA Systems for Enabling Next Generation Diesel Engine Efficiency and After-Treatment Optimization. SAE Tech. Pap. (2010). doi:10.4271/2010-01-1189 Economic Commission for Europe of the United Nations (UN/ECE). Regulation No 49 Uniform provisions concerning the measures to be taken against the emission of gaseous and particulate pollutants from compression-ignition engines and positive ignition engines for use in vehicles. Off. J. Eur. Union 171, (2013). Pedrozo, V. B. & Zhao, H. Improvement in high load ethanol-diesel dual-fuel combustion by Miller cycle and charge air cooling. Appl. Energy 210, 138–151 (2018). Pedrozo, V. B., May, I., Lanzanova, T. D. M. & Zhao, H. Potential of internal EGR and throttled operation for low load extension of ethanol–diesel dual-fuel reactivity controlled compression ignition combustion on a heavy-duty engine. Fuel 179, 391–405 (2016). Pedrozo, V. B., May, I. & Zhao, H. Characterization of Low Load Ethanol Dual-Fuel Combustion using Single and Split Diesel Injections on a Heavy-Duty Engine. SAE Tech. Pap. (2016). doi:10.4271/2016-01-0778 Pedrozo, V. B., May, I. & Zhao, H. Exploring the mid-load potential of ethanol-diesel dualfuel combustion with and without EGR. Appl. Energy 193, 263–275 (2017). Reitz, R. D. Directions in internal combustion engine research. Combust. Flame 160, 1–8 (2013). Edwards, S. P., Frankle, G. R., Wirbeleit, F. & Raab, A. The Potential of a Combined Miller Cycle and Internal EGR Engine for Future Heavy Duty Truck Applications. SAE Tech. Pap. (1998). doi:10.4271/980180 Martins, M. E. S. & Lanzanova, T. D. M. Full-load Miller cycle with ethanol and EGR: Potential benefits and challenges. Appl. Therm. Eng. 90, 274–285 (2015). Zhao, J. Research and application of over-expansion cycle (Atkinson and Miller) engines – A review. Appl. Energy 185, 300–319 (2017). Kokjohn, S. L., Hanson, R. M., Splitter, D. a & Reitz, R. D. Fuel reactivity controlled compression ignition (RCCI): a pathway to controlled high-efficiency clean combustion. Int. J. Engine Res. 12, 209–226 (2011). The European Parliament and the Council of the European Union. Directive 2009/28/EC. Off. J. Eur. Union 140, (2009). Ramachandran, S. & Stimming, U. Well to wheel analysis of low carbon alternatives for road traffic. Energy Environ. Sci. 8, 3313–3324 (2015).

15

Real‑time capable combustion simulation of a dual‑fuel engine for hardware‑in‑the‑loop application Stefan Kraft, Dr. M. Moser MAN Energy Solutions SE; Prof. Dr. C. Büskens, Dr. M. Echim Center for Industrial Mathematics (ZeTeM), Universität Bremen

© Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2019 W. Siebenpfeiffer, Heavy-Duty-, On- und Off-Highway-Motoren 2018, Proceedings, https://doi.org/10.1007/978-3-658-25889-4_12

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Real‑time capable combustion simulation of a dual‑fuel engine for hardware‑in‑the‑loop …

1 Introduction and motivation Due to increasing restrictive legislation, modern DF-engines become more and more important, especially in marine application to meet the IMO Tier III limits in coastal areas, without using complex exhaust gas after-treatment systems. Compared to conventional combustion processes in diesel or gas engines, the characteristics of the Dual-Fuel process are not fully understand and the increased degree of freedom leads to a demanding application and test effort. To handle the resulting complexity for the development of engine control functions, it is essential to support the development process with suitable simulation methods. As a result, model- and simulation-based methods like Model-/Software- and Hardware-in-the-loop (HIL) simulation as well as Rapid Control Prototyping were established und integrated in the V-model of the development process. With a special significance for the Hardware-in-the-loop simulation, to test and perform basic application tasks on the developed software on the ECUs. Thus enables to validate the software extensive and automated on a connected ECU-network. By this, the increase of control functions along with the rise of testand application effort can be controlled and the otherwise vital testbed time can be reduced.

1.1 Motivation For test execution on a HIL-testbed, a suitable engine model is required, which determines the system reaction to the output of the control function. The focus in this paper lays on the combustion relevant subjects in functional development and therefore a model that depicts the combustion process in a medium-speed engine is discussed.

Figure 1: Overview of combustion model types (Seykens)

2

Real‑time capable combustion simulation of a dual‑fuel engine for hardware‑in‑the‑loop …

There a multiple methods available (pictured in Figure 1) to model the combustion process, each for its own suited purpose. Starting from empirical (0D) models, with low complexity and computational effort, more complex phenomenological models and finally high complex 3D CFD-simulation. Due to the deployment on a Hardware-in-the-loop system, computing time is a fundamental criterion. Therefor the most common method for HIL-application is the so called vibe function, an exponential function that describes the heat release. While it is easy to handle it heavily relies on measurement data to fit it to the according engine and due to its data driven mentality it lacks the capacity of extrapolation.

1.2 Objective On account of the wide engine variety in the medium-speed sector, data driven approaches are not very well suited for this purpose. Therefore a combustion model has been developed which focus on physical behavior of the combustion process to gain more independence from measurement data and enable extrapolation of the model. For this reason, models that are normally in the combustion development process used were taken and accordingly adapted, that they could be used in a real-time environment. That comes along with a decrease in model accuracy which is acceptable because the main focus of the model lays in representing the behavior of the combustion due to the output of the control functions. Furthermore a high flexibility and an easy to parameterize approach were more important.

1.3 Hardware-in-the-loop simulation Figure 2 shows the closed control loop on an MAN Dual-Fuel engine. The measured in cylinder pressure is evaluated in the Combustion Pressure Module and with the results the Injection Module calculates the injection parameters for the next cycle. In HIL-simulation, the engine and the pressure sensor are replaced by a real-time computer with I/O functionality. The benefit of HIL-simulation is the possibility to automate and reproduce test cases. Furthermore test cases that exceed the real engine capabilities can be tested (i.e. higher speed limits) without destroying a prototype engine.

3

Real‑time capable combustion simulation of a dual‑fuel engine for hardware‑in‑the‑loop …

Figure 2: Closed control loop (Rempel)

The HIL-testbed at MAN Energy Solutions that is deployed in System Automation & Control department consists of a dSPACE real-time computer, a ECU-network as well as the necessary dummy loads. The basis of the real-time computer is a multicore processor, which enables the outsourcing of the combustion model on an extra core, while the main engine model runs on a different core. The main engine model provides the input for the combustion model. This multicore application is necessary to fulfil the hard real-time requirements. That means that the reaction of the system to the input signal has to be within a certain time limit. The required sampling time of the model can be derived via the Nyquist-Shannon sampling theorem (Formula 1). It indicates that the cutoff frequency has to be more than two times the frequency of the stimulated system (here the CPM). ୌ୍୐ ൑

େ୔୑ ʹ

(1)

Because of high gradients in conjunction with the discretization of the model, the calculation step size had to be reduced to 0.1°ca (which is already lower than the cutoff frequency), to ensure a stable behavior in all operating points. That means that if the simulated engine runs with 500 rpm, the sampling time would be 3.33e-5 seconds / 30 kHz.

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Real‑time capable combustion simulation of a dual‑fuel engine for hardware‑in‑the‑loop …

2 Model description Figure 3 shows the section of a MAN 51/60 DF engine with its main cylinder- and injection components. The homogenous lean mixture is ignited by a small amount of liquid Diesel (pilotoil) in the main combustion chamber. The injected fuel degrades to droplets because of the high pressure and temperature during the compression stroke and mixes with the surrounding mixture. When the auto ignition temperature is reached, the combustion starts and spreads rapidly through the mixture.

Figure 3: Section of a DF-engine with main components

With this in mind, the model is divided in three parts: The Diesel pilot injection, the ignition process and the main gas combustion, all three embedded in a 0Dthermodynamic (TD) cylinder simulation. In the beginning, the model is initialised with the starting values, coming from the main engine model. This happens at inlet valve closing (IVC). Figure 4 shows the main interface and starting parameters: Information about fuelling, charge air properties and crank train kinematics.

5

Real‑time capable combustion simulation of a dual‑fuel engine for hardware‑in‑the‑loop … Intake Manifold (Pressure, Temperature, lambda)

Fuelling (Rail Pressure, Injection Timing)

Kinematics (Speed, Volumina)

Combustion

Heat Release

Figure 4: Model initialisation and main interface The flowchart of the combustion model (Figure 5) visualizes the process that happens successively during the simulation. After initialization, the isentropic compression calculation takes place until the start of injection. Followed by the calculation of the Diesel pilot spray until the ignition occurs. And finally the main combustion calculation until the fuel is burned and the exhaust valve opening (EVO). Initialisation

Compression Calculation

Pilot Injection? No

Yes

Diesel Spray Calculation

Ingnition?

Yes

Main Combustion Calculation

No

Combustion End?

Yes

Calculation End

No

Figure 5: Flowchart of combustion model The surrounding 0D-thermodyanmic simulation is based on the equations of energy and mass conservation: ݀݉ ݀݉ா ݀݉஺ ݀݉௟௘௔௞ ݀݉஻ ൌ െ െ ൅ ݀߮ ݀߮ ݀߮ ݀߮ ݀߮ ‫ܳ݀ ܸ݀݌‬஻ ݀ܳௐ ܷ݀ ݀݉ா ݀݉஺ ݀݉௟௘௔௞ ൌെ ൅ െ ൅ ݄ா െ ݄஺ െ ݄஺ ݀߮ ݀߮ ݀߮ ݀߮ ݀߮ ݀߮ ݀߮

(2)

(3)

The model was implemented in Matlab/Simulink. Second step was implementing the components separated in a C++ environment where the parameter identification took place (see Chapter 3). The achieved results were then again implemented into the Simulink model and verified on the HIL-testbed.

6

Real‑time capable combustion simulation of a dual‑fuel engine for hardware‑in‑the‑loop …

2.1 Diesel Pilot The modelling of the pilot injection was done via the package-spray-model, based on the works of Hiroyasu and Stisch, extend by the approach of Walther regarding the ignition delay. Hereby the injection jet is divided in single packages and for every package the entrainment and droplet evaporation is calculated. Figure 6 displays the flowchart of the calculation steps.

Cylinder State

Turbulence Calculation

Diesel Spray Injection

Package Calculation

Diesel Droplet Calculation

Ingnition Delay Calculation

Temperature Pressure Density Viscosity

Ingnition?

Yes

Main Combustion Calculation

No

Figure 6: Flowchart of Diesel pilot calculation The droplet calculation is calculated by the following differential equation system: ݂ሺ݀‫ݔ‬ଶ ǡ ݀‫ݔ‬ଷ ǡ ‫ݔ‬ଶ ǡ ǥ ሻ ݀ܶ஽௥௢௣௟௘௧ ݀‫ݔ‬ଵ ‫ݔ‬ሶ ሺ‫ݐ‬ሻ ൌ ൭݀‫ݔ‬ଶ ൱ ൌ ቌ ݀݉஽௥௢௣௟௘௧ ቍ ൌ  ቌ݂൫ܵ‫ܦܯ‬ǡ ܲ஼௬௟ ǡ ݄ܵǡ ǥ ൯ቍ ݀‫ݔ‬ଷ ݀ܳ௖௢௡௩௘௞௧௜௩ ݂ሺ‫ݔ‬ଵ ǡ ܵ‫ܦܯ‬ǡ ܰ‫ݑ‬ǡ ǥ ሻ ‫ݔ‬ଵ ܶ஽௥௢௣௟௘௧ ‫ݔ‬ሺ‫ݐ‬ሻ ൌ ൭‫ݔ‬ଶ ൱ ൌ  ቌ ݉஽௥௢௣௟௘௧ ቍ ‫ݔ‬ଷ ܳ௖௢௡௩௘௞௧௜௩

(4)

(5)

The consequential calculated packaged temperature is used for the ignition delay calculation

2.2 Ignition For the evaluation of the ignition timing, the one equation model (Wolfer) was considered, adjusted for a Dual fuel engine. The timing is described via an Arrheniusequation and depends on the pressure, temperature and constants which have to be identified. The ignition delay is calculated for every time step, because through the compression, the temperature, pressure and composition of the mixture are changing.

7

Real‑time capable combustion simulation of a dual‑fuel engine for hardware‑in‑the‑loop …

߬௓௏ ൌ ‫ܥ‬ଵ

߯௉௜௟௢௧ ିଵǤଶଵ

ߣ௏ ‫ܲ כ‬஼௬௟

ଵǤଵଽ ‫݁ כ‬

ሺ

஼మ ሻ ்಴೤೗

(6)

To take these changes into account, the ignition integral from injection begin on is determined. The combustion starts, when the ignition integral exceeds the value 1.

න

௧

଴

ͳ ݀‫ ݐ‬൐ ͳ ߬௓௏

(7)

2.3 Main combustion The modelling of the main gas combustion is based on the works of Auer and Walther. Thereby with the flame speed and area, the mass flow into the flame is calculated as well as the burning of the fuel and mass flow out of the flame, which determines the heat release rate. Figure 7 shows the calculation process of the main combustion.

Cylinder State

Turbulence Calculation

Flamespeed & Area Calculation

Massflow Calculation

Burnrate Calculation

Thermodynamics & Kinematics Calculation

Temperature Pressure Density Viscosity

Combustion End?

Yes

Combustion End

No

Figure 7: Flowchart of main gas combustion With the hereby used equations, the following 7 states are present: ‫݁ݏ݈ܽ݁݁ݎݐܽ݁ܪ‬ ‫ݔ‬ଵ ܳ‫݉ݑݏ‬ ‫݁ݎݑݐܽݎ݁݌݉݁ݐݎ݈݁݀݊݅ݕܥ‬ ‫ݔ‬ଶ ܶ஼௬௟ ‫݈݁ݑ݂݀݁݊ݎݑܤ‬ ‫ݔ‬ଷ ݉஻ ݇݁ ൌ  ‫ݕ݃ݎ݁݊݁ܿ݅ݐ݁݊݅݇ݐ݈݊݁ݑܾݎݑݐ‬ ‫ݔ‬ሺ‫ݐ‬ሻ ൌ ‫ݔ‬ସ ൌ  ‫ݔ‬ହ ‫ݎ‬௙௟௔௠௘ ݂݈ܽ݉݁‫ݏݑ݅݀ܽݎ‬ ‫଺ݔ‬ ݉௜௡ ‫݈݂݄݁݉ܽ݁ݐ݋ݐ݊݅ݏݏ݈ܽ݉݁ݑܨ‬ ‫ی ଻ݔۉ‬ ‫݉ ۉ‬ி ‫ی‬ ‫ی ݈݂݄݁݉ܽ݁ݐ݊݅ݏݏ݈ܽ݉݁ݑܨ ۉ‬

8

(8)

Real‑time capable combustion simulation of a dual‑fuel engine for hardware‑in‑the‑loop …

Which are characterized in the following differential equation system which their dependencies: ݂ሺ݀‫ݔ‬ଷ ǡ ǥ ሻ ݀‫ݔ‬ଵ ݀ܳ஻ ݂ሺ݀‫ݔ‬ଵ ǡ ܲ஼௬௟ ǡ ݀ܳ௪ ǡ ǥ ሻ ݀‫ݔ‬ଶ ݀ܶ ݀‫ݔ‬ଷ ݀݉஻ ݂ሺ‫ ଺ݔ‬ǡ ‫ݔ‬ଶ ǡ ǥ ሻ ‫ݔ‬ሶ ሺ‫ݐ‬ሻ ൌ ݀‫ݔ‬ସ ൌ ݀݇݁ ൌ  ݂ሺ‫ݔ‬ସ ǡ ‫ݔ‬ଶ ǡ ǥ ሻ ‫ݐ̴ݏ‬ ݀‫ݔ‬ହ ݂ሺ‫ݔ‬ସ ǡ ‫ݔ‬ଶ ǡ ǥ ሻ ݀݉௜௡ ݀‫଺ݔ‬ ݂ሺ݀‫ݔ‬ହ ǡ ‫ܣ‬ிி ǡ ǥ ሻ ‫݉݀ ۉ ی ଻ݔ݀ۉ‬ி ‫ی‬ ݂ሺ݀‫ ଺ݔ‬ǡ ݀‫ݔ‬ଷ ሻ ‫ۉ‬ ‫ی‬

(9)

3 Nonlinear parameter identification The aim of nonlinear parameter identification is to determine the parameters of a nonlinear model such that the model matches the observed measurements. Automatic and efficient parameter identification requires mathematical nonlinear optimization methods. Nonlinear optimization is a key feature for many applications in industry and science. The general question in this context is how free variables of a model must be chosen to minimize a defined objective function while maintaining certain constraints.

3.1 Mathematical background The non-linear optimization problem is defined as follows: let ‫ א ݖ‬Թ௡ be the optimization vector (e.g. model parameters). Furthermore, let ‫ܨ‬ǣ Թ௡ ՜ Թ denote the objective function and ‰ǣԹ୬ ՜  Թሼ୪౟ ሽ , ŠǣԹ୬ ՜  Թሼ୪౛ሽ denote general non-linear constraint functions. Then ‹௭ ‫ܨ‬ሺ‫ݖ‬ሻ

‫ݏ‬Ǥ ‫ݐ‬Ǥ  ݃௜ ሺ‫ݖ‬ሻ  ൑ Ͳǡ ݅ ൌ ͳǡ ǥ ǡ ݈௜

(10)

݄௝ ሺ‫ݖ‬ሻ ൌ Ͳǡ ݆ ൌ ͳǡ ǥ ǡ ݈௘ 

is called a non-linear program (NLP). In general there are several different algorithms to solve such problems. All of them are some kind of specialization of Newton’s method. The solver WORHP ("We Optimize Really Huge Problems") was especially developed for large-scale, sparse non-linear optimization. WORHP uses either a sparse sequential quadratic programming method (SQP) with interior point method for the quadratic sub problem or an interior point method on the non-linear level. The software design was focused on high robustness and application-driven design [1].

9

Real‑time capable combustion simulation of a dual‑fuel engine for hardware‑in‑the‑loop …

The SQP approach is an iterative method that approximates the optimization problem locally by quadratic sub problems with linear constraints. In general one has to assume that ‫ܨ‬, ݃, and ݄ are twice continously differentiable. The Lagrangian ‫ܮ‬ሺ‫ݖ‬ǡ ߣǡ ߤሻǣ ൌ ‫ܨ‬ሺ‫ݖ‬ሻ ൅ ߣ் ݃ሺ‫ݖ‬ሻ ൅ ߤ் ݄ሺ‫ݖ‬ሻ

(11)

combines objective and constraint functions taking multipliers ߣ and ߤ into account. Within the iterative process of the SQP approach the resulting subproblem in iteration ݇ with ‫ ܪ‬ሾ௞ሿ ǣ ൌ ‫׏‬ଶ௭௭ ‫ܮ‬ሺ‫ ݖ‬ሾ௞ሿ ǡ ߣሾ௞ሿ ǡ ߤ ሾ௞ሿ ሻ is ଵ

‹ ‫׏‬௭ ‫ܨ‬ሺ‫ ݖ‬ሾ௞ሿ ሻ் ݀ ൅ ்݀ ‫ ܪ‬ሾ௞ሿ ݀ ଶ

ௗ

•Ǥ –Ǥ݃௜ ሺ‫ ݖ‬ሾ௞ሿ ሻ ൅ ‫׏‬௭ ݃௜ ሺ‫ ݖ‬ሾ௞ሿ ሻ் ݀ ൑ Ͳ ݄௝ ሺ‫ ݖ‬ሾ௞ሿ ሻ ൅ ‫׏‬௭ ݄௝ ሺ‫ ݖ‬ሾ௞ሿ ሻ் ݀ ൌ Ͳ

ǡ ‫ ݅׊‬ൌ ͳǡ Ǥ Ǥ Ǥ ǡ ݈௜ ǡ

(12)

ǡ ‫ ݆׊‬ൌ ͳǡ Ǥ Ǥ Ǥ ǡ ݈௘ Ǥ

is called quadratic sub problem of NLP. The iterative scheme of the algorithm is as follows: • choose ሺ‫ ݖ‬ሾ଴ሿ ǡ ߣሾ଴ሿ ǡ ߤ ሾ଴ሿ ሻ ‫ א‬Թ௡ ൈ Թ௟೔ ൈ Թ௟೐ and set ݇ǣ ൌ Ͳ.

• if ሺ‫ ݖ‬ሾ௞ሿ ǡ ߣሾ௞ሿ ǡ ߤ ሾ௞ሿ ሻ fulfills some stopping criterion ՜ STOP.

• calculate ݀௞ ‫ א‬Թ௡ of the quatratic subproblem with ߣሾ௞ାଵሿ and ߤ ሾ௞ାଵሿ .

• set ‫ ݖ‬ሾ௞ାଵሿ ǣ ൌ ‫ ݖ‬ሾ௞ሿ ൅ ݀ ሾ௞ሿ and ݇ǣ ൌ ݇ ൅ ͳ go to (2).

The main benefit of non-linear optimization with SQP methods is its local convergence property. Due to the usage of second-order derivatives, one can prove that the algorithm exhibits locally quadratic convergence. Furthermore WORHP uses special structures of the underlying optimization problems to explore sparse matrix algorithms and to solve real-world parameter identification problems efficiently.

3.2 Relevant application To solve a problem of nonlinear dynamic parameter identification, feasible starting values are necessary. Feasible means in this context, that the initial value problem has a solution. Therefore the starting values are accordingly initialized: ‫ݔ‬ଵ Ͳ ‫ݔ‬ଶ ܶ଴ ‫ݔ‬ଷ Ͳ ‫ݔ‬ሺͲሻ ൌ ‫ݔ‬ସ ൌ  ݇݁଴ ‫ݔ‬ହ Ͳ ‫଺ݔ‬ Ͳ ‫ی ଻ݔۉ‬ ‫ی Ͳ ۉ‬

10

(13)

Real‑time capable combustion simulation of a dual‑fuel engine for hardware‑in‑the‑loop …

With T0 and ke0 at IVC. Furthermore boundaries have been set in the boundary condition and constraints, to prevent, that the problem could be solved mathematically correct but doesn’t make sense in a physical point of view (e.g. negative mass). Four parameters were implemented in the main combustion model to adjust the rate of heat release to the measurements, see table 1. Table 1: Parameters used in the model P1 P2 P3 P4

Function Tune reaction rate Tune turbulent kinetic energy Tune inflammation Tune combustion fading

Their influence, effects and in which way they are used to shape the heat release rate, is shown in figure 8.

Figure 8: Influence of the parameters on the heat release

4 Validation and Discussion Two objects have to be discussed. First if the model is runnable in real-time on the HIL- testbed, otherwise it would be pointless. Second how accurate the model is, compared to measurements taken from a real engine.

11

Real‑time capable combustion simulation of a dual‑fuel engine for hardware‑in‑the‑loop …

4.1 Model validation The analyzation of the simulation results showed that the amount of packages calculated in the diesel spray has only little influence of the ignition timing. Figure 9 provides the effects of the SOI variation on ignition & combustion characteristics.

Figure 9: SOI variation and effects on ignition & combustion characteristics The influence of the two parameters C1 and C2 that are used to adjust the ignition delay calculation accordingly to the measurement data (Formula 6) is shown in figure 10. C2 represents the activation energy and is bounded to the gas composition used. C1is used to adapt to external influencing factors and is the more relevant parameter for the adaption.

Figure 10: Influence of parameters C1 & C2

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Real‑time capable combustion simulation of a dual‑fuel engine for hardware‑in‑the‑loop …

Figure 11 shows the comparison between a measured heat release rate and the one coming from the simulation. The Coefficient of determination R² is 0.9143.

Figure 11: Comparison of simulation and measurement Due to the high variations in gas combustion, a mean value, sampled over 100 measured heat release rates, was taken as base for the measurement. Furthermore it was cut at the 2%- and 98% conversion point, therefore the “head start” of the measured heat release. The ledge in the beginning is due to that the model not yet includes the energy release from the pilot oil.

4.2 Simulink & HIL Real-Time After identifying the parameters, the Simulink model (Figure 12) was implemented on the HIL-testbed and validated, to check if it fulfils the real-time requirements. The turnaround times for the different subsystems were analyzed and are shown in table 2.

Figure 12: Implemented Simulink model

13

Real‑time capable combustion simulation of a dual‑fuel engine for hardware‑in‑the‑loop …

Figure 13 presents the turnaround time of the 18-Cylinder engine model running on the HIL-testbed. Depending on the firing angle configuration, several cylinders are being calculated in parallel and different sequential tasks (see table 2), this explaining the fluctuation in computing time. It also can be seen, that the overall turnaround time is below the limit of 3e-5 seconds but it is desired to increase the distance to that limit because of peaks that can occur in the computation process.

Figure 13: Turnaround time 18V-engine A model calculation analyses revealed the distribution of the calculation times for the different sub models. The diesel pilot calculation as well as the main gas combustion each takes up a quarter of the calculation time. The remains are split up between the 0D-thermodyanmic calculation as well as the computation of material properties (See figure 14). Looking at the calculation of one cylinder, the combustion cycle can be divided into four sequentially running phases. Table 2 shows these phases as well as which module is active and the average turnaround time per cylinder per task. Table 2: Turnaround time sub models Interval

Model active

IVC to SOI

Cylinder

SOI to ignition

Cylinder + Diesel pilot

~7e-6

Ignition to EVO

Cylinder + Main combustion

~7e-6

EVO to IVC

-

14

Turnaround time [s] ~3.5e-6

~2.5e-6

Real‑time capable combustion simulation of a dual‑fuel engine for hardware‑in‑the‑loop …

Share of turnaround time Diesel Pilot Main combustion Ignition Thermodynamics & properties Figure 14: Share of turnaround time along sub models

5 Summary & Outlook A phenomenological combustion model was presented for the calculation of the heat release of a dual fuel medium-speed engine. The model consists of the main aspects of the DF-engine: Pilot injection & main gas combustion. To adjust the model with the help of measurement data, free parameters were introduced and with the help of WORHP, a software for nonlinear parameter identification, identified. While the validation for running on the HIL-testbed for the implemented 18V-engine was satisfied, it has yet to prove that it is suitable for the simulation of different variants of Dual fuel engines (e.g. smaller bore, various gas mixtures and valve timings). Furthermore, there are still several additions to expand the model e.g. to include the energy release of the pilot oil to the overall heat release. Thinking about future application, the extension with a knock- or emission model (also based on physicalprincipals), regarding the upcoming challenges in emission reduction, seems desirable. Another purpose for the model lies in the field of control optimization. Because in addition, WORHP also offers the possibility to solve optimal control problems. Therefore the model could be used for optimizing control algorithms.

15

Real‑time capable combustion simulation of a dual‑fuel engine for hardware‑in‑the‑loop …

6 References Walther, H-P., Wachtmeister, G., Phänomenologisches Verbrennungsmodell für Magerkonzept-Gasmotoren mit Piloteinspritzung. Forschungsvorhabens (Nr.960) Auer, M., (2008) Erstellung eines phänomenologischen Modells zur Vorausberechnung des Brennverlaufs von Gasmotoren. Abschlussbericht (FVV) MagerkonzeptGasmotoren Verbrennungsmodelle, Heft:885-2009 Stiesch, G., (2003) Modeling Engine Spray and Combustion Processes. BerlinHeidelbergNewYork: Springer, ISBN:3-540-00682-6 Zahn, S., (2012) Arbeitsspielaufgelöste Modellbildung und Hardware-in-the-LoopSimulation von Pkw-Dieselmotoren mit Abgasturboaufladung. Dissertation Technische Hochschule Darmstadt Rempel, A., (2015), MAN Diesel & Turbo SE „Characteristic combustion values based control for medium speed DF engines “ in: Dessauer Gasmotoren Konferenz Unfug, F., (2016), MAN Diesel & Turbo SE „Investigation on Dual Fuel Engine Gas Combustion using Tomographic In-Cylinder Measurement Technique and Simultaneous High Speed OH-Chemiluminescence Visualization, SAE Technical Paper 201601-2308 Seykens, X., (2010), Development and validation of a phenomenological diesel engine combustion model, ISBN: 978-90-386-2133-3 Hiroyasu H., (1974), Fuel droplet size distribution in a diesel combustion chamber. SAE Paper 740715; Wolfer,H., (1938), Der Zündverzug im Dieselmotor, VDI Forschungsheft 392, 1938

Büskens, C., (2012). The esa nlp solver worhp. In Modeling and Optimization in Space Engineering, pages 85–110. Springer;

16

Formulating to meet the lubrication challenges of modern gas engines to prolong oil life and maximize engine protection Dr. Jonathan M. Hughes Technologist – Lubes Product Development EMEA Infineum UK Ltd.

© Springer Fachmedien Wiesbaden GmbH, ein Teil von Springer Nature 2019 W. Siebenpfeiffer, Heavy-Duty-, On- und Off-Highway-Motoren 2018, Proceedings, https://doi.org/10.1007/978-3-658-25889-4_13

1

Formulating to meet the lubrication challenges of modern gas engines to prolong …

1 Introduction Over the past few decades the world’s population has grown considerably, and continues to do so. Combined with an overall increase in standards of living the global demand for energy has increased and is expected to continue to rise. Natural gas is increasingly being seen as one of the solutions to cater for this increased energy demand. As a fuel it is readily available, flexible and affordable. It is also a much cleaner burning option than most traditional hydrocarbon fuels. One of the ways that gas can be used is as the fuel source for stationary gas engines, either involved in power generation directly or in the movement of gas from the wellhead to the customer. As more and more engines come into service, operators are increasingly looking to maximise the return on their investment. This demand has led original equipment manufacturers (OEMs) to introduce design changes to their newest generation of engines to increase both energy efficiency and power output. Additionally, there is also the drive to reduce emissions, such as NOx, methane and volatile organic hydrocarbons. Examples of some of the methods employed include: – – – – – –

Adoption of Miller cycle timing1-6123456 Increased Brake Mean Effective Pressure (BMEP)2-5 Changes in turbo-chargers3-6 Changes in piston bowl geometry4 Changes in piston design and metallurgy4 Movement to lean burn combustion6

Figure 1: Comparison of oxidation response and base number retention between a high powered (high efficiency) and standard gas engine design.

These design changes have resulted in modern engines becoming a much more severe lubrication environment than their historic counterparts. A result, lubricants with sufficient performance 10-15 years may no longer be capable of providing adequate protection in newer design engines, or the service life of an oil can be severely reduced (Figure 1).

2

Formulating to meet the lubrication challenges of modern gas engines to prolong …

To meet these challenges and ensure that current lubricants are suitable for modern engines, formulators are continually looking to improve and develop new lubricants that can maintain engine protection and prolong oil life. This requires extensive use of laboratory testing programs before taking candidates onto fired engine testing and ultimately into the field. However, as well as testing, formulation experience and a deep understanding of the underlying chemistry of the lubricant and its environment are critical to enable formulators to produce lubricants capable of providing adequate engine protection and oil life. In addition to a base oil, natural gas engine oils (NGEOs) contain an additive package constituting up to 15% of the total mass of the lubricant (Figure 2). This additive package contains various chemicals which have been carefully combined to prolong the lifetime of the oil and aid in the protection of the engine. Understanding the performance of the additives and their correct balance in a fully formulated lubricant is key challenge designing new lubricants to meet the demands of high efficiency engines.

Figure 2: Breakdown of the constituents of an NGEO and their respective functions.

2 Methodology and Experimental 2.1 Deposit Analysis Deposits were collected from three locations within a high BMEP (>20 bar) gas engine; the rocker covers, the oil filter and the used oil. The engine had been operating on pipeline natural gas in CHP service at full load. The engine had been operational for ~8,500 hrs and during that time had operated with several different oils. The used oil had an operating life of 1364 hrs. The samples were analysed by transition electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX) and Raman spectroscopy to determine chemical and physical structure. Results of similar analysis on soot isolated from Euro 5 and Euro 6 heavy duty diesel engines were used for comparison.

3

Formulating to meet the lubrication challenges of modern gas engines to prolong …

2.2 Focused Beam Reflectance Measurements (FBRM) Focused beam reflectance measurements (FBRM) testing was conducted with a Mettler Toledo Particle Track G400 using a proprietary test procedure. The additives under investigation were added to a fully formulated used oil with 1364 running hours in a high BMEP (>20 bar) natural gas engine in CHP service operating at full load.

2.3 Oxidation/Nitration Bench Testing The test rig was set up in a similar way to GFC T021-A-90. The operating conditions in which NOx was included in the gas flow are propriety.

2.4 Fired Engine Testing Engine testing was carried out in a Cummins GTA 8.3 SLB operated on a test bed following proprietary operating conditions.

3 Results and Discussion 3.1 Formulating for Improved Deposit Control Historically, when developing lubricants for use in natural gas engines the main driver for formulators has been to prolong oil life. Resisting oxidation/nitration and preventing base depletion and acid generation. With modern engines increasing power output and BMEP it is expected that temperatures and pressures in the engine will also. This will place a greater thermal stress on the lubricant which will lead to increased oil degradation. This has the potential to result in an increased build-up of carbonaceous deposits. Formulators use additives such as dispersants and detergents to help manage this carbonaceous material within the oil helping to maintaining engine cleanliness and prevent damage. To correctly select and combine these additives it is critical to understand the chemical make-up and physical structure of the carbonaceous material as this will define the way it interacts with the additives.

3.1.1 Deposit Analysis 3.1.1.1 Size & Physical Structure Analysis TEM figure 3 shows that, irrespective of location, the deposits had a similar size and morphology. With a mean particle diameter of 22 nm (median: 20 nm) and 90% of particles falling within a range of 11 – 36 nm. The appearance and size of the particles is comparable to soot particles found in diesel engines7 suggesting a similar mechanism

4

Formulating to meet the lubrication challenges of modern gas engines to prolong …

of formation. While diesel soot is formed from incomplete combustion of fuel, in a lean burn gas engine operating on gas comprising primarily of methane with a significant molar excess of oxygen, the level of incomplete combustion is expected to be negligible. This suggests that the carbonaceous materials result from the incomplete combustion of lubricant present in the combustion chamber rather than a liquid fuel.

Figure 3: (Left) TEM images of particles isolated form a used NGEO & (Right) size distribution of the particles.

Preparation for TEM analysis i.e. dilution in a solvent and sonication, can break the structure of many larger agglomerates. This means that while TEM suggests that deposits formed in cold spots of the engine originate from similar primary particles, it cannot give any information on the structure of the final deposits. SEM (figure 4) analysis indicates the final structures, formed by the agglomeration of the primary particles, are different depending on where in the engine they form. However, the similarity does suggest that deposits formed throughout the engine originate from the same initial precursors. Those from the rocker cover formed stacked lamella-like layers whereas those isolated from the oil filter formed amorphous particles in the 101 micron size range.

Figure 4: SEM analysis of deposits taken from the rocker cover (left) and oil filter (right) of a high BMEP gas engine.

5

Formulating to meet the lubrication challenges of modern gas engines to prolong …

3.1.1.2 Elemental & Chemical Structure Analysis As well as morphology, the level of interaction between additives and deposits, and ultimately their effectiveness at maintaining engine cleanliness, is dependent on the elemental and surface chemical composition of the deposits themselves. EDX analysis (Table 1) of deposits collected from the oil filters showed that the gas engine deposits had a much higher oxygen to carbon ratio than diesel soot. There was also a significantly higher concentration of elements attributed to lubricant additives e.g. calcium, zinc, phosphorous and sulphur. This indicates that deposits are formed from combustion of the lubricant rather than the fuel. An NGEO will typically be ≤ 0.6 % SASH and ≤300 ppm phosphorous whereas HDD diesel oils will typically be ≥ 1% SASH and 800 – 1200 ppm phosphorous resulting in higher initial concentration of additive elements than a gas engine oil. Table 1: Surface elemental composition of NGEO deposits and HDD soot as measured by EDX Element Carbon Oxygen Calcium Zinc Phosphorus Sulphur

Surface Percentage (% w/w) Gas Engine HDD Engine 69 ±3 88 ±4 21 ±2 9 ±2 4.1 ±1 0.8 ±0.3 0.5 ±0.1 1.2 ±0.3

0.8 ±0.2 0.3 ±0.03 0.3 ±0.1 0.4 ±0.1

The XPS analysis (table 2) is aligned with the EDX results showing a higher ratio of oxygen to carbon for the gas engine deposits compared to HDD soot. As well as the lower proportion of carbon, there were also differences in the chemical environment of the carbon, with a much lower proportion of C-H moieties and higher concentrations of carbonyl and carbonate moieties. Raman spectrographic analysis (table 3) of the deposits showed a higher D to G ratio for the gas engine deposits compared to HDD soot indicating that a much lower proportion of the carbon atoms present in NGEO deposits were sp2 hybridised, or graphitic, than in diesel soot. The primary mechanism of dispersant action is the binding of lone electron pairs in the head of the dispersant to the graphitic sheets of soot. A reduction in the proportion of graphitic carbon could suggest that NGEO deposits would be ‘harder’ to disperse effectively.

6

Formulating to meet the lubrication challenges of modern gas engines to prolong …

Table 2: Comparison of surface atomic composition of HDD soot and NGEO deposits determined by XPS analysis. Element Carbon C-C graphite C-H C-O : C-(O)-C bridge C=O : N-C=O O-C=O CO3 Oxygen OH : O=C O-C Zinc Calcium Nitrogen Amine : Amide Nitrate (NOx) Phosphorus Sulfur S-C SOx

Gas Engine Deposits (At. %) 78.4 6.8 60.5 5.1 1.2 3.8 1.0 17.0 12.3 4.6 0.32 1.83 0.98 0.98 0.13 0.40 0.95 0.11 0.80

HDD Soot (At. %) 87.1 8.6 72.2 3.3 1.1 1.6 0.4 10.1 5.3 4.8 0.23 0.50 1.00 0.96 0.10 0.26 0.57 0.14 0.43

Table 3: Raman analysis of HDD soot and NGEO deposits. Sample Gas Engine Deposits Heavy Duty Diesel Soot

D:G ratio 0.91 0.40

The similarities between the size and shape of the primary particles of the gas engine deposits and diesel soot (at least when initially formed) indicates the that the particles are formed in a similar way to diesel soot. It is suggested that the lubricant present in the combustion chamber undergoes pyrolysis during combustion leading to precursors which will begin to nucleate and experience growth to primary particles.8 Many of these parties will be expelled in the exhaust gases but some will enter the crankcase carried by blow-by gases where they can contaminate the lubricant. Once there they will continue to agglomerate further forming large structures unless they are effectively dispersed by additives in the lubricant. As these are believed to be a relatively new type of

7

Formulating to meet the lubrication challenges of modern gas engines to prolong …

deposits within the literature, little is currently known about how the interaction properties with dispersants will differ. It may be that conventional dispersant additives and formulation approaches will not be sufficient to provide effective cleanliness for modern gas engines and new additives and approaches will be required.

3.1.2 Additive Effects on Lubricant Dispersancy To formulate lubricants with effective field performance it is critical for formulators to have access to relevant laboratory tests and screeners which accurately mimic engine conditions. While there already exist several tests and procedures to test lubricants for effective dispersancy, the majority have been developed to screen lubricants for liquid fuelled engines. As discussed in the previous section, deposits found in modern gas engines are chemically dissimilar to those in liquid fuelled engines i.e. gasoline and diesel and therefore it cannot be assumed that existing tests and screeners will be effective at allowing formulators to select the correct balance of additives when developing lubricants for modern gas engines. FBRM was investigated in an effort to develop a tool to investigate the effectiveness of dispersant additives for gas engine oils. FBRM is a tool that has previously been used to measure the dispersancy of ashpalhtenes in marine lubricants9 where a reduction in the total number of counts has shown to correspond to improved dispersancy. FRBM was used to measure the cord length distribution and counts of several used oils with different running hours from a modern high BMEP gas engine. Figure 5 shows an increasing particulate count throughout the lifetime of the oil showing that FRBM can be used to successfully measure increasing contamination of the oil.

Figure 5: Impact of increasing oil life on FBRM counts.

While the exact relationship between cord length and particle diameter and between total cord counts and particle concentration is not fully understood in the literature10,11

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Formulating to meet the lubrication challenges of modern gas engines to prolong …

changes in cord length or counts compared to a base line from an identical or similar system can be used to show relative changes in particle size or concentration. The deposit analysis discussed in section 3.1.1 shows that primary particles have an average diameter of 22 nm, well below the 0.08 µm detection limit for FBRM. Therefore, the FBRM probe will only be able to detect larger agglomerates. An effective dispersant additive will break up these agglomerates reducing the size below the detection limit of FRBM resulting in a corresponding decrease in counts. In general, a greater concentration of dispersant additive(s) resulted in a reduction in counts compared with the baseline oil (figure 6), which is not surprising. However, there was considerable variation between additives and combinations of additives with some being more effective than others in improving dispersancy when compared on an identical mass basis. For example, as can be seen in figure 6 when two types of dispersant chemistry were compared (type A and type B), the chemistry of the type B dispersants were on average more effective than type A. Additionally, there were also some combinations of additive that resulted in an increase in counts implying that these additives were promoting agglomeration and reducing the overall dispersancy of the oil. For example, figure 6 additive 4 is shown to reduce dispersancy, this additive is known to be very effective at soot dispersancy and is commonly used in HDD applications. This demonstrates that it is not a simple case of adding more dispersant and improving performance, it is necessary to select the right additives and combinations at the level to ensure a formulation is effective.

Figure 6 Changes in FBRM counts of a used natural gas engine oil upon addition of different dispersant additives and combinations.

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Formulating to meet the lubrication challenges of modern gas engines to prolong …

3.2 Formulating to Extend Oil Life Laboratory testing is used extensively by formulators to undertake large volumes of short time-scale performance testing on experimental lubricants. However, to formulate effectively it is critical to have laboratory screener tests which will correlate to field performance. Many of the laboratory tests used by the industry for pre-engine performance screening of NGEOs have previously been developed for use in screening lubricants for use in other types of, primarily liquid fuelled, engines. As the combustion of natural gas is distinct from most liquid fuels applying these tests to the evaluation of NGEOs can in some instances be un-representative of field performance.

3.2.1 Comparison of Laboratory to Field Performance Figure 7 compares the oxidation resistance of three oils in a blown air oxidation test (Extended GFC T021-A-90) run in the laboratory with their performance in the same model of a lean burn natural gas engine operating in compression service.

Figure 7: Comparison of the oxidation and nitration performance of three different oils in a bench test GFC T021-A-90 (extended) and a lean burn engine.

In the laboratory Oil A and Oil B exhibit similar levels of oxidation resistance at the end of test despite having different oxidation profiles whereas Oil C has less resistance to oxidation than both Oil A and Oil B. In all cases nitration is minimal (below the detectable limit