Potential and Limitations of Dual Fuel Operation of High Speed Large Engines

[EN] The aim of this paper is to identify and investigate the potential and limitations of diesel-gas combustion concepts for high speed large engines operated in gas mode with very small amounts of pilot fuel (<5% diesel fraction). Experimental tests were carried out on a flexible single cylinder research engine (displacement 6.24 dm(3)) equipped with a common rail system. Various engine configurations and operating parameters were varied and the effects on the combustion process were analyzed. The results presented in this paper include a comparison of the performance of the investigated dual fuel concept to those of a state-of-the-art monofuel gas engine and a state-of-the-art monofuel diesel engine. Evaluation reveals that certain limiting factors exist that prevent the dual fuel engine from performing as well as the superior gas engine. At the same NOx level of 1.3 g/kWh, the efficiency of the dual fuel engine is approximate to 3.5% pts. lower than that of the gas engine. This is caused by the weaker ignition performance of the injected pilot fuel compared to that of the gas scavenged prechamber of the gas engine. On the other hand, the dual fuel concept has the potential to compete with the diesel engine. The dual fuel engine can be operated at the efficiency level of the diesel engine yet with significantly lower NOx emissions (3.5 g/kWh and 6.3 g/kWh, respectively). Since the injection of pilot fuel is of major importance for flame initialization, and thus for the main combustion event of the dual fuel engine, optical investigations in a spray box, measurements of injection rates, and three-dimensional (3D) computational fluid dynamics (CFD) simulation were conducted to obtain even more detailed insight into these processes. A study on the influence of the diesel fraction shows that diminishing the diesel fraction from 3% to lower values has a significant impact on engine performance because of the effects of such a reduction on injection, ignition delay, and initial flame formation. The presented results illustrate which operating strategy is beneficial for engine performance in terms of low NOx emissions and high efficiency. Moreover, potential measures can be derived which allow for further optimization of the diesel-gas combustion process.The authors would like to acknowledge the financial support of the COMET Competence Centres for Excellent Technologies Programme of the Austrian Federal Ministry for Transport, Innovation and Technology (BMVIT); the Austrian Federal Ministry of Science, Research and Economy (BMWFW); and the Provinces of Styria, Tyrol, and Vienna for the K1-Centre LEC EvoLET. The COMET Programme is managed by the Austrian Research Promotion Agency (FFG). Austrian Research Promotion Agency (FFG) (844604).Redtenbacher, C.; Kiesling, C.; Malin, M.; Wimmer, A.; Pastor, JV.; Pinotti, M. (2018). Potential and Limitations of Dual Fuel Operation of High Speed Large Engines. Journal of Energy Resources Technology. 140(3):1-10. https://doi.org/10.1115/1.4038464S1101403Krishnan, S. R., Srinivasan, K. K., Singh, S., Bell, S. R., Midkiff, K. C., Gong, W., … Willi, M. (2003). Strategies for Reduced NOx Emissions in Pilot-Ignited Natural Gas Engines. Journal of Engineering for Gas Turbines and Power, 126(3), 665-671. doi:10.1115/1.1760530Raihan, M. S., Guerry, E. S., Dwivedi, U., Srinivasan, K. K., & Krishnan, S. R. (2015). Experimental Analysis of Diesel-Ignited Methane Dual-Fuel Low-Temperature Combustion in a Single-Cylinder Diesel Engine. Journal of Energy Engineering, 141(2). doi:10.1061/(asce)ey.1943-7897.0000235Sell, J., 2015, “Marine Klassifikation Von Gasmotoren—Beweggründe, Anforderungen, Herausforderungen,” Ninth Dessau Gas Engine Conference, Dessau, Germany, Apr. 16–17, pp. 13–20.Kiesling, C., Redtenbacher, C., Kirsten, M., Wimmer, A., Imhof, D., Berger, I., and García-Oliver, J., 2016, “Detailed Assessment of an Advanced Wide Range Diesel Injector for Dual Fuel Operation of Large Engines,” CIMAC Congress, Helsinki, Finland, June 6–10, Paper No. 78.http://www.lec.at/news-entries/detailed-assessment-of-an-advanced-wide-range-diesel-injector-for-dual-fuel-operation-of-large-engines/?lang=enEichmeier, J., Wagner, U., & Spicher, U. (2012). Controlling Gasoline Low Temperature Combustion by Diesel Micro Pilot Injection. Journal of Engineering for Gas Turbines and Power, 134(7). doi:10.1115/1.4005997Nieman, D. E., Dempsey, A. B., & Reitz, R. D. (2012). Heavy-Duty RCCI Operation Using Natural Gas and Diesel. SAE International Journal of Engines, 5(2), 270-285. doi:10.4271/2012-01-0379Srinivasan, K. K., Krishnan, S. R., Singh, S., Midkiff, K. C., Bell, S. R., Gong, W., … Willi, M. (2004). The Advanced Injection Low Pilot Ignited Natural Gas Engine: A Combustion Analysis. Journal of Engineering for Gas Turbines and Power, 128(1), 213-218. doi:10.1115/1.1915428Srinivasan, K. K., Krishnan, S. R., & Qi, Y. (2013). Cyclic Combustion Variations in Dual Fuel Partially Premixed Pilot-Ignited Natural Gas Engines. Journal of Energy Resources Technology, 136(1). doi:10.1115/1.4024855Tomita, E., Kawahara, N., Piao, Z., and Yamaguchi, R., 2002, “Effects of EGR and Early Injection of Diesel Fuel on Combustion Characteristics and Exhaust Emissions in a Methane Dual Fuel Engine,” SAEPaper No. 2002-01-2723.10.4271/2002-01-2723Krishnan, S. R., Biruduganti, M., Mo, Y., Bell, S. R., & Midkiff, K. C. (2002). Performance and heat release analysis of a pilot-ignited natural gas engine. International Journal of Engine Research, 3(3), 171-184. doi:10.1243/14680870260189280Laiminger, S., Trapp, C., Schaumberger, H., and Fouquet, M., 2011, “Die nächste Generation von Jenbacher Gasmotoren von GE—die wegweisende Kombination von zweistufiger Aufladung und innovativen Brennverfahren,” Seventh Dessau Gas Engine Conference, Dessau, Germany, Mar. 24–25, pp. 39–48.Dec, J. E. (1997). A Conceptual Model of DI Diesel Combustion Based on Laser-Sheet Imaging*. SAE Technical Paper Series. doi:10.4271/970873Krenn, M., Redtenbacher, C., Pirker, G., and Wimmer, A., 2015, “A New Approach for Combustion Modeling of Large Dual-Fuel Engines,” Heavy-Duty-, on- und Off-Highway-Motoren, 10 Internationale MTZ-Fachtagung, Speyer, Germany, pp. 1–14.Krenn, M., Pirker, G., Wimmer, A., Djuranec, S., Meier, M. C., Waldenmaier, U., and Zhu, J., 2014, “Methodology for Analysis and Simulation of Dual Fuel Combustion in Large Engines,” THIESEL Conference on Thermo- and Fluid Dynamic Processes in Direct Injection Engines, Valencia, Spain, Sept. 9–12, pp. 1–19.https://pure.tugraz.at/portal/en/publications/methodology-for-analysis-and-simulation-of-dual-fuel-combustion-in-large-engines(e3cf3100-3151-46af-9061-a04156df3522).htmlSchlatter, S., Schneider, B., Wright, Y., & Boulouchos, K. (2012). Experimental Study of Ignition and Combustion Characteristics of a Diesel Pilot Spray in a Lean Premixed Methane/Air Charge using a Rapid Compression Expansion Machine. SAE Technical Paper Series. doi:10.4271/2012-01-0825Kirsten, M., Pirker, G., Redtenbacher, C., Wimmer, A., & Chmela, F. (2016). Advanced Knock Detection for Diesel/Natural Gas Engine Operation. SAE International Journal of Engines, 9(3), 1571-1583. doi:10.4271/2016-01-0785Vandersickel, A., 2011, “Two Approaches to Auto-Ignition Modelling for HCCI Applications,” Doctoral thesis, ETH Zurich, Zurich, Germany, p. 20.https://www.research-collection.ethz.ch/bitstream/handle/20.500.11850/43686/eth-4813-01.pdfCiezki, H. K., & Adomeit, G. (1993). Shock-tube investigation of self-ignition of n-heptane-air mixtures under engine relevant conditions. Combustion and Flame, 93(4), 421-433. doi:10.1016/0010-2180(93)90142-pPfahl, U., Fieweger, K., and Adomeit, G., 1996, “Self-Ignition of Diesel-Relevant Hydrocarbon-Air Mixtures Under Engine Conditions,” 26th Symposium (International) on Combustion/the Combustion Institute, Pittsburgh, PA, pp. 781–789

Strategic green infrastructure planning in Germany and the UK: a transnational evaluation of the evolution of urban greening policy and practice

The evolution of Green Infrastructure (GI) planning has varied dramatically between nations. Although a grounded set of principles are recognized globally, there is increasing variance in how these are implemented at a national and sub-national level. To investigate this the following paper presents an evaluation of how green infrastructure has been planned for in England and Germany illustrating how national policy structures facilitate variance in application. Adopting an evaluative framework linked to the identification of GI, its development and monitoring/ feedback the paper questions the impacts on delivery of intersecting factors including terminology, spatial distribution and functionality on effective GI investment. This process reviews how changing policy structures have influenced the framing of green infrastructure policy, and subsequent impact this has on the delivery of green infrastructure projects

Environmental Consciousness in Germany 2000

Environmental consciousness and conduct in areas relevant to the environment. Topics: relevance of the environmental problem: general well-being living in Germany; importance of political problems such as unemployment, provision of housing, preserving the social state, combating crime, foreigner questions, environmental protection and competitive ability of business (scale); importance of selected goals of environmental protection. Environmental quality: judgement on environmental quality in Eastern and Western Germany, in Germany over-all, world-wide and in one's own city; largest environmental problem in one's own municipality; personal image of nature as self-regulating, sensitive, withstanding burdens within limits or unpredictable; perceived personal jeopardy from air pollution by cars and industry, water pollution and climate changes from the "greenhouse effect"; judgement on personal impact of noise, exhausts and bad air. Environmental attitudes: personal stand on environmental protection: orientation on environment or pleasure; trust in technology or one's own initiative; affective-cognitive and conative aspects of environmental protection (scale); technology and business; willingness to pay higher prices, higher taxes and restriction on standard of living for environmental protection. Consumption and household: paying attention to low energy consumption and readiness for higher expenditures for energy-saving devices when purchasing household equipment; knowledge about the introduction of the option to change electricity companies and personal conduct after this; using eco-electricity or intent to use eco-electricity in spite of additional cost. Environmentally conscious shopping practices: paying attention to the environmental compatibility of products when shopping; orientation on identification of environmentally compatible products; knowledge and paying attention to the "blue angel"; willingness to pay more for environmentally conscious and environmentally compatible products. Traffic and mobility: possession and number of cars in general and cars with reduced consumption in one's household; expected reaction to a doubling of the gasoline price: switching to bicycle or OEPNV {local public passenger transport}, doing without some trips or buying a more economical car; frequency of using a car; frequency of using bicycle, train and airplane in the last year; attitude to a speed limit; attitude to car-free zones in larger cities as well as additional streets for bicycle traffic, to establishing more restricted traffic zones and speed limit of 30 KM/H in residential areas; agreement with traffic policy measures such as expansion of the OEPNV {local public passenger transport}, the bicycle network and transferring freight traffic to rail transport; attitude to construction of the magnetic suspension train (Transrapid); attitude to introduction of a car-free days each year in one's municipality; trips with the bicycle without a real destination, "just for fun"; number of vacation trips last year; use of means of transport when shopping for household; distance to shops. Health: perceived current and future health burden from environmental problems; hereditary or environmentally caused allergic illnesses; personal experiences with allergic illnesses or in personal surroundings; age of persons affected; type of allergic symptoms (illnesses of the skin or respiratory tracts) and information on the causes (food, additives etc.); strength of personal impairment from allergy or the allergy of members of the household. Future scenarios: assumed events in the next 20 to 50 years such as shortage of drinking water, abandoning nuclear energy, war over raw materials and water, increase in long-distance travels, increased conversion to biological farming, 3-liter cars and cars with other forms of power, increase in global environmental pollution, noticeable increase in climate temperature. Environmental policies and citizen participation: evaluation of extent of current environmental policy measures; desired measures of the Federal Government against increase in ozone levels: speed limit, driving prohibition, education campaign or no measures; assessment of the risk of atomic energy; agreement with the FRG's abandoning nuclear energy; assessment of existing environmental protection laws as adequate or inadequate; importance of reducing gases harmful to the climate and evaluation of political measures for this; feeling of progress in the last 5 years regarding cleanliness of inshore waters, purity of the air, condition of soil, climate protection, conservation of energy and protection of nature; assessment of the risk of gene technology and orientation of the government on safety or health in the area of gene technology; attitude to foods processed with gene technology; political participation in the area of environmental protection and authorities and institutions consulted; membership in environmental protection organizations and assessment of participation in residential area and in personal circle of friends; knowledge about the "local agenda 21" initiative; willingness to participate in affairs in the residential district; interest or commitment in certain topic areas (health, third world, traffic etc.); knowledge about the discussion of an ecological tax reform; agreement with selected statements on ecological tax reform; familiarity and understanding of the term "sustained development"; trust in the problem-solving ability of selected institutions and organizations as well as of the political parties; interest in politics. Information practices: credibility of sources of information; information conduct relative to environmental problems through selected sources such as private and public television, radio, conversations with friends, regional and national press, weekly and technical publications; evaluation of extent and manner of media reporting about environmental problems; Internet access in household and frequency of use; personal environmental conduct; frequency of practising selected environmentally compatible actions (scale). Demography: sex; year of birth; highest education degree; employment activity; occupational position; marital status; living together with a partner; number of children; size of household and composition of household; party preference (Sunday question); religious denomination; religiousness; personal income; household income; growing up in a large city, small town or a village. Interviewer rating: form of housing; residential area; traffic situation of residential area; ZIP (postal) code.Umweltbewußtsein und Verhalten in umweltrelevanten Bereichen. Themen: Relevanz des Umweltproblems: Allgemeines Wohlbefinden, in Deutschland zu leben; Wichtigkeit politischer Probleme wie Arbeitslosigkeit, Wohnraumversorgung, Erhalt des Sozialstaates, Verbrechensbekämpfung, Ausländerfragen, Umweltschutz und Wettbewerbsfähigkeit der Wirtschaft (Skalometer); Wichtigkeit ausgewählter Ziele des Umweltschutzes. Umweltqualität: Beurteilung der Umweltqualität in Ost- und Westdeutschland, in Gesamtdeutschland, weltweit und in der eigenen Stadt; größtes Umweltproblem in der eigenen Gemeinde; persönliches Bild von der Natur als selbstregulierend, empfindlich, begrenzt belastbar oder unberechenbar; empfundene persönliche Gefährdung durch Luftverschmutzung durch Autos und Industrie, Wasserverschmutzung und Klimaveränderungen durch den "Treibhauseffekt"; Beurteilung der persönlichen Betroffenheit von Lärm, Abgasen und schlechter Luft. Umwelteinstellungen: Eigene Haltung zum Umweltschutz: Umwelt- oder Genußorientierung; Vertrauen in die Technik oder Eigeninitiative; affektiv-kognitive und konative Aspekte des Umweltschutzes (Skala); Technik und Wirtschaft; Bereitschaft zur Zahlung höherer Preise, höherer Steuern und Einschränkung des Lebensstandards für den Umweltschutz. Konsum und Haushalt: Beachtung eines niedrigen Energieverbrauchs und Bereitschaft zu höheren Ausgaben für energiesparende Geräte beim Kauf von Haushaltsgeräten; Kenntnis der eingeführten freien Wählbarkeit des Stromlieferanten und eigenes Verhalten daraufhin; Bezug von Ökostrom bzw. Absicht, Ökostrom trotz Aufpreis zu beziehen. Umweltbewußtes Einkaufsverhalten: Beachten der Umweltverträglichkeit von Produkten beim Einkauf; Orientierung an Kennzeichnungen umweltfreundlicher Produkte; Kenntnis und Beachten des "Blauen Engels"; Bereitschaft zur Zuzahlung für umweltbewußte und umweltfreundliche Produkte. Verkehr und Mobilität: Besitz und Anzahl von Autos allgemein und verbrauchsreduzierten Autos im eigenen Haushalt; voraussichtliche Reaktion bei Verdoppelung des Benzinpreises: Umsteigen auf Fahrrad oder ÖPNV, Wegeverzichte oder sparsameres Auto kaufen; Nutzungshäufigkeit eines Autos; Häufigkeit der Nutzung von Fahrrad, Bahn und Flugzeug im letzten Jahr; Einstellung zu einer Geschwindigkeitsbegrenzung; Einstellung zu PKW-freien Zonen in größeren Städten sowie zusätzliche Straßen für den Fahrradverkehr, zur Einrichtung mehr verkehrsberuhigter Zonen und Geschwindigkeitsbegrenzung auf Tempo 30 in Wohngebieten; Zustimmung zu verkehrspolitischen Maßnahmen wie Ausbau des ÖPNV, des Radnetzes und Verlagerung des Güterverkehrs auf die Schiene; Einstellung zum Bau der Magnetschwebebahn (Transrapid); Einstellung zur Einführung eines autofreien Tages im Jahr in der eigenen Gemeinde; ziellose Fahrten mit dem Fahrrad "nur so zum Spaß"; Anzahl an Urlaubsreisen im letzten Jahr; Verkehrsmittelnutzung bei Haushaltseinkäufen; Entfernung zur Einkaufsstätte. Gesundheit: Empfundene derzeitige und zukünftige Gesundheitsbelastung durch Umweltprobleme; erbliche oder umweltbedingte allergische Erkrankungen; persönliche Erfahrungen mit allergischen Erkrankungen oder im persönlichen Umfeld; Alter der betroffenen Personen; Art der allergischen Symptome (Erkrankungen der Haut oder Atemwege) und Angabe der Ursachen (Nahrungsmittel, Zusatzstoffe etc.); Stärke der persönlichen Beeinträchtigung durch eigene Allergie oder die Allergie der Haushaltsmitglieder. Zukunftsszenarien: Vermutete Ereignisse in den nächsten 20 bis 50 Jahren wie Trinkwasserknappheit, Atomausstieg, Kriege um Rohstoffe und Wasser, Zunahme von Fernreisen, vermehrte Umstellung auf biologischen Anbau, 3-Liter-Autos und Autos mit anderen Antriebsformen, Zunahme globaler Umweltverschmutzung, spürbare Klimaerwärmung. Umweltpolitik und Bürgerbeteiligung: Bewertung des Umfangs derzeitiger umweltpolitischer Maßnahmen; gewünschte Maßnahmen der Bundesregierung gegen den Anstieg der Ozonwerte: Tempobeschränkung, Fahrverbot, Aufklärungskampagnen oder keine Maßnahmen; Einschätzung der Gefährlichkeit von Atomenergie; Zustimmung zum Atomausstieg der BRD; Einschätzung der bestehenden Umweltschutzgesetze als ausreichend oder ungenügend; Wichtigkeit der Verringerung klimaschädlicher Gase und Bewertung politischer Maßnahmen dafür; Fortschrittsempfinden in den letzten 5 Jahren hinsichtlich der Gewässerreinheit, Sauberkeit der Luft, Zustand des Bodens, zum Klimaschutz, der Energieeinsparung und zum Naturschutz; Einschätzung der Gefährlichkeit von Gentechnik und der Sicherheits- bzw. Gesundheitsorientierung des Staates im Bereich der Gentechnik; Einstellung zu gentechnisch behandelten Lebensmitteln; politische Partizipation im Bereich Umweltschutz und zu Rate gezogene Behörden und Institutionen; Mitgliedschaft in Umweltschutzorganisationen und Einschätzung der Beteiligung im Wohnbezirk und im eigenen Bekanntenkreis; Kenntnis der "lokale Agenda 21"-Initiative; Bereitschaft zur Beteiligung bei Angelegenheiten im Wohnbezirk; Interesse oder Engagement in bestimmten Themenbereichen (Gesundheit, Dritte Welt, Verkehr etc.); Kenntnis der Diskussion um eine ökologische Steuerreform; Zustimmung zu ausgewählten Aussagen zur ökologischen Steuerreform; Bekanntheit und Verständnis des Begriffs der "nachhaltigen Entwicklung"; Vertrauen in die Problemlösungs-Kompetenz ausgewählter Einrichtungen und Organisationen sowie der politischen Parteien; Politikinteresse. Informationsverhalten: Glaubwürdigkeit von Informationsquellen; Informationsverhalten, bezogen auf Umweltprobleme durch ausgewählte Quellen wie privates und öffentliches Fernsehen, Hörfunk, Gespräche mit Bekannten, regionale und überregionale Presse, Wochen- und Fachzeitschriften; Bewertung des Umfangs und der Art der Medienberichterstattung über Umweltprobleme; Internetzugang im Haushalt und Nutzungshäufigkeit; persönliches Umweltverhalten; Häufigkeit der Ausübung ausgewählter umweltfreundlicher Handlungen (Skala). Demographie: Geschlecht; Geburtsjahr; höchster Bildungsabschluß; Erwerbstätigkeit; berufliche Stellung; Familienstand; Zusammenleben mit einem Partner; Kinderzahl; Haushaltsgröße und Haushaltszusammensetzung; Parteipräferenz (Sonntagsfrage); Konfession; Religiosität; eigenes Einkommen; Haushaltseinkommen; Aufwachsen in einer Großstadt, Kleinstadt oder einem Dorf. Interviewerrating: Wohnform; Wohngegend; Verkehrssituation der Wohngegend, Postleitzahl