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Forschungsbericht 2011 / Hochschule für Angewandte Wissenschaften - Fachhochschule Regensburg
(2011)
To investigate the combustion and emission behavior of straight vegetable oils (SVO), jatropha oil, soybean oil, and diesel fuel were tested. For this research, a 2.2L common-rail engine with a two-stage turbocharging concept was equipped with a cylinder pressure indication system, an exhaust-gas analyzer, an AVL Micro Soot sensor and a Scanning Mobility Particle Sizer 3936 (SMPS) device to detect the particle-size-distribution (PSD). At a low and mid-load engine-operating point (EOP), the thermodynamic and emissions were investigated under various exhaust gas recirculation (EGR) rates with respect to the PSD. Moreover, the injection behavior of the three test fuels was analyzed separately using an injection rate analyzer. This procedure facilitates the thermodynamic investigations of the engine process and allows the calculation of the hydraulic delay (HD) as well as the ignition delay (ID). The ID of the SVO fuels compared to diesel fuel was found to be lower at all engine-operating modes, while jatropha oil always showed the shortest ID. In the particulate-nitrogen oxide (NOX) trade-off, the SVO fuels showed higher particulate matter (PM) emissions at the low-load EOP, whereas the PM emissions of diesel fuel overtop the SVO fuels at a higher engine load. With increased EGR-rates, a rise in the particle size was observed for all fuels. At the low-load EOP, the SVO fuels showed larger particles for high EGR-rates. This effect also changed by increasing the engine-load to the mid-load EOP, wherein the particle size of the diesel fuel emissions is higher by applying elevated EGR-rates.
Pure rapeseed oil fuel (R100) according to standard DIN 51605 is a greenhouse gas saving option for the mobility sector. With its high energy density close to diesel fuel, R100 is suitable to operate non-road mobile machinery with a high power demand and long operating time, where electric drives reach their limits. Advantages are indicated for its use in environmentally sensitive areas like agriculture since R100 is highly biodegradable and non-toxic. However, R100 is characterised by differing physical and chemical properties compared to diesel. The objective of the research is to investigate the differences in the ignition and combustion behaviour of R100 compared to diesel fuel (DF). For this purpose, a constant volume combustion chamber is used, which is equipped with a modern solenoid injector for engines of non-road mobile machinery. The researched injector shows a different hydraulic behaviour when using R100 compared to DF in that the injected fuel mass is lower with R100 than with DF. In combination with the 14 % by mass lower calorific value, less energy output is determined with R100. When varying the injection pressure, the impact on the ignition delay and combustion behaviour is much higher for R100 than for DF. Specifically, an increase of the injection pressure supports mixture preparation and thus partially compensates the differing physical properties of R100.
The results of ignition delay measurements and net heat release analysis are as follows: At low load conditions with low injection pressure as well as a low combustion chamber temperature and pressure, R100 ignites later and shows a further delayed combustion compared to diesel. The opposite is observed for medium and high load conditions, where R100 ignites faster and without delayed combustion in comparison to DF. Thus, an adjustment of the heat release of R100 at the same level as for DF is possible by modifying the injection strategy.
The research shows that for an optimised combustion of R100 the injection settings must be adjusted for every operation point separately. The results indicate how the injection parameters should be adjusted for different load conditions to realise a high-quality engine calibration for R100.
An effective way to reduce greenhouse gas emissions (GHGs) is to use rurally produced straight jatropha oil as a substitute for diesel fuel. However, the different physical and chemical properties of straight vegetable oils (SVOs) require a customized setup of the combustion engine, particularly of the injection timing and quantity. Therefore, this study demonstrates the differences in the injection and combustion processes of jatropha oil compared to diesel fuel, particularly in terms of its compatibility with exhaust gas recirculation (EGR).
A 2.2 l common-rail diesel engine with a two-stage turbocharging concept was used for testing. To examine the differences in injection rate shaping of diesel fuel and jatropha oil, the injector was tested with an injection rate analyzer using both the fuels. To investigate the combustion process, the engine was mounted at an engine test bench and equipped with a cylinder pressure indication system. All limited emissions, as well as fuel consumption, were measured.
Various injection strategies, boost and rail pressure levels were tested at different EGR rates in terms of their impact on the combustion process. EGR in particular offers a great potential in the case of jatropha oil combustion due to its oxygen content. In addition, the investigation of injection rate shaping in combination with cylinder pressure analysis allowed a detailed thermodynamic evaluation of the combustion process. Ignition delay (ID) was also analyzed using a new method to calculate the start of combustion (SOC)
The use of alternative fuels in high-power non-road mobile machinery (NRMM) combustion engines is a possible way to substitute fossil fuel. By using pure vegetable oil fuels, like rapeseed oil fuel (DIN 51605), the greenhouse gases can be reduced effectively. Due to the differences in physical and chemical properties, a modification of the engine control unit calibration is necessary to adapt the working process on the fuel. Without modifications, the engine power output with rapeseed oil fuel is lower than with diesel fuel because of the smaller energy content. By adapting the engine settings, like the injection fuel mass, the power loss can be compensated but it accompanies with a higher fuel consumption. The engine emissions at part load conditions show, that there are benefits in particle emissions by using rapeseed oil at similar NOx emissions. Therefore, a design of experiment setup was initiated on a selected engine operation point to determine the effects of further parameters, like rail pressure, manifold pressure and injection pattern, on the process and to see the potential of an optimized calibration.
In this paper, we present a new approach to determine the estimated time of arrival (ETA) for bus routes using (Deep) Graph Convolutional Networks (DGCNs). In addition we use the same DGCN to detect detours within a route. In our application, a classification of routes and their underlying graph structure is performed using Graph Learning. Our model leads to a fast prediction and avoids solving the vehicle routing problem (VRP) through expensive computations. Moreover, we describe how to predict travel time for all routes using the same DGCN Model. This method makes it possible not to use a more computationally intensive approximation algorithm when determining long travel times with many intermediate stops, but to use our network for an early estimate of the quality of a route. Long travel times, in our case result from the use of a call-bus system, which must distribute many passengers among several vehicles and can take them to places without a regular stop. For a case study, the rural town of Roding in Bavaria is used. Our training data for this area results from an approximation algorithm that we implemented to optimize routes, and to generate an archive of routes of varying quality simultaneously.
Als fairer Beitrag Deutschlands zur Einhaltung der globalen 1,5-Grad-Grenze werden 16 Orientierungspunkte für eine klimaverträgliche Energieversorgung vorgestellt. Es wird davon ausgegangen, dass hierfür die deutschen energiebedingten CO2-Emissionen in etwa 15 Jahren weitgehend auf Null sinken müssen. Energieeinsparung hilft, den notwendigen Ausbau von regenerativen Erzeugungskapazitäten zu verringern. Der Verkehrssektor kann ebenso wie die Bereiche Prozess- und Gebäudewärme hierzu wesentlich beitragen. Die Kernenergie ist mit großen Risiken belastet und kann nicht hinreichend schnell aufgebaut werden. Biomasse in Form von Energiepflanzen zu nutzen, ist ineffizient und steht im Konflikt mit anderen Arten der Landnutzung. Importe klimaneutral erzeugter Energieträger in sehr großem Umfang erfordern extrem große Investitionen im Ausland. Sie sind eine ungesicherte Option auf die Zukunft.
Entscheidend ist daher der ausreichend schnelle Ausbau von Photovoltaik (PV) und Windkraft in Deutschland. Schätzungsweise kann der Elektrizitätsbedarf im Jahr 2030 z.B. durch den Ausbau auf ca. 350 GW PV und ca. 150 GW Windkraft nahezu vollständig regenerativ gedeckt werden. Damit ließe sich eine zum großen Teil elektrifizierte Mobilität und Wärmeversorgung betreiben und ein Teil des benötigten "grünen" Wasserstoffs in Deutschland bereitstellen. Hierfür ist ein jährlicher Zubau von durchschnittlich ca. 30 GW PV und ca. 9 GW Windkraft nötig. Dies ist ca. sechs- (PV) bzw. dreimal (Wind) so hoch wie bisher vorgesehen und verlangt eine gesellschaftliche Kraftanstrengung. Ein weiter verzögerter Ausbau müsste mit noch deutlich größeren gesellschaftlichen Anstrengungen für drastische Energieeinsparungen oder Importe erneuerbarer Energie ausgeglichen werden. Insgesamt könnte dies noch deutlich schwieriger zu realisieren sein, als ein ambitionierter Ausbau. Da der Aufbau der Kapazitäten mehrere Jahre erfordert, ist es möglich nachzusteuern, z. B. wenn erkennbar wird, dass sich ein ausreichend großer globaler Markt für Importe entwickelt. Bis dahin ist es aus Verantwortung gegenüber der Zukunft und im Sinne des Pariser Vertrages empfehlenswert, die hier genannten Ausbauziele zu verfolgen.
Grüner, also aus erneuerbaren Energien hergestellter Wasserstoff und daraus abgeleitete Syntheseprodukte sind für die Dekarbonisierung von Industrieprozessen, den Flug- und Schiffsverkehr sowie für die Absicherung der Energieversorgung bei Dunkelflauten nötig. Ohne die genannten Ausbauziele für Wind und Solar noch drastisch weiter zu erhöhen, stehen diese Produkte für Straßenverkehr und Wärmeversorgung jedoch nicht in ausreichenden Mengen zur Verfügung. Techniken zum Ausgleich zwischen Elektrizitätsangebot und -nachfrage sind verfügbar und sollten rechtzeitig auf- bzw. ausgebaut werden. Hierzu gehören: Stromaustausch mit den Nachbarländern, Flexibilisierung des Verbrauchs und Energiespeicherung. Für deren Integration sowie den Ausbau der Netze sollten zügig verbesserte rechtliche Rahmenbedingungen geschaffen werden.
Die Kosten eines klimaverträglichen Energiesystems sind mittel- bis langfristig nicht höher als im derzeitigen System. Gleichzeitig entstehen Arbeitsplätze und Exportchancen durch Aufbau, Betrieb und Wartung einer regenerativen Energieversorgung in Deutschland und die energetische Gebäudesanierung. Die politischen Rahmenbedingungen entscheiden, ob eine klimaverträgliche Energieversorgung Deutschlands gelingt.
Forschung 2019
(2019)