The developers of modern advanced diesel engine technologies face a significant tradeoff when it comes to reducing both greenhouse gas and air emissions: Many measures which reduce nitrogen oxide emissions lead to a significant increase in fuel consumption. At the Autumn Meeting of the Research Association for Combustion Engines (FVV) in Würzburg scientists presented new approaches to reconcile both objectives.
To further improve the overall emissions characteristic of a diesel engine it is not sufficient to ensure the perfect functioning of the emission control system only. The utmost goal of engine developers is to even reduce raw emissions in the engine.
In addition to design measures, the engine control system thereby plays a crucial role: Different variable systems need to be aligned so that the emission limit values set by the legislator are met by the engine while consuming as little fuel as possible. Three of the most important interdependant calibration factors in a typical passenger car diesel engine are the injection time, the amount of exhaust gas recirculated into the cylinder and the air flow within the cylinder which can be influenced, for example, through connecting or disconnecting an inlet channel.
Scientists at ETH Zurich reported on a FVV research project proposing an optimised feedback emissions control system for diesel engines
The new technique is to calculate the combustion process in the engine by means of the so-called “heat curve” and to control the engine based on the results of this calculation. The emission control system of modern advanced diesel engines relies on the feedback of physical emission sensors, for instance for determining the NOx content in the exhaust gas.
"Even though our new calculation model could do perfectly without such physical sensors, we do not want to replace but supplement them by a virtual sensor network", explained Professor Dr Konstantinos Boulouchos, ETHZ Institute for Energy Technology.
Together with his colleagues from the Institute for Dynamic Systems and Control (IDSC), his research team validated the calcualtion results at the test bench: The emissions control system based on feedback via the virtual sensors delivered similar high quality results as were achieved by using an heuristic control strategy. This also includes dynamic test cycles as the WLTC (World Light-Duty Cycle Test), the introduction of which is currently under discussion.
An optimised high-performance engine control system may in the future also solve another problem of modern diesel engines: The combustion process is very dynamic – thus enabling a vehicle to react instantly when the driver steps on the accelerator pedal. Physical sensors detecting the raw emissions always respond with a delay of up to two seconds on the change in the engine operating conditions. Add to this the inertia of the exhaust gas aftertreatment systems. This leads for very short periods to increased emissions. “We are confident that we can halve these latency periods with modern control methods" said Boulouchos.
Japan and Europe researching together
Not only Europe but also Japan focuses its research activities on how the emissions of the diesel engine can be further reduced. Professor Dr Jin Kusaka from Waseda University in Tokyo presented to the auditorium the research priorities of the Japan Research Association of Automotive Internal Combustion Engines (AICE). AICE, too, is looking for ways to control the regeneration of the particle filter more accurately.
Since for each cleaning operation, additional fuel is injected, an exact knowledge of the actual load status over the life of the vehicle may result in significant fuel savings. For both oxidation as well as for SCR catalysts different concepts are examined that work at lower temperatures. This is important to reduce cold start emissions which are always increased. Another approach is to reduce the deposits caused by the exhaust gas recirculation in the engine. This would allow to permanently operate at higher exhaust gas recirculation rates, and the resulting drop in temperature would lead to lower NOx formation.
The AICE Research Association, founded in 2014 by the Japanese vehicle manufacturers, is a FVV partner organisation. Dietmar Goericke, Managing Director of the German Research Association for Combustion Engines (FVV) concluded:
"The fact that we in Europe as well as our partners in Japan continue our intense research activities on the diesel engine, shows the potential that lies in this combustion principle. The diesel engine is the most climate-friendly drive system designed for mobile applications. By means of further research efforts it will be possible cutting emissions even further even in real driving conditions."
Petra Tutsch | idw - Informationsdienst Wissenschaft
It Takes Two: Structuring Metal Surfaces Efficiently with Lasers
15.03.2017 | Fraunhofer-Institut für Lasertechnik ILT
FOSA LabX 330 Glass – Coating Flexible Glass in a Roll-to-Roll Process
07.03.2017 | Fraunhofer-Institut für Organische Elektronik, Elektronenstrahl- und Plasmatechnik FEP
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
24.03.2017 | Materials Sciences
24.03.2017 | Physics and Astronomy
24.03.2017 | Physics and Astronomy