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Karlsruhe, Germany

Kraljevic I.,Fraunhofer Institute for Chemical Technology | Kollmeier H.-P.,Fraunhofer Institute for Chemical Technology | Spicher U.,MOT GmbH
ASME 2015 Internal Combustion Engine Division Fall Technical Conference, ICEF 2015 | Year: 2015

This paper presents the analysis of a Rankine cycle unit applied to improve overall efficiency of a hybrid electric vehicle (HEV). Exhaust waste heat is recovered from the internal combustion engine (ICE) and is converted into electrical power that is fed into the electrical system on board. The discontinuously available exhaust waste heat from the ICE operating cycle is stored as sensible heat in a pressurized working fluid applying the principle of a Ruths storage tank. Thus, it can provide almost constant mass flows to the expansion device during discharge in contrast to the standard Rankine cycle. It is also shown that the outlined system configuration leads to faster engine warm up resulting in optimum ICE operating conditions improving fuel economy. The benefits of a mild HEV versus conventional car powertrain are outlined step by step in a vehicle simulation. Additionally, improvement in fuel economy achieved by applying an additional Rankine cycle is demonstrated in the New European Driving Cycle (NEDC). Copyright © 2015 by ASME. Source

Busch S.,Karlsruhe Institute of Technology | Disch C.,MOT GmbH | Kubach H.,Karlsruhe Institute of Technology | Spicher U.,Karlsruhe Institute of Technology
SAE Technical Papers | Year: 2010

Investigations of the fuel injection processes in a spark ignition direct injection engine have been performed for two different fuels. The goal of this research was to determine the differences between isooctane, which is often used as an alternative to gasoline for optical engine investigations, and a special, non-fluorescing, full boiling range multicomponent fuel. The apparent vaporization characteristics of isooctane and the multicomponent fuel were examined in homogeneous operating mode with direct injection during the intake stroke. To this end, simultaneous Mie scattering and planar laser induced fluorescence imaging experiments were performed in a transparent research engine. Both fuels were mixed with 3-Pentanone as a fluorescence tracer. A frequency-quadrupled Nd:YAG laser was used as both the fluorescent excitation source and the light scattering source. To help counter possible attenuation effects, the laser beam was split into two laser light sheets that were directed into the combustion chamber from opposing sides. Two CCD cameras, which were positioned perpendicular to the laser light sheet, simultaneously detected the LIF and Mie scattering signals at various crank angles for individual engine cycles. This enabled the detection of both the liquid and the gas phases of the injection events. An injection pressure variation was performed to examine the influence of fuel pressure on apparent vaporization behavior. Simultaneous Mie scattering and LIF imaging was performed for injection pressures of 200, 150 and 100 bar. Differences in the vaporization characteristics of each fuel are described in the context of the averaged Mie scattering and LIF images. Copyright © 2010 SAE International. Source

Bach F.,Karlsruhe Institute of Technology | Hampe C.,MOT GmbH | Wagner U.,Karlsruhe Institute of Technology | Spicher U.,Karlsruhe Institute of Technology | Sauer C.,MTU AG
ASME 2012 Internal Combustion Engine Division Fall Technical Conference, ICEF 2012 | Year: 2012

This paper describes the operation of a heavy duty six-cylinder engine in a dual fuel, Low Temperature Combustion (LTC) mode with very low engine-out NOx und soot emissions according to the US EPA Tier IV final emission limits in the corresponding C1 test cycle. This operation mode makes use of a short pilot injection of diesel fuel, which is injected directly into the cylinder, to ignite a highly diluted, premixed gasoline air mixture. Multicylinder engine operation could be demonstrated over the entire engine operating map with loads of up to 2 MPa BMEP. Expensive aftertreatment systems for NOx and soot emissions are not required. This paper also discusses the challenges involved with the implementation of this combustion system on a multicylinder engine. When transferring the dual fuel LTC from a single cylinder research engine to a multicylinder engine, the design of some engine components, e.g. the camshaft and the piston, were changed. The intake manifold is modified with port fuel injectors for ideal gasoline mixture preparation and equal distribution to all cylinders. To avoid cylinder imbalances, it is possible to control the injected masses of gasoline and diesel fuel for the pilot injection on a per-cylinder basis. Achieving high dilution for ignition delay via EGR and boosted intake pressure to avoid high pressure rise rates and knocking presents challenges for the two-stage turbocharger design. Additionally, high EGR rates and EGR cooling for increased loads are addressed. Finally, experiments to determine the significant control parameters for the combustion process are performed on the engine. In the course of these investigations, dual fuel LTC could be transferred from a single cylinder research engine to a multicylinder engine; previously obtained single-cylinder operating conditions could be achieved even at high loads. Copyright © 2012 by ASME. Source

Spicher U.,Karlsruhe Institute of Technology | Sarikoc F.,MOT GmbH
13th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery 2010, ISROMAC-13 | Year: 2010

Engine downsizing is a promising method to reduce the fuel consumption of internal combustion engines. The principle of engine downsizing is generally realized by a combination of several measures. The combination of gasoline direct injection and turbo-charging lead to increased engine efficiencies, reduced engine sizes, and a reduction of CO 2-emissions at a comparable power output. Therefore, present and future developments of all automotive manufacturers are mainly focused on downsizing concepts that employ turbocharging and gasoline direct injection. One significant problem with a gasoline direct injection engine, operating at part load, is the realization of a fast and stable mixture preparation process, particularly in turbocharged, stratified operation. Another difficulty is the occurrence of knocking combustion at high engine load. Due to these unfavourable conditions, the gasoline direct injection engine with stratified mixture formation in combination with turbocharging has not yet been introduced into the automotive market. Currently, turbocharged engines with gasoline direct injection operate only with homogeneous and stoichiometric mixtures. Copyright © 2010 by ISROMAC-13. Source

Bertsch M.,MOT GmbH | Beck K.W.,MOT GmbH | Spicher U.,Karlsruhe Institute of Technology | Kolmel A.,Andreas Stihl AG and Co. KG | And 3 more authors.
SAE Technical Papers | Year: 2012

The combustion processes optimization is one of the most important factors to enhancing thermal efficiency and reducing exhaust emissions of combustion engines [1; 2]. Future emission regulations for small two-stroke SI engines require that the emissions of gases causing the greenhouse effect, such as carbon dioxide, to be reduced. One possible way to reduce exhaust gas emissions from two-stroke small off-road engines (SORE) is to use biogenic fuels. Because of their nearly closed carbon dioxide circuit, the emissions of carbon dioxide decrease compared to the use of fossil fuels. Also biogenic fuels have a significant influence on the combustion process and thus the emissions of different exhaust gas components may be reduced. Besides greenhouse gases, several other exhaust gas components need to be reduced because of their toxicity to the human health. For example, aromatic hydrocarbons cause dangerous health problems, and can be reduced by using alkylate fuel. This research shows the potential of gasoline or alkylate fuel blended with alcohol to reduce exhaust gas emissions. Blends of these fuels with ethanol, 1-butanol and 2-butanol were used. The exhaust gases were analyzed both with standard exhaust gas analyzers and with a Fourier Transform Infrared Spectroscope (FTIR). The combustion process was analyzed by interpreting the indicated incylinder pressure. Thus the influence of alcoholic blends causing combustion phenomena such as knocking was regarded. Copyright © 2012 SAE International. Source

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