Heiko Kubach
Karlsruhe Institute of Technology
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Publication
Featured researches published by Heiko Kubach.
International Journal of Engine Research | 2013
Florian Schumann; Fatih Sarikoc; S. Buri; Heiko Kubach; Ulrich Spicher
The combination of gasoline direct injection and turbocharging is a promising method to reduce the fuel consumption of internal combustion engines through engine downsizing, which leads to increased engine efficiencies and a reduction of CO2 emissions at a comparable power output. Spray-guided direct injection allows overall lean and unthrottled operation, which is realized with a highly stratified mixture at part load. However, exhaust gas aftertreatment with conventional three-way catalysts is currently not possible. Furthermore, insufficient mixture preparation, especially at the upper load limit of stratified charge operation, causes increased particulate matter emissions. This paper discusses the advantages of engine downsizing, by gasoline direct injection in combination with turbocharging, to reduce fuel consumption and presents the results of experimental and numerical investigations of stratified exhaust gas recirculation in a single-cylinder gasoline engine to reduce nitrogen oxide emissions. The radial exhaust gas stratification was achieved by a spatial and temporal separated induction of exhaust gas and fresh air, performed by specially shaped baffles and impulse charge valves in the inlet port. The thermodynamic and optical investigations with injection pressures up to 1000 bar demonstrate the capability to reduce soot emissions in a spray-guided direct-injection engine.
SAE transactions | 2004
Heiko Kubach; Amin Velji; Ulrich Spicher; Wolfgang Fischer
Contemporary diesel engines are high-tech power plants that provide high torques at very good levels of efficiency. By means of modern injecting-systems such as Common-Rail Injection, combustion noise and emissions could be influenced positively as well. Diesel engine are therefore used increasingly in top-range and sports cars.
International Journal of Engine Research | 2010
S. Buri; Heiko Kubach; Ulrich Spicher
Abstract The gasoline direct-injection engine with spray-guided combustion is one of the most promising strategies to reduce fuel consumption and CO2 emissions of spark-ignition engines. This benefit results primarily from lean and unthrottled operation, which is realized with a highly stratified mixture at part load. At the upper load limit of stratified charge operation, charge stratification is insufficient to realize substantial fuel economy benefits, especially when using multihole injectors. This can be attributed to a lower injector flowrate than is available from outward-opening piezo injectors. One measure to increase the flowrate is to increase the injection pressure. A higher stratification gradient thereby can be achieved, which leads to combustion at richer air–fuel ratios. As a result, combustion duration and hydrocarbon emissions decrease. The enhanced evaporation due to the increased injection pressure reduces soot emissions. This paper presents the results of thermodynamic and optical investigations at the upper load limit of stratified charge operation in a spray-guided direct-injection engine. To this end, variations of the injection pressure from 200 to 1000 bar are performed. The associated effects on mixture preparation and soot formation are investigated. The mixture preparation process and flame propagation information are recorded using a high-speed intensified complementary metal oxide semiconductor (CMOS) camera. In order to investigate soot formation and oxidation behaviour, soot concentrations are measured using the extended two-colour method.
ASME 2012 Internal Combustion Engine Division Spring Technical Conference | 2012
Fino Scholl; Denis Neher; Maurice Kettner; Philipp Hügel; Heiko Kubach; Markus Klaissle
Spark ignition constitutes the most common way of mixture inflammation for gas engines of CHP units (combined heat and power). However, spark plug durability is limited due to spark erosion. High maintenance costs as a result of frequent spark plug replacements are the consequence. Beside the durability aspect, the inflammation of lean mixtures makes high demands on the inflammation process itself. Due to the small reactive mixture volume, the level of air-fuel ratio as well as the efficiency increase is limited. The ignition by means of a hot surface enables an increase of the reactive mixture volume and, as a result, an enhancement of the lean burn limit.A hot surface ignition (HSI) system was developed for stationary lean burn operation in due consideration of low manufacturing costs and electrical characteristics that allow a reliable control of the ignition timing. The main component of the inflammation element is a pin-shaped glow plug, whose temperature can be regulated by adjusting the electrical power. Due to external influences such as fluctuating ambient pressure and gas quality a control unit is essential for securing an optimal combustion phasing of the engine.Several designs of hot surface ignition, including passive prechamber and shielded versions, were tested on a single cylinder test bed engine operating with a homogeneous air-petrol mixture. The engine tests were accompanied by 3D flow simulations. The trials showed that the power consumption, and hence the temperature of the hot surface, as well as the flow conditions around the glow plug have a strong influence on the ignition timing. Furthermore, a strong correlation between the mean combustion chamber temperature and combustion phasing became evident. Based on this coherence, it was possible to develop a closed-loop control that adjusts the combustion phasing by controlling the combustion chamber temperature at a stationary operating point.The shielded inflammation element stood out to be the target-aiming version of hot surface ignition. It is characterised by an accelerated inflammation which allows reducing the cycle-to-cycle variations compared to prechamber spark ignition and, hence, to enhance the lean burn limit. As a result, a significant improvement of the efficiency-NOx trade-off is possible.The obtained results provide the basis for further trials on a gas engine CHP module operating with natural gas.Copyright
Archive | 2018
Christian Disch; Jürgen Pfeil; Heiko Kubach; Thomas Koch; Ulrich Spicher; Olaf Thiele
Mit der absehbaren Einfuhrung neuer gesetzlicher Zertifizierungszyklen (WLTP) und unter Berucksichtigung des realen Kundenfahrverhaltens (RDE – Real Driving Emissions), gewinnt die Untersuchung der transienten Betriebsphasen eines Verbrennungsmotors zunehmend an Bedeutung. Eine detaillierte Analyse dieser Ubergangszustande stellt dabei besondere Herausforderungen sowohl an die eingesetzte Messtechnik als auch an die angewandte Entwicklungsmethodik. Dies wird vor dem Hintergrund deutlich, dass meist nur einige wenige Arbeitsspiele wahrend dieser transienten Betriebsphasen fur die vergleichsweise hohen Emissionen verantwortlich sind.
Archive | 2015
Philipp Hügel; Thomas Koch; Heiko Kubach
Der Schichtbetrieb mit strahlgefuhrter Benzin-Direkteinspritzung ist eine vielversprechende Technik, um die CO2-Emissionen von Ottomotoren zu senken. Die Hauptursachen fur die hohen Wirkungsgrade bei Teillast sind die niedrigen Ladungswechselverluste aufgrund des ungedrosselten Motorbetriebs und der hohe thermische Wirkungsgrad durch das global magere Gemisch. Ein weiterer oft genannter Grund fur die hohe Effizienz sind die geringen Wandwarmeverluste im Schichtbetrieb (1), (2), die meist durch isolierende Luftpolster zwischen verbranntem Gemisch und Brennraumwand (3), (4) erklart werden.
Archive | 2013
Daniel Ghebru; Christian Donn; Wolfgang Zulehner; Heiko Kubach; Uwe Wagner; Ulrich Spicher; Wolfgang Puntigam; Klaus Strasser
A high accuracy of full-vehicle thermal models are required to predict the vehicle heat-up behaviour at every conceivable combination of driving cycle and ambient air temperature down to −20 °C. Within this work a methodology for modelling the thermal behaviour of an IC-engine is presented. The focus lies on the heat-path beginning with the combustion process followed by heat conduction through the combustion chamber walls and convective heat transfer between engine structure and coolant. The thermal engine model is coupled with other models (HVAC-system, powertrain, etc.) by an independent co-simulation platform in order to describe the virtual vehicle as a whole. Finally, the model validation is performed with two different driving cycles at two different start temperatures. Using the described full-vehicle model the potential of a heat storage system is discussed for several heat-up strategies.
MTZ worldwide | 2010
Volker Gross; Heiko Kubach; Ulrich Spicher; Robert Schiessl; Ulrich Maas
Laser-induced ignition has shown huge advantages for the combustion of lean air-fuel mixtures in SI engines. A research project founded by the FVV under “DI Laserzundung” and No. 928 was set up at the Institute for Reciprocating Engines (IFKM) and the Institute for Technical Thermodynamics (ITT) at the Karlsruhe Institute of Technology (KIT) to investigate the potential of the laser-induced ignition. The emphasis was on improving combustion initiation and heat release during a direct injection with a spray-guided combustion.
MTZ - Motortechnische Zeitschrift | 2010
Volker Gross; Heiko Kubach; Ulrich Spicher; Robert Schiessl; Ulrich Maas
Die laserinduzierte Zundung im Ottomotor hat in der Vergangenheit grose Vorteile bei der Entflammung magerer Luft-Kraftstoff-Gemische gezeigt. Im Rahmen des FVV-Vorhabens „DI-Laserzundung“, Nr. 928, wurden am Institut fur Kolbenmaschinen (IFKM) und am Institut fur Technische Thermodynamik (ITT) des Karlsruher Instituts fur Technologie (KIT) die Potenziale der Laserzundung untersucht. Die Optimierung von Entflammung und Brennverlauf bei der Direkteinspritzung mit strahlgefuhrtem Brennverfahren stand dabei im Vordergrund.
SAE International journal of engines | 2013
Stefan Palaveev; Max Magar; Heiko Kubach; Robert Schiessl; Ulrich Spicher; Ulrich Maas