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Experimental Investigation of a RCCI Combustion Concept with In-Cylinder Blending of Gasoline and Diesel in a Light Duty Engine

FEV GmbH-Hans Rohs, Bastian Holderbaum
FEV Group Holding GmbH-Thomas Körfer
Published 2015-09-06 by SAE International in United States
Within this study a dual-fuel concept was experimentally investigated. The utilized fuels were conventional EN228 RON95E10 and EN590 Diesel B7 pump fuels. The engine was a single cylinder Diesel research engine for passenger car application. Except for the installation of the port fuel injection valve, the engine was not modified. The investigated engine load range covered low part load operation of IMEP = 4.3 bar up to IMEP = 14.8 bar at different engine speeds. Investigations with Diesel pilot injection showed that the dual-fuel approach can significantly reduce the soot/NOx-trade-off, but typically increases the HC- and CO-emissions. At high engine load and gasoline mass fraction, the premixed gasoline/air self-ignited before Diesel fuel was injected.Reactivity Controlled Compression Ignition (RCCI) was subsequently investigated in a medium load point at IMEP = 6.8 bar. Here, the impact of EGR, gasoline mass fraction and DI injection pressure and timing on emissions and combustion behavior were investigated. Despite elevated HC- and CO-emissions, it was possible to achieve a higher efficiency while simultaneously keeping the engine-out NOx-emissions below the EU-6.1 level.…
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An Experimental Investigation of Dual-Fuel Combustion in a Light Duty Diesel Engine by In-Cylinder Blending of Ethanol and Diesel

SAE International Journal of Engines

FEV GmbH-Hans Rohs, Bastian Holderbaum, Thomas Körfer
Institute for Combustion Engines, RWTH Aachen University-Benedikt Heuser, Florian Kremer, Stefan Pischinger
  • Journal Article
  • 2015-01-1801
Published 2015-09-01 by SAE International in United States
This study investigated dual-fuel operation with a light duty Diesel engine over a wide engine load range. Ethanol was hereby injected into the intake duct, while Diesel was injected directly into the cylinder. At low loads, high ethanol shares are critical in terms of combustion stability and emissions of unburnt hydrocarbons. As the load increases, the rates of heat release become problematic with regard to noise and mechanical stress. At higher loads, an advanced injection of Diesel was found to be beneficial in terms of combustion noise and emissions. For all tests, engine-out NOx emissions were kept within the EU-6.1 limit.
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The Oxidation Potential Number: An Index to Evaluate Inherent Soot Reduction in D.I. Diesel Spray Plumes

SAE International Journal of Engines

FEV GmbH-Hans Rohs
RWTH Aachen Univ.-Barbara Graziano, Benedikt Heuser, Florian Kremer, Stefan Pischinger
  • Journal Article
  • 2015-01-1934
Published 2015-09-01 by SAE International in United States
A new index to evaluate the inherent soot reduction in a diesel-like spray plume is proposed in this study. The index is named “Oxidation Potential Number” and was derived with the help of a computational fluid dynamics (CFD) software. C8 - C16 n-alkanes, 1-alcohols and di-n-ethers were studied with the help of this index over four part load engine operating conditions, representative of a C-class diesel vehicle. The CFD modelling results have shown that C8 molecules feature a higher potentiality to reduce the soot. Thus, C8 molecules were tested in a single cylinder diesel engine over the same operating conditions. In conclusion, the proposed index is compared with the soot engine out emission.
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On the Potential of Oxygenated Fuels as an Additional Degree of Freedom in the Mixture Formation in Direct Injection Diesel Engines

SAE International Journal of Fuels and Lubricants

FEV GmbH-Hans Rohs
PCFC RWTH Aachen University-Karl Alexander Heufer
  • Journal Article
  • 2015-01-0890
Published 2015-04-14 by SAE International in United States
The current and future restrictions on pollutant emissions from internal combustion engines require a holistic investigation of the abilities of alternative fuels to optimize the combustion process and ensure cleaner combustion. In this regard, the Tailor-made Fuels from Biomass (TMFB) Cluster at Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University aims at designing production processes for biofuels as well as fuels optimal for use in internal combustion engines. The TMFB Cluster's scientific approach considers the molecular structure of the fuels as an additional degree of freedom for the optimization of both the production pathways and the combustion process of such novel biofuels. Thus, the model-based specification of target parameters is of the utmost importance to improve engine combustion performance and to send feedback information to the biofuel production process. In particular, computational fluid dynamics is used to underscore the role of the thermo-physical properties on the soot emissions in internal combustion engines. Utilizing a preliminary established sensitivity analysis, it was possible to identify C8 straight chain oxygenated molecules as the optimal candidate for the inherent reduction of…
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Modelling a Gasoline Compression Ignition (GCI) Engine Concept

Concawe-Roger F. Cracknell, Javier Ariztegui, Thomas Dubois, Heather Hamje, Leonardo Pellegrini, David Rickeard, Kenneth D. Rose
FEV GmbH-Karl Alexander Heufer, Hans Rohs
Published 2014-04-01 by SAE International in United States
Future engines and vehicles will be required to reduce both regulated and CO2 emissions. To achieve this performance, they will be configured with advanced hardware and engine control technology that will enable their operation on a broader range of fuel properties than today.Previous work has shown that an advanced compression ignition bench engine can operate successfully on a European market gasoline over a range of speed/load conditions while achieving diesel-like engine efficiency and acceptable regulated emissions and noise levels. Stable Gasoline CI (GCI) combustion using a European market gasoline was achieved at high to medium engine loads but combustion at lower loads was very sensitive to EGR rates, leading to longer ignition delays and a steep cylinder pressure rise. In general, the simultaneous optimisation of engine-out emissions and combustion noise was a considerable challenge and the engine could not be operated successfully at lower load conditions without an unrealistic amount of boost pressure.To identify ways to improve the lower load performance of a GCI engine concept, Computational Fluid Dynamics and KIVA simulations have now been…
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Characterisation of Fuel Ignition under Partly Homogeneous Diesel Combustion

FEV GmbH-Vinod Karthik Rajamani, Hans Rohs
Published 2014-04-01 by SAE International in United States
Legislative restrictions on the currently limited exhaust gas components and the future CO2 emissions limits have led to intensive research in the field of alternative fuels and innovative combustion approaches. Increased homogeneity of air-fuel mixture through advanced injection is one combustion approach, which potentially reduces engine-out nitrogen oxide and particulate emissions, with good fuel consumption in certain load ranges. Ignition characteristics under homogenous combustion conditions differ from those under heterogeneous conditions. Among other reasons, this is due to the increased role of low temperature chemistry with increasing homogeneity.The ignition behaviour of diesel fuels is characterised by the Cetane number (CN), which is, however, determined at significant higher temperatures than those prevalent during ignition under homogenous combustion. As a result, its relevance as a fuel characteristic number requires evaluation. In this work, the relevance of CN and other candidates as a characteristic number has been analysed under partly homogeneous combustion conditions.The investigations have been performed on a single cylinder heavy duty diesel engine. Increased mixture homogeneity was achieved through multiple pilot injections in addition to a…
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Crude Tall Oil-Based Renewable Diesel as a Blending Component in Passenger Car Diesel Engines

SAE International Journal of Fuels and Lubricants

FEV GmbH-Hans Rohs, Andreas Kolbeck
Institute for Combustion Engines, RWTH Aachen University-Benedikt Heuser
  • Journal Article
  • 2013-01-2685
Published 2013-10-14 by SAE International in United States
The residue and waste streams of existing industry offer feasible and sustainable raw materials for biofuel production. All kind of biomass contains carbon and hydrogen which can be turned into liquid form with suitable processes. Using hydrotreatment or Biomass-to-Liquid technologies (BTL) the liquid oil can be further converted into transportation biofuels.Hydrotreatment technology can be used to convert bio-oils and fats in to high quality diesel fuels that have superior fuel properties (e.g. low aromatic content and high cetane number) compared to regular diesel fuel and first generation ester-type diesel fuel. UPM has developed a new innovative technology based on hydrotreatment that can be used to convert Crude Tall Oil (CTO) into high quality renewable diesel fuel.This study concentrated on determining the functionality and possible effects of CTO based renewable diesel as a blending component on engine emissions and engine performance. Tested fuels were Euro Stage IV diesel (CEC RF-06-03) as reference fuel and 30% CTO renewable diesel, blended with Euro Stage IV diesel.The results showed that CTO based renewable diesel blend properties were comparable to…
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Vehicle Demonstration of Naphtha Fuel Achieving Both High Efficiency and Drivability with EURO6 Engine-Out NOx Emission

SAE International Journal of Engines

FEV GmbH-Philipp Adomeit, Hans Rohs
Institute for Combustion Engines, RWTH Aachen University-Benedikt Heuser
  • Journal Article
  • 2013-01-0267
Published 2013-04-08 by SAE International in United States
Demand for transport energy is growing but this growth is skewed heavily toward commercial transport, such as, heavy road, aviation, marine and rail which uses heavier fuels like diesel and kerosene. This is likely to lead to an abundance and easy availability of lighter fractions like naphtha, which is the product of the initial distillation of crude oil. Naphtha will also require lower energy to produce and hence will have a lower CO₂ impact compared to diesel or gasoline. It would be desirable to develop engine combustion systems that could run on naphtha. Many recent studies have shown that running compression ignition engines on very low Cetane fuels, which are very similar to naphtha in their auto-ignition behavior, offers the prospect of developing very efficient, clean, simple and cheap engine combustion systems. Significant development work would be required before such systems could power practical vehicles. Naphtha has much lower Cetane compared to a conventional European diesel fuel.The aim of this study is to investigate if and how an existing modern diesel engine could be run…
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Potential Soot and CO Reduction for HSDI Diesel Combustion Systems

FEV Motorentechnik-Philipp Adomeit, Michael Becker, Hans Rohs
LTFD, RWTH Aachen-Andreas Greis, Gerd Grünefeld
Published 2006-04-03 by SAE International in United States
The current direction for Diesel combustion system development is towards homogenization, in order to reduce particulate and NOx emissions. However, a strong increase of carbon monoxide emissions (CO) is frequently noted in combination with enhanced homogenization.Therefore, the current investigation focuses on a detailed analysis of the particulate - CO trade-off using a laser-optical and multidimensional CFD investigation of the combustion process of a swirl HSDI system. The CFD methodology involves reduced kinetics for soot formation and oxidation and a three-step CO model. These models are validated by a detailed comparison to optical measurements of flow, spray penetration and the spatial distribution of soot, temperature and oxygen concentration.The results obtained show that high concentrations of CO occur as an intermediate combustion reaction product. Subsequently, CO and soot are oxidized in large areas of the combustion chamber. In part load operation, CO emissions are mainly caused by dilution effects in the early phases of combustion. However, the engine's soot emissions are caused by insufficient oxidization.Soot generation and oxidation are found to be strongly impacted by the slight…
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