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Meeting the EURO VI NOx Emission Legislation using a EURO IV Base Engine and a SCR/ASC/DOC/DPF Configuration in the World Harmonized Transient Cycle

Haldor Topsoe A/S-Andreas Vressner, Par Gabrielsson, Ioannis Gekas, Enric Senar-Serra
Published 2010-04-12 by SAE International in United States
To reach the very strict Euro VI regulations of PM and NOx for heavy-duty trucks, it will be necessary to apply integrated catalytic solutions for removal of both PM and NOx. The most cost-effective solution would be to base the Euro VI system on Euro IV/V base engines, without EGR, and apply a high efficiency aftertreatment system, able to reduce the NOx from the common 7-8 g/kWh down to the Euro VI level at 0.4 g/kWh. The described system consists of a catalytic configuration, where the SCR catalyst is placed directly downstream of the diesel engine followed by an ammonia slip catalyst (ASC) and diesel injection over an oxidation catalyst (DOC) and a catalyzed diesel particulate filter (cDPF). One of the advantages of this system configuration is that, in this way, the SCR catalyst is protected from high temperatures during filter regeneration, and that the SCR catalyst has the fastest heat-up required for good performance in the low-temperature biased test cycle used for testing the Euro VI compliance. Thus the SCR catalyst can be the…
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NOx Reduction Potential of V-SCR Catalyst in SCR/DOC/DPF Configuration Targeting Euro VI Limits from High Engine NOx Levels

Haldor Topsøe A/S, Denmark-Ioannis Gekas, Andreas Vressner, Keld Johansen
Published 2009-04-20 by SAE International in United States
To reach the EPA ‘10 and Euro VI strict regulations of PM and NOx for heavy duty trucks it will be necessary to apply integrated catalytic solutions for removal of both PM and NOx. The described system consists of an alternative catalytic configuration where the SCR catalyst is placed downstream of the diesel engine followed by diesel injection over an oxidation catalyst (DOC) and a catalysed diesel particulate filter (cDPF). One of the advantages of this system configuration is that the SCR catalyst in this way is protected from high temperatures during filter regeneration and that the SCR catalyst has the fastest heat up required for good performance in cold test cycles. The SCR catalyst can therefore be of a standard V-based type that is already proven technology for Euro IV and Euro V compliance in Europe. Another advantage is that the DOC and cDPF act as clean-up catalysts for any possible ammonia slip from the SCR catalyst. The system was tested on an engine test bed using a Euro II 12-l truck engine having…
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Validation of a Self Tuning Gross Heat Release Algorithm

Lund Technical University-Vittorio Manente, Andreas Vressner, Per Tunestal, Bengt Johansson
Published 2008-06-23 by SAE International in United States
The present paper shows the validation of a self tuning heat release method with no need to model heat losses, crevice losses and blow by. Using the pressure and volume traces the method estimates the polytropic exponents (before, during and after the combustion event), by the use of the emission values and amount of fuel injected per cycle the algorithm calculates the total heat release. These four inputs are subsequently used for computing the heat release trace. The result is a user independent algorithm which results in more objective comparisons among operating points and different engines.In the present paper the heat release calculated with this novel method has been compared with the one computed using the Woschni correlation for modeling the heat transfer. The comparison has been made using different fuels (PRF0, PRF80, ethanol and iso-octane) making sweeps in relative air-fuel ratio, engine speed, EGR and CA 50.
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Combustion Chamber Geometry Effects on the Performance of an Ethanol Fueled HCCI Engine

Lund University-Andreas Vressner, Rolf Egnell, Bengt Johansson
Published 2008-06-23 by SAE International in United States
Homogeneous Charge Compression Ignition (HCCI) combustion is limited in maximum load due to high peak pressures and excessive combustion rate. If the rate of combustion can be decreased the load range can be extended. From previous studies it has been shown that by using a deep square bowl in piston geometry the load range can be extended due to decreased heat release rates, pressure rise rates and longer combustion duration compared to a disc shaped combustion chamber. The explanation for the slower combustion was found in the turbulent flow field in the early stages of the intake stroke causing temperature stratifications throughout the charge. With larger temperature differences the combustion will be longer compared to a perfectly mixed charge with less temperature variations. The methods used for finding this explanation were high-speed cycle-resolved chemiluminescence imaging and fuel tracer planar laser induced fluorescence (PLIF), together with large eddy simulations (LES). In this paper the performance of the deep square bowl in piston, a disc shaped and a classical diesel bowl combustion chamber were compared in all-metal…
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Study on Combustion Chamber Geometry Effects in an HCCI Engine Using High-Speed Cycle-Resolved Chemiluminescence Imaging

Division of Combustion Engines, Lund University-Andreas Vressner, Anders Hultqvist, Bengt Johansson
Published 2007-04-16 by SAE International in United States
The aim of this study is to see how geometry generated turbulence affects the Rate of Heat Release (ROHR) in an HCCI engine. HCCI combustion is limited in load due to high peak pressures and too fast combustion. If the speed of combustion can be decreased the load range can be extended. Therefore two different combustion chamber geometries were investigated, one with a disc shape and one with a square bowl in piston. The later one provokes squish-generated gas flow into the bowl causing turbulence. The disc shaped combustion chamber was used as a reference case. Combustion duration and ROHR were studied using heat release analysis. A Scania D12 Diesel engine, converted to port injected HCCI with ethanol was used for the experiments. An engine speed of 1200 rpm was applied throughout the tests. The effect of air/fuel ratio and combustion phasing was also studied. The behavior of the heat release was correlated with high speed chemiluminescence imaging for both combustion chamber geometries. Optical access was enabled from beneath by a quartz piston and a…
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Visualization of Laser-Assisted HCCI Combustion With Natural Gas as Fuel

Graz University of Technology-Kurt Iskra, Theo Neger
Lund Univ.-Andreas Vressner, Anders Hultqvist, Bengt Johansson
  • Technical Paper
  • 2006-05-0267
Published 2006-10-22 by Society of Automotive Engineers of Japan in Japan
Lasers can be used as an alternative ignition source to spark ignition in engines where low cycle-to-cycle variations in the ignition point is in great demand. Previous studies have proved that laser ignition in SI engines can be used to decrease the cycle-to-cycle variations in the combustion normally caused by quenching in the spark plug electrode gap. Laser ignition is also known to reduce the ignition delay and the combustion duration. Another advantage is the possibility to place the ignition source in a more suitable location in the combustion chamber, for example, to suppress knock. Simultaneous ignition sources are a further measure to affect these parameters and implementation is just a matter of optical arrangement. Laser ignition can also be used to support HCCI combustion during operating conditions that are not favorable such as misfire or late combustion phasing. In this study laser ignition has been tested in an HCCI engine running with natural gas as fuel. A Scania D12 diesel engine was converted to single-cylinder HCCI operation by the use of port fuel injection…
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Cycle Resolved Wall Temperature Measurements Using Laser-Induced Phosphorescence in an HCCI Engine

Division of Combustion Engines, Lund Institute of Technology-Andreas Vressner, Bengt Johansson
Division of Combustion Physics, Lund Institute of Technology-Gustaf Särner, Mattias Richter, Marcus Aldén
Published 2005-10-24 by SAE International in United States
Cycle resolved wall temperature measurements have been performed in a one cylinder port injected optical Scania D12 truck engine run in HCCI mode. Point measurements at various locations were made using Laser-Induced Phosphorescence (LIP). Single point measurements with thermographic phosphors utilize the temperature dependancy of the phosphorescence decay time. The phosphorescence peak at 538 nm from the thermographic phosphor La2O2S:Eu was used to determine temperature. A frequency tripled 10 Hz pulsed Nd:YAG laser delivering ultra violet (UV) radiation at 355 nm was used for excitation of the phosphor. Detection in the spectral region 535 - 545 nm was performed every cycle with a photo multiplier tube connected to a 3 GHz oscilloscope. Measurements were made at four points on the cylinder head surface and two points on the outlet and inlet valves respectively. For each location measurements were made at different loads and at different crank angle degrees (CAD). The aim of the presented work was to study the feasibility of using LIP for single shot, cycle resolved wall temperature measurements.
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Combustion Chamber Wall Temperature Measurement and Modeling During Transient HCCI Operation

Lund Institute of Technology-Carl Wilhelmsson, Andreas Vressner, Per Tunestål, Bengt Johansson, Gustaf Särner, Marcus Aldén
Published 2005-10-24 by SAE International in United States
In this paper the combustion chamber wall temperature was measured by the use of thermographic phosphor. The temperature was monitored over a large time window covering a load transient.Wall temperature measurement provide helpful information in all engines. This temperature is for example needed when calculating heat losses to the walls. Most important is however the effect of the wall temperature on combustion. The walls can not heat up instantaneously and the slowly increasing wall temperature following a load transient will affect the combustion events sucseeding the transient. The HCCI combustion process is, due to its dependence on chemical kinetics more sensitive to wall temperature than Otto or Diesel engines. In depth knowledge about transient wall temperature could increase the understanding of transient HCCI control.A “black box” state space model was derived which is useful when predicting transient wall temperature. To produce a model the engine is run with the load described by a Pseudo Random Binary Sequence (PRBS). Standard system identification methodology was then applied to acquire a state space model which calculate the combustion…
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Quantification of the Formaldehyde Emissions from Different HCCI Engines Running on a Range of Fuels

Div. of Combustion Engines, Department of Heat and Power Engineering Lund Institute of Technology-Mikael Lemel, Anders Hultqvist, Andreas Vressner, Henrik Nordgren, Håkan Persson, Bengt Johansson
Published 2005-10-24 by SAE International in United States
In this paper, the formaldehyde emissions from three different types of homogenous charge compression ignition (HCCI) engines are quantified for a range of fuels by means of Fourier Transform Infra Red (FTIR) spectroscopic analysis. The engines types are differentiated in the way the charge is prepared. The characterized engines are; the conventional port fuel injected one, a type that traps residuals by means of a Negative Valve Overlap (NVO) and finally a Direct Injected (DI) one. Fuels ranging from pure n-heptane to iso-octane via diesel, gasoline, PRF80, methanol and ethanol were characterized.Generally, the amount of formaldehyde found in the exhaust was decreasing with decreasing air/fuel ratio, advanced timing and increasing cycle temperature. It was found that increasing the source of formaldehyde i.e. the ratio of heat released in the cool-flame, brought on higher exhaust contents of formaldehyde. The application of a standard three-way catalyst completely removed formaldehyde from the exhaust stream.
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Fuel Effects on Ion Current in an HCCI Engine

Division of Combustion Engines, Lund Institute of Technology-Andreas Vressner, Anders Hultqvist, Per Tunestål, Bengt Johansson
Toyota Motor Corp.-Ryo Hasegawa
Published 2005-05-11 by SAE International in United States
An interest in measuring ion current in Homogeneous Charge Compression Ignition (HCCI) engines arises when one wants to use a cheaper probe for feedback of the combustion timing than expensive piezo electric pressure transducers. However the location of the ion current probe, in this case a spark plug, is of importance for both signal strength and the crank angle position where the signal is obtained. Different fuels will probably affect the ion current in both signal strength and timing and this is the main interest of this investigation. The measurements were performed on a Scania D12 engine in single cylinder operation and ion current was measured at 7 locations simultaneously. By arranging this setup there was a possibility to investigate if the ion current signals from the different spark plug locations would correlate with the fact that, for this particular engine, the combustion starts at the walls and propagates towards the centre of the combustion chamber. The fuels investigated were isooctane, n-heptane, PRF80, gasoline, diesel, ethanol and methanol. A special interest was how the ion…
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