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2017-09-16
Journal Article
2017-01-9183
Tine Christiansen, Johanne Jensen, Andreas Åberg, Jens Abildskov, Jakob Huusom
A methodology for the development of catalyst models is presented. Also, a methodology of the implementation of such models into a modular simulation tool, which simulates the units in succession, is presented. A case study is presented illustrating how suitable models can be found and used for simulations. Such simulations illustrate the behavior of the individual units and the overall system. It is shown how, by simulating the units in succession, the entire after treatment system can be tested and optimized, because the integration makes it possible to observe the effect of the modules on one another.
2016-04-05
Technical Paper
2016-01-0041
Florin Maticu, Paul Pop, Christian Axbrink, Mafijul Islam
Abstract The automotive electronic architectures have moved from federated architectures, where one function is implemented in one ECU (Electronic Control Unit), to distributed architectures, where several functions may share resources on an ECU. In addition, multicore ECUs are being adopted because of better performance, cost, size, fault-tolerance and power consumption. In this paper we present an approach for the automatic software functionality assignment to multicore distributed architectures. We consider that the systems use the AUTomotive Open System ARchitecture (AUTOSAR). The functionality is modeled as a set of software components composed of subtasks, called runnables, in AUTOSAR terminology.
2016-04-05
Technical Paper
2016-01-0860
Fredrik R. Westlye, Michele Battistoni, Scott A. Skeen, Julien Manin, Lyle M. Pickett, Anders Ivarsson
Abstract This work investigates the effects of cavitation on spray characteristics by comparing measurements of liquid and vapor penetration as well as ignition delay and lift-off length. A smoothed-inlet, converging nozzle (nominal KS1.5) was compared to a sharp-edged nozzle (nominal K0) in a constant-volume combustion vessel under thermodynamic conditions consistent with modern compression ignition engines. Within the near-nozzle region, the K0 nozzle displayed larger radial dispersion of the liquid as compared to the KS1.5 nozzle, and shorter axial liquid penetration. Moving downstream, the KS1.5 jet growth rate increased, eventually reaching a growth rate similar to the K0 nozzle while maintaining a smaller radial width. The increasing spreading angle in the far field creates a virtual origin, or mixing offset, several millimeters downstream for the KS1.5 nozzle.
2016-04-05
Journal Article
2016-01-0734
Scott A. Skeen, Julien Manin, Lyle M. Pickett, Emre Cenker, Gilles Bruneaux, Katsufumi Kondo, Tets Aizawa, Fredrik Westlye, Kristine Dalen, Anders Ivarsson, Tiemin Xuan, Jose M Garcia-Oliver, Yuanjiang Pei, Sibendu Som, Wang Hu, Rolf D. Reitz, Tommaso Lucchini, Gianluca D'Errico, Daniele Farrace, Sushant S. Pandurangi, Yuri M. Wright, Muhammad Aqib Chishty, Michele Bolla, Evatt Hawkes
The 4th Workshop of the Engine Combustion Network (ECN) was held September 5-6, 2015 in Kyoto, Japan. This manuscript presents a summary of the progress in experiments and modeling among ECN contributors leading to a better understanding of soot formation under the ECN “Spray A” configuration and some parametric variants. Relevant published and unpublished work from prior ECN workshops is reviewed. Experiments measuring soot particle size and morphology, soot volume fraction (fv), and transient soot mass have been conducted at various international institutions providing target data for improvements to computational models. Multiple modeling contributions using both the Reynolds Averaged Navier-Stokes (RANS) Equations approach and the Large-Eddy Simulation (LES) approach have been submitted. Among these, various chemical mechanisms, soot models, and turbulence-chemistry interaction (TCI) methodologies have been considered.
2015-09-06
Technical Paper
2015-24-2468
Kar Mun Pang, Hiew Mun Poon, Hoon Kiat Ng, Suyin Gan, Jesper Schramm
Abstract This work concerns the modelling of soot formation process in diesel spray combustion under engine-like conditions. The key aim is to investigate the soot formation characteristics at different ambient temperatures. Prior to simulating the diesel combustion, numerical models including a revised multi-step soot model is validated by comparing to the experimental data of n-dodecane fuel in which the associated chemistry is better understood. In the diesel spray simulations, a single component n-heptane mechanism and the multi-component Diesel Oil Surrogate (DOS) model are adopted. A newly developed C16-based model which comprises skeletal mechanisms of n-hexadecane, heptamethylnonane, cyclohexane and toluene is also implemented. Comparisons of the results show that the simulated liftoff lengths are reasonably well-matched to the experimental measurement, where the relative differences are retained to below 18%.
2014-10-13
Journal Article
2014-01-2576
Hiew Mun Poon, Hoon Kiat Ng, Suyin Gan, Kar Mun Pang, Jesper Schramm
This work is an extension to a previously reported work on chemical kinetic mechanism reduction scheme for large-scale mechanisms. Here, Perfectly Stirred Reactor (PSR) was added as a criterion of data source for mechanism reduction instead of using only auto-ignition condition. As a result, a reduced n-hexadecane mechanism with 79 species for diesel fuel surrogate was successfully derived from the detailed mechanism. Following that, the reduced n-hexadecane mechanism was validated under auto-ignition and PSR conditions using zero-dimensional (0-D) closed homogeneous batch reactor in CHEMKIN-PRO software. Agreement was achieved between the reduced and detailed mechanisms in ignition timing predictions and the reduced n-hexadecane mechanism was able to reproduce species concentration profiles with a maximum error of 40%. Accordingly, two-dimensional (2-D) Computational Fluid Dynamic (CFD) simulations were performed to study the spray combustion phenomena within a constant volume bomb.
2014-10-13
Journal Article
2014-01-2900
Muhammed Fasil, Daniel Plesner, Jens Honore Walther, Nenad Mijatovic, Joachim Holbøll, Bogi Bech Jensen
This paper investigates the heat dissipation in the hub motor of an electric two-wheeler using lumped parameter (LP), finite element (FE) and computational fluid dynamic (CFD) models. The motor uses external rotor permanent magnet brushless DC topology and nearly all of its losses are generated in the stator. The hub motor construction restricts the available conductive paths for heat dissipation from the stator to the ambient only through the shaft. In contrast to an internal rotor structure, where the stator winding losses are diffused via conduction, here convection plays a major role in loss dissipation. Therefore, a LP thermal model with improved convection modelling has been proposed to calculate the temperature of the components inside the hub motor. The developed model is validated with the FE thermal model and the test data. In addition, CFD tools has been used to accurately model the internal and the external flow as well as the convective heat transfer of the hub motor.
2014-04-01
Technical Paper
2014-01-1254
Kar Mun Pang, Mehdi Jangi, Xue-Song Bai, Jesper Schramm
Abstract In this reported work, 2-dimsensional computational fluid dynamics studies of n-heptane combustion and soot formation processes in the Sandia constant-volume vessel are carried out. The key interest here is to elucidate how the chemical kinetics affects the combustion and soot formation events. Numerical computation is performed using OpenFOAM and chemistry coordinate mapping (CCM) approach is used to expedite the calculation. Three n-heptane kinetic mechanisms with different chemistry sizes and comprehensiveness in oxidation pathways and soot precursor formation are adopted. The three examined chemical models use acetylene (C2H2), benzene ring (A1) and pyrene (A4) as soot precursor. They are henceforth addressed as nhepC2H2, nhepA1 and nhepA4, respectively for brevity. Here, a multistep soot model is coupled with the spray combustion solver to simulate the soot formation/oxidation processes.
2011-09-11
Technical Paper
2011-24-0181
Rasmus Cordtz, Anders Ivarsson, Jesper Schramm
This work presents the experimental investigation of Diesel Particulate Filter (DPF) regeneration and a calibration procedure of a 1D DPF simulation model based on the commercial software AVL BOOST v. 5.1. Model constants and parameters are fitted on the basis of a number of steady state DPF experiments where the DPF is exposed to real engine exhaust gas in a test bed. The DPF is a silicon carbide filter of the wall flow type without a catalytic coating. A key task concerning the DPF model calibration is to perform accurate DPF experiments because measured gas concentrations, temperatures and soot mass concentrations are used as model boundary conditions. An in-house-developed raw exhaust gas sampling technique is used to measure the soot concentration upstream the DPF which is also needed to find the DPF soot burn rate.
2011-08-30
Technical Paper
2011-01-2000
Jesper Ahrenfeldt, Ulrik Birk Henriksen, Torben Kvist
Experimental investigations have been conducted with two identical small scale SI gas engines gen-sets operating on biomass producer gas from thermal gasification of wood. The engines where operated with two different compression ratios, one with the original compression ratio for natural gas operation 9.5:1, and the second with a compression ratio of 18.5:1. It was shown that high compression ratio SI engine operation was possible when operating on biomass producer gas from a TwoStage gasifier. The results showed an increase in the electrical efficiency from 31% to 35% when the compression ratio was increased. The influence of ignition timing on emissions was investigated during high compression ratio operation. It was shown that for λ=1.4 the NOx emission decreases by almost a factor 3, when the timing is retarded from 13° to 7° before top dead center.
2008-06-23
Technical Paper
2008-01-1535
Kim R. Hansen, Claus S. Nielsen, Spencer C. Sorenson, Jesper Schramm
The low auto-ignition temperature, rapid evaporation and high cetane number of dimethyl ether (DME) enables the use of low-pressure direct injection in compression ignition engines, thus potentially bringing the cost of the injection system down. This in turn holds the promise of bringing CI efficiency to even the smallest engines. A 50cc crankcase scavenged two-stroke CI engine was built based on moped parts. The major alterations were a new cylinder head and a 100 bar DI system using a GDI-type injector. Power is limited by carbon monoxide emission but smoke-free operation and NOx < 200ppm is achieved at all points of operation.
2008-04-14
Journal Article
2008-01-0731
Hideaki Nagano, Shinsuke Kato, Shengwei Zhu, Yoshiichi Ozeki, Kazuhiko Matsunaga, Takuya Kataoka
In order to evaluate the ventilation characteristics of car interior, a model experiment was performed. Part 1 deals with the air flow properties in a half-scale car model. In this paper, a trace gas experimental method equipped with Flame Ionization Detector (FID) systems is introduced to examine the local ventilation efficiency and inhaled air quality in the car, which was ventilated at a flow rate of 100 m3/h and kept in an isothermal environment of 28°C in the experiment. Here, ventilation efficiency was evaluated by means of the Scales for Ventilation Efficiencies (SVEs), and inhaled air quality in terms of the influences of passive smoke and foot odor was evaluated by means of the Contribution Ratio of Pollution source 1 (CRP1). Therefore, calculation methods using trace gas concentration values were suggested for these indices, which were proposed based on the Computational Fluid Dynamics (CFD) technique.
2007-10-29
Technical Paper
2007-01-4008
Ulrik Larsen, Peter Lundorf, Anders Ivarsson, Jesper Schramm
The described investigation was carried out under the umbrella of IEA Advanced Motor Fuels Agreement. The purpose was to evaluate the emissions of carbon monoxide (CO), unburned hydrocarbons (HC), nitrogen oxides (NOx), particulate matter (PM) and polycyclic aromatic hydrocarbons (PAH) from vehicles fuelled by Fischer Tropsch (FT) based diesel and gasoline fuel, compared to the emissions from ordinary diesel and gasoline. The comparison for diesel fuels was based on a literature review, whereas the gasoline comparison had to be based on our own experiments, since almost no references were found in this field. In this context measurement according to the Federal Test Procedure (FTP) and the New European Driving Cycle (NEDC) were carried out on a chassis dynamometer with a directly injected gasoline vehicle. Experiments were carried out with a reference fuel, a fuel based 70% on FT and an alkylate fuel (Aspen), which was taken to be the ultimate formula of FT gasoline.
2007-07-23
Technical Paper
2007-01-1921
Keld Johansen, Søren Dahl, Gurli Mogensen, Søren Pehrson, Jesper Schramm, Anders Ivarsson
A novel base metal-palladium catalytic coating was applied on commercial silicon carbide wall flow diesel filters and tested in an engine test bench. This catalytic coating limits the NO2 formation and even removes NO2 within a wide temperature range. Soot combustion, HC conversion and CO conversion properties are comparable to current platinum-based coatings, but at a lower cost. This paper compares the results from engine bench tests of present commercial solutions as regards NO2-, HC-, CO-removal and soot combustion with the novel coating. Furthermore, emission test results from base metal-palladium coated diesel particulate filters installed on operating taxis and related test cycle data are presented. A significant reduction in NO2 emission compared to present technology is measured.
2007-07-23
Technical Paper
2007-01-1860
Troels Dyhr Pedersen, Jesper Schramm
An experimental study has been carried out on the homogeneous charge compression ignition (HCCI) combustion of Dimethyl Ether (DME). The study was performed as a parameter variation of engine speed and compression ratio on excess air ratios of approximately 2.5, 3 and 4. The compression ratio was adjusted in steps to find suitable regions of operation, and the effect of engine speed was studied at 1000, 2000 and 3000 RPM. It was found that leaner excess air ratios require higher compression ratios to achieve satisfactory combustion. Engine speed also affects operation significantly.
2001-05-07
Technical Paper
2001-01-2013
Ion M. Sivebaek, Spencer C. Sorenson, Joergen Jakobsen
This paper describes the development and test of a viscometer capable of handling dimethyl Ether (DME) and other volatile fuels. DME has excellent combustion characteristics in diesel engines but the injection equipment can break down prematurely due to extensive wear when handling this fuel. It was established, in earlier work, that the wear in the pumps is substantial even if the lubricity of DME is raised to a believed acceptable level using anti-wear additives. An influence of the viscosity on the wear in the pumps was suspected. The problem, up to now, was that the viscosity of DME has only been estimated or calculated but never actually measured. In the present work a volatile fuel viscometer (VFVM) was developed. It is of the capillary type and it was designed to handle DME, neat or additised. The kinematic and dynamic viscosities of pure DME were measured at 0.185 cSt and 0.122 cP at 25 °C respectively.
2000-10-16
Technical Paper
2000-01-2823
C. Søgaard, J. Schramm, T. K. Jensen
Application of a known hydrogen containing fuel called reformed natural gas (RNG) has been realized in a stationary combustion engine with success. The aim for this is to reduce unburned hydrogen emissions (UHC) from the engine together with an increase in efficiency. The fuel contains mainly methane, hydrogen and minor amounts of carbon dioxide. A small-scale unit for onboard production of RNG has been built in order to avoid the dependence of artificial supplementation of hydrogen. The production is carried out through means of steam reforming of natural gas. The RNG-unit together with theoretical considerations for estimating fuel composition and issues of caution are described. Theoretical studies show a potential for varying the hydrogen content between 8 and 30 vol%. Studies also show potential for remarkable increases in the methane number relative to that of the natural gas. A test engine has been fueled with RNG.
2000-03-06
Technical Paper
2000-01-0260
Alain Chevalier, Christian Winge Vigild, Elbert Hendricks
With the tightening of exhaust emission standards, wide bandwidth control of the air/fuel ratio (AFR) of spark ignition engines has attracted increased interest recently. Unfortunately, time delays associated with engine operation (mainly injection delays and transport delays from intake to exhaust) impose serious limitations to the achievable control bandwidth. With a proper choice of sensors and actuators, these limitations can be minimized provided the port air mass flow can be accurately predicted ahead in time. While the main objective of this work is to propose a complete AFR controller, the main focus is on the problems associated with port air mass flow prediction.
2000-03-06
Technical Paper
2000-01-1261
Alain Chevalier, Martin Müller, Elbert Hendricks
Because there are no production-type sensors which are able to measure the flow directly at the intake port, it is becoming common practice to use models of varying complexity to infer the port air mass flow from other measurements. Given the tight requirements of modern air/fuel ratio (AFR) control strategies, the accuracy of these models needs to be better than ever, during steady-state of course (though λ feedback strategies are by design very robust), but mainly during transient operation. This paper describes why conventional models might be inaccurate during engine transients.
2000-03-06
Technical Paper
2000-01-0268
Christian Winge Vigild, Alain M. R. Chevalier, Elbert Hendricks
Many modern control strategies for engine control are based on event based sampling. Operating the control strategy in the event domain makes it possible to obtain samples at specific crank shaft angles in the engine cycle, which is often desirable for certain control strategies. One of the biggest disadvantages involved with event based strategies is signal aliasing at low engine speeds or a high computational burden at higher engine speeds. This paper presents an easy solution to the aliasing problem above. If the data between the event based samples is stored using a time based strategy, it is shown here that a subsequent treatment of the sampled data as a time series together with a suitable low pass filter structure can avoid aliasing.
1999-03-01
Technical Paper
1999-01-0854
Christian Winge Vigild, Karsten P.H. Andersen, Elbert Hendricks, Michael Struwe
Long term stoichiometric Air/Fuel Ratio (AFR) control of an SI engine is at the present mainly maintained by table mapping of the engine's fresh air intake as a function of the engine operating point. In order to reduce a stationary error in the AFR to zero the table based control normally works in conjunction with a PI feedback from a HEGO sensor. The effective bandwidth of this feedback loop is quite small and seldom exceeds 2 Hz. This is altogether too small for accurate transient AFR control. This paper presents a new λ (normalized Air/Fuel Ratio) control methodology (H∞ control) which has a somewhat larger bandwidth and can guarantee robustness with respect to selected engine variable and parameter variations.
1999-03-01
Technical Paper
1999-01-0909
Michael Fons, Martin Muller, Alain Chevalier, Christian Vigild, Elbert Hendricks, Spencer C. Sorenson
Mean Value Engine Models (MVEMs) are simplified, dynamic engine models which are physically based. Such models are useful for control studies, for engine control system analysis and for model based engine control systems. Very few published MVEMs have included the effects of Exhaust Gas Recirculation (EGR). The purpose of this paper is to present a modified MVEM which includes EGR in a physical way. It has been tested using newly developed, very fast manifold pressure, manifold temperature, port and EGR mass flow sensors. Reasonable agreement has been obtained on an experiemental engine, mounted on a dynamometer.
1998-02-23
Technical Paper
981065
Per B. Jensen, Mads B. Olsen, Jannik Poulsen, Christian Vigild, Elbert Hendricks
Long term control of the AFR (Air/Fuel Ratio) of spark ignition engines is currently accomplished with a selvoscillating PI control loop. Because of the intake/exhaust time delay, the oscillation frequency and hence bandwidth of this loop is small. This paper describes a new approach to the design of this control loop using a novel observer system. In this way the bandwidth of this important loop is increased by a factor of 2 - 6 times, leading to more accurate overall AFR control. Moreover the observer approach is so robust and allows such feedback levels that it reduces significantly the accuracy required in the calibration of the base fuel control system with which it is be used. It can be used with either conventional- or advanced observer based- base fuel strategies.
1998-02-23
Technical Paper
980784
Martin Müller, Elbert Hendricks, Spencer C. Sorenson
An important paradigm for the modelling of naturally aspirated (NA) spark ignition (SI) engines for control purposes is the Mean Value Engine Model (MVEM). Such models have a time resolution which is just sufficient to capture the main details of the dynamic performance of NA SI engines but not the cycle-by-cycle behavior. In principle such models are also physically based, are very compact in a mathematical sense but nevertheless can have reasonable prediction accuracy. Presently no MVEMs have been constructed for intercooled turbocharged SI engines because their complexity confounds the simple physical understanding and description of such engines. This paper presents a newly constructed MVEM for a turbocharged SI engine which contains the details of the compressor and turbine characteristics in a compact way. The model has been tested against the responses of an experimental engine and has reasonable accuracy for realistic operating scenarios.
1997-10-01
Technical Paper
972960
Kent Frølund, Jesper Schramm
Engine experiments were carried out on a six cylinder DI-diesel engine using synthetic fuel and lubricant containing no PAH (Polycyclic Aromatic Hydrocarbons) [1]. By selectively doping the fuel and oil with pyrene, the effect of fuel and oil originating PAH on the exhaust emissions could be investigated. The experimental results are analyzed in a new way by suggesting a general transport model for PAH. By estimating as many transport quantities as possible it is attempted to gain knowledge about the most dominant mechanisms. The main finding is not surprisingly that for commercial fuels containing substantial concentrations of PAH, the by far major contributor to exhaust PAH is unburned fuel PAH. The concentration of PAH in the oil sump affects only weakly the PAH concentration in the exhaust for engines operating on commercial fuels. The PAH desorbing from the liner are getting burned efficiently, thereby being insignificant.
1997-05-01
Technical Paper
971665
Rasmus Christensen, S. C. Sorenson, Michael G. Jensen, Ken Friis Hansen
A naturally aspirated, direct injection diesel engine was modified in order to be run on dimethyl ether (DME), with a conventional pump-line-nozzle system. The effects of various modifications to engine timing and the injection system as well as EGR were experimentally determined. Compared to the original diesel engine, the NOx emissions were reduced by over 70% through the use of suitable timing, lowered injector opening pressure and EGR. Particulate emissions were very low, and represent over a 90% reduction as compared to the original diesel version. The original pump-line-nozzle injection system was found to be not well suited to DME operation, CO and HC emissions were substantially higher due to secondary injections, caused by high pressure oscillations and residual pressure with the DME.
1997-02-24
Technical Paper
970471
Morten W. Jørgensen, S. C. Sorenson
The paper presents a 2-dimensional model for the calculation of the regeneration process in a wall flow diesel particulate filter. The model includes heat transfer by conduction and convection, a model for particle combustion based on diffusive burning of individual particles, and flow through the channels and across the filter walls. It was found that only the pressure drop across the walls need be considered for normal regeneration conditions. Comparisons between model predictions and experimental results for spatial dependent temperature time histories, and integrated degree of regeneration are used to validate the model. The validations were carried out for a series of severe regenerations, where there are large changes in flow and temperature throughout the process. Relative magnitudes of energy flows due to combustion, convection, and conduction are presented, as well as parametric studies of the effects of temperature, oxygen concentration and soot loading.
1997-02-24
Technical Paper
970615
Per B. Jensen, Mads B. Olsen, Jannik Poulsen, Elbert Hendricks, Michael Fons, Christian Jepsen
In general most engine models for control applications have been constructed using regressions fitting and measured engine data. Such techniques have also been used to model the dynamic performance of engines. Unfortunately regression equation models are very complex and do not show directly the physical reality from which they emerge. This has for example made it impossible to write down explicitly the dymanic equations for, for example, the air exchange process in an SI engine in any form other than as the manifold pressure state equation. In recent a publication a Mean Value Engine Model (MVEM) has been constructed for an SI engine which is physically based and which has a simple physical form which can be immediately understood and manipulated.
1997-02-24
Technical Paper
970181
Nikolai Ladegaard, Spencer C. Sorenson, Jesper Schramm, Linda Gratz, Per Stobbe
Studies were performed with three commonly used additive metals, cerium copper, and iron, with a conventional and a low sulfur fuel in order to investigate fuel additive effects on engine particulate emissions before a particulate filter. Measurements were made on a 4 cylinder direct injection diesel engine and included total particulate mass, soluble organic fraction for both fuels, and polynuclear aromatic hydrocarbon emissions for the low sulfur fuel. The cerium based additive reduced the emissions with both fuels, with the largest effect being on the non-SOF fraction. With the other additives and the high sulfur fuel, non-SOF emissions were increased, increasing total particulate emissions. Copper was found to reduce the polynuclear aromatic hydrocarbons, and cerium was found to have the least effect. The use of an SiC wall flow filter reduced particulate and polynuclear aromatic emissions by over 90%.
1996-10-01
Technical Paper
961977
Rasmus Christensen, Michael Bo Hansen, Jesper Schramm, Mona-Lise Binderup, Vivian Jorgensen
The main purpose of this study was to investigate the influence of diesel engine conditions on the mutagenic activity of the exhaust. Special emphasis was put on investigation of the influence of nitrogen oxides content. Experiments with a diesel engine have been carried out in the laboratory and the emissions of carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NOx) and particulate matter (PM) have been measured at different engine conditions. The particulate matter was extracted in order to obtain the soluble organic fraction (SOF), and this fraction was analyzed for mutagenic activity in the Salmonella/microsome assay (AMES test). It was found that the mutagenic activity evidently depended on the PAH content (PAH = Polycyclic Aromatic Hydrocarbons) of the exhaust gas rather than the NOx content. However, the percentage of the direct mutagenic activity of the total mutagenic activity increased as the NOx content in the exhaust gas increased.
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