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Viewing 1 to 30 of 1708
2000-10-16
Technical Paper
2000-01-2831
Börje Grandin, Ingemar Denbratt, Joakim Bood, Christian Brackmann, Per-Erik Bengtsson
It is generally accepted that knocking combustion influences the heat transfer in SI engines. However, the effects of heat transfer on the onset of knock is still not clear due to lack of experimental data of the thermal boundary layer close to the combustion chamber wall. This paper presents measurements of the temperature in the thermal boundary layer under knocking and non-knocking conditions. The temperature was measured using dual-broadband rotational Coherent anti-Stokes Raman Spectroscopy (CARS). Simultaneous time-resolved measurements of the cylinder pressure, at three different locations, and the heat flux to the wall were carried out. Optical access to the region near the combustion chamber wall was achieved by using a horseshoe-shaped combustion chamber with windows installed in the rectangular part of the chamber. This arrangement made CARS temperature measurements close to the wall possible and results are presented in the range 0.1-5 mm from the wall.
2000-10-16
Technical Paper
2000-01-2830
L. Peron, A. Charlet, P. Higelin, B. Moreau, J. F. Burq
One way of improving electronic engine control is to get an insight into the combustion process, using a direct measurement method: this means the sensor must be put straight into the combustion chamber. The reference for analyzing combustion development is the cylinder pressure sensor. Due to the price of this sensor and the added complexity for cylinder head design and manufacturing, cylinder pressure sensors are not conceivable today for mass production. An alternative to the cylinder pressure sensor is the ionization sensor. It seems to be very promising for electronic engine control. Several publications have already demonstrated the benefits of ionization currents sensing for misfire detection, knock detection, closed loop ignition control, air-fuel ratio estimation. On the contrary, other publications have shown severe limitations of the ionization sensor. For example, fuel composition or additives can influence the ionization current.
2000-10-16
Technical Paper
2000-01-2829
Magnus Hellring, Ulf Holmberg
In this paper a novel ion current based estimation scheme for the in-cylinder pressure peak position (PPP) is proposed. A reliable estimate is constructed by appropriate signal processing based on local curvatures of the post flame phase of the ion current. The peak-finding algorithm is simple and easy to implement in an engine control unit for feedback control of the combustion phasing. Results on real data, sampled onboard a commercial car are presented. Further, the performance of the algorithm is compared to two state of the art algorithms for PPP estimation from the ion current. The comparison shows that the algorithm presented in this paper outperforms its competitors1.
2000-10-16
Technical Paper
2000-01-2828
Sadami Yoshiyama, Eiji Tomita, Yoshisuke Hamamoto
In order to investigate the relation between ion current and combustion characteristics, the ion current signal from a spark plug as an ion probe, pressure history and flame development were measured in a homogeneous propane-air mixture in closed combustion chambers. The flame propagation was measured by Schlieren photography technique. When negative bias is applied to the central electrode of the spark plug, the ion current flows only due to an early flame kernel existing near the spark plug. When positive bias is applied to the central electrode, the ion current flows from the central electrode to the combustion chamber wall and to the ground electrode. Consequently, the ion current is dominated by the contact area between the flame and the combustion chamber wall. The appearance period of ion-current is related to the combustion duration. This method was applied to the combustion analysis of the spark ignition engine.
2000-10-16
Technical Paper
2000-01-2835
Daniel Blomqvist, Stefan Byttner, Ulf Holmberg, Thorsteinn Rögnvaldsson
Abstract This paper compares several strategies for air-fuel ratio transient control. The strategies are: A factory standard look-up table based system (a SAAB Trionic 5), a feedback PI controller with and without feed-forward throttle correction, a linear feed-forward control algorithm, and two nonlinear feed-forward algorithms based on artificial neural networks. The control strategies have been implemented and evaluated in a SAAB 9000 car during a transient driving test, consisting of an acceleration in the second gear from an engine speed of 1500 rpm to 3000 rpm. The best strategies are found to be the neural network based ones, followed by the table based factory system. The two feedback PI controllers offer the poorest performance.
2000-10-16
Technical Paper
2000-01-2833
C. F. Kaminski, J. Hult, M. Richter, J. Nygren, A. Franke, M. Aldén, S. Lindenmaier, A. Dreizler, U. Maas, R. B. Williams
This paper reports on the development of novel time resolved spectroscopic imaging techniques for the study of spark ignition phenomena in combustion cells and an SI-engine. The techniques are based on planar laser induced fluorescence imaging (PLIF) of OH radicals, on fuel tracer PLIF, and on chemiluminescence. The techniques could be achieved at repetition rates reaching several hundreds of kilo-Hz and were cycle resolved. These techniques offer a new path along which engine related diagnostics can be undertaken, providing a wealth of information on turbulent spark ignition.
2000-10-16
Technical Paper
2000-01-2832
A. Cairns, C. G. W. Sheppard
A novel dual seeding method has been developed to obtain full bore cyclically resolved simultaneous flame images and associated velocity fields in an optically accessed single cylinder research spark ignition engine. The technique has been used to study interaction between the propagating flame and in-cylinder gas motion. Light generated by a fast repetition rate copper vapour laser was formed into a thin light sheet, which passed horizontally through the disc shaped combustion space of a spark ignition engine having complete overhead optical access. Mie scattered light from relatively sparse and large particles (∼65μm) at successive intervals allowed flow definition by particle tracking velocimetry. Simultaneous scattering from dense small seed (∼0.22μm) was used to generate flame front images, which were digitised and analysed to quantify turbulent flame structure and development. The flame was shown to have significant effect on local unburned gas motion as well as vice versa.
2000-10-16
Technical Paper
2000-01-2839
Johan Wallesten, Jerzy Chomiak
Lean gas engines have a potential for a significant reduction in both fuel consumption and emission levels. The use of a small pre-chamber with controlled stoichiometric or rich mixture composition is an effective way to deal with ignition problems in such engines. A constant volume vessel equipped with a device for generation of turbulence of known quantities is used to study the operation of a cylindrical pre-chamber of 1% of the main chamber volume. Pressure was measured in the main chamber and Schlieren images of the flame initiation and propagation in the main chamber were recorded for all set-ups. The investigation of the pre-chamber is focused on the position of the spark within the pre-chamber. Spark locations close to the orifice and close to the opposite wall as well as in the middle of the pre-chamber were tested and flame evolution and pressure history were studied.
2000-10-16
Technical Paper
2000-01-2837
Daniel E. Davison, Stephen J. Cornelius, Nick Collings, Keith Glover
This paper presents experimental data showing unexpected transient behaviour in several production universal exhaust gas oxygen (UEGO) sensors. The spike-like transients occur when passing through the stoichiometric point, and are particularly significant when passing from rich to lean. The paper illustrates how the spikes are affected by exhaust gas flow rate, deviation of air-to-fuel ratio (AFR) from stoichiometry, and rate of change of AFR while passing through stoichiometry. The spikes are most sensitive to the rate at which AFR passes through stoichiometry. Brief discussions on possible causes for the spikes, and on undesirable consequences for feedback control applications, are included.
2000-10-16
Technical Paper
2000-01-2838
P. J. Shayler, L. D. Winborn, A. Scarisbrick
The dilution of lubricating oil by fuel has adverse effects on engine wear, oil lubricity, air/fuel ratio control and feedgas emissions. Dilution is one of the factors limiting oil change intervals. The level and rate of accumulation depend on engine operating conditions and patterns of vehicle use. The work reported here develops and evaluates an empirical model to predict accumulation characteristics. This is aligned to requirements for predictions of dilution build-up in service. Predictions are shown to be in good agreement with data given in the literature. The model is used to investigate the influence of patterns of vehicle use on dilution.
2000-10-16
Technical Paper
2000-01-2836
Brigitte M. Castaing, Jim S. Cowart, Wai K. Cheng
A cycle by cycle analysis of engine behavior during the first few cycles of cranking and start-up was performed on a production four-cylinder engine. Experiments were performed to elucidate the effects of initial engine position (rest position after last engine shut-down), first and second cycle fueling, engine temperature, and spark timing on fuel delivery to the cylinder, engine-out Hydrocarbon (EOHC) emissions, and Gross Indicated Mean Effective Pressure (IMEPg). The most important effect of the piston starting position is on the first firing cycle engine rpm, which influences the IMEPg through combustion phasing. Because of the low rpm values for the first cycle, combustion is usually too advanced with typical production engine ignition timing. For both the hot start and the ambient start, the threshold for firing is at an in-cylinder air equivalence ratio (λ) of 1.1.
2000-10-16
Technical Paper
2000-01-2843
I. Y. Ohm, Y. S. Cho
The mechanism of axial stratification was investigated in a port injection SI engine. The port swirl and tumble number characterized the ports. The experiment consisted of a steady flow rig test for defining flow characteristics, engine test for finding lean misfire limit, fuel behavior tracing in a steady flow rig for the understanding basic stratification, fuel motion visualization in motored engine for the investigating real stratification process and flame capturing under known stratified conditions. The results show that not only swirl but also tumble affects axial stratification with the interaction of injection timing. It was also observed that stable initial flame improved engine stability by stratification, but the flame propagation pattern and direction was not affected by stratified condition, load, air-fuel ratio and fuel phase but by bulk in-cylinder flow pattern.
2000-10-16
Technical Paper
2000-01-2842
I. Y. Ohm, Y. S. Cho
The Fuel stratification process has been investigated in the cylinder of an axially stratified lean burn engine by visualizing fuel behavior. Planar laser light sheet from an Nd:YAG laser has been illuminated through the transparent quartz cylinder of a single cylinder optical engine. Mie scattered light has been captured through the quartz window in the piston head with an ICCD camera. Fuel has been replaced with an ethanol droplets to utilize an atomized fuel spray for visualization purposes. Swirl ratios have been varied by changing cylinder heads with different swirl numbers and injection time has been varied to find the effect of fuel stratification. A higher lean mixture limit was achieved when the fuel remained at the combustion chamber as stratified with the proper combination of fuel injection timing swirl flow.
2000-10-16
Technical Paper
2000-01-2841
Marios Ioannou, Christopher J. E. Nightingale
A technique has been developed to detect the deposition of liquid fuel on the cylinder bore of running IC engines. A key feature of the technique is its ability to avoid the lubricating oil affecting the signal indicating the presence of fuel. The technique has been demonstrated on a single-cylinder engine converted to take cylinder heads from recent production 2- and 4-valve, port-injected, vee-8 engines. Cylinder head design, engine cooling water temperature and injection timing have all been shown to influence the amount of fuel deposited.
2000-10-16
Technical Paper
2000-01-2809
Li Fan, Rolf D. Reitz
A new ignition and combustion model has been developed and tested for use in premixed spark-ignition engines. The ignition model is referred to as the Discrete Particle Ignition Kernel (DPIK) model, and it uses Lagrangian markers to track the flame-front growth. The model includes the effects of electrode heat transfer on the early flame kernel growth process, and it is used in conjunction with a characteristic-time-scale combustion model once the ignition kernel has grown to a size where the effects of turbulence on the flame must be considered. A new term which accounts for the effect of air-fuel ratio, was added to the combustion model for modeling combustion in very lean and very rich mixtures. The flame kernel size predicted by the DPIK model was compared with measurements of Maly and Vogel. Furthermore, predictions of the electrode heat transfer were compared with data of Kravchik and Heywood.
2000-10-16
Technical Paper
2000-01-2840
Fredrik Westin, Börje Grandin, Hans-Erik Ångström
In this investigation the influence on knock from the residual gas in the cylinder is investigated. Gas was sampled from inside the cylinder prior to ignition, the Residual Gas Fraction, RGF, was determined and the Knock Intensity, KI, was measured. By altering the exhaust backpressure the RGF was changed. By measuring the knock intensity for different RGF the influence on knock from residual gas was investigated. It is shown that with increased residual gas fraction the knock propensity of the engine is increased, and subsequently, decreased RGF gives lower knock intensity. This is showed by the fact that, with maintained knock intensity at 30 kPa, the ignition timing can be advanced as much as 5 Crank Angle Degrees, CAD, if the RGF is reduced with 15%.
2000-10-16
Technical Paper
2000-01-2810
Changyou Chen, Mark E. A. Bardsley, Richard J. R. Johns
In this paper, a new two-zone flamelet model is suggested. In the combustion model, each cell is divided by the flame front to two zones: unburned zone and burned zone. The unburned zone consists of air, fuel vapour and residual gases, whilst the burned zone contains combustion products. The unburned zone is further divided into two regions: segregate region and fully mixed region. The combustion is decoupled as two sequential events: mixing and burning. The turbulent mixing is governed by the large eddy structure, taking the effect of fuel drop spacing into consideration. The turbulent burning rate is further decomposed into three terms: laminar burning velocity for combustion chemistry, turbulence enhanced burning rate and flame strain factor for flame quenching. The turbulent burning rate is evaluated based on fractal geometry and basic dimensional analysis of turbulent flame.
2000-10-16
Technical Paper
2000-01-2807
C. Hasse, N. Peters
Abstract Quenching of premixed flames at cold walls is investigated to study the importance of the model fuel choice for combustion modeling. Detailed chemical mechanisms for two different fuels, namely the low-molecular-weight fuel methane, and the more complex fuel iso-octane are employed. For both fuels the response of the flame to the very rapid heat loss at the cold wall is studied. The most important and significant difference between methane and iso-octane for this problem is the postquench oxidation of unburned hydrocarbons. Methane shows fast oxidation of unburned fuel and intermediate hydrocarbons whereas postquench oxidation for iso-octane is slow especially for the intermediate hydrocarbons. Furthermore, the Soret effect which is usually considered to be of minor importance appears to be important in modeling the rate limiting diffusion process. This is caused by different directions of the thermal diffusive transport for certain species.
2000-10-16
Technical Paper
2000-01-2808
Ronny Lindgren, Ingemar Denbratt
A literature survey was carried out to examine the advances in knowledge regarding spray impingement on surfaces over the last five years. Published experiments indicate that spray impingement is controlled by various spray parameters, surface conditions, and liquid properties. One disadvantage of the published results is that the experiments have mainly been conducted with water droplets or diesel fuel, often at atmospheric conditions. A sensitivity analysis was performed for one common impingement model. The purpose was to investigate how the model described different phenomena when different parameters were changed, including wall temperature, wall roughness and injection velocity of the spray. The model tested showed sensitivity to surface roughness, whereas changes in wall temperature only resulted in increased evaporation from the surface. The increase of injection velocity resulted in a decrease of fuel on the wall by 70%.
2000-10-16
Technical Paper
2000-01-2815
Nigel Clark, James E. Boyce, Wenwei Xie, Mridul Gautam, Donald W. Lyons, Keith Vertin, Chuck A. LeTavec, Timothy C. Coburn
Emissions from heavy-duty vehicles may be reduced through the introduction of clean diesel formulations, and through the use of catalyzed particulate matter filters that can enjoy increased longevity and performance if ultra-low sulfur diesel is used. Twenty over-the-road tractors with Detroit Diesel Series 60 engines were selected for this study. Five trucks were operated on California (CA) specification diesel (CARB), five were operated on ARCO (now BP Amoco) EC diesel (ECD), five were operated on ARCO ECD with a Johnson-Matthey Continuously Regenerating Technology (CRT) filter and five were operated on ARCO ECD with an Engelhard Diesel Particulate Filter (DPX). The truck emissions were characterized using a transportable chassis dynamometer, full-scale dilution tunnel, research grade gas analyzers and filters for particulate matter (PM) mass collection. Two test schedules, the 5 mile route and the city-suburban (heavy vehicle) route (CSR), were employed.
2000-10-16
Technical Paper
2000-01-2813
Kari Eränen, Lars-Eric Lindfors, Anna Niemi, Pernilla Elfving, Lennart Cider
Selective catalytic reduction (SCR) of NOx has been tested using different hydrocarbons as reducing agents over an Ag/Al2O3 catalyst, both in laboratory reactors and a diesel engine test bench. The hydrocarbons tested were octane, iso-octane, octanol, octanal, octanoic acid, 1-octene, a mixture of propane-propene, dodecane, a mixture of dodecanal-dodecane and a low sulphur diesel fuel. For the C8-hydrocarbons the maximum conversions, about 80 %, occurred at a much lower temperature (down to 350 °C) and over a wider temperature range compared to the propane-propene mixture (maximum conversion at 525 °C). Also dodecane and diesel fuel gave more than 70 % conversion between 300 °C and 500 °C. In the diesel test bench a continuous NOx conversion up to 50 % was measured with a fuel penalty of 0.3-4.0 %.
2000-10-16
Technical Paper
2000-01-2817
Timothy V. Johnson
The key diesel emission control papers of the last 12 months have been summarized. In addition, the emerging US and European light-duty and heavy-duty tailpipe regulations are compared. Results are reported on light-duty diesel filtration regeneration systems and experiences, including effects of ash build-up and some recent modeling work. On the heavy-duty side, optimization of SCR catalysts and systems are described, as well as experiences with the first integrated SCR/filter systems, which are already achieving “Euro V” 2008 standards. An update on NOx adsorbers is also provided. The results with new NOx formulations are described, as well as the system performance in a light-duty diesel application.
2000-10-16
Technical Paper
2000-01-2814
John L. Calabrese, Joseph A. Patchett, Karl Grimston, Gary W. Rice, Gregory W. Davis
Urea based mobile Selective Catalytic Reduction (SCR) systems typically use a pulse width modulated injector to control the amount of reductant added to the exhaust stream. Additionally, an air assist system is provided to ensure uniform distribution of the reductant in the exhaust and to prevent injector clogging. We report on the adaptation of a commercially available pulse width modulated injector for use with a urea solution and an air assist. Flow rates and flow rate reproducibility were determined at combinations of pulse width, frequency and injector pressure drop selected to span the injector operating range. After correcting for density, deviations in flowrates were determined from the published injector calibration data when using n-heptane. These deviations were not uniform across the injector map. At the combination of low pulse width and high frequency, the deviation from the published n-heptane calibration data was the greatest.
2000-10-16
Technical Paper
2000-01-2821
Keith Vertin, Kevin Chandler, Chuck LeTavec, Stephen Goguen, Donald Keski-Hynnila, Sougato Chatterjee, Gerry Smith, Kevin Hallstrom
Previous studies have shown that regenerating particulate filters are very effective at reducing particulate matter emissions from diesel engines. Some particulate filters are passive devices that can be installed in place of the muffler on both new and older model diesel engines. These passive devices could potentially be used to retrofit large numbers of trucks and buses already in service, to substantially reduce particulate matter emissions. Catalyst-type particulate filters must be used with diesel fuels having low sulfur content to avoid poisoning the catalyst. A project has been launched to evaluate a truck fleet retrofitted with two types of passive particulate filter systems and operating on diesel fuel having ultra-low sulfur content. The objective of this project is to evaluate new particulate filter and fuel technology in service, using a fleet of twenty Class 8 grocery store trucks. This paper summarizes the truck fleet start-up experience.
2000-10-16
Technical Paper
2000-01-2822
Mike Frailey, Paul Norton, Nigel N. Clark, Donald W. Lyons
Significant numbers of transit buses now operate on natural gas. With support of the U.S. Department of Energy, the National Renewable Energy Laboratory has evaluated the cost, performance, and emissions of alternative fuel buses around the country. In this study, three natural gas and three closely matched diesel buses were compared. The buses, built by World Trans, were 26′5″long and used 1997 Cummins B-series engines. Particulate matter and oxides of nitrogen emissions from the natural gas buses were significantly lower than those from the diesel buses. However, the diesel buses had lower operating costs and higher fuel efficiency than the natural gas buses.
2000-10-16
Technical Paper
2000-01-2818
Ralph D. Nine, Nigel Clark, Paul Norton
Chassis based emissions characterization of heavy-duty vehicles has advanced over the last decade, but the understanding of the effect of test schedule on measured emissions is still poor. However, this is an important issue because the test schedule should closely mimic actual vehicle operation or vocation. A wide variety of test schedules was reviewed and these cycles were classified as cycles or routes and as geometric or realistic. With support from the U.S. Department of Energy Office of Transportation Technologies (DOE/OTT), a GMC box truck with a Caterpillar 3116 engine and a Peterbilt over the road tractor-trailer with a Caterpillar 3406 engine were exercised through a large number of cycles and routes. Test weight for the GMC was 9,980 kg and for the Peterbilt was 19,050 kg. Emissions characterization was performed using a heavy-duty chassis dynamometer, with a full-scale dilution tunnel, analyzers for gaseous emissions, and filters for PM emissions.
2000-10-16
Technical Paper
2000-01-2820
Murari Mohon Roy, Hideyuki Tsunemoto, Hiromi Ishitani, Jiro Akiyama, Toshitaka Minami, Masahiro Noguchi
This study investigated the influence of aldehyde and hydrocarbon components (HC components) on exhaust odor in DI diesel engines. Aldehyde is an important odorous group in exhaust, and it correlates well with exhaust odor at any engine condition. Formaldehyde (HCHO) in the exhaust has been identified as an important component causing irritating odor. Water-washing of exhaust gases does not trap HC components, while most of the odorous components are trapped with remarkable odor reductions. This indicates that the HC components in the exhaust have no direct effect on exhaust odor. However, the exhaust odor increases with increases in the concentration of the low boiling point HC components. This maybe due to the increase in intermediate odorous compounds like aldehydes, organic acids, or other oxygenated compounds in the combustion condition where the low boiling point HC components increase.
2000-10-16
Technical Paper
2000-01-2825
Christian Nellen, Konstantinos Boulouchos
Combustion engines for decentralized power generation or cogeneration in general, are subject to increasingly stringent pollutant emissions regulations. Motivated by the Europe-;wide lowest allowable NOx levels in Switzerland - particularly in the Zurich metropolitan area with 50 mg/Nm3 at 5% O2 - and in close cooperation with industry, the I.C. Engines and Combustion Laboratory (LVV) of the Swiss Federal Institute of Technology Zurich (ETHZ) has investigated some new operating concepts and engine processes in order to overcome the dilemma between low emissions and high efficiency, which is usually encountered in engine optimization. Our final approach thereby involves the Exhaust Gas Recirculation (EGR) combined with stoichiometric mixture (λ = 1) and a 3-way catalytic converter. The engine is supercharged and the intake mixture aftercooled for high power density and thermal efficiency.
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.
2000-10-16
Technical Paper
2000-01-2824
T. K. Jensen, J. Schramm, C. Søgaard, J. Ahrenfeldt
Experiments have been conducted on a gas fueled spark ignition engine using natural gas and two hydrogen containing fuels. The hydrogen containing fuels are Reformulated Natural Gas (RNG) and a mixture of 50% (Vol.) natural gas and 50% (Vol.) producer gas. The producer gas is a synthetic gas with the same composition as a gas produced by gasification of biomass. The hydrocarbon emission, measured as the percentage of hydrocarbons in the fuel, which passes unburned through the engine, was for the mixture of natural gas and producer gas up to 50% lower than the UHC emissions using natural gas as fuel. The UHC emission from the experiments using reformulated natural gas was 15% lower at lean conditions. Furthermore, both hydrogen-containing fuels have a leaner lean burn limit than natural gas. The combustion processes from the experiments have been analyzed using a three-zone heat release model, which is taking the effect of crevices into account.
Viewing 1 to 30 of 1708

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