Criteria

Text:
Display:

Results

Viewing 241 to 270 of 58649
2009-06-15
Journal Article
2009-01-1909
S. Liebsch, O. Dingel, J. Maass, M. Günther, M. Kratzsch, S. Zwahr
The startability of SI engines, especially of DISI engines, is the greatest challenge when using ethanol blended fuels. The development of a suitable injection strategy is therefore the main engineering target when developing an ethanol engine with direct injection. In order to limit the test efforts of such a program, a vaporization model has been created that provides the quantity of vaporized fuel depending on pressure and on start and end, respectively number and split relation of injections. This model takes account of the most relevant fuel properties such as density, surface tension and viscosity. It also considers the interaction of the spray with cylinder liner, cylinder head and piston. A comparison with test results shows the current status and the need for action of this simulation model.
2009-06-15
Technical Paper
2009-01-1911
Wanhua Su, Yingying Lu, Wenbin Yu, Changqing Wang, Yiqiang Pei, Yongliang Sun, Yunqiang Li, Zhongfu Yu, Jinfeng Wang
A concept of high density-low temperature combustion (HD-LTC) is put forward in this paper, showing potential of its high thermal efficiency and very low engine-out emissions by engine experimental and CFD modeling study. A single cylinder test engine has been built-up equipped with mechanisms of variable boost pressure and intake valve closing timing (IVCT). By delaying IVCT and raising boost pressure to certain values according to engine loads, the in-cylinder charge density is regulated much higher than in conventional engines. It is found that the high charge density can play the role of rising of heat capacity as exhaust gas recirculation (EGR) does. Thereby low temperature combustion is realized with less EGR (about 18~19% oxygen concentration) to achieve very low NOx and soot emissions, which is extremely important at high and full loads.
2009-06-15
Technical Paper
2009-01-1912
Akihiko Azetsu, Hiroaki Ito
The effects of CO2 and N2 mixing and the effect of O2 concentration on intermittent spray combustion were examined experimentally under the same condition of ambient temperature and pressure, and the same injection pressure. Through the systematic experiments, it was confirmed that the O2 concentration is the dominant factor affecting ignition delay and combustion duration. The flame temperature becomes lower with the decrease of O2 concentration mainly due to the dilution effect. The decrease of flame temperature due to the dilution effect and that due to the thermal/chemical effect of CO2 was quantified. Concerning the soot production, with the decrease of O2 concentration, it is suppressed during the early stage of combustion, however it becomes higher in the middle to later stage of combustion.
2009-06-15
Technical Paper
2009-01-1913
Michal Vojtisek-Lom, Martin Pechout, Josef Blažek, Lubomír Moc, Tomáš Hlavenka
This paper reports on particulate matter (PM) emissions measurement on a turbocharged direct injection tractor diesel engine with a mechanically controlled injection pump operated alternately on diesel fuel and fuel-grade rapeseed oil heated to 70-90°C. PM emissions were measured using standard gravimetric method, with supplemental online measurements with a semi-condensing integrating forward laser beam scattering detector and a measuring ionization chamber. All three measurements were in good agreement and show that the operation on heated rapeseed oil results, compared to operation on diesel fuel, in moderate decreases in PM emissions at moderate and higher speeds and loads, and substantial increases in PM at low speeds and loads. Low-speed, low-load operation on vegetable oil therefore needs to be addressed even if the engine appears to produce acceptable emissions during standard tests.
2009-06-15
Technical Paper
2009-01-1914
Michal Vojtisek-Lom, Josef Blažek, Martin Dufek, Michael Fenkl
This paper reports on the experimental investigation of the combustion of heated rapeseed oil in a typical tractor engine, which was operated alternately on heated rapeseed oil and diesel fuel without any adjustments of the injection pump. At intermediate to high engine rpm and loads, onset of combustion occurred earlier on rapeseed oil. This was correlated with increased emissions of nitrogen oxide and earlier onset of pressure rise in the injector, and independent of fuel temperature. At low rpm and loads, the onset of the combustion occurred later on rapeseed oil and was correlated with elevated emissions of hydrocarbons; this deterioration was exacerbated by prolonged low-load operation and by low fuel temperatures.
2009-06-15
Technical Paper
2009-01-1915
M. Costa, B. Iorio, U. Sorge, S. Alfuso
Results of an experimental campaign conducted on a multi-hole gasoline injector are used to assess a numerical model for the spray dynamics suitable to be employed for the prediction of a GDI engine pressure cycle. The considered injector generates a spray with a hollow-ellipsoid footprint structure on a plane perpendicular to the spray axis. Spray penetration lengths and cone angles are measured at different injection pressures and total injected masses in an optically accessible vessel containing nitrogen at controlled conditions of temperature and pressure. Injected mass flow rate is measured on a Bosch tube. The numerical simulation is performed within the AVL Fire™ code environment. As a first step, the gasoline is considered as entering a constant volume environment containing nitrogen, in order to reproduce the effected experiments. Measured injection flow rates and cone angles are used as input variables for the model.
2009-06-15
Journal Article
2009-01-1916
Claudia O. Iyer, Jianwen Yi
A systematic methodology has been employed to develop the Duratec 3.5L EcoBoost combustion system, with focus on the optimization of the combustion system including injector spray pattern, intake port design, piston geometry, cylinder head geometry. The development methodology was led by CFD (Computational Fluid Dynamics) modeling together with a testing program that uses optical, single-cylinder, and multi-cylinder engines. The current study shows the effect of several spray patterns on air-fuel mixing, in-cylinder flow development, surface wetting, and turbulence intensity. A few sets of injector spray patterns are studied; some that have a wide total cone angle, some that have a narrow cone angle and a couple of optimized injector spray patterns. The effect of the spray pattern at part load, full load and cold start operation was investigated and the methodology for choosing an optimized injector is presented.
2009-06-15
Journal Article
2009-01-1978
Shu Gequn, Li Min, Wei Haiqiao
The simulation of main bearing load plays an important role in engine multi-body dynamics simulation, seemingly influencing the simulation of strength, vibration and acoustics. It is necessary to conduct engine bench test to validate the result of simulation. More attention has been paid to the flexibility of engine blocks and crankshafts, but not on the installing conditions of engine test bench, such as the stiffness of mounts, the presence of the connecting flange and the elasticity of shaft coupling, which are easy to ignore. The work presented here focuses on the influence of bench installation conditions on the multi-body dynamics simulation of an engine. A flexible multi-body dynamics model of a 4100QB diesel engine is built by employing the modal synthesis technique in the software ADAMS. By comparing the simulation results of different models, the effects of the connecting flange, the stiffness of mounts and the elasticity of shaft coupling are discussed.
2009-06-15
Technical Paper
2009-01-1974
M.S. Boulahlib, S. Boukebbab, F. Gaci, O. Kholai
The effects of various loads and climatic conditions, as well as the engine’s characteristics on the thermal balance and a modification of the engine air-cooling system are presented. Thermal balance tests were conducted for engine thermal efficiency, heat loss through the exhaust gases, heat loss to the cooling air and unaccounted losses (i.e. heat lost by lubricating oil, radiation). While performance tests were in respect to the brake power, specific consumption was tested at different loads, and at ambient air temperature. The analysis of the statistics, and the experimental measurements, reveal interesting aspects of the engine heat transfers. A modification of the cooling system by adding fins at the engine inlet is carried out in order to reduce the thermal charge on the fourth cylinder.
2009-06-15
Technical Paper
2009-01-1972
Andrew M. Ickes, Dennis N. Assanis, Stanislav V. Bohac
Premixed diesel combustion is intended to supplant conventional combustion in the light to mid load range. This paper demonstrates the operating load limits, limiting criteria, and load-based emissions behavior of a direct-injection, diesel-fueled, premixed combustion mode across a range of test fuels. Testing was conducted on a modern single-cylinder engine fueled with a range of ultra-low sulfur fuels with cetane number ranging from 42 to 53. Operating limits were defined on the basis of emissions, noise, and combustion stability. The emissions behavior and operating limits of the tested premixed combustion mode are independent of fuel cetane number. Combustion stability, along with CO and HC emissions levels, dictate the light load limit. The high load limit is solely dictated by equivalence ratio: high PM, CO, and HC emissions result as overall equivalence ratio approaches stoichiometric.
2009-06-15
Journal Article
2009-01-1973
W. J. Marr, L. J. Hamilton, J. S. Cowart
Single cylinder diesel engine cycle resolved startup experiments were performed at two different Compression Ratios. At CR18 (CR = 18) conventional engine starting resulted in a broad range of acceptable startup equivalence ratios (φ). However, reducing the CR to 16 resulted in problematic engine starting regardless of fuel level. In an effect to produce robust engine starting at lower CRs the engine was motored first. This allowed for strong starting performance coupled with high load fueling levels. For both CRs, IMEPg and exhaust CO2% increased as fueling level increased. However, while in-cylinder CO2% exceeded exhaust CO2% for moderate φ, this trend was reversed as fueling was reduced. Exhaust CO% was minimal except for stoichiometric fueling at CR18. Peak NOx production occurred at CR18 and φ = 0.55. Exhaust UHCs were maximized for higher fueling cases but dropped quickly after start. Similarly, ignition delay increased with φ but decreased during warm-up.
2009-06-15
Technical Paper
2009-01-1969
A. A. Boretti, H. C. Watson
Direct Injection (DI) is believed to be one of the key strategies for maximizing the thermal efficiency of Spark Ignition (SI) engines and meeting the ever-tightening emissions regulations. This paper explores the use of propane and methane gas fuels in a 1.5 liter SI four cylinder gasoline engine with double over head camshafts, four valves per cylinder, and a centrally located DI injector. With DI technology, the injection timing can be set to avoid fuel bypassing the engine during valve overlap into the exhaust system prior to combustion. DI of fuel reduces the embedded air displacement effects of gaseous fuels and lowers the charge temperature. Injection timings and compression ratio are optimized for best performances at Wide Open Throttle (WOT) conditions when configured to achieve homogeneous charge at stoichiometry or run lean jet controlled stratified.
2009-06-15
Journal Article
2009-01-1971
T. Lucchini, G. D’Errico, D. Ettorre, G. Ferrari
A numerical investigation on a series of Diesel spray experiments in constant-volume vessels is proposed. Non reacting conditions were used to assess the spray models and to determine the grid size required to correctly predict the fuel-air mixture formation process. To this end, not only computed liquid and vapor penetrations were compared with experimental data, but also a detailed comparison between computed and experimental mixture fraction distributions was performed at different distances from the injector. Grid dependency was reduced by introducing an Adaptive Local Mesh Refinement technique (ALMR) with an arbitrary level of refinement. Once the capabilities of the current implemented spray models have been assessed, reacting conditions at different ambient densities and temperatures were considered. A Perfectly Stirred Reactor (PSR) combustion model, based on a direct integration of complex chemistry mechanisms over a homogenous cell, was adopted.
2009-06-15
Technical Paper
2009-01-1968
Merkourios Gogos, Dimitrios Savvidis, John Triandafyllis
The scope of this work was to study the impact of the ignition timing on the engine’s performance on an old technology vehicle fuelled by ethanol/petrol blends. Many previous studies have been published on the subject, but most of them were carried on SI engines using bench dynamometers. In this work, a 1.3 L Ford Escort equipped with a carburettor and without a catalytic converter was tested on a chassis dynamometer. Blends with ethanol concentrations of 10%, 20% and 50% per volume were used and the results were compared with the reference LRP fuel. All tests were performed at three different constant speeds of 30, 50 and 90 km/h, under full load with wide open throttle. Torque and rpm of the engine were recorded by the chassis dynamometer’s software. The fuel consumption was measured by means of the gravimetric method. All measurements were taken at three different settings of the advance angle, at 0°, 4° and 12° BTDC.
2009-06-15
Technical Paper
2009-01-1967
M. A. Kalam, H. H. Masjuki, T. M. I. Mahlia, M. A. Fuad, Ku Halim, A. Ishak, M. Khair, A. Yusoff, A. Shahrir
This paper presents experimental test results of a new compressed natural gas direct injection (CNG-DI) engine that has been developed from modification of a multi cylinder gasoline port injection (PI) engine. The major modifications done are (1) the injection system has been modified to gas direct injection using new high pressure gas injectors, (2) compression ratio has been changed from 10 to 14 through modification of piston and cylinder head, and (3) new spark plugs with long edge were used to ignite the CNG fuel. The CNG pressure at common rail was kept at 20 bar to be injected into engine cylinder. The engine has been operated with full throttle conditions to compare all the results with original base engine such as gasoline port injection engine and the CNG bi-fuel engine where the base engine has been converted to bi-fuel injection system to be operated with gasoline and CNG fuels.
2009-06-15
Technical Paper
2009-01-1965
F. Piscaglia, A. Montorfano, A. Onorati
A new fast and efficient parallel numerical solver for reacting and compressible flows through porous media has been developed in the OpenFOAM® (Open Field Operation and Manipulation) CFD Toolbox. With respect to the macroscopic model for porous media originally available in OpenFOAM®, a different mathematical approach has been followed: the new implemented solver makes use of the physical normal components resulting from the velocity expansion in the unit orthogonal vector basis to compute the Darcy pressure drop across the porous medium. Also, an additional sink term to account for the increased flow friction over the porous wall has been included into the momentum equation. In the new solver, the pressure correction equation is still able to achieve a faster convergency at very low permeability of the medium, also when it is associated with grid non-orthogonality.
2009-06-15
Journal Article
2009-01-1962
Julian T. Kashdan, Patricia Anselmi, Bruno Walter
The simultaneous reduction of engine-out nitrogen oxide (NOx) and particulate emissions via low-temperature combustion (LTC) strategies for compression-ignition engines is generally achieved via the use of high levels of exhaust gas recirculation (EGR). High EGR rates not only result in a drastic reduction of combustion temperatures to mitigate thermal NOx formation but also increases the level of pre-mixing thereby limiting particulate (soot) formation. However, highly pre-mixed combustion strategies such as LTC are usually limited at higher loads by excessively high heat release rates leading to unacceptable levels of combustion noise and particulate emissions. Further increasing the level of charge dilution (via EGR) can help to reduce combustion noise but maximum EGR rates are ultimately restricted by turbocharger and EGR path technologies.
2009-06-15
Journal Article
2009-01-1963
Julian T. Kashdan, Benoist Thirouard
Single cylinder optical engines are used for internal combustion (IC) engine research as they allow for the application of qualitative and quantitative non-intrusive, diagnostic techniques to study in-cylinder flow, mixing, combustion and emissions phenomena. Such experimental data is not only important for the validation of computational models but can also provide a detailed insight into the physical processes occurring in-cylinder which is useful for the further development of new combustion strategies such as gasoline homogeneous charge compression ignition (HCCI) and Diesel low temperature combustion (LTC). In this context, it is therefore important to ensure that the performance of optical engines is comparable to standard all-metal engines. A comparison of optical and all-metal engine combustion and emissions performance was performed within the present study.
2009-06-15
Technical Paper
2009-01-1960
J. CANDY, L. GUERBE
In reciprocating internal combustion engines, the gas that leaks at the piston, rings and liner system is usually called blow-by. The blow-by is a complex mixture of air, burned and unburned gases and oil mist. In order to avoid external pollution, the blow-by is recycled in the air intake system. This is called Closed Crankcase Ventilation (CCV). The CCV is the cause of major issues as air intake system fouling, oil consumption and contribution to the exhaust catalyst poisoning phenomena. During the recent decades a quite simple oil separation system based on baffles was acceptable. Emissions regulations are now tougher and a more efficient blow-by separation system is required. Knowledge of the engine parameters and of the blow-by characteristics, including droplets size distribution, oil mass flow and chemical composition is mandatory. Several separation principles are known, all have advantages and drawbacks.
2009-06-15
Technical Paper
2009-01-1961
S. Cong, G. P. McTaggart-Cowan, C. P. Garner
This paper proposes a method of determining residual gas fraction (RGF) by sampling the CO2 concentration in the exhaust manifold of a single cylinder HSDI diesel engine. During a skip-fire event, the CO2 concentration in the exhaust gas for the last firing cycle and the subsequent motoring cycle were measured using a fast-response emissions analyzer. The ratios of these two values are shown to be indicative of the RGF. To simulate the increase in exhaust pressure found with EGR or aftertreatment systems, the exhaust back pressure was elevated using an exhaust throttle. The intake pressure was held constant over a range of engine speed and load conditions. The results demonstrate that the RGF increases linearly with increasing exhaust back pressures for all engine operating conditions.
2009-06-15
Technical Paper
2009-01-1958
Wolfgang Hanke, Ralf Buschbeck, Steve Letourneau, Doug Sinclair, Athanassios Skiadas, Mitsuru Urabe, Masaaki Takiguchi
An ultra-lightweight piston and conrod without small end bush, combined with a ring pack designed for minimized friction is analyzed and demonstrated as an optimized power cylinder system in a high performance gasoline engine. Component and system analysis for optimizing the design, materials used and design features are reviewed, along with durability, NVH and friction testing results. Results are compared to other benchmark power cylinder system components for weight, performance and value.
2009-06-15
Technical Paper
2009-01-1959
Gareth Floweday
In three recent engine testing research projects involving comparisons of Low Temperature Fischer Tropsch (LTFT) synthetic diesel with conventional crude derived diesel, findings have included indications of significantly lower engine cylinder wear rates in engines running on Fischer Tropsch (FT) diesel. Close examination of the engine oil analysis from the second comparative study has strongly indicated that the differences in cylinder wear rate can be ascribed to the choice of fuel. None of the three studies were originally formulated for this aspect of comparison and only the second study is able to prove that this is in fact a fuel specific advantage attributed to FT diesel fuel. This paper reports on the details of the three projects in respect to this issue, presents analysis of the experimental data and preliminary investigations attempted in an effort to understand this phenomenon.
2009-06-15
Journal Article
2009-01-1956
A. S. Kuleshov
A multi-zone, direct-injection (DI) diesel combustion model, the so-called RK-model, has been developed and implemented in a full cycle simulation of a turbocharged engine. The combustion model takes into account: transient evolution of fuel sprays, interaction of sprays with swirl and walls, evolution of near-wall flow formed after spray-wall impingement depending on impingement angle and local swirl velocity, interaction of Near-Wall Flows (NWF) formed by adjacent sprays, influence of temperatures of gas and walls in the zones on evaporation rate. In the model the fuel spray is split into a number of specific zones with different evaporation conditions including zone on the cylinder liner and on the cylinder head. The piston bowl is assumed to be a body of revolution with arbitrary shape. The combustion model supports central and non-central injector as well as the side injection system. NOx formation model uses Detail Kinetic Mechanism (199 reactions with 33 species).
2009-06-15
Technical Paper
2009-01-1957
Nobuyuki Kawahara, Eiji Tomita, Takuya Kadowaki
In this study, fuel concentration measurements in a spark-ignition (SI) engine with ethanol blended gasoline were carried out using an optical sensor installed in the spark plug with laser infrared absorption technique. The spark plug sensor for in-situ fuel concentration measurement was applied to a port injected SI engine. The molar absorption coefficients of ethanol blended gasoline were determined for various pressures and temperatures in advance using a constant volume vessel with electric heating system. Ethanol blended gasoline with high volumetric ratios shows lower molar absorption coefficients due to lower molar absorption coefficients of ethanol. The molar absorption coefficients of ethanol blended gasoline can be estimated by considering the molar fraction of each component.
2009-06-15
Journal Article
2009-01-1954
B. Scott Brown, Steven N. Rogak, Sandeep Munshi
A new fuel injector prototype for heavy-duty engines has been developed to use direct-injection natural gas with small amounts of entrained diesel as an ignition promoter. This “co-injection” is quite different from other dual-fuel engine systems, where diesel and gas are introduced separately. Reliable compression-ignition can be attained, but two injections per engine cycle are needed to minimize engine knock. In the present paper the interactions between diesel injection mass, combustion timing, engine load, and engine speed are investigated experimentally in a heavy-duty single-cylinder engine. For the tests with this injector, ignition delay ranged from 1.2–4.0 ms (of which injector delay accounts for ~0.9 ms). Shorter ignition delays occurred at higher diesel injection masses and advanced combustion timing. At ignition delays shorter than 2.0 ms, knock intensity decreased with increasing ignition delay.
2009-06-15
Journal Article
2009-01-1955
B. Kerschgens, C. Felsch, A. Vanegas, N. Peters
Recently, a consistent mixing model for the two-way coupling of a CFD code and a zero-dimensional multi-zone code was developed. This work allowed for building an interactively coupled CFD-multi-zone approach that can be used to model HCCI combustion. In this study, the interactively coupled CFD-multi-zone approach is applied to PCCI combustion in a 1.9l FIAT GM Diesel engine. The physical domain in the CFD code is subdivided into multiple zones based on one phase variable (fuel mixture fraction). The fuel mixture fraction is the dominant quantity for the description of nonpremixed combustion. Each zone in the CFD code is represented by a corresponding zone in the zero-dimensional multi-zone code. The zero-dimensional multi-zone code solves the chemistry for each zone, and the heat release is fed back into the CFD code. The thermodynamic state of each zone, and thereby the phase variable, changes in time due to mixing and source terms (e.g., vaporization of fuel, wall heat transfer).
2009-06-15
Technical Paper
2009-01-1952
Keshav S. Varde, Nanda Kumar Manoharan
Gasoline-ethanol blends are being used or have been considered as a fuel for spark ignition engines. The motivation for using the blends varies in indifferent parts of the world and even in regions within a country. The increasing cost of gasoline, combined with regional tax incentives, is one of the reasons for increased interests in gasoline-ethanol blends in recent years in the U.S. Many vehicular engines are not designed to use a specific gasoline-ethanol blend. Rather, the engines have multi-blend capability, ranging from E0 to about E85. It is plausible that engine-out emissions will vary depending on the blend being used which may be further impacted by the level of EGR used with the blends. The present work was carried out to investigate engine out emissions when a vehicular spark-ignition engine was operated on E0 and E85 and different levels of EGR. A 4-cylinder, 2.5 liter, PFI engine was used in the experimental investigation.
2009-06-15
Technical Paper
2009-01-1953
Hwan Young Jae
A new continuously variable transmission has been developed. The new transmission could convert step transmissions to continuously variable transmissions with an electric motor and two planetary gear sets connected with a worm gear. The output speed of the transmission is determined by the speed of the electric motor instead of the input speed. On the other hand, the output torque comes from the input torque and does not depend on the torque of the electric motor. The output speed could be easily changed by controlling the speed of the electric motor of a small power. The overall structure of the transmission with a step transmission is simple and efficient since a torque converter is not needed for the transmission.
2009-06-15
Journal Article
2009-01-1950
Mehrzad Kaiadi, Per Tunestål, Bengt Johansson
Combination of right EGR rates with turbocharging has been identified as a promising way to increase the maximum load and efficiency of heavy duty spark-ignited natural gas engines. With stoichiometric conditions a three way catalyst can be used which means that regulated emissions can be kept at very low levels. However dilution limit is limited in these types of engines because of the lower burnings rate of natural gas with higher EGR rates. One way to extend the dilution limit of a natural gas engine is to run the engine with Hythane (natural gas+ some percentage hydrogen). Previously benefits of hydrogen addition to a Lean Burn natural-gas fueled engine was investigated [1] however a complete study for stoichiometric operation was not performed. This paper presents measurements made on a heavy duty 6-cylinder natural gas engine.
2009-06-15
Journal Article
2009-01-1951
Graeme Wallace, Jacques Blondy, Walter Mirabella, Ekkehard Schulte-Körne, Jorma Viljanen
Ethyl tertiary butyl ether (ETBE) has been used as a high octane blending component since the early 1990's. However the strong interest in renewable energy has led to a dramatic increase in its use. This has also resulted in a substantial number of technical studies being carried out around the world to assess its performance with respect to vehicle performance, distribution system compatibility, environmental impact and toxicology. The purpose of this paper is to provide a comprehensive, up to date review of these data. Particular focus will be given to its positive impact on CO2 emissions.
Viewing 241 to 270 of 58649

Filter

  • Range:
    to:
  • Year: