Refine Your Search

Topic

Author

Search Results

Journal Article

Automated Model Fit Method for Diesel Engine Control Development

2014-04-01
2014-01-1153
This paper presents an automated fit for a control-oriented physics-based diesel engine combustion model. This method is based on the combination of a dedicated measurement procedure and structured approach to fit the required combustion model parameters. Only a data set is required that is considered to be standard for engine testing. The potential of the automated fit tool is demonstrated for two different heavy-duty diesel engines. This demonstrates that the combustion model and model fit methodology is not engine specific. Comparison of model and experimental results shows accurate prediction of in-cylinder peak pressure, IMEP, CA10, and CA50 over a wide operating range. This makes the model suitable for closed-loop combustion control development. However, NO emission prediction has to be improved.
Technical Paper

Experimental Validation of Vanes with Reduced Vaneless Space to Improve Transient Behavior of Variable Geometry Turbines

2013-09-08
2013-24-0121
To increase the efficiency of a Variable Geometry Turbine at low massflow rates the vaneless space of the vanes is reduced. It is researched if this modification can reduce turbo lag. A turbine with modified vane ring is installed in the exhaust of a naturally aspirated engine and wide open throttle accelerations are performed to test the turbine performance. The new (reduced vaneless space) vane configuration induced a lower exhaust backpressure which allowed the engine to accelerate faster. The acceleration from 1500 to 3000 RPM was an average of 8 % faster for the new vane configuration. This in turn increased the massflow rate through the turbine which caused the power available to the turbine to be similar in compared vane rings. The initial turbine speeds was lower for the new vane configuration but it quickly caught up with the conventional configuration because the turbine acceleration was higher. The turbine efficiency was higher for the new vane configuration in most cases.
Technical Paper

A First Implementation of an Efficient Combustion Strategy in a Multi Cylinder Two-Stage Turbo CI-Engine Producing Low Emissions While Consuming a Gasoline/EHN Blend

2013-09-08
2013-24-0103
A Gasoline Compression Ignition combustion strategy was developed and showed its capabilities in the heavy duty single cylinder test-cell, resulting in indicated efficiencies up to 50% and low engine out emissions applying to EU VI and US 10 legislations while the soot remained at a controllable 1.5 FSN. For this concept a single-cylinder CI-engine was used running at a lambda of ∼1.6 and EGR levels of ∼50% and a modified injection strategy. Part of this strategy was also the use of a gasoline blended with an ignition improver, giving the blend a cetane number in the range of regular diesel; ∼50. In this paper a step is taken towards implementation of this combustion concept into a multi-cylinder light duty standalone CI-engine. A standard CI-engine was modified so that its gas-exchange system could deliver the requested amounts of EGR and lambda.
Technical Paper

Styrofoam Precursors as Drop-in Diesel Fuel

2013-09-08
2013-24-0108
Styrene, or ethylbenzene, is mainly used as a monomer for the production of polymers, most notably Styrofoam. In the synthetis of styrene, the feedstock of benzene and ethylene is converted into aromatic oxygenates such as benzaldehyde, 2-phenyl ethanol and acetophenone. Benzaldehyde and phenyl ethanol are low value side streams, while acetophenone is a high value intermediate product. The side streams are now principally rejected from the process and burnt for process heat. Previous in-house research has shown that such aromatic oxygenates are suitable as diesel fuel additives and can in some cases improve the soot-NOx trade-off. In this study acetophenone, benzaldehyde and 2-phenyl ethanol are each added to commercial EN590 diesel at a ratio of 1:9, with the goal to ascertain whether or not the lower value benzaldehyde and 2-phenyl ethanol can perform on par with the higher value acetophenone. These compounds are now used in pure form.
Technical Paper

Literature Study and Feasibility Test Regarding a Gasoline/EHN Blend Consumed by Standard CI-Engine Using a Non-PCCI Combustion Strategy

2013-09-08
2013-24-0099
A literature and experimental study was done to create an overview of the behavior of gasoline combusted in a CI-engine. This paper creates a first overview of the work to be done before implementing this Gasoline Compression Ignition concept in a multi-cylinder engine. According to literature the gasoline blend will have advantages over diesel. First the shorter molecular chain of the gasoline makes it less prone to soot. Second the lower density gives the gasoline a higher nozzle exit speed resulting in better mixing capabilities. Third the lower density and higher volatility lets the spray length decrease. This lowers the chance of wall-impingement, but creates worse mixing conditions looking from a spray point of view. The CO and HC emissions tend to increase relative to operation with diesel fuel, NOx emissions largely depend on the choice of combustion strategy and could be influenced by the nitrogen bound to the EHN molecule that is used as an ignition improver.
Technical Paper

Spray Analysis of the PFAMEN Injector

2013-09-08
2013-24-0036
In an earlier study, a novel type of diesel fuel injector was proposed. This prototype injects fuel via porous (sintered) micro pores instead of via the conventional 6-8 holes. The micro pores are typically 10-50 micrometer in diameter, versus 120-200 micrometer in the conventional case. The expected advantages of the so-called Porous Fuel Air Mixing Enhancing Nozzle (PFAMEN) injector are lower soot- and CO2 emissions. However, from previous in-house measurements, it has been concluded that the emissions of the porous injector are still not satisfactory. Roughly, this may have multiple reasons. The first one is that the spray distribution is not good enough, the second one is that the droplet sizing is too big due to the lack of droplet breakup. Furthermore air entrainment into the fuel jets might be insufficient. All reasons lead to fuel rich zones and associated soot formation.
Journal Article

Butanol-Diesel Blends for Partially Premixed Combustion

2013-04-08
2013-01-1683
Partially Premixed Combustion has shown the potential of high efficiency, emissions of nitrogen oxides (NOx) and soot below future emissions regulations, and acceptable acoustic noise. Low-octane-number gasoline fuels were shown to be most suitable for this concept, with the reactivity determining the possible load range. Other researchers have used several refinery streams, which might be produced by a refinery if they were required to do so without additional investment. Some of refinery streams are, however, not expected to be commercially available on the short term. For the present investigation, n-butanol (BuOH) has been selected as a blend component in diesel, and is used from 50 - 100%. The blends then have a reactivity range similar to the refinery streams, so single-cylinder engine tests for their emission and efficiency performance can also be used to determine their applicable load range.
Journal Article

Commercial Naphtha Blends for Partially Premixed Combustion

2013-04-08
2013-01-1681
Partially Premixed Combustion has shown the potential of low emissions of nitrogen oxides (NOx) and soot with a simultaneous improvement in fuel efficiency. Several research groups have shown that a load range from idle to full load is possible, when using low-octane-number refinery streams, in the gasoline boiling range. As such refinery streams are not expected to be commercially available on the short term, the use of naphtha blends that are commercially available could provide a practical solution. The three blends used in this investigation have been tested in a single-cylinder engine for their emission and efficiency performance. Besides a presentation of the sensitivity to injection strategies, dilution levels and fuel pressure, emission performance is compared to legislated emission levels. Conventional diesel combustion benchmarks are used for reference to show possible improvements in indicated efficiency.
Technical Paper

Modeling of Conventional and Early Diesel Injection Combustion Characteristics using FGM Approach

2013-04-08
2013-01-1108
The wide range of diesel engine operating conditions demand for a robust combustion model to account for inherent changes. In this work, the Flamelet Generate Manifold (FGM) approach is applied, in STAR-CD framework, to simulate the conventional injection- and early injection-timing (PCCI like) combustion regimes. Igniting Counter flow Diffusion Flamelets (ICDFs) and Homogeneous Reactors (HRs) are used to tabulate chemistry for conventional and PCCI combustion modes, respectively. The validation of the models with experimental data shows that the above consideration of chemistry tabulation results in accurate ignition delay predictions. The study reveals that a moderate amount of 5 different pressure levels is necessary to include in the FGM database to capture the ignition delay in both combustion regimes.
Technical Paper

Combustion Phasing Controllability with Dual Fuel Injection Timings

2012-09-10
2012-01-1575
Reactivity controlled compression ignition through in-cylinder blending gasoline and diesel to a desired reactivity has previously been shown to give low emission levels and a clear simultaneous efficiency advantage. To determine the possible viability of the concept for on-road application, the control space of injection parameters with respect to combustion phasing is presented. Four injection strategies have been investigated, and for each the respective combustion phasing response is presented. Combustion efficiency is shown to be greatly affected by both the injection-timing and injection-strategy. All injection strategies are shown to break with the common soot-NOx trade-off, with both smoke and NOx emissions being near or even below upcoming legislated levels. Lastly, pressure rise rates are comparable with conventional combustion regimes with the same phasing. The pressure rise rates are effectively suppressed by the high dilution rates used.
Technical Paper

Correlating Flame Location and Ignition Delay in Partially Premixed Combustion

2012-09-10
2012-01-1579
Controlling ignition delay is the key to successfully enable partially premixed combustion in diesel engines. This paper presents experimental results of partially premixed combustion in an optically accessible engine, using primary reference fuels in combination with artificial exhaust gas recirculation. By changing the fuel composition and oxygen concentration, the ignition delay is changed. To determine the position of the flame front, high-speed visualization of OH-chemiluminescence is used, enabling a cycle-resolved analysis of OH formation. A clear correlation is observed between ignition delay and flame location. The mixing of fuel and air during the ignition delay period defines the local equivalence ratio, which is estimated based on a spherical combustion volume for each spray. The corresponding emission measurements using fast-response analyzers of CO, HC and NOX confirm the decrease in local equivalence ratio as a function of ignition delay.
Technical Paper

Review on the Effects of Dual-Fuel Operation, Using Diesel and Gaseous Fuels, on Emissions and Performance

2012-04-16
2012-01-0869
In recent years the automotive industry has been forced to reduce the harmful and pollutant emissions emitted by direct-injected diesel engines. To accomplish this difficult task various solutions have been proposed. One of these proposed solutions is the usage of gaseous fuels in addition to the use of liquid diesel. These gaseous fuels have more gasoline-like properties, such as high octane numbers, and thereby are resistant against auto-ignition. Diesel on the other hand, has a high cetane number which makes it prone to auto-ignition. In this case the gaseous fuel is injected in the inlet manifold, and the diesel is direct injected in the cylinder at the end of the compression stroke. Thereby the diesel fuel spontaneously ignites and acts as an ignition source. The main goals for the use of a dual-fuel operation with diesel and gaseous fuels are the reduction of particulate matter (PM) and nitrogen oxides (NOx) emission.
Technical Paper

Modeling Fuel Spray Auto-ignition using the FGM Approach: Effect of Tabulation Method

2012-04-16
2012-01-0157
The Flamelet Generated Manifold (FGM) method is a promising technique in engine combustion modeling to include tabulated chemistry. Different methodologies can be used for the generation of the manifold. Two approaches, based on igniting counterflow diffusion flamelets (ICDF) and homogeneous reactors (HR) are implemented and compared with Engine Combustion Network (ECN) experimental database for the baseline n-heptane case. Before analyzing the combustion results, the spray model is optimized after performing a sensitivity study with respect to turbulence models, cell sizes and time steps. The standard High Reynolds (Re) k-ε model leads to the best match of all turbulence models with the experimental data. For the convergence of the mixture fraction field an appropriate cell size is found to be smaller than that for an adequate spray penetration length which appears to be less influenced by the cell size.
Technical Paper

Emission Performance of Lignin-Derived Cyclic Oxygenates in a Heavy-Duty Diesel Engine

2012-04-16
2012-01-1056
In earlier research, a new class of bio-fuels, so-called cyclic oxygenates, was reported to have a favorable impact on the soot-NOx trade-off experience in diesel engines. In this paper, the soot-NOx trade-off is compared for two types of cyclic oxygenates. 2-phenyl ethanol has an aromatic and cyclohexane ethanol a saturated or aliphatic ring structure. Accordingly, the research is focused on the effect of aromaticity on the aforementioned emissions trade-off. This research is relevant because, starting from lignin, a biomass component with a complex poly-aromatic structure, the production of 2-phenyl ethanol requires less hydrogen and can therefore be produced at lower cost than is the case for cyclohexane ethanol.
Technical Paper

Gasoline-Diesel Dual Fuel: Effect of Injection Timing and Fuel Balance

2011-12-15
2011-01-2437
Recently, some studies have shown high efficiencies using controlled auto-ignition by blending gasoline and diesel to a desired reactivity. This concept has been shown to give high efficiency and, because of the largely premixed charge, low emission levels. The origin of this high efficiency, however, has only partly been explained. Part of it was attributed to a lower temperature combustion, originating in lower heat losses. Another part of the gain was attributed to a faster, more Otto-like (i.e. constant volume) combustion. Since the concept was mainly demonstrated on one single test setup so far, an experimental study has been performed to reproduce these results and gain more insight into their origin. Therefore one cylinder of a heavy duty test engine has been equipped with an intake port gasoline injection system, primarily to investigate the effects of the balance between the two fuels, and the timing of the diesel injection.
Journal Article

Direct Injection of Diesel-Butane Blends in a Heavy Duty Engine

2011-12-06
2011-01-2400
Increasing fuel prices keep bringing attention to alternative, cheaper fuels. Liquefied Petroleum Gas (LPG) has been well known for decades as an alternative fuel for spark ignition (SI) passenger cars. More recently, aftermarket LPG systems were also introduced to Heavy Duty transport vehicles. These (port fuel) systems either vaporize the liquid fuel and then mix it with intake air, or inject fuel into the engine's intake ports. While this concept offers significant fuel cost reductions, for aftermarket certification and large-scale OEM use some concerns are present. Unburned hydrocarbons (UHC) and carbon monoxide (CO) emissions are known to be high because of premixed charge getting trapped into crevices and possibly being blown through during valve-overlap. Apart from the higher emission levels, this also limits fuel efficiency and therefore cost savings.
Technical Paper

On-Board Plasma Assisted Fuel Reforming

2011-09-11
2011-24-0088
It is well known that the addition of gaseous fuels to the intake manifold of diesel engines can have significant benefits in terms of both reducing emissions of hazardous gases and soot and improving fuel economy. Particularly, the addition of LPG has been investigated in numerous studies. Drawbacks, however, of such dual fuel strategies can be found in storage complexity and end-user inconvenience. It is for this reason that on-board refining of a single fuel (for example, diesel) could be an interesting alternative. A second-generation fuel reformer has been engineered and successfully tested. The reformer can work with both gaseous and liquid fuels and by means of partial oxidation of a rich fuel-air mix, converts these into syngas: a mixture of H₂ and CO. The process occurs as partial oxidation takes place in an adiabatic ceramic reaction chamber. High efficiency is ensured by the high temperature inside the chamber due to heat release.
Technical Paper

Non-Equilibrium Plasma Ignition for Internal Combustion Engines

2011-09-11
2011-24-0090
High-voltage nanosecond gas discharge has been shown to be an efficient way to ignite ultra-lean fuel air mixtures in a bulk volume, thanks to its ability to produce both high temperature and radical concentration in a large discharge zone. Recently, a feasibility study has been carried out to study plasma-assisted ignition under high-pressure high-temperature conditions similar to those inside an internal combustion engine. Ignition delay times were measured during the tests, and were shown to be decreasing under high-voltage plasma excitation. The discharge allowed instant control of ignition, and specific electrode geometry designs enabled volumetric ignition even at high-pressure conditions.
Journal Article

Direct Injection of High Pressure Gas: Scaling Properties of Pulsed Turbulent Jets

2010-10-25
2010-01-2253
Existing gasoline DI injection equipment has been modified to generate single hole pulsed gas jets. Injection experiments have been performed at combinations of 3 different pressure ratios (2 of which supercritical) respectively 3 different hole geometries (i.e. length to diameter ratios). Injection was into a pressure chamber with optical access. Injection pressures and injector hole geometry were selected to be representative of current and near-future DI natural gas engines. Each injector hole design has been characterized by measuring its discharge coefficient for different Re-levels. Transient jets produced by these injectors have been visualized using planar laser sheet Mie scattering (PLMS). For this the injected gas was seeded with small oil droplets. The corresponding flow field was measured using particle image velocimetry (PIV) laser diagnostics.
Journal Article

The Influence of Fuel Properties on Transient Liquid-Phase Spray Geometry and on Cl-Combustion Characteristics

2009-11-02
2009-01-2774
A transparent HSDI CI engine was used together with a high speed camera to analyze the liquid phase spray geometry of the fuel types: Swedish environmental class 1 Diesel fuel (MK1), Soy Methyl Ester (B100), n-Heptane (PRF0) and a gas-to-liquid derivate (GTL) with a distillation range similar to B100. The study of the transient liquid-phase spray propagation was performed at gas temperatures and pressures typical for start of injection conditions of a conventional HSDI CI engine. Inert gas was supplied to the transparent engine in order to avoid self-ignition at these cylinder gas conditions. Observed differences in liquid phase spray geometry were correlated to relevant fuel properties. An empirical relation was derived for predicting liquid spray cone angle and length prior to ignition.
X