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| 2. |
- Alriksson, Malin, 1980, et al.
(författare)
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Low Temperature Combustion in a Heavy Duty Diesel Engine Using High Levels of EGR
- 2006
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627.
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Tidskriftsartikel (refereegranskat)abstract
- The possibilities for extending the range of engine loads in which soot and NOx emissions can be minimised by using low temperature combustion in conjunction with high levels of EGR was investigated in a series of experiments with a single cylinder research engine. The results show that very low levels of both soot and NOx emissions can be achieved at engine loads up to 50 % by reducing the compression ratio to 14 and applying high levels of EGR (up to approximately 60 %). Unfortunately, the low temperature combustion is accompanied by increases in fuel consumption and emissions of both HC and CO. However, these drawbacks can be reduced by advancing the injection timing. The research engine was a 2 litre direct injected (DI), supercharged, heavy duty, single cylinder diesel engine with a geometry based on Volvo's 12 litre engine, and the amount of EGR was increased by adjusting the exhaust back pressure while keeping the charge air pressure constant.
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| 3. |
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| 4. |
- Andersson, Mats, 1963, et al.
(författare)
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Evaporation of Gasoline-Like and Ethanol-Based Fuels in Hollow-Cone Sprays Investigated by Planar Laser-Induced Fluorescence and Mie Scattering
- 2011
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627. ; , s. 2011-01-1889-
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Tidskriftsartikel (refereegranskat)abstract
- The evaporation of different fuels and fuel components in hollow-cone sprays at conditions similar to those at stratified cold start has been investigated using a combination of planar laser-induced fluorescence (LIF) and Mie scattering. Ketones of different volatility were used as fluorescent tracers for different fuel components in gasoline-like model fuels and ethanol-based fuels. LIF and Mie images were compared to evaluate to what extent various fuel components had evaporated and obtained a spatial distribution different from that of the liquid drops, as a function of fuel temperature and time after start of injection. A selective and sequential evaporation of fuel components of different volatility was found.
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| 5. |
- Beatrice, C., et al.
(författare)
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Emission reduction technologies for the future low emission rail diesel engines: EGR vs SCR
- 2013
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- The EU emission standards for new rail Diesel engines are becoming even more stringent. EGR and SCR technologies can both be used to reduce NOx emissions; however, the use of EGR is usually accompanied by an increase in PM emissions and may require a DPF. On the other hand, the use of SCR requires on-board storage of urea. Thus, it is necessary to study these trade-offs in order to understand how these technologies can best be used in rail applications to meet new emission standards. The present study assesses the application of these technologies in Diesel railcars on a quantitative basis using one and three dimensional numerical simulation tools. In particular, the study considers a 560 kW railcar engine with the use of either EGR or SCR based solutions for NOx reduction. The NOx and PM emissions performances are evaluated over the C1 homologation cycle. The simulation results indicate that either EGR or SCR based solutions can be used to achieve Stage IIIB NOx limits for the 560 kW engine, with an acceptable trade-off regarding BSFC in the case of EGR solutions. In the case of EGR, though, a DPF is necessary to meet Stage IIIB PM limits. Furthermore, SCR based solutions have the potential to go beyond the Stage IIIB NOx limit by scaling up the size of the SCR device and the on-board urea storage. Copyright © 2013 SAE International.
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| 6. |
- Beatrice, Carlo, et al.
(författare)
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Experimental Assessment on Exploiting Low Carbon Ethanol Fuel in a Light-Duty Dual-Fuel Compression Ignition Engine
- 2020
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Ingår i: Applied Sciences (Switzerland). - : MDPI AG. - 2076-3417. ; 10:20
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Tidskriftsartikel (refereegranskat)abstract
- Compression ignition (CI) engines are widely used in modern society, but they are also recognized as a significative source of harmful and human hazard emissions such as particulate matter (PM) and nitrogen oxides (NOx). Moreover, the combustion of fossil fuels is related to the growing amount of greenhouse gas (GHG) emissions, such as carbon dioxide (CO2). Stringent emission regulatory programs, the transition to cleaner and more advanced powertrains and the use of lower carbon fuels are driving forces for the improvement of diesel engines in terms of overall efficiency and engine-out emissions. Ethanol, a light alcohol and lower carbon fuel, is a promising alternative fuel applicable in the dual-fuel (DF) combustion mode to mitigate CO2 and also engine-out PM emissions. In this context, this work aims to assess the maximum fuel substitution ratio (FSR) and the impact on CO2 and PM emissions of different nozzle holes number injectors, 7 and 9, in the DF operating mode. The analysis was conducted within engine working constraints and considered the influence on maximum FSR of calibration parameters, such as combustion phasing, rail pressure, injection pattern and exhaust gas recirculation (EGR). The experimental tests were carried out on a single-cylinder light-duty CI engine with ethanol introduced via port fuel injection (PFI) and direct injection of diesel in two operating points, 1500 and 2000 rpm and at 5 and 8 bar of brake mean effective pressure (BMEP), respectively. Noise and the coefficient of variation in indicated mean effective pressure (COVIMEP) limits have been chosen as practical constraints. In particular, the experimental analysis assesses for each parameter or their combination the highest ethanol fraction that can be injected. To discriminate the effect on ethanol fraction and the combustion process of each parameter, a one-at-a-time-factor approach was used. The results show that, in both operating points, the EGR reduces the maximum ethanol fraction injectable; nevertheless, the ethanol addition leads to outstanding improvement in terms of engine-out PM. The adoption of a 9 hole diesel injector, for lower load, allows reaching a higher fraction of ethanol in all test conditions with an improvement in combustion noise, on average 3 dBA, while near-zero PM emissions and a reduction can be noticed, on the average of 1 g/kWh, and CO2 compared with the fewer nozzle holes case. Increasing the load insensitivity to different holes number was observed.
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| 7. |
- Berntsson, Andreas, 1978, et al.
(författare)
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A LIF-study of OH in the Negative Valve Overlap of a Spark-assisted HCCI Combustion Engine
- 2008
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627.
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Tidskriftsartikel (refereegranskat)abstract
- Future requirements for emission reduction from combustionengines in ground vehicles might be met byusing the HCCI combustion concept. In this study,negative valve overlap (NVO) and low lift, short duration,camshaft profiles, were used to initiate HCCIcombustion by increasing the internal exhaust gas recirculation(EGR) and thus retaining sufficient thermalenergy for chemical reactions to occur when a pilot injectionwas introduced prior to TDC, during the NVO.One of the crucial parameters to control in HCCI combustionis the combustion phasing and one way of doingthis is to vary the relative ratio of fuel injected inpilot and main injections. The combustion phasing isalso influenced by the total amount of fuel supplied tothe engine, the combustion phasing is thus affectedwhen the load is changed. This study focuses on thereactions that occur in the highly diluted environmentduring the NVO when load and pilot to main ratio arechanged.To monitor these reactions, planar laser-induced fluorescence(PLIF) from OH radicals was analyzed ina series of experiments with an optical single-cylinderengine, since these radicals are known to be associatedwith high temperature reactions. A series of experimentswas also performed using a multi-cylinderengine with varied NVO timings, which showed thatthe combustion phasing was influenced by both theratio between the pilot and main injection amountsand the total amount of fuel. Data acquired from correspondingoptical analysis showed the occurrenceof OH radicals (and thus high temperature reactions)during the NVO in all tested operating conditions. Theresults also indicate that the extent of the high temperaturereactions was influenced by both varied parameters,since decreasing the relative amount of the pilotinjection and/or increasing the total amount of fuel ledto larger amounts of OH radicals.
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| 8. |
- Berntsson, Andreas, 1978, et al.
(författare)
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HCCI Combustion Using a Spark Ignited Stratified Charge
- 2006
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Ingår i: Society of Automotive Engineers of Japan, annual congress.
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Tidskriftsartikel (refereegranskat)abstract
- Requirements for further reductions for fuel consumption and emissions might be met by using HCCI combustion, provided that certain challenges can be overcome the most important of which is to develop ways to control the combustion.In this study a combination of SI and HCCI combustion was investigated, in which a SI stratified charge is used to initiate the HCCI combustion. Both hydrogen and a mixture of iso-octane and n-heptane were used as fuels for the stratification charge. The hybrid combustion concept was found to give better control of combustion timing and the CA50 could be controlled by varying the injection timing and stratification amount.
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| 9. |
- Berntsson, Andreas, 1978, et al.
(författare)
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HCCI Combustion Using Charge Stratification for Combustion
- 2007
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Ingår i: SAE.
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Tidskriftsartikel (refereegranskat)abstract
- This work evaluates the effect of charge stratification oncombustion phasing, rate of heat release and emissionsfor HCCI combustion. Engine experiments in both opticaland traditional single cylinder engines were carried outwith PRF50 as fuel. The amount of stratification as wellas injection timing of the stratified charge was varied.It was found that a stratified charge can influencecombustion phasing, increasing the stratification amountor late injection timing of the stratified charge leads to anadvanced CA50 timing. The NOX emissions follows theCA50 advancement, advanced CA50 timing leads tohigher NOX emissions. Correlation between CA50 canalso be seen for HC and CO emissions when theinjection timing was varied, late injection and therebyadvanced CA50 timing leads to both lower HC and COemissions. This trend can not be seen when thestratification amount was varied, increased stratificationamount leads to higher CO emission and for operatingcondition with late CA50 timing the HC emissions alsoincrease with increasing stratification amount. Opticalstudies, with high speed CCD camera, show that anincrease in stratification leads to poor combustion qualitynear the cylinder walls, due to leaner mixtures near thecylinder walls and this results in higher HC and COemissions.The maximum rate of heat release depends onstratification amount - a larger amount gives a lower rateof heat release but the main heat release is advanced.Varied injection timing results in different phasing of themain heat releases.The use of charge stratification for HCCI combustion canlead to a larger operating range, due to its effect oncombustion phasing and rate of heat release, since theupper load range is partly restricted by too high rates ofheat release leading to high pressure oscillations andthe lower load to late combustion phasing leading tohigh cycle-to-cycle variations.
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| 10. |
- Berntsson, Andreas, 1978, et al.
(författare)
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HCCI combustion using charge stratification for combustion control
- 2007
-
Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627.
-
Tidskriftsartikel (refereegranskat)abstract
- This work evaluates the effect of charge stratification on combustion phasing, rate of heat release and emissions for HCCI combustion. Engine experiments in both optical and traditional single cylinder engines were carried out with PRF50 as fuel. The amount of stratification as well as injection timing of the stratified charge was varied. It was found that a stratified charge can influence combustion phasing, increasing the stratification amount or late injection timing of the stratified charge leads to an advanced CA50 timing. The NOx emissions follows the CA50 advancement, advanced CA50 timing leads to higher NOx emissions. Correlation between CA50 can also be seen for HC and CO emissions when the injection timing was varied, late injection and thereby advanced CA50 timing leads to both lower HC and CO emissions. This trend can not be seen when the stratification amount was varied, increased stratification amount leads to higher CO emission and for operating condition with late CA50 timing the HC emissions also increase with increasing stratification amount. Optical studies, with high speed CCD camera, show that an increase in stratification leads to poor combustion quality near the cylinder walls, due to leaner mixtures near the cylinder walls and this results in higher HC and CO emissions. The maximum rate of heat release depends on stratification amount - a larger amount gives a lower rate of heat release but the main heat release is advanced. Varied injection timing results in different phasing of the main heat releases. The use of charge stratification for HCCI combustion can lead to a larger operating range, due to its effect on combustion phasing and rate of heat release, since the upper load range is partly restricted by too high rates of heat release leading to high pressure oscillations and the lower load to late combustion phasing leading to high cycle-to-cycle variations. Copyright © 2007 SAE International.
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