| 1. |
- Adlercreutz, Ludvig, et al.
(författare)
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Correlating particle number emissions to the rotation of the piston ring
- 2023
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Ingår i: SAE International Journal of Fuels and Lubricants. - : SAE International. - 1946-3960 .- 1946-3960. ; 16:3
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Tidskriftsartikel (refereegranskat)abstract
- Reaching the particle emissions regulatory limits for the combustion engine is a challenge for developers.Particle filters have been the standard solution to reduce particle emissions, but filters arelimited in storage capacity and need to be regenerated, a process emitting more carbon dioxide(CO2) as more fuel is consumed to regenerate the filter. In previous research, it was found that theengine can emit large spikes in particle numbers (PNs) under stationary operating conditions. Thesespikes were several orders of magnitude higher than for the base particle emissions level and occurredseemingly at random. The source of the spikes was believed to be the cylinder-piston-ring systemand as 50–99% of the particles stemmed from these spikes, the influence on the particle emissionsmade it an interesting investigation to find the root cause of it. The experiments were performedfor different piston ring loads, locked ring positions, and different oil compositions. The resultsindicate a possibility to control the PN emissions through the experiment alterations, with lockedpiston rings having the greatest influence at a higher load. There was no clear relation between ringrotation and flutter with the spikes observed. The locked piston ring configurations did indicate thering gap not to be the main contributor to the spiking as fully aligned gaps did not result in thehighest levels of particle emissions. Variations to the oil composition indicate that a high-volatilityoil will emit higher levels of small, sub-10 nm particles compared to the standard baseline oil. Ahigh-viscosity oil instead lowers the particle emissions, possibly due to the higher inner friction athigh temperatures reducing the oil ingress into the combustion chamber. The link between the PNspiking phenomenon and the oil pathway past the piston ring was not established through theexperiments reported in this publication.
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| 2. |
- Hong, Beichuan, Ph.D. student, 1989-, et al.
(författare)
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Energy and exergy characteristics of an ethanol-fueled heavy-duty SI engine at high-load operation using lean-burn combustion
- 2023
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Ingår i: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311 .- 1873-5606. ; , s. 120063-120063
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Tidskriftsartikel (refereegranskat)abstract
- Ethanol, as the most produced renewable biofuel, is considered a promising low-carbon alternative to petroleum-based fuels in the transport sector due to its high energy density and auto-ignition resistance. The lean-burn combustion in spark-ignition (SI) engines has the potential to further improve thermal efficiency in regard to knock mitigation and the reduction of combustion temperature. However, the characteristics of lean-burn combustion in an ethanol-fueled engine in relation to the combustion losses and the gas-exchange process remain unclear, especially for high-load operation. This study contributes with a deeper understanding of the high-load performance of an ethanol-fueled heavy-duty SI engine using lean-burn combustion. Based on the experimental results from a single-cylinder engine test, a 6-cylinder engine model is built by integrating a validated predictive combustion model to characterize the lean-burn combustion process. The engine’s thermal efficiency and combustion phasing are evaluated for knock limited operation and then compared to the theoretical optimum which is regardless of knock. The energy and exergy balances are applied to evaluate the effect of dilution with excess air ratios up to 1.8. Losses through heat transfer, exhaust flow, and incomplete combustion are quantified. In addition, entropy generated through combustion is discussed to identify the relationship between exergy destruction and different operating conditions. In the context of lean-burn combustion, the thermal efficiency at high-load operation incrementally increases from 40.4% at stoichiometric condition to 47.3% at an excess air ratio of 1.8. At the same time, the exergy destruction through combustion increases by 3.3 percentage points across the selected dilution range. Furthermore, the challenging requirements to realize lean-burn combustion with lower exhaust gas temperatures and higher intake boost pressures is assessed through an exergy analysis of the turbocharging system.
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| 3. |
- Lius, Andreas, 1990-, et al.
(författare)
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Cycle-To-Cycle Effects and Knock Prediction using Spark Induced Disturbances on a PFI Methanol HD SI Engine
- 2022
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Ingår i: SAE Powertrains, Fuels & Lubricants Conference & Exhibition, Krakow, 6-8 September, 2022.. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International.
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Konferensbidrag (refereegranskat)abstract
- Stoichiometric operation of a Port Fueled Injection (PFI) Spark-Ignited (SI) engine with a three-way catalytic converter offers excellent CO2 reduction when run on renewable fuel. The main drawbacks with stoichiometric operation are the increased knock propensity, high exhaust temperature and reduced efficiency. Knock is typically mitigated with a reactive knock controller, with retarded ignition timing whenever knock is detected and the timing then slowly advanced until knock is detected again. This will cause some cycles to operate with non-ideal ignition timing. The current work evaluates the possibility to predict knock using the measured and modelled temperatures at Inlet Valve Closing (IVC) and Top Dead Center (TDC). Feedback effects are studied beyond steady state operation by using induced ignition timing disturbances. The approach is based on a deterministic controller where the timing is advanced beyond steady state knock limited operation or vastly retarded to produce warmer residuals in the following cycle. The results indicate that for the current engine there is no feedback effect. Chemical kinetics explains the lack of feedback due to lack of reactivity at TDC conditions. The chemical kinetic study in conjunction with the established auto ignition models described by Livengood-Wu reveals that the charge mixture entered a region of reactivity around the 50% burned point. It was also found that knocking and non-knocking cycles can have overlapping thermodynamic trajectories but for knocking cycles there is less dispersion. The study uses a solver which corrects the IVC temperature to minimize the error between observed knock onset and the point where the Livengood-Wu expression reaches unity for a knocking cycle. The corrections were found to have a correlation to uncaptured evaporation effects. Combined experimental and modelling results were in line with previous findings, namely that cycle-to-cycle combustion variations are plausibly explained by early flame propagation.
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| 4. |
- Lius, Andreas, 1990-, et al.
(författare)
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Evaluation of Cylinder State Estimator using Fuel Evaporation Assessment in a PFI Methanol HD SI Engine
- 2022
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Ingår i: SAE Powertrains, Fuels & Lubricants Conference & Exhibition, Krakow, September 6-8, 2022.. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International.
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Konferensbidrag (refereegranskat)abstract
- Modern spark-ignited (SI) engines offer excellent emission reduction when operated with a stoichiometric mixture and a three-way catalytic converter. A challenge with stoichiometric compared to diluted operation is the knock propensity due to the high reactivity of the mixture. This limits the compression ratio, thus reducing engine efficiency and increasing exhaust temperature. The current work evaluated a model of conditions at inlet valve closing (IVC) and top dead center (TDC) for steady state operation. The IVC temperature model is achieved by a cycle-to-cycle resolved residual gas fraction estimator. Due to the potential charge cooling effect from methanol, a method was proposed to determine the fraction of fuel sourced from a wall film. Determining the level of charge cooling is important as it heavily impacts the IVC and TDC temperatures. This method is based on air flow measurement and comparing information from the compression event during a transient from fired to motored conditions, while keeping the intake density constant. Experiments were conducted on a high compression ratio (14:1) heavy duty (HD) single cylinder research engine (SCRE). The fuel was methanol, injected via port fuel injection (PFI). The results indicate that the latent heat of vaporization of the fuel is far from being fully utilized, due to inherent design limitations of the intake system. It was also found that charge cooling could be altered by utilizing features of the swirl optimized cylinder head, while the same features also hinted that some stratification was possible. Accurate estimation of the IVC state and the later thermodynamic evolution is important for any closed cycle analysis. The result from the IVC and TDC condition estimators indicate that it is possible to capture expected trends.
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| 5. |
- Lius, Andreas, 1990-, et al.
(författare)
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Experimental and chemical-kinetic evaluation of a heavy-duty methanol PFI engine with direct water injection
- 2024
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Ingår i: Fuel. - : Elsevier Ltd. - 0016-2361 .- 1873-7153. ; 359
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Tidskriftsartikel (refereegranskat)abstract
- Internal combustion engines are still widely used for propulsion in modern vehicles. Upcoming emission legislation imposes stricter limits on exhaust emissions. One method to achieve emission compliance is by using a three-way catalyst (TWC), which offers excellent emission reduction if the mixture is stoichiometric. However, stoichiometric mixtures in spark-ignited engines have the drawback of increased knock propensity. Knock can be mitigated by using water injection, which serves as both a diluent and utilizes latent heat to reduce the temperature, thereby reducing the reactivity of the unburned mixture. Methanol as a fuel has received more attention thanks to its high research octane number (RON) and its potential to contribute to decarbonization when produced as e- or bio-methanol. In the current study, Direct Water Injection (DWI) was evaluated on a Heavy-Duty (HD) single-cylinder research engine fueled by methanol. This work aims to fill a research gap on methanol-fueled engines with water injection. A direct injection system of water was chosen as it offers the freedom to inject during the closed cycle. Furthermore, a chemical kinetic study on the oxidation of stoichiometric methanol–water mixtures was conducted based on findings in the literature suggesting that, under certain conditions, water mixed with alcohol (in this case, ethanol) can reduce the ignition delay. The experimental results demonstrate that DWI effectively suppresses knock and reduced Nitrogen Oxides (NOx), albeit with deteriorated combustion efficiency. The chemical kinetic study suggested that at lower to intermediate temperatures, water acts as an efficient third-body collider, which lowers the ignition delay. However, this effect is not significant for the typical timescales encountered in HD engines.
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| 6. |
- Adlercreutz, Ludvig, 1983-
(författare)
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On Alternative Fuels for Internal Combustion Engines : A study of biodiesel, gaseous methane and methanol
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis covers some of the environmental impacts of internalcombustion engines running on alternative fuels. The focus of thestudies conveyed is the reduction of greenhouse gases and particleemissions, as these two factors are of great importance for the pathsthat road transportation is facing. The main area covered is heavyduty engines for truck applications, but a study on methane fuel andhow gaseous methane can be used to reduce CO2 emissions in lightduty engines is also included. The literature studies executed inrelation to the different studies and publications are based on aholistic perspective of the difficulties of implementing alternativefuels for a heavy duty application, mainly in the perspective ofgaseous fuels.The experimental studies have been performed as studies in singlecylinder engine test cell setups. The areas of investigation were:- Accelerated testing of Biodiesel injector fouling, whichcould increase the particle and CO2 emissions from theengine- Using methane to potentially reduce CO2 by up to 50%compared to gasoline in a light duty application- In-cylinder flow optimisation to improve combustionstability in a heavy duty engine and thereby lowering theCO2-emissions.- Particle emissions originating from the entrainment oflubricating oil in the combustion chamber and how reducedoil ash content can affect the particle emissions from theengine.The outcome of these studies showed that it was possible to createan accelerated test procedure capable of fouling the injector in justone day. The reduction in CO2 for the light duty engine running onmethane was possible to reach close to 50%. This was done byincreasing the compression ratio, advancing the spark anddownsizing the engine.IIThe heavy duty methane engine study indicates that there is anoptimum combination between the design parameters in thecombustion chamber in order to be able to control the combustionspeed. The relation between particle emission and engine oil ashcontent showed that the entrainment of oil into the combustionchamber made the largest impact, before the ash content causedfurther impact on particle emissions.This work is to be seen as insights into areas in which the alternativefuels may contribute to reduce the environmental impact, mainly ofCO2, of the internal combustion engine. The vision is that it will helpto provide for a greener tomorrow and a better future for many.
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| 7. |
- Adlercreutz, Ludvig, et al.
(författare)
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Optimizing the Natural Gas Engine for CO2 reduction
- 2016
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191.
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Konferensbidrag (refereegranskat)abstract
- With alternative fuels having moved more into market in light of their reduction of emissions of CO2 and other air pollutants, the spark ignited internal combustion engine design has only been affected to small extent. The development of combustion engines running on natural gas or Biogas have been focused to maintain driveability on gasoline, creating a multi fuel platform which does not fully utilise the alternative fuels' potential. However, optimising these concepts on a fundamental level for gas operation shows a great potential to increase the level of utilisation and effectiveness of the engine and thereby meeting the emissions legislation. The project described in this paper has focused on optimising a combustion concept for CNG combustion on a single cylinder research engine. The ICE's efficiency at full load and the fuels characteristics, including its knock resistance, is of primary interest - together with part load performance and overall fuel consumption. In the process of increasing the efficiency of the engine the following areas have been of primary interest, increased compression ratio, thermal load at high cylinder pressure and the use of EGR to further increase efficiency. The overall goal in the project was to reduce the CO2-emissions while maintaining the performance and characteristics of the engine. The ambition is to reduce specific tail-pipe CO2-emissions in g/kWh by 50% compared to a modern gasoline engine. The goal was close to being reached at 45% reduction at full load and 25-34% on part load. This was done by theoretically downsizing the engine and increasing the specific performance of the engine.
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| 8. |
- Adlercreutz, Ludvig, et al.
(författare)
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Particle Emission Measurements in a SI CNG EngineUsing Oils with Controlled Ash Content
- 2019
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191.
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Konferensbidrag (refereegranskat)abstract
- Clean combustion is one of the inherent benefits of using a high methane content fuel, natural gas or biogas. A single carbon atom in the fuel molecule results, to a large extent, in particle-free combustion. This is due to the high energy required for binding multiple carbon atoms together during the combustion process, required to form soot particles. When scaling up this process and applying it in the internal combustion engine, the resulting emissions from the engine have not been observed to be as particle free as the theory on methane combustion indicates. These particles stem from the combustion of engine oil and its ash content. One common practice has been to lower the ash content to regulate the particulate emissions, as was done for diesel engines. For a gas engine, this approach has been difficult to apply, as the piston and valvetrain lubrication becomes insufficient. However, the low particle emissions from the combustion of CNG does allow for an investigation of particle contribution from engine oil ash content with only a minor particle contribution from the fuel itself. The hypothesis for this study is that there is a relationship between the engine oil ash content and the particulate emissions from a CNG engine. The investigation was conducted for several operating points with varying engine speeds and load on a single cylinder engine. The single cylinder approach was chosen to reduce sources of engine oil intrusion in the combustion chamber. The obtained results were not in line with the hypothesis, the particle emissions from the lower ash content oil did not decrease in number but the size of the particles did. The results also showed a spiking behavior in the particulate emissions, originating from the lubrication oil consumption past the piston rings. Mass flow through the engine proved to affect the particle size distribution as well as the total number of particles for all levels of oil ash content.
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| 9. |
- Adlercreutz, Ludvig, et al.
(författare)
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Variation in Squish Length and Swirl to Reach Higher Levels of EGRin a CNG Engine
- 2019
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Ingår i: SAE Technical Paper Series. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191.
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Konferensbidrag (refereegranskat)abstract
- Gaseous methane fuel for internal combustion engineshave proved to be a competitive source of propulsionenergy for heavy duty truck engines. Using biogascan even reduce the carbon footprint of the truck to near-zerolevels, creating fully environmentally friendly transport. Gasengines have already been on the market and proved to be apopular alternative for buses and waste transport. However,for long haulage these gas engines have not been on par withthe equivalent diesel engines. To improve the power and efficiencyof EURO VI gas engines running stoichiometrically, adirect way forward is adding more boost pressure and sparkadvance in combination with more EGR to mitigate knock.Using in-cylinder turbulence to achieve higher mixing rate,the fuel can still be combusted efficiently despite the increasedfraction of inert gases. In this paper, previous findings onin-cylinder air flows for diesel engine simulations are investigatedfor the applicability on to stoichiometric gas combustion.Two key parameters were identified, swirl and squish.By varying the levels of swirl with different squish lengths inthe piston design, the in-cylinder flow motion is altered toinvestigate its effect on stoichiometric gas combustion. Thetesting was performed on a single cylinder research engineoperated in the equivalent multi cylinder engine operatingpoints. The results show that previous modelling findings areverified on the pre-mixed gas combustion studied. By choosingswirl and squish for the design of the gas engine, it is possibleto increase the combustion speed and thus the fraction of EGRin the combustion charge, without the latter having a negativeimpact on the combustion.
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| 10. |
- Ainouz, Filip, et al.
(författare)
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Correlation of oil originating particle emissions and knock in a PFI HD SI engine fueled with methanol
- 2023
-
Konferensbidrag (refereegranskat)abstract
- A viable option to reduce global warming related to internal combustion engines is to use renewable fuels, for example methanol. However, the risk of knocking combustion limits the achievable efficiency of SI engines. Hence, most high load operation is run at sub-optimal conditions to suppress knock. Normally the fuel is a limiting factor, however when running on high octane fuels such as methanol, other factors also become important. For example, oil droplets entering the combustion chamber have the possibility to locally impact both temperature and chemical composition. This may create spots with reduced octane number, hence making the engine more prone to knock. Previous research has confirmed a connection between oil droplets in the combustion chamber and knock. Furthermore, previous research has confirmed a connection between oil droplets in the combustion chamber and exhaust particle emissions. However, the co-variation between oil originating particle emissions and knock has not been investigated. The current study examines the connection between knock and particle number in the exhaust, when running on fuel with low soot production. A single cylinder spark ignited heavy-duty engine was used. It was equipped with port fuel injection and fueled with methanol, which produces very little soot at lambda 1. Consequently, the measured exhaust particle numbers were assumed to origin essentially from engine oil. Three grades of oil, in combination with three piston ring configurations, were used to vary the amount of oil entering the combustion chamber. Results from knock limited operation at both medium and high engine load showed that an increased number of particles in the exhaust was associated with an increased likelihood of knock. The authors find the hypothesis that an increase in particle number correlates with an increase in auto-ignition tendency to be confirmed.
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