| 1. |
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| 2. |
- Csontos, Botond
(författare)
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Analysis of the Interaction between Soft Particles and Fuel Filter Media
- 2021
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Ingår i: SAE International Journal of Fuels and Lubricants. - : SAE International. - 1946-3952 .- 1946-3960. ; 14:3
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Tidskriftsartikel (refereegranskat)abstract
- The transportation industry is currently in a transition toward the use of zero-emission vehicles;however, reaching it will take a considerable amount of time. In the meantime, a diesel powertrainwill remain the workhorse for most heavy-duty transportation. In order to reduce the engine’senvironmental impact, biofuels, such as biodiesel, are used as drop-in fuels or fuel blends. The useof drop-in fuels may create challenges for the fuel system since sticky deposits can precipitate andcause injector malfunctioning or premature fuel filter plugging. It has been concluded in the pastthat these deposits have been caused by soft particles. In this article, soft particles created throughthe degradation of biodiesel and their effect on filters are studied. The article aims to analyze fuelfilters and investigate the materials responsible for soft particle separation. The study includes threepre filters and three main filters that are commercially available truck filters. Different membranetypes and membranes with different pore sizes were tested in order to comprehend their potentialfor fuel filtration. The tests were conducted using a custom-built fuel filter rig, where pressure buildupwas measured online. The removal efficiency was assessed by gas chromatography-mass spectrometry(GC-MS) and inductively coupled plasma (ICP). The materials of the filters were examined byFourier-transform infrared spectroscopy (FTIR), scanning electron microscopy/energy-dispersiveX-ray spectroscopy (SEM/EDX), and thermogravimetric analysis (TGA). The analysis revealed novelresults from the interaction of soft particles and different filter media. The filters show similarperformance for the commercial fuel filters with respect to soft particle removal and pressure buildupand thus the tendency for fuel filter plugging, where the efficiency for total calcium ion removal wasaround 40% for pre-filters and 60% for main filters. The material analysis shows that the particlesare most likely removed mainly by the cellulose layer of the filter paper, and filters with glass fibershowed higher capacity. In addition, the membrane filters prove to show good potential for softparticle removal, with the highest removal of 72%; however, their use in practice needs to be furtherevaluated in actual fuel systems.
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| 3. |
- Du, Chengjun, 1985, et al.
(författare)
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Effects of Nozzle Geometry on the Characteristics of an Evaporating Diesel Spray
- 2016
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Ingår i: SAE International Journal of Fuels and Lubricants. - : SAE International. - 1946-3952 .- 1946-3960. ; 9:3, s. 21-
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Tidskriftsartikel (refereegranskat)abstract
- The effects of nozzle geometry on diesel spray characteristics were studied in a spray chamber under evaporating conditions using three single-hole nozzles, one cylindrical and two convergent, designated N1 (outlet diameter 140 μm, k-factor 0), N2 (outlet diameter140 μm, k-factor 2) and N3 (outlet diameter 136 μm, k-factor 2). Spray experiments were performed with each nozzle at two constant gas densities (15 and 30 kg/m3) and an ambient temperature (673 K) at which evaporation occurs, with injection pressures ranging from 800 to 1600 bar. A light absorption and scattering method using visible and UV light was implemented, and shadow images of liquid and vapor phase fuel were recorded with high-speed video cameras. The cylindrical nozzle N1 yielded larger local vapor cone angles than the convergent nozzles N2 and N3 at both gas densities, and the difference became larger as the injection pressureincreased. The vapor phase penetration values for nozzle N1 and N3 were quite similar and always lower than those for N2. This is consistent with the impingement measurements, which showed that the momentum flux of nozzle N1 was only slightly greater than that of nozzle N3, while that of nozzle N2 was substantially greater. The vapor volume fractions measured along the spray’s center line were well explained by the one-dimensional transient diesel jet model, indicating that diesel spray vaporization is controlled by turbulent fuel-air mixing.
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| 4. |
- Du, Chengjun, 1985, et al.
(författare)
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The Influence of Ethanol Blending in Diesel fuel on the Spray and Spray Combustion Characteristics
- 2014
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Ingår i: SAE International Journal of Fuels and Lubricants. - : SAE International. - 1946-3952 .- 1946-3960. ; 7(3):November 2014, s. 823-832
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Tidskriftsartikel (refereegranskat)abstract
- The influence of ethanol blending in Diesel fuel on the spray and spray combustion characteristics was investigated by performing experiments in an optically accessible high-pressure / high-temperature spray chamber under non-evaporating, evaporating and combusting conditions. Three fuels were investigated: (1) Diesel - a European Diesel based on the EN590 standard; (2) E10 - a blend of Diesel containing 10% ethanol and 2% emulsion additive; and (3) E20 - a blend of Diesel containing 20% ethanol and 2% emulsion additive. A constant gas density of 24.3 kg/m3 was maintained under non-evaporating (30 °C, 21.1 bar), evaporating (350 °C, 43.4 bar), low combustion temperature (550 °C, 57.3 bar) and high combustion temperature (600 °C, 60 bar) conditions. A single-hole injector with a nozzle diameter of 0.14 mm was used and injection pressure was held constant at 1350 bar. Various optical methods were used to characterize the non-combusting and combusting sprays.Despite the differences in the fuels' compositions, they did not differ significantly with respect to their liquid phase spray penetrations or cone angles under non-evaporating or evaporating conditions. However, under combusting conditions, reducing the ambient temperature increased the ignition delay and delayed the onset of soot formation for all fuels. Under equivalent combustion conditions, E10 and E20 had longer ignition and soot formation delays than Diesel. As the ethanol content of the fuel was increased from 0% to 20%, the lift-off length increased and the detectable soot luminescence decreased.
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| 5. |
- Hemdal, Stina, 1974, et al.
(författare)
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Stratified cold start sprays of gasoline-ethanol blends
- 2009
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Ingår i: SAE International Journal of Fuels and Lubricants. - : SAE International. - 1946-3952 .- 1946-3960. ; 2:1, s. 683-696
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Tidskriftsartikel (refereegranskat)abstract
- Gasoline and gasoline-ethanol sprays from an outward-opening piezo-injector were studied in a constant volume/pressure chamber using high-speed imaging and phase doppler anemometry (PDA) under stratified cold start conditions corresponding to a vehicle ambient temperature of 243 K (-30 °C/-22 °F); in-cylinder air pressure of 5 bar, air temperature of 350 K (-30 °C/-22 °F) and fuel temperature of 243 K. The effects of varying in-cylinder pressure and temperature, fuel injection pressure and fuel temperature on the formation of gasoline, E75 and pure ethanol sprays were investigated. The results indicate that fuel composition affects spray behaviour, but less than expected. Furthermore, varying the temperature of the fuel or the air surrounding the spray also had minor effects. As expected, the fuel injection pressure was found to have the strongest influence on spray formation under stratified conditions.
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| 6. |
- Joelsson, Tobias, et al.
(författare)
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Large Eddy Simulation and Experiments of the Auto-Ignition Process of Lean Ethanol / Air Mixture in HCCI Engines
- 2008
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Ingår i: SAE International Journal of Fuels and Lubricants. - : SAE International. - 1946-3952 .- 1946-3960. ; 1:1, s. 1110-1119
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Tidskriftsartikel (refereegranskat)abstract
- Recent experiments and numerical studies have showed that piston geometry has a significant effect on the homogeneous charge compression ignition (HCCI) process. There are two effects generated by the combustor geometry: the geometry affects the flow/turbulence in the cylinder; the geometry also affects the temperature stratification. The temperature stratification is more directly responsible for the observed alteration of the auto-ignition process. To clarify this issue further we present in this paper a study of two engines with the same geometry but difference ways of cooling. Measurement of the two engines~a metal engine and quartz piston engine, both with the same piston bowl geometry~is carried out. Large eddy simulation (LES) is used to simulate the flow, the temperature field and the auto-ignition process in the two engines. The fuel is ethanol with a relative air/fuel ratio of 3.3. It is found that lower temperature stratification is established in the metal engine under similar conditions as the optical quartz engine due to the more effective cooling of the piston in the metal engine configuration. The combustion phasing in the two engines is the same by controlling the intake temperature. Both measurements and LES show a more rapid auto-ignition in the metal engine than in the optical engine with the same piston geometry. This confirms the conclusion that large temperature stratification can decrease the pressure-rise-rate and thereby increase the load of HCCI engines. The dependence of temperature stratification on the wall temperature and intake temperature is systematically studied using LES.
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| 7. |
- Kaiadi, Mehrzad, et al.
(författare)
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Closed-Loop Combustion Control for a 6-Cylinder Port-Injected Natural-gas Engine
- 2009
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Ingår i: SAE International Journal of Fuels and Lubricants. - : SAE International. - 1946-3952 .- 1946-3960. ; 1:1, s. 1232-1241
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Tidskriftsartikel (refereegranskat)abstract
- High EGR rates combined with turbocharging has been identified as a promising way to increase the maximum load and efficiency of heavy-duty spark ignition engines. With stoichiometric conditions a three-way catalyst can be used which means that regulated emissions can be kept at very low levels. Obtaining reliable spark ignition is difficult however with high pressure and dilution. There will be a limit to the amount of EGR that can be tolerated for each operating point. Open-loop operation based on steady state maps is difficult since there is substantial dynamics both from the turbocharger and from the wall heat interaction. The proposed approach applies standard closed-loop lambda control for controlling the overall air/fuel ratio for a heavy-duty, 6-cylinder, port-injected natural gas engine. A closed-loop load control is also applied for keeping the load at a constant level when using EGR. Furthermore, cylinder pressure-based dilution limit control is applied on the EGR in order to keep the coefficient of variation at the desired level of 5%. This way confirms that the EGR ratio is kept at its maximum stable level all times. Pumping losses decrease due to the further opening of the throttle, thereby the gas exchange efficiency improves and since the regulator keeps track of the changes the engine all the time operates in a stable region. Our findings show that excellent steady-state performance can be achieved using closed-loop combustion control for keeping the EGR level at the highest level while the stability level is still good enough.
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| 8. |
- Kaiadi, Mehrzad, et al.
(författare)
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How hythane with 25% Hydrogen can affect the Combustion in a 6-Cylinder Natural-Gas Engine
- 2010
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Ingår i: SAE International Journal of Fuels and Lubricants. - : SAE International. - 1946-3952 .- 1946-3960. ; 3:2, s. 47-59
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Tidskriftsartikel (refereegranskat)abstract
- Using alternative fuels like Natural Gas (NG) has shown good potentials on heavy duty engines. Heavy duty NG engines can be operated either lean or stoichiometric diluted with EGR. Extending Dilution limit has been identified as a beneficial strategy for increasing efficiency and decreasing emissions. However dilution limit is limited in these types of engines because of the lower burnings rate of NG. One way to extend the dilution limit of a NG engine is to run the engine on Hythane (natural gas + some percentage hydrogen). Previously effects of Hythane with 10% hydrogen by volume in a stoichiometric heavy duty NG engine were studied and no significant changes in terms of efficiency and emissions were observed. This paper presents results from measurements made on a heavy duty 6-cylinder NG engine. The engine is operated with NG and Hythane with 25% hydrogen by volume and the effects of these fuels on the engine performance are studied. Different experiments were designed and performed to investigate the parameters like knocking margin, dilution limit, lean limit, different efficiencies, emissions and maximum load of the engine. The experiments were performed successfully and the results showed modest improvement in lean, and dilution limit. Slightly changes in emissions and knocking margins are also observed.
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| 9. |
- Kaiadi, Mehrzad, et al.
(författare)
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Using Hythane as a Fuel in a 6-Cylinder Stoichiometric Natural-gas Engine
- 2009
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Ingår i: SAE International Journal of Fuels and Lubricants. - : SAE International. - 1946-3952 .- 1946-3960. ; 2:1, s. 932-939
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Tidskriftsartikel (refereegranskat)abstract
- 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. Three different experiments were designed and tested to investigate first of all if the engine encounters too severe knocking problems, second how and why, Hythane affect the running and finally how lean limit and dilution limit will be improved. The experiments were performed successfully and the results showed no significant differences between natural gas and Hythane in terms of efficiency and emissions when engine operates stoichiometric.
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| 10. |
- Kösters, Anne, 1983, et al.
(författare)
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A Numerical Study of the Effect of EGR on Flame Lift-off in n-Heptane Sprays Using a Novel PaSR Model Implemented in OpenFOAM
- 2012
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Ingår i: SAE International Journal of Fuels and Lubricants. - : SAE International. - 1946-3952 .- 1946-3960. ; 5:2, s. 604-610
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Tidskriftsartikel (refereegranskat)abstract
- The effect of exhaust gas recirculation (EGR) on flame lift-off in non-stationary n-heptane sprays was studied under Diesel engine-like conditions using numerical simulation involving complex chemistry and a novel partially stirred reactor (PaSR) model of subgrid turbulence-chemistry interaction. The flame-stabilization mechanism is a result of complex physical and chemical interactions and cannot be described by a simplified theory. To leading order it is determined by the chemical reaction time at the leading edge, the turbulent diffusivity, and the flow velocity; so that there exists a balance between the local convection velocity and the triple-flame propagation speed. In this study of ignition and flame formation and stabilization processes, the VSB2 stochastic blob-and-bubble spray model was used in combination with the volume reactor fraction model (VRFM) implemented in OpenFOAM. The reacting volume fraction in the VRFM was determined by solving for mixture fraction, progress variable, and their variances in order to estimate the non-uniformities of the fluid cell; rather than simply taking the ratio of the mixing and chemistry time-scales. The chemistry is described by a reduced n-heptane mechanism with 36 species involved in 81 reactions. The simulated lift-off trends are compared to available experimental data from the Engine Combustion Network, Sandia National Laboratories [1].
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| 11. |
- Lee, Uisung, et al.
(författare)
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Well-to-Wheels Emissions of Greenhouse Gases and Air Pollutants of Dimethyl Ether from Natural Gas and Renewable Feedstocks in Comparison with Petroleum Gasoline and Diesel in the United States and Europe
- 2016
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Ingår i: SAE International Journal of Fuels and Lubricants. - : SAE International. - 1946-3952 .- 1946-3960. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Dimethyl ether (DME) is an alternative to diesel fuel for use in compression-ignition engines with modified fuel systems and offers potential advantages of efficiency improvements and emission reductions. DME can be produced from natural gas (NG) or from renewable feedstocks such as landfill gas (LFG) or renewable natural gas from manure waste streams (MANR) or any other biomass. This study investigates the well-to-wheels (WTW) energy use and emissions of five DME production pathways as compared with those of petroleum gasoline and diesel using the Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET®) model developed at Argonne National Laboratory (ANL). The five DME pathways include 1) fossil NG with large-scale DME plants, 2) methanol from fossil NG with large-scale plants for both methanol and DME (separately), 3) LFG with small-scale DME plants, 4) manure-based biogas with small-scale DME plants, and 5) methanol from black liquor gasification with small-scale DME plants. This study analyzes DME production and use in the U.S. and Europe, and in two vehicle classes (light and heavy duty vehicles [LDVs and HDVs]). The WTW results show significant reductions in fossil fuel consumption and greenhouse gas (GHG) emissions by DME compared to gasoline and diesel if DME is produced from LFG and manure-based biogas. When methanol from black liquor is used for DME production, there are reductions in GHG emissions, though smaller than DME produced from LFG and MANR. Meanwhile, fossil NG-based DME produced in large-scale DME plants or from NG-based methanol shows GHG emissions at the similar level as petroleum diesel does.
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| 12. |
- Lewander, Magnus, et al.
(författare)
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Investigation of the Combustion Characteristics with Focus on Partially Premixed Combustion in a Heavy Duty Engine
- 2008
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Ingår i: SAE International Journal of Fuels and Lubricants. - : SAE International. - 1946-3952 .- 1946-3960. ; 1:1, s. 1063-1074
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Tidskriftsartikel (refereegranskat)abstract
- Partially Premixed Combustion (PPC) has shown its potential by combining high combustion controllability with emission characteristics that are close to those of an HCCI engine. In order to get PPC the ignition delay needs to be long enough for the fuel and air to mix prior to combustion. This can be achieved by injecting the fuel sufficiently early while running with high EGR.In order to find out where and how PPC occurs a map that shows the changes in combustion characteristics with injection timing and EGR was created. The combustion characteristics were studied in a six cylinder heavy duty engine where the Start of Injection (SOI) was swept from early to late injection over a wide range of EGR levels. The emissions were monitored during the sweeps and in the most promising regions, with low emissions and high efficiency, additional changes in injection pressure and engine speed were applied to get a more versatile picture of the combustion.
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| 13. |
- Lima Ochoterena, Raul, 1978, et al.
(författare)
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Time and spatially resolved temperature measurements of a combusting diesel spray impinging on a wall
- 2008
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Ingår i: SAE International Journal of Fuels and Lubricants. - : SAE International. - 1946-3952 .- 1946-3960. ; 1:SAE-2008-01-1608, s. 970-983
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Tidskriftsartikel (refereegranskat)abstract
- The interaction between a combusting diesel spray and a wallwas studied by measuring the spray flame temperature timeand spatially resolved. The influence of injection sequences,injection pressure and gas conditions on the heat transfer betweenthe combusting spray and the wall was investigated bymeasuring the flame temperature during the complete injectionevent.The flame temperature was measured by an emission based opticalmethod and determined by comparing the relative emissionintensities from the soot in the flame at two wavelength intervals.The measurements were done by employing a monochromaticand non intensified high speed camera, an array of mirrors, interferencefilters and a beam splitter. The studies were carriedout in the Chalmers High Pressure High Temperature (HP/HT)spray rig at conditions similar to those prevailing in a direct injecteddiesel engine prior to the injection of fuel. Fuel was injectedinto the combustion chamber by a common rail systemusing an injector with a single hole nozzle. The combustingspray impinged on a wall whose temperature was similar to thecombustion chamber gas temperature.Results of these experiments show variations in the flame temperatureas a consequence of the interaction between the combustingspray and the wall. There is a reduction in the flametemperature after impingement followed by a temperature riseas the wall is heated up by the flame. The effects caused by injectionpressure, injection sequences and gas temperature leadto differences
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| 14. |
- Marklund, Pär
(författare)
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Permeability measurements of sintered and paper based friction materials for wet clutches and brakes
- 2010
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Ingår i: SAE 2010 Powertrains, Fuels and Lubricants Meeting. - : Society of Automotive Engineers, Incorporated. ; 3:2, s. 857-864
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Wet clutches are important components used in the transmission and drive trains of many modern vehicles. The clutches transfer torque via the friction between a number of friction discs and the friction characteristics is therefore of great importance for the overall behavior of the vehicles. The friction characteristics is governed by a number of parameters such as lubricant base oil and additives, type and permeability of the friction material and temperature and surface roughness of the interacting surfaces. The permeability is considered to influence time of engagement and supply the sliding interface with lubricant and additives during engagement. In this work, a permeability measurement method suitable for wet clutch friction materials is thus used to measure the permeability of friction materials of different types; sintered bronze and paper based materials. The investigated friction materials come from different vehicle applications such as Limited Slip Differentials and Automatic Transmissions. The investigation also includes measurements made with different types of lubricants such as mineral based lubricants, mineral based VHVI lubricants and ester based lubricants. As comparison similar permeability measurements are made with water since the permeability, according to Darcy's law, should not be influenced by the percolating fluid.It is found that even though permeability is considered to be a material parameter the measured permeability for a certain material will vary depending on which fluid that is used in the measurements. Therefore, if a detailed absolute value of the permeability is of interest, i.e. for use in simulations models, the permeability should be measured with the fluid that is going to be used in the clutch or brake application in order to obtain a detailed result. However the results show that if the permeability only is compared between different materials the test fluid is of less importance as long as the same fluid is used in all investigations.
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| 15. |
- Mizuno, Hiroyasu, et al.
(författare)
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Nanorheology and nanotribology of two-component liquid crystal
- 2009
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Ingår i: SAE International Journal of Fuels and Lubricants. - : SAE International. - 1946-3952 .- 1946-3960. ; 1:1, s. 1517-1523
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Tidskriftsartikel (refereegranskat)abstract
- Rheological and tribological properties of a model lubricant consisting of a two-component liquid crystal, mixtures of Sudan Black B (dye) and 4-cyano-4'-hexylbiphenyl (6CB, liquid crystal), nano-films confined between mica surfaces were studied as functions of the surface separation distance (D) and the normal load (N). The compositions of Sudan Black B/6CB binary system were determined by FECO spectroscopy. The rheological properties which reflects the structuring and packing of binary system were examined employing the resonance shear measurement with varying the separation distance at the nanometer resolution. FECO spectroscopy revealed that apparent extinction coefficient of Sudan Black B/6CB increased monotonically with decreasing D, especially below ca. 6 nm, at all initial dye concentrations studied, 0.06-1.03 wt%. This indicated the increase in the Sudan Black B concentration in the gap between mica surfaces with the decreasing D, due to the interaction of a large planar structure dye, Sudan Black B, with mica surface. The resonance shear measurement revealed the sudden drop of the amplitude during the shear, which was not observed for one component 6CB. This drop corresponded to the stick-slip transition, which reflected the structural change in the confined dye/liquid crystal from the solid-like to liquid-like state. The combination of FECO spectroscopy and resonance shear measurement can give insights into the properties of multi-component mixtures depending on their composition.
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| 16. |
- Nygård, Alexander, et al.
(författare)
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Disintegration Mechanisms of Intermittent Liquid Jets
- 2016
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Ingår i: SAE International Journal of Fuels and Lubricants. - : SAE International. - 1946-3952 .- 1946-3960. ; 9:1, s. 91-99
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Tidskriftsartikel (refereegranskat)abstract
- It has been observed that intermittent injection leads to improved spray characteristics in terms of mixing and gas entrainment. Although some experimental work has been carried out in the past, the disintegration mechanisms that govern the breakup of intermittent jets remain unknown. In this paper we have carried out a systematic numerical analysis of the breakup of pulsated jets under different injection conditions. More specifically, the duty cycle (share of active injection during one cycle) is varied, while the total cycle time is kept constant. The advection of the liquid phase is handled through the Volume of Fluid approach and, in order to provide an accurate, yet computationally acceptable, resolution of the turbulent structures, the implicit Large Eddy Simulation has been adopted. The results show that the primary disintegration results from a combination of stretching, collision and aerodynamic interaction effects. Moreover, there exists a strong coupling between stretching and collision as stretching makes the pulse thinner prior to the contact between pulses. In this work, the purpose is to study the collision contribution to breakup in terms of the near nozzle pulse disintegration rate. When approaching the low duty cycle limit, this effect is significant because of the lower liquid volume of the pulse. In contrast, for a high duty cycle, the stretching effect is limited and a wide tail region remains as an obstruction for following pulses. However, the integral momentum of the pulse is maintained to a larger degree that has an adverse effect on the outcome of the collision event.
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| 17. |
- Tornehed, Petter, et al.
(författare)
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Towards a Model for Engine Oil Hydrocarbon Particulate Matter : SAE paper number 2010-01-2098
- 2010
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Ingår i: SAE International Journal of Fuels and Lubricants. - : SAE International. - 1946-3952 .- 1946-3960. ; 3:2, s. 543-558
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Tidskriftsartikel (refereegranskat)abstract
- The drive to reduce particle emissions from heavy-duty diesel engines has reached the stage where the contribution from the lubricant can have a major impact on the total amount of particulate matter (PM).This paper proposes a model to predict the survival rate (unburnt oil divided by oil consumption) of the hydrocarbons from the lubricant consumed in the cylinder. The input data are oil consumption and cylinder temperature versus crank angle.The proposed model was tuned to correlate well with data from a six-cylinder heavy-duty diesel engine that meets the Euro 5 legislation without exhaust gas aftertreatment.The measured (and modelled) oil survival shows a strong correlation with engine power. The maximum oil survival rate measured (19%) was at motoring conditions at high speed. For this engine, loads above 100 kW yielded an oil survival rate of nearly zero.
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| 18. |
- Trajkovic, Sasa, et al.
(författare)
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Investigation of different valve geometries and valve timing strategies and their effect on regenerative efficiency for a pneumatic hybrid with variable valve actuation
- 2008
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Ingår i: SAE Technical Paper Series. - : SAE International. - 0148-7191.
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Konferensbidrag (refereegranskat)abstract
- In the study presented in this paper a single-cylinder Scania D12 diesel engine has been converted to work as a pneumatic hybrid. During pneumatic hybrid operation, the engine can be used as a 2-stroke compressor for generation of compressed air during vehicle deceleration and during vehicle acceleration the engine can be operated as an air-motor driven by the previously stored pressurized air. The compressed air is stored in a pressure tank connected to one of the inlet ports. One of the engine inlet valves has been modified to work as a tank valve in order to control the pressurized air flow to and from the pressure tank. In order to switch between different modes of engine operation there is a need for a VVT system and the engine used in this study is equipped with pneumatic valve actuators that uses compressed air in order to drive the valves and the motion of the valves are controlled by a combination of electronics and hydraulics. This paper describes the introduction of new tank valve geometry to the system with the intent to increase the pneumatic hybrid regenerative efficiency. The new tank valve has a larger valve head diameter than the previously used setup described in order to decrease the pressure drop over the tank valve. In order to ensure tank valve operation during high in-cylinder pressures the valve is combined with an in-house developed pneumatic valve spring which makes the tank valve pressure compensated. A comparison between the old and the new tank valve geometry and their effect on the pneumatic hybrid efficiency has been done. Also, optimization of the valve timings for both CM (Compressor Mode) and AM (Air-motor Mode) has been done in order to achieve further improvements on regenerative efficiency.
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| 19. |
- Yamaguchi, Akichika, et al.
(författare)
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Air Motion Induced by Ultra-High Injection Pressure Sprays for Gasoline Direct Injection Engines
- 2020
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Ingår i: SAE International Journal of Fuels and Lubricants. - : SAE International. - 1946-3952 .- 1946-3960. ; 13:3, s. 223-235
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Tidskriftsartikel (refereegranskat)abstract
- The fuel injection pressures used in gasoline direct injection (GDI) engines have increased in recent years to improve fuel efficiency and reduce emissions. Current GDI engines use injection pressures of up to 350 bar, and there is evidence that even higher fuel injection pressures could yield further improvements in atomization. Higher injection pressures could also improve mixture formation by increasing the spray velocity; however, the research with higher injection pressures over 1000 bar is limited due to a limit of mechanical components. This manuscript summarizes experimental investigations into the effect of injection pressure, injection mass, and nozzle shape on spray-induced air motion with ultrahigh injection pressure over 1000 bar. Fuel sprays were generated at a range of injection pressures with different injection masses and nozzle geometries, and Particle Image Velocimetry (PIV) was performed using a Charge-coupled device (CCD) camera and an Nd:YAG (neodymium-doped yttrium aluminium garnet) laser to characterize the vector fields in the surrounding air and the rate of air entrainment into the sprays. Sprays generated with higher injection pressures and injection masses induced stronger large-scale air motion: an injection pressure of 1500 bar with an injection mass of only 5 mg caused almost the same amount of air entrainment as an injection pressure of 200 bar with an injection mass of 27 mg. However, the spray-induced air motion dissipated within 5 ms after the end of injection (EOI) in all cases. The air entrainment rate was also increased by using a divergent nozzle rather than a convergent one. Interactions between the spray and the surrounding air are thus strengthened by using a high injection pressure and a divergent nozzle.
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| 20. |
- Zhang, Tankai, 1988, et al.
(författare)
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An Experimental Study on the Use of Butanol or Octanol Blends in a Heavy Duty Diesel Engine
- 2015
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Ingår i: SAE International Journal of Fuels and Lubricants. - : SAE International. - 1946-3952 .- 1946-3960. ; 8:3, s. 610-621
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Tidskriftsartikel (refereegranskat)abstract
- Global warming driven by “greenhouse gas” emissions is an increasingly serious concern of both the public and legislators. A potentially potent way to reduce these emissions and conserve fossil fuel resources is to use n-butanol, iso-butanol or octanol (2-ethylhexanol) from renewable sources as alternative fuels in diesel engines. The effects of adding these substances to diesel fuel were therefore tested in a single-cylinder heavy duty diesel engine operated using factory settings. These alcohols have better calorific values, flash points, lubricity, cetane numbers and solubility in diesel than shorter-chain alcohols. However, they have lower cetane numbers than diesel, so either hydrotreated vegetable oil (HVO) or Di-tertiary-butyl peroxide (DTBP) was added to the diesel-alcohol mixtures to generate blends with the same Cetane Number (CN) as diesel. Blends containing 10 and 20% of n-butanol or iso-butanol, or 30 % octanol were tested at four operating points from the European Stationary Cycle. The same engine settings were used in all cases. The average engine performance in tests with the blends was similar to that achieved with pure diesel but the blends generated less cycle-to-cycle variation. The brake thermal efficiency was similar for all the fuels but the brake specific fuel consumption was slightly higher for the blends due to their lower calorific value. Because of their oxygen content, the blends produced much lower emissions of soot and carbon monoxide than were achieved with diesel. Blends yielded slightly higher NOx emissions than pure diesel and all the fuels produced similar hydrocarbon emissions. Possibly because of its branched molecular structure, the iso-butanol blends yielded slightly higher soot emissions than the n-butanol blends. Because HVO contains no aromatics, its addition to fuel blends reduced soot emissions. Overall, these results confirm the substantial potential of renewable longer-chain alcohols as components of blended diesel fuels.
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| 21. |
- Ekholm, Kent, et al.
(författare)
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Ethanol-Diesel Fumigation in a Multi-Cylinder Engine
- 2009
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Ingår i: SAE International Journal of Fuels and Lubricants. - 1946-3952. ; 1:1, s. 26-36
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Tidskriftsartikel (refereegranskat)abstract
- Fumigation was studied in a 12 L six-cylinder heavy-duty engine. Port-injected ethanol was ignited with a small amount of diesel injected into the cylinder. The setup left much freedom for influencing the combustion process, and the aim of this study was to find operation modes that result in a combustion resembling that of a homogeneous charge compression ignition (HCCI) engine with high efficiency and low NOx emissions. Igniting the ethanol-air mixture using direct-injected diesel has attractive properties compared to traditional HCCI operation where the ethanol is ignited by pressure alone. No preheating of the mixture is required, and the amount of diesel injected can be used to control the heat release rate. The two fuel injection systems provide a larger flexibility in extending the HCCI operating range to low and high loads. It was shown that cylinder-to-cylinder variations present a challenge for this type of combustion. By using closed-loop cylinder-individual control of pressure derivatives and IMEP with the amounts of fuels injected, combustion was successfully harmonized between the cylinders. Successful fumigation operation was verified up to 18.4 bar BMEP at a fixed engine speed of 1450 rpm. Two load points (4.6 bar BMEP and 9.2 bar BMEP) were studied in detail. Different diesel injection timings, diesel ratios, and EGR rates were investigated, and comparisons were drawn to pure diesel operation of the same engine. At medium load (9.2 bar BMEP), it was possible to obtain a stable HCCI-like combustion with low NOx emissions (0.1 g/kWh), reasonably high brake efficiency (38 %), and low pressure derivatives (5 bar/CAD). High load operation (18.4 bar BMEP) resulted in low pressure derivatives (5.5 bar/CAD), acceptable brake efficency (38 %), and relatively low NOx emissions (0.34 g/kWh).
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