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Technical Paper

Injector Tip Design Improvement of the Diesel Injectors

2011-04-12
2011-01-1397
Parameters of the fuel economy and the exhaust gases pollution of the high-speed diesel engines, with unshared and half-shared combustion chambers, are predetermined by processes of fuel spray and fuel-air mixture creation. The parameters of these processes (fuel spraying and development of flame structure dynamic) appreciably depend from design features of a flowing part of the injector tips. The major parameters of the injector tips design are the spraying nozzles length and the ratio of the length these nozzles to their diameters. The experimental research of the D-245.12C type diesel engine has been carried out. Fuel injectors of the diesel engine were equipped with injector tips of different spray nozzles lengths. The experimental data show improvement fuel efficiency, reduction of emissions and smoke due to optimization of geometries in the injector tip.
Technical Paper

Fuel Effects on HCCI Operation in a Spark Assisted Direct Injection Gasoline Engine

2011-08-30
2011-01-1763
The fuel effects on HCCI operation in a spark assisted direct injection gasoline engine are assessed. The low load limit has been extended with a pilot fuel injection during the negative valve overlap (NVO) period. The fuel matrix consists of hydrocarbon fuels and various ethanol blends and a butanol blend, plus fuels with added ignition improvers. The hydrocarbon fuels and the butanol blend do not significantly alter the high or the low limits of operation. The HCCI operation appears to be controlled more by the thermal environment than by the fuel properties. For E85, the engine behavior depends on the extent that the heat release from the pilot injected fuel in the NVO period compensates for the evaporative cooling of the fuel.
Technical Paper

Effects of Injection Pressure, Timing and EGR on Combustion and Emissions Characteristics of Diesel PCCI Engine

2011-08-30
2011-01-1769
Effects of injection parameters on combustion and emission characteristics of diesel PCCI engine operating on optical and test engine was investigated. PCCI combustion was achieved through slightly narrow included angle injector, low compression ratio coupled with exhaust gas recirculation. Analysis based on diesel spray evolution, combustion process visualization and analysis was carried out. Spray penetration was evaluated and related to the exhaust emissions. Advancing the injection timing and EGR extended the ignition delay, decreased NOx emissions and increased HC, smoke and CO emissions. Higher injection pressure led to low emissions of NOx, smoke, HC and comparable CO. Optimum spray targeting position for minimum emission was identified. Impingement on the piston surface led to deterioration of emissions and increased fuel consumption while spray targeting the upper edge of Derby hat wall showed improvement in emission and engine performance.
Technical Paper

Effects of Mixedness and Ignition Timings on PCCI Combustion with a Dual Fuel Operation

2011-08-30
2011-01-1768
A dual fuel operation with different reactivity fuels has the possibility of optimizing performance and emissions in premixed charge compression ignition engines by controlling the spatial concentration and distribution of both fuels. In the present study, n-heptane and i-octane were independently injected through two different injectors. In-cylinder pressure analysis and emissions measurement were performed in a compression ignition engine. Injection timings, fuel quantity ratio between the injections were changed for the two cases, in which one fuel was injected using a port fuel injection system while the other was directly injected into the cylinder, in order to drastically vary mixture distributions and ignition timings. In addition, an optical diagnostic was performed in a rapid compression and expansion machine to develop an understanding of the ignition processes of the two mixtures.
Technical Paper

A new Approach in AdBlue Dosing to Improve Performance and Durability of SCR Systems for the Use in Passenger Cars up to Heavy Duty Vehicles

2011-08-30
2011-01-2095
SCR technology is becoming more and more important for the segment of diesel-driven passenger cars. Due to space and functional demands the dependency of SCR performance on a uniform supply of ammonia into the catalytic substrates is highly increased. Both an even distribution of the AdBlue® spray and a completed evaporation and decomposition of the droplets are the key to achieve the desired ammonia spread. Evaluation of the influence of spray quality on the AdBlue® decomposition and catalyst performance are leading to a new approach in dosing, using a special nozzle and air-supply strategy. The resulting new technology is evaluated and compared to the state of the art.
Technical Paper

Analysis of In-cylinder Flow and Fuel Vapor Concentration Distribution in Gasoline Direct Injection Engine

2011-08-30
2011-01-2052
This paper details the air-fuel mixing process in a gasoline direct injection (DI) engine. Laser measurement techniques such as particle image velocimetry (PIV) and laser induced fluorescence (LIF) were employed on the optical engine with a transparent cylinder to analyze the in-cylinder flow and fuel vapor concentration. In addition, firing tests were conducted using an actual engine. Test results showed that the multi-stage injection is effective for air-fuel mixing and improvement of combustion stability.
Technical Paper

Transmission Electron Microscopy of Soot Particles sampled directly from a Biodiesel Spray Flame

2011-08-30
2011-01-2046
For better understanding of soot formation and oxidation processes in a biodiesel spray flame, the morphology, microstructure and sizes of soot particles directly sampled in a spray flame fuelled with soy-methyl ester were investigated using transmission electron microscopy (TEM). The soot samples were taken at different axial locations in the spray flame, 40, 50 and 70 mm from injector nozzle, which correspond to soot formation, peak, and oxidation zones, respectively. The biodiesel spray flame was generated in a constant-volume combustion chamber under a diesel-like high pressure and temperature condition (6.7 MPa, 1000K). Density, diameter of primary particles and radius of gyration of soot aggregates reached a peak at 50 mm from the injector nozzle and was lower or smaller in the formation or oxidation zones of the spray.
Technical Paper

Optimization of Hydrogen Jet Configuration by Single Hole Nozzle and High Speed Laser Shadowgraphy in High Pressure Direct Injection Hydrogen Engines

2011-08-30
2011-01-2002
A new ignition-combustion concept named PCC (Plume Ignition Combustion Concept), which ignite rich mixture plume in the middle of injection period or right after injection of hydrogen is completed, is proposed by the authors in order to reduce NOx emissions in high engine load conditions with minimizing trade-offs on thermal efficiency. In this study fundamental requirements of hydrogen jet to optimize PCC are investigated by using single and multi-hole nozzle with a combination of high speed laser shadowgraphy to visualize propagating flame. As a result, it was infered that igniting the mixture plume in the middle of injection period with minimizing jet penetration to chamber wall is effective reducing NOx formation even further.
Journal Article

Influence of injection strategy in a high-efficiency hydrogen direct injection engine

2011-08-30
2011-01-2001
Energy security and climate change are two of the main drivers for development of sustainable and renewable transportation solutions. Entities around the globe have been working on strategic plans to reduce energy consumption and curb greenhouse gas emissions. In this context hydrogen is frequently mentioned as the fuel and energy carrier of the future. The U.S. Department of Energy's (DOE's) FreedomCAR and Vehicle Technologies (FCVT) Program has identified hydrogen-powered internal combustion engine (ICE) vehicles as an important mid-term technology on the path to a large-scale hydrogen economy. DOE has set challenging goals for hydrogen internal combustion engines including 45% peak brake thermal efficiency (BTE). This paper summarizes recent research engine test results employing hydrogen direct injection with different injection strategies.
Technical Paper

A Method for the Estimation of the Service Life of a Precision Guiding Interface “Needle - Nozzle Body” of a Common-Rail-Injector for High Rail Pressures

2011-08-30
2011-01-2020
The analysis of type and form of the loading in the guidance between the needle and body of a CR-injector, as well as the transformation of friction energy on the contact surfaces which absorbs mechanical and thermal loads with deforming and heating the contact layer is presented. The dominant parameters of friction and wear for the investigated interface (radial force, mode of friction, relation for the nominal and real contact areas etc.) are shown in function of different values of rail pressures, varying from 500 to 3000 bar. A special coefficient of accumulation of energy is defined. With these coefficient the analysis of thermal- and stress-conditions for the precision tribosystem become possible. Furthermore this leads to the calculation of the intensity of wear for the mentioned components of the nozzle.
Technical Paper

Development of High Pressure H2 Gas Injectors, Capable of Injection at Large Injection Rate and High Response Using a Common-rail Type Actuating System for a 4-cylinder, 4.7-liter Total Displacement, Spark Ignition Hydrogen Engine

2011-08-30
2011-01-2005
Key requirements of engines for vehicles are large output power and high efficiency, low emission as well as small size and light weight. Hydrogen combustion engines with direct injection have the characteristics to meet these factors. Tokyo City University, former Musashi Institute of Technology, has studied hydrogen fueled engines with direct injection since 1971. The key technology in the development of hydrogen fueled engines is the hydrogen injector for direct injection with the features such as high injection rate, high response and no hydrogen gas leakage from the needle valve of the hydrogen injector. A common-rail type system to actuate the needle valves of the high pressure hydrogen injectors was intentionally applied to fulfill good performances such as large injection rate, high response and no hydrogen gas leakage.
Journal Article

High-Pressure Hydrogen Jet and Combustion Characteristics in a Direct-Injection Hydrogen Engine

2011-08-30
2011-01-2003
Hydrogen spark-ignition (SI) engines based on direct-injection (DI) promise significant advantages in terms of thermal efficiency and power output, as well as a means of overcoming problems related to knocking, backfiring, and pre-ignition. In a DI hydrogen engine, the fuel/air mixture is formed by injecting a jet of hydrogen into the air inside the combustion chamber. An Ar-ion laser beam was used as a light source to visualize the hydrogen jet in a constant-volume chamber. This allowed us to study the structure of the jet in addition to other physical processes resulting from hydrogen gas injection. Combustion experiments were conducted in a single-cylinder SI optical research engine equipped with a DI system to detect the early kernel growth assisted by the spark, as well as flame propagation. Various equivalence ratios and fuel injection timings were analyzed to identify the effects on combustion.
Technical Paper

Improvement of Combustion of CNG Engine using CNG Direct Injection and Gas-jet Ignition Method

2011-08-30
2011-01-1994
Lean combustion is a useful mean to improve performance of a CNG engine. However, conventional premixed fuel injection method limits the lean combustible range. Lean combustion for CNG has problems such as misfire and THC emission. This study proposes the gas-jet ignition method to extend lean combustible limit of CNG engines. Results show that CNG engine can be operated at equivalence ratio ranges from 0.3 and 0.8 by applying two-stage injection combined with gas-jet ignition. First-injection timing is one of important parameter that affects THC emissions. Analyses of in-cylinder pressure histories and CFD calculation explain that combustion stability and THC emission are affected by fuel distribution. The distribution is controlled by the first and second injection timing. The second injection achieves good ignitability. The THC emission is caused by over-lean mixture in the cylinder in the case of early timing of first injection.
Journal Article

Effects of Ethanol Content on Gasohol PFI Engine Wide-Open-Throttle Operation

2009-06-15
2009-01-1907
The NOx emission and knock characteristics of a PFI engine operating on ethanol/gasoline mixtures were assessed at 1500 and 2000 rpm with λ =1 under Wide-Open-Throttle condition. There was no significant charge cooling due to fuel evaporation. The decrease in NOx emission and exhaust temperature could be explained by the change in adiabatic flame temperature of the mixture. The fuel knock resistance improved significantly with the gasohol so that ignition could be timed at a value much closer or at MBT timing. Changing from 0% to 100% ethanol in the fuel, this combustion phasing improvement led to a 20% increase in NIMEP and 8 percentage points in fuel conversion efficiency at 1500 rpm. At 2000 rpm, where knocking was less severe, the improvement was about half (10% increase in NIMEP and 4 percentage points in fuel conversion efficiency).
Technical Paper

Evaluation of 5 to 20% Biodiesel Blend on Heavy-duty Common-rail Diesel Engine

2009-06-15
2009-01-1894
The higher portion of biodiesel blended fuel will result in lower power output since biodiesel itself has lower energy input (B20 gave about 3% lower torque output at peak torque speed). In the ELR (Engine Load Response) Test Cycle, biodiesel blended fuel emitted less smoke than diesel fuel, while CO and NOx emission of biodiesel blended fuel and diesel fuel are comparable. Biodiesel particulate matter (PM) seemed to be higher than diesel fuel. In addition, additized biodiesel blended fuels (B5, B10 and B20) proved qualitative in oxidation stability, acid value, etc. Biodiesel specific lubricant confirmed its functions by evaluating the viscosity increase, fuel dilution, TAN, TBN and wear metal content during engine durability test. The used oil analysis affirmed that the lubricant could effectively be used with particular biodiesel blended fuel in advanced, heavy-duty common-rail DI diesel engines.
Technical Paper

The Effect of Biodiesel on PAHs, Nitro-PAHs and Oxy-PAHs Emissions from a Light Vehicle Operated Over the European and the Artemis Driving Cycles

2009-06-15
2009-01-1895
This study examines the effects of neat soy-based biodiesel (B100) and its 50% v/v blend (B50) with low sulphur automotive diesel on vehicle PAH emissions. The measurements were conducted on a chassis dynamometer with constant volume sampling (CVS) according to the European regulated technique. The vehicle was a Euro 2 compliant diesel passenger car, equipped with a 1.9 litre common-rail turbocharged direct injection engine and an oxidation catalyst. Emissions of PAHs, nitro-PAHs and oxy-PAHs were measured over the urban phase (UDC) and the extra-urban phase (EUDC) of the type approval cycle (NEDC). In addition, for evaluating realistic driving performance the non-legislated Artemis driving cycles (Urban, Road and Motorway) were used. Overall, 12 PAHs, 4 nitro-PAHs, and 6 oxy-PAHs were determined. The results indicated that PAH emissions exhibited a reduction with biodiesel during all driving modes.
Journal Article

Development of a Direct Injection High Efficiency Liquid Phase LPG Spark Ignition Engine

2009-06-15
2009-01-1881
Direct Injection (DI) is believed to be one of the key strategies for maximizing the thermal efficiency of Spark Ignition (SI) engines and meet the ever-tightening emissions regulations. This paper explores the use of Liquefied Petroleum Gas (LPG) liquid phase fuel in a 1.5 liter SI four cylinder gasoline engine with double over head camshafts, four valves per cylinder, and centrally located DI injector. The DI injector is a high pressure, fast actuating injector enabling precise multiple injections of the finely atomized fuel sprays. With DI technology, the injection timing can be set to avoid fuel bypassing the engine during valve overlap into the exhaust system prior to combustion. The fuel vaporization associated with DI reduces combustion chamber and charge temperatures, thereby reducing the tendency for knocking. Fuel atomization quality supports an efficient combustion process.
Technical Paper

Extending the Load Range of a Natural Gas HCCI Engine using Direct Injected Pilot Charge and External EGR

2009-06-15
2009-01-1884
Natural gas is a challenging fuel for HCCI engines because its single-stage ignition and rapid combustion make it difficult to optimize combustion timing over a significant load range. This study investigates direct injection of a pilot quantity of high-cetane fuel near TDC as a range extension and combustion control mechanism for natural gas HCCI engines. The EGR and load range is studied in a supercharged natural gas HCCI engine equipped with external EGR, intake heating and a direct injection system for n-heptane pilot fuel. The operating range and emissions are of primary interest and are compared between both the baseline HCCI engine with variable intake temperature and the direct injected HCCI (DI-HCCI) engine with constant intake temperature. Test results show the EGR and load range at fixed intake temperature can be extended using pilot direct injection.
Technical Paper

The Spray Characteristics of a Liquid Phase LPG Port Injection Type Injector for a Remodeled Diesel Engine

2009-06-15
2009-01-1879
In present days, most of researches concerned with vehicle engines have been performed to reduce vehicle emissions and to improve engine efficiency. For the requirements, LPG (Liquefied Petroleum Gas) engine which has lots of advantages such as low emission level, cheaper fuel cost and enough infrastructures has had lots of interest as an alternative fuel engine. What is more, it has a low emission level of CO2 well-known as the factor of ‘Global Warming’, thus the use of LPG engines has been increased. Especially since MPI(Multi Point Injection) type LPLi(Liquid Phase LPG injection) system was used for the fuel supply system, disadvantages of LPG engine such as low engine performance, decreased charging efficiency and cold starting difficulty have been improved and prejudices against LPG engines have been changed a lot. In light of this, the motion to use LPLi engines instead of diesel engines has been increasing.
Technical Paper

Possible Influence of High Injection Pressure on Diesel Fuel Stability: A Review and Preliminary Study

2009-06-15
2009-01-1878
Recent developments in diesel engines and fuel injection equipment combined with the change to ULSD and bio-blends have resulted in increased reports regarding deposits within injectors and filters. A review of known fuel degradation mechanisms and other relevant chemistries suggests the effects of high pressure and high shear environments should be examined as the most probable causes of increasing deposit formation. Existing fuel quality tests do not correlate with reported fouling propensity. Analytical studies have shown that there are only subtle chemical changes for the materials within the standard diesel boiling range. The implications for further scientific study are discussed.
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