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The Distillation Index (DI) is a measure of the volatility of gasoline, especially its tendency to vaporize in an engine at initial start-up and during warm up. On January 27, 1999 the U.S. domestic and import automotive manufacturers petitioned the US EPA to limit the DI of all U.S. gasoline to 1200 degrees Fahrenheit as a means of reducing in-use emissions and ensuring consistent cold start and warm-up driveability.[1] Air Improvement Resource, Inc. (AIR) completed a 1999 study that evaluated the benefits of a DI cap. Overall, the 1999 AIR study estimated that the DI cap would produce a 16 and 15 percent reduction in hydrocarbon (HC) and carbon monoxide (CO) exhaust, respectively, from gasoline vehicles nationally in 2020. [2] In 2000, the Alliance of Automobile Manufacturers sponsored a more compreshensive examination of the emission consequences of the DI cap on which this paper is based.

The effects of octane number on stratified charge combustion were investigated with single cylinder direct injection gasoline engine. Two tests were conducted. First, combustion characteristics of stratified charge combustion were studied by changing fuel octane number. Second, auto-ignition characteristics of stratified charge combustion were compared with that of homogeneous charge combustion by changing fuel component. Three types of fuels were used to change octane number and fuel component. They were single-component fuel, multi-component fuel and refinery feedstock, Unique combustion characteristics concerning octane number was found on stratified charge combustion. The increase of indicated thermal efficiency and decrease of unburned hydrocarbon were observed as octane number decreased. The difference of octane number influence between stratified charge combustion and homogeneous charge combustion was discussed.

The liquid fossil fuel contaminated by water can make some troubles in combustion processes and endurance of a combustion system. The optical sensor monitoring the water concentration instantaneously in a fuel pipeline is an effective means for controlling the fuel quality. In two component liquid flows of oil and water, the flow pattern and characteristics of water droplets are changed with various flow conditions. Then, the light scattering of the optical sensor measuring the water concentration is also dependent on the flow patterns and droplet characteristics. Therefore, it is important to investigate the detailed behavior of water droplets in the pipeline of the fuel transportation system. In this study, the flow patterns and characteristics of water droplets in the turbulent pipe flow of two component liquids of gasoline and water were investigated using optical measurements.

A comprehensive modeling is made of the transient transport processes taking place within nearly-empty axisymmetrical cylindrical liquid fuel tanks. The resulting likelihood of the formation or dissipation of flammable mixtures within the tank with time as a consequence of the transient vaporization processes of the fuel are established. Some aspects of the predicted results were validated against our corresponding experimental results involving mainly pure liquid fuels in open cylindrical containers that were nearly-empty. The effects of fuel properties, geometry and ambient conditions are considered in relation to the possibility of having the atmosphere within the tanks supporting flame propagation, in the event of the presence of an ignition source somewhere within the tank or a flame just outside the tank. The effects of changes in some operating conditions on the potential for fire spread inside liquid fuel tanks are discussed.

The Association des Constructeurs Européen d'Automobiles (ACEA) light duty diesel engine specifications requires a kinematic viscosity measurement technique for Peugeot XUD-11 BTE drain oils. This viscosity measurement is used to define the medium temperature dispersivity of soot in the drain oil.(1) This paper discusses the use of rotational rheology methods to measure the Newtonian character of XUD-11 drain oils. The calculation of the rate index using the Hershel Bulkley model indicates the level of non-Newtonian behavior of the drain oil and directly reflects the level of soot dispersion or agglomeration. This study shows that the more non-Newtonian the drain oil the greater the difference between kinematic and rotational viscosity measurements Oscillation (dynamic) rheological techniques are used to characterize build up of soot structure.

Fleet customers demand reduced operating costs. This necessitates the development of engine oils which can provide maximum fuel economy and extended oil drains, while still maintaining engine durability. This is particularly important in diesel engines produced since October 1998. These engines use retarded timing to meet EPA's emission requirements and, as a consequence in some cases, generate high soot levels in the engine oil. Extended oil drains in 1995 Caterpillar 3406E and 1996 Detroit Diesel Series 60 engines found no statistical difference in fuel economy or wear between a synthetic SAE 5W-40 and an SAE 15W-40 using API Group II base stocks. Both oils had the same API CG-4/SJ quality level. Soot levels at oil drains of 40,000-50,000 miles (64,372 - 80,465 km) ranged from 0.5-1.2%.

This paper reviews the development of a new standard for four-stroke diesel engine oils, JASO DH-1 (JASO M355: 2000). This standard was introduced to the market on April 1, 2001. It prescribes the minimum performance for engine oils conforming to four-stroke diesel engines manufactured by Japanese OEMs. This standard is composed of four engine tests and seven bench tests. The engine tests include a piston detergency test (JASO M336: 1998), valve train wear test (JASO M354: 1999), soot dispersancy test (ASTM D 5967-99) and high temperature antioxidation test (ASTM D 5533-97a). The piston detergency test and the valve train wear test were developed in Japan. The bench tests measure hot surface deposits, anti-forming, volatility, anti-corrosion, shear-stability, total base number, and seal compatibility.

A method of cleaning lubricating oil on line was investigated using a one micron bypass particulate filter followed by an infra-red heater, to remove water, dissolved gases and light diesel fractions in the oil. The impact of this oil recycler on oil quality was studied using synthetic oil in an on-road bus test. The bus was of Euro-1 emissions standard and equipped with a Cummins 6 cylinder 8.3 litre turbo-charged inter-cooled DI engine. Comparisons tests were undertaken with and without the oil recycler for about 28,000 miles. Oil samples were analysed about every 2000 miles. The results showed that the on line oil recycler achieved significant improvements in the oil quality. With the recycler, the TBN depletion rate was reduced by 52%, the TAN increase rate was reduced by 27% and the carbon accumulation rate in the oil was reduced by 42%. The fuel dilution was reduced by the recycler.

Transient dynamics of two injection flows, upstream and downstream from a swirl injector, are investigated. Capillary n-heptane pipe flow is measured using laser Doppler anemometer to obtain the instantaneous time series of centerline velocity and to reconstruct a series of instantaneous and integrated flow rates and pressure gradients. A collimated laser sheet and a high-speed video camera visualize injected spray flow. Finally, the phase Doppler anemometer measurements are introduced to analyze instantaneous patterns of droplets, velocity-size and number density in the fuel spray. All measurements are employed at similar temporal resolution close to 30 μs. Results indicate that both flows are strongly time-dependent and well correlated in time-phases. Initial transitions are completed by 100 μs. Opening or closing of the injector valve affects both flows as strong delta oscillation causes spray penetration dynamics and a post injection effect.

This paper presents results from a comprehensive experimental study of high-pressure pressure-swirl gasoline injectors tested under a range of simulated operating conditions. This study encompassed photographic analysis of single spray sequences and simultaneous measurement of axial velocity, radial velocity and diameter at point locations using the phase-doppler technique. The combination of these measurement techniques permitted an insight into the fluid dynamics of the injected spray and its development with time. Five primary stages in the spray-history were identified and numerated with experimental data.

This paper presents the results of an experimental study into the effects of fuel injection pressure on mixture formation within an optically accessed direct-injection spark-ignition (DISI) engine. Comparison is made between the spray characteristics and in-cylinder fuel distributions due to supply rail pressures of 50 bar and 100 bar subject to part-warm, part-load homogeneous charge operating conditions. A constant fuel mass, corresponding to stoichiometric tune, was maintained for both supply pressures. The injected sprays and their subsequent liquid-phase fuel distributions were visualized using the 2-D laser Mie-scattering technique. The experimental injector (nominally a hollow-cone pressure-swirl design) was seen to produce a dense filled spray structure for both injection pressures under investigation. In both cases, the leading edge velocities of the main spray suggest the direct impingement of liquid fuel on the cylinder walls.

A nephelometer system was developed to characterize engine particulate emissions from DISI engines. Results were correlated with images showing the location and history of particulates in the cylinder of an optical engine. The nephelometer's operation is based upon the dependence of scattered laser light on particulate size from a flow sampled from the exhaust of an engine. The nephelometer simultaneously measured the scattered light from angles of 20° to 160° from the forward scattering direction in 4° increments. The angular scattering measurements were then compared with calculations using a Mie scattering code to infer information regarding particulate size. Measurements of particulate mass were made based upon a correlation developed between the scattered light intensity and particulate mass samples trapped in a 0.2-micron filter. Measurements were made in a direct injection single-cylinder spark ignition research engine having a transparent quartz cylinder.

The optimization of the vaporization and mixture formation process is of great importance for the development of modern gasoline direct injection (GDI) engines, because it influences the subsequent processes of the ignition, combustion and pollutant formation significantly. In consequence, the subject of this work was the development of a measurement technique based on the laser induced exciplex fluorescence (LIF), which allows the two dimensional visualization and quantification of the in-cylinder air/fuel ratio. A tracer concept consisting of benzene and triethylamine dissolved in a non-fluorescent base fuel has been used. The calibration of the equivalence ratio proportional LIF-signal was performed directly inside the engine, at a well known mixture composition, immediately before the direct injection measurements were started.

The influence of exhaust gas recirculation (EGR) on the formation of nitric oxide (NO) was studied experimentally in a transparent gasoline direct injection engine by quantitative laser-induced fluorescence imaging. Spectral properties of the excited transition within the NO A2∑+-X2∏(0,2) band are well known from previous studies. The excitation scheme allows quantitative NO concentration measurements without detailed knowledge of the gas phase temperature. Good agreement was found with exhaust gas NOx chemi-luminescence (CLD) measurements. The experiments were carried out in an optically accessible gasoline engine featuring a direct injection cylinder head (BMW) and a Bosch injection system, based on a serial inline six-cylinder engine with an enlarged crankcase. The measurements were performed in the pentroof section of the combustion chamber.

Shaping the injection rate in Diesel engines influences combustion and emissions. Fluid-dynamic steady-state characteristics and transient response of the control valve of high-pressure, electronically controlled, injection systems are important factors for the control of the shape, duration and timing of the injection, especially during pilot injections. Computed results, obtained using a model to predict the cavitation behavior of the control valve of a high-pressure fuel injection system for Diesel engine, are presented. The numerical investigation has been made using different cavitation models, involving the hypothesis of a barotropic cavitation, or fluid dynamic model with non-equilibrium cavitation modeling. As a result, the computed mass flow values were compared with the experimental data. Calculations have been performed to investigate the influence of the transient development of the cavitation.

The aim of the present investigation is the implementation of an innovative procedure to optimise the design of a high pressure common rail electro-injector. The optimization method is based on the use of genetic programming, a search procedure developed by John Holland at the University of Michigan. A genetic algorithm (GA) creates a random population which evolves combining the genetic code of the most capable individual of the previous generation. For the present investigation an algorithm which includes the operators of crossover, mutation and elitist reproduction has been developed. This genetic algorithm allows the optimization of both single and multicriteria problems. For the determination of the multi-objective fitness function, the concept of Pareto optimality has been implemented. The performance of the multiobjective genetic algorithm was examined by using appropriate mathematical functions and was compared with the single objective one.

The use of model based approaches in areas such as simulation, control design, optimization, etc. is crucial for the development of highly sophisticated systems. This is especially true for typically very tight time-to-market frames. Physical modeling of IC engine emissions based on first principles is extremely complex and still requires by far too much calculation time. However, special fast neural networks represent a promising alternative for an accurate modeling of the emission behavior, even for dynamic conditions. This paper first describes the process of developing dynamic neural emission models. The required data is collected by a specially designed dynamic measurement strategy. The models themselves are then used for the optimization of the dynamic engine behavior concerning consumption, emissions and drivability.

Cavitating flows inside a two-dimensional valve covered orifice (VCO) nozzle were simulated by using the Space-Time Conservation Element and Solution Element (CE/SE) method in conjunction with a homogeneous equilibrium cavitation model. As a validation for present model, cavitation over a NACA0015 hydrofoil was predicted and compared with previous simulation results as well as experimental observations. The model was then used to investigate the effects on internal cavitating flows of different nozzle design parameters, such as the hole size, hole aspect-ratio, hydro-erosion radius, and orifice inclination. Under different conditions, cavitating flows through fuel injectors generated hydraulic flip, supercavitation, full cavitation, and cyclical cavitation phenomena, which are commonly observed in experiments.

A skeletal mechanism for NOx emissions is incorporated into a cycle simulation code for direct-injection (DI) Diesel engines. The skeletal mechanism consists of seven chemical reactions associated with the extended Zeldovich and N2O mechanisms. In combining the skeletal mechanism with the cycle simulation code, both a two- and a one-zone combustion model are examined. In the former, NO forms in zone 1, which is characterized by the stoichiometric flame temperature, and decomposes in zone 2, which is represented by the overall bulk cylinder temperature. For the one-zone combustion model, it is postulated that both the NO formation and decomposition processes are characterized by the stoichiometric flame temperature. The main objective of this work is to examine the relative contribution of the Zeldovich and N2O mechanisms to the NO formation and decomposition processes occurring during Diesel combustion.

Thermodynamic characteristics of premixed compression ignition combustions were clarified quantitatively by heat balance estimation. Heat balance was calculated from temperature, mole fractions of intake and exhaust gases, mass and properties of fuels. Heat balance estimation was conducted for three types of combustion; a conventional diesel combustion, a homogeneous charge compression ignition (HCCI) combustion; fuel is provided and mixed with air in an intake pipe in this case, and an extremely early injection type PREmixed lean DIesel Combustion (PREDIC). The results show that EGR should be applied for premixed compression ignition combustion to complete combustion at lower load conditions and to control ignition timing at higher load conditions. With an application of EGR, both HCCI and PREDIC showed low heat loss characteristics at lower load conditions up to 1/2 load.