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The effects of injector targeting and fuel volatility on transient fuel dynamics were studied with a comprehensive quasi-dimensional model and compared with experimental results from Part I of this report (1). The model includes the transient, convective vaporization of four multi-component fuel films coupled with a transient thermal warm-up model for realistic valve, port and cylinder temperatures (2, 3). Two injector targetings were analyzed, first with the fuel impacting the intake valve and in addition, the fuel impacting the port floor directly in front of the intake valve. The model demonstrates the importance of both component temperature and fuel impaction area on fuel vaporization, transient air fuel ratio (AFR) response and the amount of liquid fuel entering the cylinder. Generally, a smaller injector footprint area will lead to more liquid fuel entering the cylinder even if the spray is targeted at the back of the intake valve.

The occurrence of flash boiling in the fuel spray of a Port Fuel Injected (PFI) spark ignition engine has been observed and photographed during normal automotive vehicle operating conditions. The flash boiling of the PFI spray has a dramatic affect on the fuel spray characteristics such as droplet size and spray cone angle which can affect engine transient response, intake valve temperature and possibly hydrocarbon emissions. A new method of correlating the spray behavior using the equilibrium vapor/liquid (V/L) volume ratio of the fuel at the measured fuel temperature and manifold pressure is introduced.

Early research in the application of nonthermal plasma technology to reduce NOx in combustion emissions established that the chemistry resulting from the direct excitation of exhaust gas streams is dominated by oxidation of NO to NO2 and nitric acid, undesirable end products for mobile systems. An alternative to direct plasma generation in diesel exhaust has now been demonstrated to shift this exhaust NOx chemistry from oxidation toward reduction to nitrogen and oxygen. The new approach reacts NO with atomic nitrogen injected into the exhaust stream through multiple electrically excited high-speed nitrogen jets. Chemical reduction of more than half of the NO in diesel exhaust has so far been demonstrated, with only minimal production of N2O. The technology functions well in the sooty and wet conditions characteristic of diesel exhaust. A system is presently being built for testing and evaluation on exhaust slipstreams at a Caterpillar Inc. test facility.

The optimal operating condition of the patented Multi-Stage Corona Discharge System at pulsed mode has been investigated to reduce NOx emission from the exhaust gas of commercial diesel engine vehicles. The design parameters of the system have been tested at numerous operating conditions and upgraded to improve their performance. The compositions of simulated and actual exhaust gas have been measured with a typical exhaust gas analyzer downstream of the system and also analyzed with a FT-IR spectrophotometer. The removal efficiency of NO varied from 20 to 90% depending upon the flow rate and initial NO concentration. The actual residence time of exhaust within the discharge volume played an important role for optimal design. Those results are directly related to the energy consumption of the removal reaction and, ultimately, the design characteristics.

This paper reports efficient treatment of diesel emission with transient, non-equilibrium plasma created by a pulsed corona discharge. The transient plasma (∼50 ns) is found to reduce NOx emission in a flow of 1-10 liters/ second with energy cost ≤10-20 eV/molecule, corresponding to a fraction of source power of ∼5%. The efficiency of NOx reduction is a complex function of parameters that include pulse width, pulse polarity, current density, repetition rate, and reactor design. It was found that best efficiencies are correlated with a low current density (0.2A/cm2) and high repetition rate (1kHz) under high flow rate. Careful optimization of all these parameters is required to reach cost effective NOx reduction.

A set of model fuels has been designed, using the Major-Component Fuel approach, to represent a range of gasoline mid-range and back-end volatilities. The thermo-physical properties of the model fuels have been used, together with a simple model of inlet system, to calculate liquid-vapour mass fractions in the inlet system, and the composition of the inlet port wall film. This has enabled the effects of gasoline volatility, speed, load and inlet port wall temperature to be studied systematically. The results indicate that, in cold start, only some 20-30% of the injected fuel is vapourised in the inlet port, leading to an accumulation of liquid fuel in the inlet port wall film reservoir. As the engine warms up, the mass of fuel in the reservoir decreases, and its composition changes, becoming progressively richer in heavy end species. Mid-range volatility affects the cold start behaviour, whilst back-end volatility affects the approach to fully-warmed up operation.

Recent work has shown that energy efficiencies as well as yields and selectivities of the NOx reduction reaction can be enhanced by combining a plasma discharge with select catalysts. While analysis of gas phase species with a chemiluminescent NOx meter and mass spectrometer show that significant removal of NOx is achieved, high background concentrations of nitrogen preclude the measurement of nitrogen produced from NOx reduction. Results presented in this paper show that N2 from NOx reduction can be measured if background N2 is replaced with helium. Nitrogen production results are presented for a catalyst system where the catalyst is in the plasma region and where the catalyst is downstream from the plasma. The amount of N2 produced is compared with the amount of NOx removed as measured by the chemiluminescent NOx meter. The measured nitrogen from NOx reduction accounts for at least 40% of the total NOx removed for both reactor configurations.

Dielectric barrier discharges offer the advantage to excite molecules to reaction processes on a low temperature level in an O2 containing exhaust gas of gasoline or diesel engines. With the aim of a flexible coaxial reactor and a compact and efficient generator the influence of geometric and electric parameters on the reduction of exhaust gas components was determined. Geometric parameters studied were gap width, length, contour of the reactor. Electric parameters were: voltage curve, voltage height, frequency and electric power. Using the advantage of low temperature reactions it was possible to reduce the HC emission of a gasoline engine by about 35% within an electric power of 1000 W.

Destruction of NOx (200 ppm - 1%) by dielectric barrier corona discharge in zero air and nitrogen was studied at 298 K and pressure 1 atm. Effects of adding of hexane or ammonia were also evaluated. The kinetics and the products of the destruction were determined as functions of the specific discharge energy, contact time and NOx concentration. Two ranges of the specific energy deposition which reflect the competition between the destruction and production of NOx in discharge were found. At low specific energies (< 500 J/L) an efficient removal of NOx both in air and nitrogen is observed.

Solid-state electrochemical cells can be used to sense and reduce NOx from combustion exhaust gases. In the reduction process the products are N2 and O2. For these cells to be effective in fuel-lean combustion exhaust, cathode materials with high selectivity for NO vs. O2 are necessary. Numerous materials were investigated for NO adsorption and reduction selectivity using temperature programmed desorption and reaction (TPD and TPR), respectively, and a summary of that investigation is given. Ceramic cells using these materials were fabricated and used to electrocatalytically reduce NO. An enhanced electrocatalytic three-way activity for NOx reduction was demonstrated that increases the window of operation into fuel-lean conditions. A process that combines selective absorption of NOx with three-way catalytic or electrocatalytic reduction to further increase the window of operation to higher oxygen concentrations was also demonstrated.

An SAE 5W-20 ILSAC GF-2 gasoline engine oil, which improves vehicle fuel efficiency by more than 1.5% relative to conventional SAE 5W-30 gasoline engine oils, was newly developed. And the target that 1.5% fuel efficiency improvement remains more than 10,000km was also achieved. The viscosity of this oil was optimized to satisfy both fuel economy and anti-wear performances. MoDTC and thiadiazole were added to achieve the target.

The International Lubricant Standardization and Approval Committee (ILSAC) GF-2 specification requires Passenger Car Motor Oils to provide enhanced fuel economy in a modern low friction engine (ASTM Sequence VIA). The durability of this fuel economy improvement is becoming increasingly important and will be addressed in the successor to the Sequence VIA, the Sequence VIB, which proposed for ILSAC GF-3. Previous investigations have indicated that the choice of detergent system and friction modifier have a large impact on the fuel economy of a lubricant, and this study was designed to analyze these effects further. The work was carried out in three phases. In the first phase, seven detergent systems were evaluated and compared to currently available GF-2 lubricant in a vehicle equipped with a 4.6L SOHC V8 engine using a 500-mile Accelerated Mileage Accumulation (AMA) cycle.

Many studies suggest that lean-NOx SCR proceeds via oxidation of NO to NO2 by oxygen, followed by the reaction of the NO2 with hydrocarbons. On catalysts that are not very effective in catalyzing the equilibration of NO+O2 and NO2, the rate of N2 formation is substantially higher when the input NOx is NO2 instead of NO. The apparent bifunctional mechanism in the SCR of NOx has prompted the use of mechanically mixed catalyst components, in which one component is used to accelerate the oxidation of NO to NO2, and another component catalyzes the reaction between NO2 and the hydrocarbon. Catalysts that previously were regarded as inactive for NOx reduction could therefore become efficient when mixed with an oxidation catalyst. Preconverting NO to NO2 opens the opportunity for a wider range of SCR catalysts and perhaps improves the durability of these catalysts. This paper describes the use of a non-thermal plasma as an efficient means for selective partial oxidation of NO to NO2.

A Gel Permeation Chromatography-Fourier Transform Infrared (GPC-FTIR) technique is employed to monitor changes in the molecular weight distributions of polymeric oil additives caused by oil aging in vehicle and engine fuel economy tests. Before and after oil aging, the predominant high molecular weight polymers in the oil are the dispersant and viscosity index improver. That is, very few low molecular weight species are oxidized and subsequently polymerized during the fuel economy tests. Molecular changes in the dispersant and viscosity index improver are related to changes in an oil's high temperature high shear viscosity in order to determine their effect on an oil's ability to control fuel economy.

Eight engine oils were evaluated in four GM vehicles in standard EPA fuel economy (FE), vehicle-dynamometer tests. The results were compared with the FE obtained with a standard ASTM reference oil (BC). The viscosity and the friction modification effects of engine oil on vehicle FE were quantified. Combined FE performance in the vehicles ranged from almost 2 percent improvement for an SAE 0W-10 oil, to over 1.5 percent poorer FE than the reference oil for an SAE 10W-40 oil. FE in three engines (3.1L, 3.8L, and 2.3L) showed a strong dependence on the viscosity of the oil (HTHS at either 100° or 150°C). This dependence was stronger during the city portion of the EPA test (lower temperatures) than the highway portion (higher temperatures). For the 5.7L engine no significant effect of oil viscosity on FE was observed although the highest FE seemed to be obtained at an HTHS (at 150°C) viscosity near 3.1 cP.

The California Energy Commission is studying key fuel cell vehicle (FCV) infrastructure issues that need to be addressed in the next decade. This paper reports preliminary findings. A survey was conducted of industry experts on FCV technology status and related fuels. The survey includes information on leading FCV fuels, fuel production, quality, safety concerns, and other key areas. Findings indicate proton-exchange membrane FCVs are likely to be commercial by 2004, and likely fuels in the mid- and long-term include gasoline, methanol, natural gas and hydrogen. Conclusions are drawn and recommendations made to aid the state in preparing for this technology.

Oils, which do not contain Molybdenum (Mo)-based friction modifiers, were aged in vehicle and engine fuel economy tests in order to determine if the different aging protocols caused similar changes in the physical and chemical properties of these oils. Vehicle and engine tests were found to cause similar changes in the high temperature high shear (HTHS) viscosities and boundary friction coefficients of oils. We also observed that the extent of oil oxidation, nitration and volatilization occurring in the vehicle tests could be duplicated by aging in the engine tests. The fuel economy performance of aged oils was also measured in engine tests and found to be highly dependent upon the aged oil's HTHS viscosity. However, we observed that an aged oil's boundary friction coefficient, by itself, did not correlate to an aged oil's fuel economy performance in the high temperature fuel economy measurement stages of engine tests.

The effect of critical physical properties of engine oils on fuel economy performance in General Motors (GM) vehicles has been measured. Reductions in an oil's high temperature high shear viscosity, boundary friction coefficient and pressure-viscosity coefficient were found to equally improve fuel economy. These same oil properties affect fuel economy measured in the Sequence VIA engine test. However, fuel economy performance in GM vehicles is more dependent on an oil's boundary friction coefficient and pressure-viscosity coefficient than that measured in the Sequence VIA engine test. New fuel economy measurement conditions have been proposed for the Sequence VIB engine test. Changes in an oil's boundary friction coefficient were found to have the same effect on fuel economy measured under these new measurement conditions as that measured in GM vehicles.

Biomass is a potential source of renewable fuel energy, but faces several practical barriers. The cost of producing hydrogen by gasification of biomass, using natural gas as cofeedstock, is compared with gasoline as fuel for fuel cell vehicles. Methanol is considered as an essential initial step toward a hydrogen infrastructure because its cost would be competitive with petroleum fuels, its production technology is similar to that of hydrogen, and it is compatible with existing refueling infrastructure with minimum modification. The economic components of these fuel options are examined from the perspective of national interests and goals to assess their efficacy for reduction of long-term environmental impacts, dependence on imports, urban air pollution, and greenhouse gas emissions.

We compare, with respect to vehicle characteristics (design, performance, fuel economy) and infrastructure requirements (cost of producing, transporting and delivering fuel), four possible energy carrier options for use with fuel cell vehicles: compressed hydrogen gas methanol with onboard steam reforming gasoline with onboard partial oxidation synthetic middle distillates (SMD) derived from natural gas with onboard partial oxidation. Our simulations indicate that hydrogen is the preferred fuel for fuel cell vehicles in terms of vehicle weight, simplicity, first cost and fuel economy. The total capital cost for equipment to bring hydrogen to the fuel cell (including both onboard fuel processors and off-vehicle fuel infrastructure) is comparable for methanol, gasoline and SMD, and lower for hydrogen.