Search Results

The pressing need to improve U.S. energy independence and reduce climate forcing fossil fuel emissions continues to motivate the development of high-efficiency internal combustion engines. A recent trend has been to downsize and turbocharge automotive spark-ignited engines coupled with direct fuel injection to improve engine efficiency while maintaining vehicle performance. In-line with recent trends in state-of-the-art engine technology, the focus of this study is lean and EGR dilute combustion in a gasoline direct injection (GDI) engine. The lean and dilute operating limits are defined by combustion stability typically in terms of COVIMEP so experiments were carried out on an automotive size single-cylinder research engine to characterize combustion stability. From a 20,000 cycle sequence analysis, lean operating conditions exhibit binary high- to low-IMEP cycle sequences. This may be because the cycle-to-cycle feedback mechanisms are physically limited to one or two cycles.

Dual-fuel combustion using liquid fuels with differing reactivity has been shown to achieve low-temperature combustion with moderate peak pressure rise rates, low soot and NOx emissions, and high indicated efficiency. Varying fractions of gasoline-type and diesel-type fuels enable operation across a range of low- and mid-load operating conditions. Expanding the operating range to cover the full operating range of a heavy-duty diesel engine, while maintaining the efficiency and emissions benefits, is a key objective. With dissimilar properties of the two utilized fuels lying at the heart of the dual-fuel concept, a tool for enabling this load range expansion is altering the properties of the two test fuels - this study focuses on altering the reactivity of the diesel fuel component. Tests were conducted on a 13L six-cylinder heavy-duty diesel engine modified to run dual-fuel combustion with port gasoline injection to supplement the direct diesel injection.

A follow-up to the 1989 Society of Automotive Engineers (SAE) Methanol Marathon called the Methanol Challenge was held in April 1990. One of a series of engineering student competitions using alternative fuels organized and conducted by the Center for Transportation Research at Argonne National Laboratory, the Methanol Challenge pushed the technology for dedicated M85 (85% methanol, 15% hydrocarbon fuel) methanol passenger cars to new levels. The event included complete federal exhaust emissions, cold-start and driveability, performance, and fuel economy testing. Twelve teams of student engineers from the United States and Canada competed in the Challenge using Chevrolet Corsicas donated by General Motors (GM) to the schools. The winning car, from the University of Tennessee, simultaneously demonstrated extremely low emissions, dramatically increased performance, and significantly improved fuel economy.

Vehicle operation during cold-start powertrain conditions can have a significant impact on drivability, fuel economy and tailpipe emissions in modern passenger vehicles. As efforts continue to maximize fuel economy in passenger vehicles, considerable engineering resources are being spent in order to reduce the consumption penalties incurred shortly after engine start and during powertrain warmup while maintaining suitably low levels of tailpipe emissions. Engine downsizing, advanced transmissions and hybrid-electric architecture can each have an appreciable effect on cold-start strategy and its impact on fuel economy. This work seeks to explore the cold-start strategy of several passenger vehicles with different powertrain architectures and to understand the resulting fuel economy impact relative to warm powertrain operation. To this end, four vehicles were chosen with different powertrain architectures.

Two-phase flow experiments were performed with air/water mixtures in a small rectangular channel measuring 9.52 x 1.59 mm (aspect ratio equal to 6), for application to compact heat exchangers. Pressure drop and flow pattern definition data were obtained over a large range of mass qualities (0.0002 to 1) and, in the case of flow pattern data, a large range of mass fluxes (50 to 2,000 kg/m2s). A flow pattern map, based on visual observations and photographs of the flow patterns, is presented and compared with a map developed for a rectangular channel of the same aspect ratio but with dimensions twice those of the test channel, and with a map developed for a circular tube with the same hydraulic diameter of 3 mm. Pressure drop data are presented as a function of both mass quality and Martinelli parameter and are compared with state-of-the-art correlations and a modified Chisholm correlation.

A new method is proposed for controlling the temperature of high-temperature batteries namely, varying the hydrogen pressure inside of multifoil insulation by varying the temperature of a reversible hydrogen getter. Calculations showed that the rate of heat loss through 1.5 cm of multifoil insulation between a hot-side temperature of 425°C and a cold-side temperature of 25°C could be varied between 17.6 W/m2 and 7,000 W/m2. This change in heat transfer rate can be achieved by varying the hydrogen pressure between 1.0 Pa and 1000 Pa, which can be done with an available hydrogen gettering alloy operating in the range of 50°C to 250°C. This approach to battery cooling requires cylindrical insulating jackets, which are best suited for bipolar batteries having round cells approximately 10 to 18 cm in diameter.

The Natural Gas Vehicle (NGV) Challenge '92, was organized by Argonne National Laboratory. The main sponsors were the U.S. Department of Energy the Energy, Mines, and Resources - Canada, and the Society of Automotive Engineers. It resulted in 20 varied approaches to the conversion of a gasoline-fueled, spark ignited, internal combustion engine to dedicated natural gas use. Starting with a GMC Sierra 2500 pickup truck donated by General Motors, teams of college and university student engineers worked to optimize Chevrolet V-8 engines operating on natural gas for improved emissions, fuel economy, performance, and advanced design features. This paper focuses on the results of the emission event, and compares engine mechanical configurations, engine management systems, catalyst configurations and locations, and approaches to fuel control and the relationship of these parameters to engine out and tailpipe emissions of regulated exhaust constituents.

Loss mechanisms affecting the performance of an MHD seawater thruster system have been identified and discussed. Among those losses are the jet and nozzle losses, joule heating losses, surface potential and electro-chemical losses, frictional losses, and electrical end losses. Simple, but accurate, models have been used to assess the relative and absolute magnitude of these losses and to investigate their influence on the overall thruster efficiency. A parametric study has been performed for a generic full size seawater vehicle propelled by an MHD thruster at different operating conditions. The results of this study confirm that higher efficiencies can be achieved at high magnetic field strengths (> 10 Tesla). Furthermore, the results indicate that higher efficiencies can be maintained over a wide range of cruising speeds (2-20 m/s or 4-40 knots) at higher magnetic fields (20 Tesla).

In this paper, recent advances in fabrication of high-temperature superconductor wires are summarized and detailed discussion is provided on developments in near- and intermediate-term applications. Near-term applications, using presently obtainable current densities, include liquid-nitrogen depth sensors, cryostat current leads, and magnetic bearings. Intermediate-term applications, using current densities expected to be available in the near future, include fault-current limiters and short transmission lines.

A production spark ignition engine powered vehicle (3.1-L Chevrolet Lumina, model year 1990) was tested with oxygen-enriched intake air containing 25 and 28% oxygen by volume to determine if (1) the vehicle would run without difficulties and (2) there would be emissions benefits. Standard Federal Test Procedure (FTP) emissions test cycles were run satisfactorily without vehicle performance anomalies. The results of catalytic converter-out (engine with a three-way catalytic converter in place) emissions showed that both carbon monoxide and hydrocarbons were reduced significantly in all three phases of the emissions test cycle, compared with normal air (21 % oxygen). Carbon monoxide emissions from the engine (with the three-way catalytic converter removed) were significantly reduced in the cold-phase of the test cycle. The catalytic converter also had an improved carbon monoxide conversion efficiency under the oxygen-enriched air conditions.

A test series was conducted on a six-cylinder diesel engine to study the impacts of controlled factors (i.e., oxygen content of the combustion air, water content of the fuel, fuel-flow rate, and fuel-injection timing) on engine performance and emissions using Taguchi techniques. Separate experiments were conducted using a commercial-grade No. 2-diesel and a lower-grade No. 6-diesel fuel. This paper reports the test results for No. 6 fuel. Oxygen enrichment improved the combustion process with the lower-grade fuel. There was no observable change in turbocharger performance due to oxygen enrichment. The results showed significant reductions in smoke and particulate emissions, a small increase in thermal efficiency and a large increase in NOx emissions when oxygen-enriched air was used. The effect of water-emulsified fuel on NOx emissions was negligible.

A hybrid bus powered by a diesel engine and a battery pack has been analyzed over an idealized bus-driving cycle in Chicago. Three hybrid configurations, two parallel and one series, have been evaluated. The results indicate that the fuel economy of a hybrid bus, taking into account the regenerative braking, is comparable with that of a conventional diesel bus. Life-cycle costs are slightly higher because of the added weight and cost of the battery.

Statistical analyses of the acceleration capability of gasoline vehicles have focused on zero to 97 km/h acceleration rates and have concluded that peak power per kilogram is an appropriate single surrogate for acceleration capability. In this paper, statistical methods are used with data for 107 vehicles tested and reported by Consumers Union for 1986-1988 model years to estimate the determinants of contemporary gasoline vehicle acceleration capability under various conditions, adding new variables to the statistical tests reported by others. Like previous studies, this analysis determined that power and weight provide the most information about acceleration capability. Using a model formulation unlike other studies, this study found that engine displacement also provides statistically significant improvements in explanation of 0-48, 0-97, and 48-97 km/h acceleration times.

Advanced battery technology evaluations are performed under simulated electric-vehicle operating conditions at the Analysis & Diagnostic Laboratory (ADL) of Argonne National Laboratory. The ADL results provide insight into those factors that limit battery performance and life. The ADL facilities include a test laboratory to conduct battery experimental evaluations under simulated application conditions and a post-test analysis laboratory to determine, in a protected atmosphere if needed, component compositional changes and failure mechanisms. This paper summarizes the performance characterizations and life evaluations conducted during 1991 - 1992 on both single cells and multi-cell modules that encompass eight battery technologies [Na/S, Li/MS (M=metal), Ni/MH, Ni/Cd, Ni/Zn, Ni/Fe, Zn/Br, and Pb-acid]. These evaluations were performed for the Department of Energy, Office of Transportation Technologies, Electric and Hybrid Propulsion Division, and the Electric Power Research Institute.

This paper explores the impact of U.S. emission controls and fuel economy improvements on the global warming potential (GWP) of new light-duty vehicles. Fuel economy improvements have reduced the GWP of both passenger cars and light-duty trucks by lowering the per mile emissions of carbon dioxide (CO2). Further GWP reductions have been achieved by emission standards for criteria pollutants: carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). The GWP of a criteria pollutant was calculated by multiplying the emission rate by a relative global warming factor to obtain a CO2 equivalent emission rate. Both CO2 and criteria pollutant emission rates per vehicle have decreased substantially for new light-duty vehicles over the period from 1968 to 1991. Over that period, the GWP from CO2 was reduced by almost 50% in new vehicles by improving fuel economy.

A two Tesla test facility was designed, built, and operated to investigate the performance of magnetohydrodynamic (MHD) seawater thrusters. The results of this investigation are used to validate MHD thruster performance computer models. The facility test loop, its components, and their design are presented in detail. Additionally, the test matrix and its rationale are discussed. Finally, representative experimental results of the test program are presented, and are compared to pretest computer model predictions. Good agreement between predicted and measured data has served to validate the thruster performance computer models.

Advanced heat-pump cycles are being investigated for various applications. However, the working media and associated thermal design aspects require new concepts for maintaining high thermal effectiveness and phase equilibrium for achieving maximum possible thermodynamic advantages. In the present study, the heat- and mass-transfer processes in two heat-pump systems -- those based on absorption processes, and those using refrigerant mixtures -- are analyzed. The major technical barriers for achieving the ideal performance predicted by thermodynamic analysis are identified. The analysis provides general guidelines for the development of heat- and mass-transfer equipment for advanced heat-pump systems.

The U.S. Department of Energy sponsored several student engineering competitions in 1993 that provided useful information on electric and hybrid electric vehicles. The electrical energy usage from these competitions has been recorded with a custom-built digital meter installed in every vehicle and used under controlled conditions. When combined with other factors, such as vehicle mass, speed, distance traveled, battery type, and type of components, this information provides useful insight into the performance characteristics of electrics and hybrids. All the vehicles tested were either electric vehicles or hybrid vehicles in electric-only mode, and had an average energy economy of 7.0 km/kWh. Based on the performance of the “ground-up” hybrid electric vehicles in the 1993 Hybrid Electric Vehicle Challenge, data revealed a 1 km/kWh energy economy benefit for every 133 kg decrease in vehicle mass.

A two-stage Delphi study was conducted to collect expert opinion concerning long-term (2000-2020) technical and economic attributes of electric (EV) and hybrid-electric (HEV) vehicles in comparison to conventional gasoline vehicles. The study questionnaire was divided into three parts: the first addressed vehicles; the second, vehicle components; and the third, the impact on the transportation system of electric and hybrid vehicle use. This paper reports selected results from the first round of the survey. This international survey obtained information from 191 expert respondents in the automotive-technology field. The experts' skills predominantly reflected specialization in electric drivetrain vehicles and/or components.

The 1994 Hybrid Electric Vehicle Challenge provided the backdrop for collecting data and developing testing procedures for hybrid electric vehicle technology available at colleges and universities across North America. The data collected at the competition was analyzed using the HEV definitions from the draft SAE J1711 guidelines. The energy economy, percentage of electrical to total energy used, and acceleration performance was analyzed for any correlation between the over-the-road data and the commuter-sustaining, commuter-depleting, and reserve-sustaining hybrid vehicles. The analysis did not provide any direct correlation between over-the-road data and the three hybrid types. The analysis did show that the vehicle configurations provide the best information on vehicle performance. It was also clear that a comprehensive data analysis system along with a well-defined testing procedure would allow for a more complete analysis of the data.