Review of the Research Program of the Partnership for a New Generation of Vehicles Fourth Report (1998) / Chapter Skim
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2 Development of Vehicle Subsystems
2 Development of Vehicle Subsystems
Pages 20-55
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From page 20... ...
For example, the PNGV high fuel economy level of 80 mpg will require the integration of the primary power plant with energy storage devices, as well as the use of lightweight materials for the vehicle structure to reduce vehicle weight. Despite concerted efforts in the last year to develop and evaluate the various candidate systems, none of the energy conversion power trains being considered meets all of the constraints.
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From page 21... ...
Vehicle weight reduction through the use of new vehicle designs and lightweight materials will be extremely important in achieving the very ambitious fuel economy targets. The committee re-evaluated the candidate energy conversion and energy storage technologies, as well as candidate electrical and electronic systems, that were considered last year and addresses them in this chapter.
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From page 22... ...
The trade-off of fuel economy and weight involved in adding energy conversion devices with a hybrid vehicle design must be carefully evaluated because an increase in vehicle weight results in a decrease in fuel economy. Program Status and Progress The 4SDI team was very active this past year.
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From page 23... ...
Meeting the stretch research objective of 0.01 g/mile particulate emissions will require simultaneous reductions of soot and NOx and cannot be met by manipulating the soot-NOx trade-off relationship. Therefore, breakthrough improvements in engine controls to reduce emissions and for exhaust-gas after-treatment for both NOx and particulates will be required, as well as significant changes in fuels.
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From page 24... ...
Peak thermal efficiency is 2.5 percentage points below the 1997 target; however, improvements are expected in both the Generation I and II versions. Both displacement and weight-specific power are below target for 1997 by 5 and 13 percent, respectively.
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From page 25... ...
Other targets cannot be assessed from tests on a single-cylinder engine. Because of the soot-NOx trade-off inherent in CIDI engines, the more restrictive reserach objective for particulate emissions would alter the basis on which the CIDI engine has been evaluated as a potential PNGV power plant.
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From page 26... ...
NOX, particulates, and fuel economy can be significantly affected in heavy-duty diesel engines by manipulating fuel injection. The extent to which these advanced technologies can be used to improve combustion in small CIDI engines, such as those that would be used in a PNGV concept car, is not known.
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From page 27... ...
The results of early laboratory tests have been encouraging, but the technology must still be demonstrated on an engine. Estimates of the fuel economy penalty for plasma systems are in the range of 2 to 5 percent.
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From page 28... ...
The stretch research objective of 0.01 g/mile requires PNGV to change its research goals accordingly and concentrate on alternative fuels. PNGV should establish a cooperative program with the U.S.
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From page 29... ...
Although the United States cannot claim technical leadership in the general area of automotive-size diesel engines, the PNGV is well aware of the current state of the art and directions in development of this power plant. The USCAR partners are fully capable of utilizing this technology worldwide through their foreign affiliates and international agreements.
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From page 30... ...
Assessment of the Program Excellent progress has been made in the past year in all aspects of the 4SDI program. However, the identification of a stretch research objective for particulate emissions of 0.01 g/mile presents significant additional challenges to the 4SDI program in developing the CIDI engine as a PNGV power plant.
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From page 31... ...
. Because no candidate AGT engines approach the thermal efficiency goal, and in light of progress made with other candidate power plants, the PNGV has dropped the gas turbine engine from its list of promising technologies in 1997.
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From page 32... ...
With the metal AGT as an energy converter, there is no real potential for achieving the PNGV fuel economy target of 80 mpg. Programs to develop ceramic turbogenerators were briefly initiated with Allison (under GM' s HEV Program)
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From page 33... ...
If internal combustion engines can ultimately achieve close to 45 percent thermal efficiency and can economically meet the stringent emission regulations, or if fuel cells using gasoline reformate can be developed with similar efficiencies and lower or equal system costs, then the development of ceramic gas turbines by PNGV should be terminated. If not, the AGT, which has low emissions,4 the potential to provide a thermal efficiency approaching 4NOx problems become worse at higher temperatures.
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From page 34... ...
It is believed that a thermal efficiency of about 30 percent has been achieved by this automotive power plant and that many technical problems have been overcome. One exception may be the long-term containment and retention of the hydrogen working fluid used in this closed-cycle engine.
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From page 35... ...
In fact, the PNGV program seems to consider the use of gasoline as a basic requirement because of the virtual absence of infrastructure for alternative fuels (e.g., hydrogen, ethanol, and methanol)
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From page 36... ...
Until fuel cells can be introduced in large numbers, alternative fuels may be an attractive option. Before fuel cells can become prevalent, however, the difficulties and inefficiencies of processing fuels onboard the vehicle related to transients, small size units, and the temperature mismatch between gasoline reformation (about 700°C)
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From page 37... ...
Tests utilizing low-sulfur gasoline showed an output of about 40 percent hydrogen and 50 ppm of CO at an oxygen stoichiometry of about 1.25.7 In another test, an AD Little Gen-2 50-kW fuel processor was integrated with a LANL three-stage PrOx CO-cleanup system. The resulting reformate (6 to 40 ppm of CO)
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From page 38... ...
Cost Issues Cost projections for gasoline-fueled fuel-cell systems have decreased dramatically but are still very high at $500/kW, nearly double the 1997 goal of $300/kW and about an order of magnitude higher than the 2004 PNGV goal of $50/kW. However, for the first time, rigorous cost analyses are being conducted by Directed Technologies, Inc., for stacks, fuel processors, and ancillary systems.
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From page 39... ...
The combined government-industry investments in transportation fuel-cell technologies in Europe, Japan, and Canada are significant, and individual USCAR partners have responded with ambitious investments and programs of their own. Assessment of the Program Tests of fuel processors, stacks, and complete systems to date have not included emissions and energy efficiencies for cold start-ups, shutdowns, or even rapid transient operation.
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From page 40... ...
ELECTROCHEMICAL ENERGY STORAGE HEVs use energy storage systems to recover and to store braking energy, thereby enhancing overall vehicle system efficiency. Energy storage devices also provide some power during transient and peak power periods, allowing a smaller
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From page 41... ...
, the energy storage device must deliver the difference between the power demanded for rapid vehicle acceleration and the power available from the power plant, and it must deliver this power for a longer period of time. This increases the peak power demand, as well as the energy required from the storage device.
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From page 42... ...
Nickel Metal Hydride Batteries Nickel metal hydride batteries have reached the manufacturing stage for applications in electric vehicles commercialized by GM, Toyota, and Honda. VARTA, the principal contractor to DOE for development of a hybrid vehicle application, was able to meet its performance goals for 10-Ah nickel metal hydride cells.
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From page 43... ...
The committee agrees with the PNGV assessment that breakthroughs will be necessary to increase the specific energy of ultracapacitors significantly and to lower the costs before they can be considered as primary HEV energy storage devices. Assessment of the Program Considerable progress has been made in the development of full-size cells of lithium-ion batteries and of nickel/metal hydride batteries.
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From page 44... ...
The committee was encouraged that the U.S. PNGV contractors appear to be well ahead in energy storage technology for HEV applications.
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From page 45... ...
Program Status, Progress, and Plans The PNGV flywheel technical team is now confident that it is possible to design and build a practical prototype energy storage flywheel system for automotive applications. A significant amount of work on failure containment has provided more confidence that the system can be designed to comply with the established safety criteria.
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From page 46... ...
Assessment of the Program The flywheel technical team is confident that it is now possible to design and build practical energy storage flywheel systems for automotive applications. The team, working with a number of outside agencies, all of whom are providing corroborating data of various kinds, has a firm grasp on the key technology barrier, namely, containment of failure.
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From page 47... ...
Fuel cells for energy generation and flywheels for energy storage could very well be practical within the PNGV time frame. Electrification of major auxiliary functions, e.g., air conditioning and power steering, is attractive for ease of control and improved energy management and efficiency.
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From page 48... ...
The EE technical team is aware of HVAC-related work being done at the national laboratories and is coordinating the electrical requirements of the HVAC system with developments as they are evaluated and adopted by the systems analysis team and the systems engineering team. The USCAR partners have independently chosen HEV designs for the year 2000 concept vehicle.
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From page 49... ...
Recommendation. Given the critical importance of electrical and electronic systems to the success of the PNGV program, the electrical and electronic systems technical team should provide cost models to the systems analysis team as soon as possible to ensure that cost assumptions for other subsystems that rely on power electronics are consistent with the projections and targets.
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From page 50... ...
The PNGV material team also studied the possibility of using a stainless steel space frame but found that it would generate a cost penalty of $200 for a weight saving of only 22 percent, which is half of the savings needed for the Goal 3 vehicle. Aluminum and Magnesium The total potential vehicle weight savings with aluminum sheets and castings is 600 lbs; the total potential weight savings with magnesium castings alone is 150 lbs.
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From page 51... ...
The procedures and processes for recycling aluminum are also in place today, and much of the material is returned to high value automotive applications. As a matter of public record, several aluminumintensive prototype vehicles have been built outside the PNGV program by the USCAR partners and evaluated for ride, handling, NVH, crashworthiness, joining, and painting (Jewett, 1997~.
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From page 52... ...
The total potential weight savings of using metal matrix composites is only 30 to 50 lbs. The major hurdles to developing applications of this material are feedstock costs and the development of a reliable process for compositing the materials.
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From page 53... ...
existing stamping facilities for steel can be used for aluminum without major modifications. Because of aluminum's importance to weight reduction and high fuel economy, a major cooperative research and development agreement (CRADA)
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From page 54... ...
Assessment of the Program In 1997, the PNGV materials technology team and the vehicle engineering team made a thorough joint evaluation of the lightweight material candidates for the Goal 3 technology selection process. The criteria included potential weight savings, feedstock cost, manufacturing cost and feasibility, design and manufacturing experience, and the ability to recycle the material into high-value applications.
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From page 55... ...
Recommendations Recommendation. The development of the continuous casting process of aluminum sheet should be given the highest priority in terms of resources and technical support.
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