Review of the Research Program of the Partnership for a New Generation of Vehicles Second Report (1996) / Chapter Skim
Currently Skimming:
6 Powertrain Developments
6 Powertrain Developments
Pages 46-61
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 46... ...
To meet PNGV goals, roughly a twofold improvement in powertrain efficiency must be achieved while retaining the size, reliability, durability, safety, and affordability of today's cars; meeting even more stringent emissions and recyclability levels; and employing components capable of being mass produced and maintained in a manner similar to current powertrains. Even when combined with reductions in vehicle mass, aerodynamic drag, tire rolling resistance, and other energy-saving vehicle design parameters, the PNGV technical team estimates that achieving the Goal 3 fuel economy target (up to three times fuel efficiency of today's comparable vehicle)
|
From page 47... ...
These technologies are currently being pursued by PNGV for Goal 3 vehicles, all of which will operate as hybrid systems. The powertrain technologies being pursued by the PNGV for Goal 3 vehicles are as follows: four-stroke DICI engines gas turbines stirring engines fuel cells reversible energy-storage devices (namely, batteries, flywheels and ultracapacitors)
|
From page 48... ...
. direct Injection diesels spark ignition engines fuel changes to improve efficiency and reduce emissions wide ratio and continuously variable transmissions reduced engine and driveling losses The PNGV has concluded that gasoline spark-ignited, internalcombustion engines and straight electric vehicles (as opposed to hybrid electric vehicles)
|
From page 49... ...
KEY TECHNOLOGY SUMMARIES Four-Stroke Direct Injection Compression Ignition Engines Development objectives for the thermal efficiency, specific weight and specific power, cost, durability, NOx, and particulate emissions of the Direct Injection Compression Ignition (DICI) engine have been clearly specified and compared to today's engines that use diesel fuel in the PNGV Technology Roadmap.
|
From page 50... ...
The DICI engine development will also have to overcome the label of a "conventional engine" development program. In the committee's view, a variable geometry turbocharged, direct-injected, variable-swirl, compression-ignition engine with a unique lightweight structure, complex highpressure fuel system, using sophisticated electronic controls and exhaust after treatment should not in any way be considered "conventional." It currently is the most promising alternative to achieve the goals of the PNGV program within the prescribed time frame.
|
From page 51... ...
In general, R&D within and outside the PNGV has demonstrated progress in developing gas turbine engines for automotive applications. Partly, this is because of the enormous advances in automotive electronics and precision control capability that can now be applied to the gas turbine system.
|
From page 52... ...
Although progress has been made in the past year, further work is needed to reduce the size, weight, and costs of the necessary heat exchangers. Consequently, the heat recovery area is critical and must be satisfactorily resolved if the gas turbine is to be seriously considered as a prime mover within the PNGV schedule.
|
From page 53... ...
Fuel Cells The challenges faced for fuel cell system development are clearly set out in the PNGV Technical Roadmap, which lists them as: "...cost, efficiency...unattended reliability and durability." In addition it states, "PNGV cost and efficiency targets are the major challenges for fuel processing, while cost and energy density targets are the major challenges for hydrogen storage." System targets set forth in the Technical Roadmap include a peak power efficiency of 53 percent, compared with an estimate of 45 percent today; and a power density of 0.4 kW/l, and specific power of 0.4 kW/kg, both of which are about twice the estimated state of the art today. It is important to note that the efficiencies quoted above are based on the use of hydrogen as a fuel.2 Since it is unlikely that hydrogen can be stored on board a vehicle under the constraints established by PNGV Goal 3, vehicle efficiency calculations based on fuel sources may be more appropriate.
|
From page 54... ...
Several small (10 kW) methanol reformers have been designed; projections of the overall efficiency for the process of producing methanol to provide mechanical energy are on the order of 20 to 25 percent, which is approximately half the target value specificed in the PNGV Technical Roadmap.3 Hydrocarbon partial-oxidation processors may be slightly more efficient overall and are beginning to be explored.
|
From page 55... ...
As noted above, substantial progress is being made, but several major research breakthroughs are still needed for this technology to meet PNGV technical targets and schedules. Energy Storage Devices for Hybrid Electric Vehicles Energy storage remains an essential component of hybrid electric vehicles.
|
From page 56... ...
dual mode, or (3) power-assist hybrids,4 the flywheel is viewed as having potential only for the power-assist Hybrid vehicle configurations are defined as follows: (I)
|
From page 57... ...
Other issues of concern are potential gyroscopic effects coming from shock loading, self-discharge on the order of one-half of one percent per hour of stored energy, and long-term durability. There are also appreciable challenges, as yet unsolved, regarding the appropriate matching of alternator and flywheel design, electrical safety, maintainability of the system, and providing adequate and appropriate cooling (Energy Storage for the Next Generation Vehicle, 19951.
|
From page 58... ...
Progress under the PNGV program, to date, largely has been related to work performed under the DOE hybrid electric vehicle projects, but the Technical Roadmap targets several additional government agencies and other research programs for support of the developments needed for the PNGV Goal 3 vehicle. The challenge will be to coordinate these efforts such that they address the unique automotive requirements and focus on cost reduction as a primary target.
|
From page 59... ...
Fuel cells offer the greatest long-term potential fuel economy gain, with by far the most aggressive improvements required, and have demonstrated substantial progress over the past few years. Each of the various energy-storage and electrical-conversion devices being considered for hybrid powertrains faces very difficult size, weight, efficiency, and cost hurdles.
|
From page 60... ...
RECOMMENDATIONS Recommendation. The PNGV should devote substantial additional resources to the DICI hybrid powertrain in view of its relatively high potential to meet PNGV Goal 3 objectives.
|
From page 61... ...
Presented to the Standing Committee to Review the Research Program of the PNGV at National Academy of Sciences, Washington, D.C., October 31, 1995. Energy Storage for the Next Generation Vehicle.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.