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The final report for this project is:
Ernst, William D. and Shaltens, Richard K. (1993), "Automotive
Stirling Engine Development Project", Final Report, NASA
Contractor Report 190780, MTI Report 91TR15
The Abstract, part of the Summary, the main headings from the
Table of Contents and the Conclusions from this report are reproduced
below.
ABSTRACT
The development and verification of automotive Stirling engine
(ASE) component and system technology is described as it evolved
through two experimental engine designs: the Mod I and the Mod
II.
Engine operation and performance and endurance test results
for the Mod I are summarized. Mod II engine and component development
progress is traced from the original design through hardware development,
laboratory test, and vehicle installation. More than 21,000 hr.
of testing were accomplished, including 4800 hr. with vehicles
that were driven more than 59,000 miles. Mod II engine dynamometer
tests demonstrated that the engine system configuration had accomplished
its performance goals for power (60 kW) and efficiency (38.5%)
to within a few percent. Tests with the Mod II engine installed
in a delivery van demonstrated combined metro-highway fuel economy
improvements consistent with engine performance goals and the
potential for low emission levels. A modified version of the Mod
II has been identified as a manufacturable design for an ASE.
As part of the ASE project, the Industry Test and Evaluation
Program (ITEP), NASA Technology Utilization (TU) project, and
the industry-funded Stirling Natural Gas Engine program were undertaken
to transfer ASE technology to end users. The results of these
technology transfer efforts are also summarized.
SUMMARY (partial)
The objectives of the Automotive Stirling Engine (ASE) Development
project were to transfer European Stirling engine technology to
the United States and develop an ASE that would demonstrate 30%
improvement in combined metro-highway fuel economy over a comparable
spark ignition (SI) engine in the same production vehicle. In
addition, the ASE should demonstrate the potential for reduced
emissions levels while maintaining the performance characteristics
of SI engines.
Mechanical Technology Incorporated (MTI) developed the ASE
in an evolutionary manner, starting with the test and evaluation
of an existing stationary Stirling engine and proceeding through
two experimental engine designs: the Mod I and the Mod II. Engine
technology development resulted in elimination of strategic materials,
increased power density, higher temperature and efficiency operation,
reduced system complexity, long-life seals, and low-cost manufacturing
designs. ..........................
(The remaining part of the summary contains essentially the
same material that is contained in the abstract)
MAIN HEADINGS FROM TABLE OF CONTENTS
- SUMMARY
- LIST OF FIGURES
- LIST OF TABLES
- 1.0 INTRODUCTION AND BACKGROUND
- 2.0 MOD I ENGINE SUMMARY
- 3.0 MOD II ENGINE DEVELOPMENT
- 4.0 TECHNOLOGY TRANSFER
- 5.0 TECHNOLOGY STATUS AND DEVELOPMENT NEEDS
- 6.0 CONCLUSIONS
- 7.0 REFERENCES
- APPENDIX A: BIBLIOGRAPHY OF RELEVANT ASE PROJECT PUBLICATIONS
- APPENDIX B: ASE PROJECT DOCUMENTATION CATEGORIZED BY ENGINE
NUMBER
CONCLUSIONS
This final report has summarized work performed in the ASE
project. The project's success can be determined by comparing
accomplishments to the defined project goals and contract requirements.
In so doing, the following conclusions can be made:
- The potential for improvement in fuel economy for Stirling
engines over SI engines has been demonstrated. A 10 to 13% improvement
in fuel economy for the Mod II over the SI engine has been demonstrated
for the USPS LLV in the EPA driving cycle. Based on test data
obtained with the LLV, if the original Mod II Celebrity vehicle
had been retained for fuel economy demonstration, the project
goal of a 30% improvement could have been achieved. The Mod II
engine had been sized and optimized for the Celebrity. Component
optimization would also provide further improvements for USPS
LLV fuel economy.
- The potential for low emissions has been demonstrated in
the Mod II engine: CO=<2.2 g/mi, NOx=<0.9 g/mi, and HC=<0.4
g/mi with gasoline. The 1985 Federal emission limits were easily
met without using a catalyst.
- The ability to operate on a broad range of liquid fuels was
demonstrated. This evaluation was achieved not only in an engine
test cell but also in vehicle operation.
- Measured Mod II SES [Stirling Engine System] power and efficiency
performance was in excellent agreement with analytical projections,
i.e., the differences were less than 4% in power and less than
1% in efficiency.
- Vehicle performance of a Stirling engine can be predicted
from engine dynamometer test results. The Mod II-powered USPS
LLV prediction of a 10% fuel economy improvement in the EPA driving
cycle over the comparable SI-powered vehicle was verified by
experiment.
- A manufacturable Stirling engine automotive design has been
identified under the project. The engine is the Mod II (V-block
design with annular heater head) concept modified per the Deere
& Co. VA/VE study. Manufacturing costs of $3500 to $4000 were
projected by Deere & Co. for commercial production of 15,000
units per year.
- In accomplishing the objective of transferring European Stirling
engine technology to the United States, the ASE project succeeded
in establishing an extensive U.S. technology and vendor base
capable of designing, developing, and commmercializing Stirling
engines. As a further indication of successful technology transfer,
MTI, along with a gas industry consortium (GRI, NYGAS, and others)
and Hercules Engines, Inc. of Canton, Ohio, is developing a commercial
Stirling engine based on ASE technology developed in the Stirling
Natural Gas Engine Program.
- The NASA TU project demonstrated the ability of a Stirling-powered
vehicle to be operated over the road by non-Stirling personnel;
it demonstrated adequate availability and drivability.
The above report is for sale by the National Technical Information
Service, Springfield, Virginia 22161
Last updated: Wednesday, May 3, 1995
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