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TITLE AND SUBTITLE:
Development of Advanced Stirling Radioisotope Generator for Space Exploration
AUTHOR(S):
Chan, Jack; Wood, J., Gary; Schreiber, Jeffrey, G.
REPORT DATE:
2007-05-14
FUNDING NUMBERS:
WBS 138494.04.01.01
PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration John H. Glenn Research Center at Lewis Field Cleveland, Ohio 44135-3191
PERFORMING ORGANIZATION REPORT NUMBER:
E-15939
SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration Washington, DC 20546-0001
REPORT TYPE AND DATES COVERED:
Technical Memorandum
SPONSORING/MONITORING AGENCY REPORT NUMBER:
NASA/TM-2007-214806
SUPPLEMENTARY NOTES:
ABSTRACT:
Under the joint sponsorship of the Department of Energy and NASA, a radioisotope power system utilizing Stirling power conversion technology is being developed for potential future space missions. The higher conversion efficiency of the Stirling cycle compared with that of Radioisotope Thermoelectric Generators (RTGs) used in previous missions (Viking, Pioneer, Voyager, Galileo, Ulysses, Cassini, and New Horizons) offers the advantage of a four-fold reduction in PuO2 fuel, thereby saving cost and reducing radiation exposure to support personnel. With the advancement of state-of-the-art Stirling technology development under the NASA Research Announcement (NRA) project, the Stirling Radioisotope Generator program has evolved to incorporate the advanced Stirling convertor (ASC), provided by Sunpower, into an engineering unit. Due to the reduced envelope and lighter mass of the ASC compared to the previous Stirling convertor, the specific power of the flight generator is projected to increase from 3.5 to 7 We/kg, along with a 25 percent reduction in generator length. Modifications are being made to the ASC design to incorporate features for thermal, mechanical, and electrical integration with the engineering unit. These include the heat collector for hot end interface, cold-side flange for waste heat removal and structural attachment, and piston position sensor for ASC control and power factor correction. A single-fault tolerant, active power factor correction controller is used to synchronize the Stirling convertors, condition the electrical power from AC to DC, and to control the ASCs to maintain operation within temperature and piston stroke limits. Development activities at Sunpower and NASA Glenn Research Center (GRC) are also being conducted on the ASC to demonstrate the capability for long life, high reliability, and flight qualification needed for use in future missions.
SUBJECT TERMS:
Stirling; Engine; Convertor; Radioisotope power; Generator; Controller
NUMBER OF PAGES:
16
PDF AVAILABLE FROM URL:
2007/TM-2007-214806.pdf ( 1053 KB )
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