Status of the NASA Stirling Radioisotope Project


Book Description

Free-piston Stirling power conversion has been considered a candidate for radioisotope power systems for space for more than a decade. Prior to the free-piston Stirling architecture, systems were designed with kinematic Stirling engines that used linkages and rotary alternators to convert heat to electricity. These systems were able to achieve long life by lightly loading the linkages; however, the live was nonetheless limited. When the free-piston configuration was initially proposed, it was thought to be attractive due to the relatively high conversion efficiency, acceptable mass, and the potential for long life and high reliability based on wear-free operation. These features have consistently been recognized by teams that have studied technology options for radioisotope space power systems. Since free-piston Stirling power conversion was first considered for space power applications, there have been major advances in three general areas of development: hardware that has demonstrated long-life and reliability, the success achieved by Stirling cryocoolers in space, and the overall developmental maturity of the technology for both space and terrestrial applications. Based on these advances, free-piston Stirling convertors are currently being developed for space power, and for a number of terrestrial applications. They commonly operate with the power, efficiency, life, and reliability as intended, and much of the development now centers on system integration. This paper will summarize the accomplishments of free-piston Stirling power conversion technology over the past decade, review the status of development with regard to space power, and discuss the challenges that remain. Schreiber, Jeffrey G. Glenn Research Center NASA/TM-2007-214804, E-15937 WBS 138494.04.01.01 STIRLING ENGINES; NUCLEAR ELECTRIC POWER GENERATION; FREE-PISTON ENGINES; MECHANICAL ENGINEERING; TECHNOLOGY UTILIZATION; RADIOISOTOPE HEAT SOURCES; AC GENERATORS; KINEMATICS; CRYOGENIC COOLING; RADIATORS; PANELS; SIMULATORS; VIBRATION TESTS; RELIABILITY ANALYSIS; CONTROLLERS; RANDOM VIBRATION; SYSTEMS INTEGRATION




Overview of NASA Lewis Research Center Free-piston Stirling Engine Technology Activities Applicable to Space Power Systems


Book Description

An overview is presented of the National Aeronautics and Space Administration (NASA) Lewis Research Center free-piston Stirling engine activities directed toward space-power application. One of the major elements of the program is the development of advanced power conversion concepts of which the Stirling cycle is a viable candidate. Under this program the research findings of the 25 kWe opposed-piston Space Power Demonstrator Engine (SPDE) are presented. Included in the SPDE discussion are initial differences between predicted and experimental power outputs and power output influenced by variations in regenerators. Projections are made for future space-power requirements over the next few decades. A cursory comparison is presented showing the mass benefits that a Stirling system has over a Brayton system for the same peak temperature and output power.




Status of the NASA Stirling Radioisotope Project


Book Description

Free-piston Stirling power conversion has been considered a candidate for radioisotope power systems for space for more than a decade. Prior to the free-piston Stirling architecture, systems were designed with kinematic Stirling engines that used linkages and rotary alternators to convert heat to electricity. These systems were able to achieve long life by lightly loading the linkages; however, the live was nonetheless limited. When the free-piston configuration was initially proposed, it was thought to be attractive due to the relatively high conversion efficiency, acceptable mass, and the potential for long life and high reliability based on wear-free operation. These features have consistently been recognized by teams that have studied technology options for radioisotope space power systems. Since free-piston Stirling power conversion was first considered for space power applications, there have been major advances in three general areas of development: hardware that has demonstrated long-life and reliability, the success achieved by Stirling cryocoolers in space, and the overall developmental maturity of the technology for both space and terrestrial applications. Based on these advances, free-piston Stirling convertors are currently being developed for space power, and for a number of terrestrial applications. They commonly operate with the power, efficiency, life, and reliability as intended, and much of the development now centers on system integration. This paper will summarize the accomplishments of free-piston Stirling power conversion technology over the past decade, review the status of development with regard to space power, and discuss the challenges that remain. Schreiber, Jeffrey G. Glenn Research Center WBS 138494.04.01.01







Space Technology and Applications International Forum - 2000


Book Description

The proceedings document the opportunities for space science onboard the international space station (ISS), currently under construction by an international consortium. These proceedings include the latest on the construction of and payload operations on the ISS; human physiology in space; fundamental physics; engineering research and technology development; thermal control technologies for future spacecraft; propulsion technology for interstellar precursor missions; breakthrough propulsion physics; next generation commercial/civil space transportation and reusable launch systems technology; spaceport development; potential manned and unmanned space missions; and advances in energy conversion technologies. STAIF-2000 is co-sponsored by NASA Headquarters and Field Centers, DOE, and The Boeing Company, in cooperation with major professional societies. Government aerospace industry and universities exhibit and present papers.







Overview of NASA Lewis Research Center Free-piston Stirling Engine Activities


Book Description

An overview of the National Aeronautics and Space Administration (NASA) Lewis Research Center (LeRC) free-piston Stirling engine activities is presented. These include (1) a generic free-piston Stirling technology project being conducted to develop technologies generic to both space power and terrestrial heat pump applications in a cooperative, cost-shared effort with the Department of Energy (DOE)/Oak Ridge National Laboratory (ORNL); and (2) a free-piston Stirling space power technology feasibility demonstration project being conducted in support of the Defense Advanced Research Projects Agency (DARPA), DOE, NASA, SP-100 project. The generic technology effort includes extensive parametric testing of a 1 kW free-piston Stirling engine (RE-1000), development of a free-piston Stirling performance computer code, design and fabrication under contract of a hydraulic output modification for RE-1000 engine tests, and a 1000-hour endurance test, under contract, of a 3 kWe free-piston Stirling/alternator engine. The newly initiated space power technology feasibility demonstration effort addresses the capability of scaling a free-piston Stirling/alternator system to about 25 kWe; developing thermodynamic cycle efficiency greater than or equal to 70 percent of Carnot at temperature ratios in the order of 1.5 to 2.0; achieving a power conversion unit specific weight of 6 kg/kWe; operating with noncontacting gas bearings; and dynamically balancing the system. Planned engine and component design and test efforts are described.