Advanced Stirling Convertor (ASC) Technology Maturation

Wong, Wayne A.; Wilson, Scott D.; Collins, J.O.; Wilson, K. B.

doi:10.2514/6.2015-3806

Cited by 13 publications

(7 citation statements)

References 7 publications

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“…The two Stirling convertors used in the KRUSTY test, each composed of an engine and linear alternator, were made by Sunpower Inc. in 2010 as engineering units for the Advanced Stirling Radioisotope Generator (ASRG) project. [4][5][6] The units, named Advanced Stirling Convertor E2-7 and E2-8, were originally intended for durability testing and completed several centrifuge and vibration tests during the 2010 to 2012 timeframe. In November 2012 the units were upgraded to include additional features that were necessary to improve manufacturability for the flight project.…”

Section: Ib Stirling Convertors and Balancersmentioning

confidence: 99%

Heat Transport and Power Conversion of the Kilopower Reactor Test

et al. 2020

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The Kilopower reactors have been designed to provide a steady-state thermal power range between 4 and 40 kW and to convert the heat generated to an electrical output of 1 to 10 kW(electric), providing an overall system efficiency of 25%. This range of thermal and electrical power has been derived from two basic designs: the small 1-kW(electric) design and the larger 10-kW(electric) electric design intended to support science and human exploration missions for surface and in-space power. The Kilowatt Reactor Using Stirling TechnologY (KRUSTY) experiment was built using the 1-kW(electric) Kilopower design to make the test affordable by using existing infrastructure and to complete it in a 3-year timeframe. The data from the smaller, lower-mass system could be extended to the larger 10-kW(electric) system, knowing that the materials and neutronic design are similar. Each of these designs use the same fuel, heat transport systems, and power conversion systems at the appropriate scale to produce the desired electrical output power for mission use. The heat transport system uses multiple heat pipes that operate passively and do not require any electrical pumps or other parasitic loads to cool the reactor core. This type of reactor cooling provides several layers of redundancy and makes it ideal for coupling a self-regulating reactor to a variable-output power conversion system. The power converters accept the reactor heat that has been delivered by the heat pipes and create the needed electrical power through their thermodynamic Stirling cycle and linear alternator. This paper provides details about the sodium heat pipes used in the experiment, the Stirling power converters that create the electricity, and the overall power system that make up the 1-kW(electric) Kilopower reactor.

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Section: Ib Stirling Convertors and Balancersmentioning

confidence: 99%

Heat Transport and Power Conversion of the Kilopower Reactor Test

et al. 2020

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“…Sunpower has previously demonstrated gas-bearing engineering methods on cryocoolers and the ASC from the ASRG project (Ref. 17). Sunpower has identified Haynes ® 230 ® alloy (Haynes International) as the hot-end material, which has a substantial creep database, but may need to be supplemented to finalize the heater head design.…”

Section: Sunpower Inc Robust Stirling Convertor (Srsc)mentioning

confidence: 99%

Dynamic Power Convertor Development for Radioisotope Power Systems at NASA Glenn Research Center

Oriti

Wilson

2018

2018 International Energy Conversion Engineering Conference

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The Thermal Energy Conversion Branch at NASA Glenn Research Center is supporting the development of high-efficiency power convertors for use in radioisotope power systems (RPS). Significant progress was made toward such a system that utilized Stirling conversion during the 2001 to 2015 timeframe. Flight development of the Advanced Stirling Radioisotope Generator (ASRG) was canceled in 2013 by the U.S. Department of Energy (DOE) and NASA Headquarters primarily due to budget constraints, and the Advanced Stirling Convertor (ASC) technology contract was subsequently concluded in 2015. A new chapter of technology development has recently been initiated by the NASA RPS Program. This effort is considering all dynamic power convertor options, such as Stirling and Brayton cycles. Four convertor development contracts supporting this effort were awarded in 2017. The awarded contracts include two free-piston Stirling, one thermoacoustic Stirling, and one turbo-Brayton design. The technology development contracts each consist of up to three phases: design, fabrication, and test. As of May 2018, all contracts have completed the design phase, and each underwent a design review with an independent review board. Three of the contracts are planned to execute the phase 2 option for fabrication. Convertors manifesting from these development efforts will then undergo independent validation and verification (IV and V) at NASA facilities, which will consist of convertor performance and RPS viability demonstrations. Example tests include launch vibration simulation, performance mapping over the environmental temperature range, and static acceleration exposure. In parallel with this renewed development effort, Glenn is still demonstrating free-piston Stirling convertor technology using assets from previous projects. The Stirling Research Laboratory (SRL) is still operating several convertors from previous development projects, which have similarities and relevance to current contract designs. Four of these are flexure-bearing based and another six are gas bearing based. One of the flexure-bearing convertors has accumulated over 110,000 h of operation and holds the current record for maintenance-free heat-engine run time. Another flexure-bearing convertor was recently manually shut down after 105,620 h of operation, then disassembled and inspected. This inspection produced a wealth of information about the effects of this amount of run time on the technology's components. One of the engineering unit flexure-bearing convertors recently underwent a launch simulation vibration test, a static acceleration exposure up to 20 g, and was then placed on extended operation. Among the gas-bearing convertors, the longest running unit has accumulated over 70,000 h of operation. Four high-fidelity gas-bearing convertors from the ASRG project are still operating continuously for which the longest run time has reached 28,000 h.

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“…The Stirling Cycle Technology Development Project (SCTD) is funded by the RPS Program to develop Stirling-based subsystems, including convertors and controller American Institute of Aeronautics and Astronautics maturation efforts that have resulted in high fidelity hardware like the ASRG, ASC, and ACU. 1,2 The SCTD Project also performs research to develop less mature technologies with a wide variety of objectives, including increasing temperature capability to enable new environments, improving system reliability or fault tolerance, reducing mass or size, and developing advanced concepts that are mission enabling. 3 The development of the new linear alternator concepts discussed in this paper is focused on improving system reliability and reducing mass.…”

Section: Introductionmentioning

confidence: 99%