Free-piston Stirling convertors (Stirling engine with integral linear alternator) are a mature technology with demonstrated long-life, maintenance-free, degradation-free operation exceeding 46,000 hours (5+ years) on one unit. Tens of thousands of hours have been accumulated on numerous systems in beta trials, plus more than 8 million flexure-hours (900 flexure-years) on the most critical component (flexure bearings), all with no failures when operated within specifications. Vibration is a key concern for Stirling convertors in space. Recent tests have demonstrated a factor of 50 reduction in vibration, relative to a single convertor, by coupling two convertors mechanically and electrically. Even though the measured vibration level is below Jet Propulsion Laboratory (JPL) specified vibration objectives, demonstration of an additional factor of 10 vibration reduction is pending with an active vibration reduction system. Stirling cycle efficiency is well established. A four-convertor 150-W(e) end of mission (EOM) power system for deep space missions is projected to require only three general purpose heat source (GPHS) modules with conservative Inconel 718 heater heads, leaving significant efficiency improvement potential when used with higher temperature materials. Even in the unlikely scenario of one inoperative convertor, the other three convertors ramp up to provide full output. A two-convertor demonstration system, representative of one-half of a 150-W(e) power system, is described in this paper and scheduled to become operational in December 1998.


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    Title :

    Technology demonstration of a free-piston stirling advanced radioisotope space power system



    Conference:

    Space technology and applications international forum -1999 ; 1999 ; Albuquerque, New Mexico (USA)


    Published in:

    AIP Conference Proceedings ; 458 , 1 ; 1413-1419


    Publication date :

    1999-01-22


    Size :

    7 pages





    Type of media :

    Conference paper


    Type of material :

    Electronic Resource


    Language :

    English



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