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Design and Off-Design Performance of 100 kWe-Class Brayton Power Conversion SystemsThe NASA Glenn Research Center in-house computer model Closed Cycle Engine Program (CCEP) was used to explore the design trade space and off-design performance characteristics of 100 kWe-class recuperated Closed Brayton Cycle (CBC) power conversion systems. Input variables for a potential design point included the number of operating units (1, 2, 4), cycle peak pressure (0.5, 1, 2 MPa), and turbo-alternator shaft speed (30, 45, 60 kRPM). The design point analysis assumed a fixed turbine inlet temperature (1150 K), compressor inlet temperature (400 K), helium-xenon working-fluid molecular weight (40 g/mol), compressor pressure ratio (2.0), recuperator effectiveness (0.95), and a Sodium-Potassium (NaK) pumped-loop radiator. The design point options were compared on the basis of thermal input power, radiator area, and mass. For a nominal design point with defined Brayton components and radiator area, off-design cases were examined by reducing turbine inlet temperature (as low as 900 K), reducing shaft speed (as low as 50 percent of nominal), and circulating a percentage (up to 20 percent) of the compressor exit flow back to the gas cooler. The off-design examination sought approaches to reduce thermal input power without freezing the radiator.
Document ID
Document Type
Technical Memorandum (TM)
Johnson, Paul K.
(Analex Corp. Brook Park, OH, United States)
Mason, Lee S.
(NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
September 7, 2013
Publication Date
June 1, 2005
Subject Category
Spacecraft Propulsion And Power
Report/Patent Number
Meeting Information
Space Technology and Applications International Forum(Albuquerque, NM)
Funding Number(s)
WBS: WBS 22-982-10-03
Distribution Limits
Work of the US Gov. Public Use Permitted.
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