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Improving Power Density of Free-Piston Stirling EnginesAnalyses and experiments demonstrate the potential benefits of optimizing piston and displacer motion in a free piston Stirling Engine. Isothermal analysis shows the theoretical limits of power density improvement due to ideal motion in ideal Stirling engines. More realistic models based on nodal analysis show that ideal piston and displacer waveforms are not optimal, often producing less power than engines that use sinusoidal piston and displacer motion. Constrained optimization using nodal analysis predicts that Stirling engine power density can be increased by as much as 58 using optimized higher harmonic piston and displacer motion. An experiment is conducted in which an engine designed for sinusoidal motion is forced to operate with both second and third harmonics, resulting in a maximum piston power increase of 14. Analytical predictions are compared to experimental data showing close agreement with indirect thermodynamic power calculations, but poor agreement with direct electrical power measurements.
Document ID
20170001730
Acquisition Source
Glenn Research Center
Document Type
Conference Paper
Authors
Briggs, Maxwell H.
(NASA Glenn Research Center Cleveland, OH United States)
Prahl, Joseph
(Case Western Reserve Univ. Cleveland, OH, United States)
Loparo, Kenneth
(Case Western Reserve Univ. Cleveland, OH, United States)
Date Acquired
February 22, 2017
Publication Date
July 25, 2016
Subject Category
Engineering (General)
Report/Patent Number
GRC-E-DAA-TN32617
Meeting Information
Meeting: Propulsion and Energy Forum
Location: Salt Lake City, UT
Country: United States
Start Date: July 25, 2016
End Date: July 27, 2016
Sponsors: American Inst. of Aeronautics and Astronautics
Funding Number(s)
WBS: WBS 887359.04.01.02.03
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
space technology
power generation control
Stirling engines
heat engines power generation
cogeneration
aerospace engineering
thermodynamics
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