Improving Free-Piston Stirling Engine Power Density NASA/TM-2016-219144

By NASA and National Aeronautics and Space Administration

Analyses and experiments demonstrate the potential benefits of optimizing pistonand displacer motion in a free piston Stirling Engine. Isothermal analysis shows thetheoretical limits of power density improvement due to ideal motion in ideal Stirlingengines. More realistic models based on nodal analysis show that ideal piston anddisplacer waveforms are not optimal, often producing less power than engines that usesinusoidal piston and displacer motion. Constrained optimization using nodal analysispredicts that Stirling engine power density can be increased by as much as 58% usingoptimized higher harmonic piston and displacer motion. An experiment is conducted inwhich an engine designed for sinusoidal motion is forced to operate with both second andthird harmonics, resulting in a maximum piston power increase of 14%. Analyticalpredictions are compared to experimental data showing close agreement with indirectthermodynamic power calculations, but poor agreement with direct electrical powermeasurements.

• Format: Paperback
• Language: English
• ISBN: 1542546877
• ISBN13: 9781542546874
• Release Date: January 2017
• Publisher: CreateSpace Independent Publishing Platform
• Length: 148 Pages
• Weight: 0.99 lbs.
• Dimensions: 0.3" x 8.5"