Power-Optimal Control of a Stirling Engine's Frictional Piston Motion.

Area of Science:

• Thermodynamics
• Mechanical Engineering
• Energy Systems

Background:

• Stirling engines offer efficient heat-to-power conversion.
• Optimizing engine performance is crucial for energy efficiency.
• Dissipative processes like friction limit Stirling engine output.

Purpose of the Study:

• To investigate performance enhancements in alpha-Stirling engines.
• To optimize piston motion considering mechanical friction and finite heat transfer.
• To evaluate an indirect iterative gradient method against other optimization approaches.

Main Methods:

• Utilized a low-effort endoreversible Stirling engine model.
• Incorporated finite heat/mass transfer and piston friction.
• Applied an indirect iterative gradient method based on Pontryagin's maximum principle.

Main Results:

• The iterative gradient method yielded superior performance improvements compared to harmonic motion.
• Optimization results varied with different friction coefficients.
• The advanced method demonstrated significant gains over previous parameterization techniques.

Conclusions:

• Optimizing piston motion via iterative gradient methods is highly effective for enhancing Stirling engine power output.
• The study highlights the benefits of advanced numerical methods for engine design.
• Friction significantly impacts performance, necessitating sophisticated optimization strategies.