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Work and power fluctuations in a critical heat engine.
Viktor Holubec1,2, Artem Ryabov2
1Institut für Theoretische Physik, Universität Leipzig, Postfach 100 920, D-04009 Leipzig, Germany.
Physical Review. E
|January 20, 2018
Summary
Fluctuations in Stirling heat engine work output are significant near critical points. Relative work fluctuations diverge, indicating large work variations are inherent to macroscopic heat engines operating near critical conditions.
Area of Science:
- Thermodynamics
- Statistical Mechanics
- Condensed Matter Physics
Background:
- Stirling heat engines are crucial for energy conversion.
- Critical points in thermodynamics offer unique performance characteristics.
- Previous work by Campisi and Fazio suggested Carnot efficiency at finite power near critical points.
Purpose of the Study:
- To investigate output work fluctuations in Stirling heat engines.
- To compare work fluctuations with average work output.
- To analyze engine performance near a critical point.
Main Methods:
- Analysis of Stirling heat engines with interacting units as working fluid.
- Focus on thermodynamic critical points.
- Scaling analysis of work output variance.
Main Results:
- Work output variance scales with the heat capacity's critical exponent.
- Relative work fluctuations diverge unless strict scaling conditions are met.
- Work and power fluctuations do not vanish even in the infinite system size limit.
Conclusions:
- Large output work fluctuations are inseparable from macroscopic heat engines near critical points.
- Achieving Carnot efficiency at finite power near critical points is challenged by significant work fluctuations.
- These fluctuations dominate the performance of heat engines operating in critical regimes.
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