Ecological efficiency of finite-time thermodynamics: A molecular dynamics study

Area of Science:

• Thermodynamics
• Statistical Mechanics
• Computational Physics

Background:

• Carnot engines are theoretical benchmarks for heat engine efficiency.
• Endoreversible thermodynamics models engines with internal irreversibilities.
• Molecular dynamics simulations offer a powerful tool for studying nanoscale engines.

Purpose of the Study:

• To perform a molecular dynamics simulation of a two-dimensional Carnot engine.
• To optimize engine performance, including power output and ecological efficiency.
• To investigate the validity of endoreversible models for near-ideal gas systems.

Main Methods:

• Molecular dynamics simulation of a two-dimensional Carnot engine.
• Optimization of engine performance through control of piston velocity.
• Comparison of simulation results with ideal gas approximations and endoreversible models.

Main Results:

• Maximum power and ecological efficiencies were computed.
• Near-ideal gas working substance exhibited endoreversible Carnot-like behavior, validating the model.
• A novel approximation for endoreversible heat engines and Joule-Brayton cycles closely matched simulation data.

Conclusions:

• The study validates the flexibility of endoreversible models in describing heat engine dynamics.
• A maximum ecological efficiency formula (η=1-τ^{3/4}) effectively describes the simulated cycle's behavior.
• The findings contribute to understanding heat engine operability under maximum power and ecological conditions.