The Saturated and Supercritical Stirling Cycle Thermodynamic Heat Engine Cycle*

On the assumption that experimentally validated tabulated thermodynamic properties of saturated fluids published by the National Institute of Standards and Technology are accurate, a theoretical thermodynamic cycle can be demonstrated that produces a net-negative entropy generation to the universe. The experimental data on the internal energy can also be used to obtain a simple, empirical equation for the change in internal energy of a real fluid undergoing isothermal expansion and compression. This demonstration provides experimental evidence to the theory that temperature-dependent intermolecular attractive forces can be an entropic force that can enhance the thermodynamic efficiency of a real-fluid macroscopic heat engine to exceed that of the Carnot efficiency. A practical modification of the Stirling thermodynamic heat engine cycle will be presented. This engine uses supercritical argon gas to take advantage of the attractive intermolecular forces of the working fluid to assist in compressing the working fluid, increasing the overall heat engine efficiency.

https://doi.org/10.1063/1.5043523