Abstract: The inventor claims a heat engine that follows a modification of the Stirling thermodynamic heat engine cycle; the monatomic working fluid is a saturated gas at the beginning of the isothermal compression stage, and ends up a mixed-phase fluid at the end of the compression. A proximate piston compresses and expands surrounding ideal gas helium, to function as a regeneration mechanism of this Stirling cycle and minimize the temperature difference during heat transfer. This cycle takes advantage of the temperature-dependent attractive intermolecular forces of the working fluid to assist in compressing the working fluid partially into a liquid, reducing the input compression work and increasing the overall heat engine efficiency.

Abstract: An internally reversible thermodynamic heat pump cycle of isentropic expansion, isochoric heating, and isothermal compression, and using a constant-temperature heat source and sink. This heat pump cycle has a Coefficient of Performance that exceeds the Carnot maximum Coefficient of Performance for its maximum temperature range; this heat pump does not violate the second law of thermodynamics.

Abstract: The inventor claims a heat engine that follows a modification of the Stirling thermodynamic heat engine cycle. This cycle uses supercritical argon gas to take advantage of the attractive intermolecular forces of the working fluid to assist in compressing the working fluid, reducing the input compression work and the heat output during isothermal compression, as well as reducing the heat input during isothermal expansion, and increasing the overall heat engine efficiency. This cycle utilizes accumulators to ensure the working fluid is heated and cooled isochorically, and a proximate piston-cylinder filled with ideal-gas helium is used in lieu of a regenerator during the isochoric heating and cooling. All of these modifications serve to increase the overall thermodynamic efficiency of the heat engine cycle.

Abstract: An internally reversible thermodynamic heat pump cycle of isentropic expansion, isochoric heating, and isothermal compression, and using a constant-temperature heat source and sink. This heat pump cycle has a COP that exceeds the Carnot maximum COP for its maximum temperature range; this heat pump does not violate the second law of thermodynamics.

Abstract: The inventor claims a heat engine that follows a modification of the Stirling thermodynamic heat engine cycle; the novel aspect is that the monatomic working fluid is a saturated gas at the beginning of the isothermal compression stage, and ends up a mixed-phase fluid at the end of the compression. This cycle takes advantage of the attractive intermolecular forces of the working fluid to assist in compressing the working fluid partially into a liquid, reducing the input compression work and increasing the overall heat engine efficiency.