A method for generating power from a heat source includes mixing a refrigerant in a liquid phase with a lubricating oil, heating the mixture to evaporate the refrigerant, mixing the heated mixture with additional refrigerant in a superheated phase, and atomizing the lubricating oil to disperse the lubricating oil within the refrigerant. The atomized lubricating oil and the refrigerant are passed through a decompressor to generate an electrical current. The refrigerant may be an organic material having a boiling point below about 35 C. Related systems and heat engines are also disclosed.

The present invention discloses a magnetohydrodynamics power system which utilizes low temperature heat source. Variable control of the operation of the system, along with determining configurations for specific cases, are made possible by selecting the refrigerant, liquid metal circuit geometry, and by adjusting the system condensing pressure and/or temperature. Adjustable condensing pressure and/or temperature allows the system to react to changing ambient temperature and maximize power output. Adjusting condensing pressure and/or temperature of the system is made possible with a variable condenser pressure controller. The variable condenser pressure controller allows utilization of the physical properties of the refrigerant over a wide range of condensing temperatures/pressures, including pressures in the vacuum range. Meanwhile rare earth permanent magnets in paired Halbach arrays are used in the magnetohydrodynamics generator to augment the magnetic field, and a series electrode connection is made possible to achieve a high voltage output.

A method of operating a heat cycle system, wherein the heat cycle system comprises a working fluid, which is cycled through a circuit comprising a compressor, a condenser, an expander unit, and an evaporator and wherein the expander unit is configured to generate a rotating mechanical motion, comprises operating the evaporator at an evaporator working fluid evaporation capacity that is at least about 110% of the nominal evaporator working fluid evaporation capacity. There is also disclosed a heat cycle system as well as a method of modifying a heat cycle system.