System and process for generation of electrical power

A method for producing power comprising:

• providing a water vapor stream comprising at least 50 mass % water vapor;
• providing a fluid stream comprised of a fluid in liquid or supercritical phase, where the fluid of the fluid stream is formed of one or more constituents selected from the group consisting of molecular nitrogen, argon, a chemical compound having a boiling point of at most 65° C. at 0.101 MPa and a latent heat of vaporization of at least 350 kJ/kg, and a chemical compound having a boiling point of at most 65° C. at 0.101 MPa and a specific heat capacity as a liquid of at least 1.9 kJ/kg-° K, where the one or more constituents comprise at least 50% of the fluid;
• thermally contacting the water vapor stream and the fluid stream and exchanging heat between the water vapor stream and the fluid stream to condense water from the water vapor stream and to heat the fluid stream, where the heated fluid stream is comprised of the fluid in gaseous or supercritical phase;
• expanding the heated fluid stream to produce an expanded fluid stream comprised of the fluid in liquid phase and to generate mechanical power;
• in the step of thermally contacting the water vapor stream and the fluid stream, controlling the mass flow rate of the fluid stream, or the mass flow rate of the water vapor stream, or the mass flow rates of both the fluid stream and the water vapor stream to maintain the temperature of liquid phase fluid of the expanded fluid stream at or below 10° C.;
• and
• generating electrical power from the mechanical power.