Patent ID: 6981377

Claim:
System for generation of electricity from waste heat and solar sources, comprising in operative combination: a) a closed loop, refrigerant working fluid circuit comprising: i) at least one heat exchanger providing heat energy from a waste heat or solar source to convert said working fluid from a liquid pressurized refrigerant to a heated gas refrigerant under pressure; ii) an expander driven by said heated, pressurized refrigerant working fluid to produce power to an output shaft, said working fluid pressure being thereby reduced, and said expander comprises a screw compressor that is oriented to run in reverse in said circuit so that said refrigerant working fluid drives said output shaft while dropping in temperature, and wherein said expander is selected from a continuous and a multi-stage screw compressor; iii) a generator driven by said screw compressor output shaft to produce electricity, said generator is selected from an induction-type generator and a synchronous-type generator; iv) a condenser for reducing said lowered pressure refrigerant working fluid gas temperature thereby converting the working fluid gas to a liquid at the condensation temperature or below of said working fluid; v) a pump for pressurizing and circulating said refrigerant working fluid in said circuit, said pump is driven by a variable frequency drive; and vi) conduits interconnecting said heat exchanger, said expander, said condenser and said pump in a closed loop refrigerant circuit, said working fluid is selected from R123, 245FA, R134A, R22, organic refrigerants, and said circuit includes an emergency refrigerant working fluid gas bypass around said expander; and b) a controller for monitoring said generator and selected temperatures and pressures of the refrigerant working fluid in pressurized liquid or gas form in said circuit, and for providing control signals to control said pump variable frequency drive, screw compressor and generator.