US Patent 7987676 Two-phase expansion system and method for energy recovery

A closed loop expansion system for energy recovery includes a heat exchanger for using heat from a heat source to heat a working fluid of the closed loop expansion system to a temperature below the vaporization point of the working fluid; a radial inflow expander for receiving the working fluid from the heat exchanger and for expanding and partially vaporizing the working fluid; a screw expander for receiving the working fluid from the radial inflow turbine and for further expanding and vaporizing the working fluid; and a condenser for receiving the working fluid from the screw expander and for liquefying the working fluid.