Patent ID: 8006496

Claim:
An engine for converting heat into mechanical output using a working fluid in a closed circulating system, the engine comprising: at least one pump to pressurize the working fluid from a first pressure to a second pressure, wherein the second pressure is higher than the first pressure; a heat receiving portion of a regenerative heat exchanger; said heat receiving portion configured to receive the working fluid from said pump, said regenerative heat exchanger configured to add heat to the working fluid; a heating device to supply additional heat to the working fluid to raise the working fluid to a desired working temperature substantially above its critical temperature; a first scroll expander coupled with a shaft and having an inlet coupled with the heating device to receive the working fluid, the first scroll expander to generate the mechanical output to rotate the shaft through the expansion of the working fluid from the inlet to an outlet of the first scroll expander; a second scroll expander coupled with the shaft and having an inlet coupled with the outlet of the first scroll expander, the second scroll expander to further generate the mechanical output to rotate the shaft through further expansion of the working fluid from the inlet of the second scroll expander to an outlet of the second scroll expander; a heat transmitting portion of said regenerative heat exchanger configured to receive the expanded working fluid from the outlet of said second scroll expander and pass it therethrough; a condenser connected between an outlet of said heat transmitting portion of said regenerative heat exchanger and said at least one pump to reduce temperature of the working fluid to a low cycle temperature; and a power control valve to adjust the mechanical output of the engine by adjusting a mass flow of the working fluid in the closed circulating system; wherein the at least one pump is adapted to compensate for the adjustment of the mass flow rate by maintaining the second pressure in a specified range.