Rankline-Brayton engine powered solar thermal aircraft
View Patent ↗A solar thermal powered aircraft powered by heat energy from the sun. A Rankine-Brayton hybrid cycle heat engine is carried by the aircraft body for producing power for a propulsion mechanism, such as a propeller or other mechanism for enabling sustained free flight. The Rankine-Brayton engine has a thermal battery, preferably containing a lithium-hydride and lithium mixture, operably connected to it so that heat is supplied from the thermal battery to a working fluid. A solar concentrator, such as reflective parabolic trough, is movably connected to an optically transparent section of the aircraft body for receiving and concentrating solar energy from within the aircraft. Concentrated solar energy is collected by a heat collection and transport conduit, and heat transported to the thermal battery. A solar tracker includes a heliostat for determining optimal alignment with the sun, and a drive motor actuating the solar concentrator into optimal alignment with the sun based on a determination by the heliostat.
1. A Rankine-Brayton hybrid thermodynamic cycle heat engine comprising:
a pump for pressurizing a sub-critical pressure liquid-phase working fluid to a supercritical pressure; heat storage means for storing thermal energy and using the stored thermal energy to heat the supercritical pressure liquid-phase working fluid to a supercritical temperature, supercritical pressure phase; a positive displacement expander for substantially adiabatically expanding the supercritical temperature, supercritical pressure working fluid to reduce the pressure of the working fluid back to a sub-critical pressure level; and a condenser in thermal contact with the ambient environment for condensing the sub-critical pressure working fluid back to the sub-critical temperature liquid phase, whereby thermal energy from said heat storage means is converted to mechanical energy; and
means for controlling the supercritical pressurization of working fluid produced by the pump, said means for controlling including a pressure gauge for measuring the pressure level of the supercritical pressure working fluid.
2. A Rankine-Brayton hybrid thermodynamic cycle heat engine comprising:
a pump for pressurizing a sub-critical pressure liquid-phase working fluid to a supercritical pressure; heat storage means for storing thermal energy and using the stored thermal energy to heat the supercritical pressure liquid-phase working fluid to a supercritical temperature, supercritical pressure phase; a positive displacement expander for substantially adiabatically expanding the supercritical temperature, supercritical pressure working fluid to reduce the pressure of the working fluid back to a sub-critical pressure level; and a condenser in thermal contact with the ambient environment for condensing the sub-critical pressure working fluid back to the sub-critical temperature liquid phase, whereby thermal energy from said heat storage means is converted to mechanical energy,
wherein said heat storage means comprises a thermal container and a mixture of lithium hydride and lithium metal contained therein.
3. The engine of claim 2 ,
wherein said mixture of lithium hydride and lithium metal is in substantial equilibrium with dissociation products, including hydrogen gas, and liquid phase lithium and lithium hydride.
4. The engine of claim 2 ,
wherein said thermal container includes an inner containment shell structure and an outer vacuum shell supporting an evacuated space therebetween.
5. The engine of claim 4 ,
wherein said thermal container includes thermal battery insulation in said evacuated space comprising multiple layers of highly reflective material to shield against radiation.