Rankline-Brayton Engine Powered Solar Thermal Aircraft

• US 20100162702A1
• Filed: 07/30/2009
• Published: 07/01/2010
• Est. Priority Date: 04/30/2004
• Status: Active Grant

• Current Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Original Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Inventors: Bennett, Charles L.
• Granted Patent: US 8,132,412 B2
• Time in Patent Office: Days
• US Class Current: 60/659
• CPC Class Codes: B64C 39/024 of the remote controlled vehicle type, i.e. RPV
• CPC Class Codes: B64D 27/023 of rocket type, e.g. for assisting taking-off or braking
• CPC Class Codes: B64D 27/24 using steam or spring force jet aircraft B64D27/16
• CPC Class Codes: B64D 27/353 using solar cells
• CPC Class Codes: B64U 10/25 Fixed-wing aircraft VTOL aircraft B64U10/20
• CPC Class Codes: B64U 30/10 Wings
• CPC Class Codes: B64U 30/40 Empennages, e.g. V-tails foldable or collapsible UAVs B64U20/50
• CPC Class Codes: B64U 50/13 using external fans or propellers
• CPC Class Codes: F01K 15/02 for driving vehicles, e.g. locomotives
• CPC Class Codes: F01K 25/08 using special vapours
• CPC Class Codes: F01K 3/004 Accumulation in the liquid branch of the circuit
• CPC Class Codes: F01K 7/32 the engines using steam of critical or overcritical pressure
• CPC Class Codes: F03G 6/065 having a Rankine cycle
• CPC Class Codes: F03G 6/068 having other power cycles, e.g. Stirling or transcritical, supercritical cycles; combined with other power sources, e.g. wind, gas or nuclear
• CPC Class Codes: Y02E 10/46 Conversion of thermal power into mechanical power, e.g. Rankine, Stirling or solar thermal engines
• CPC Class Codes: Y02T 50/50 On board measures aiming to increase energy efficiency
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft
• CPC Class Codes: Y02T 90/40 Application of hydrogen technology to transportation, e.g. using fuel cells

Abstract

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.

Claims

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.

2. The engine of claim 1,

wherein the working fluid of said Rankine-Brayton heat engine is selected from the group consisting of ethene, ethane, and CO₂.

3. The engine of claim 1,

wherein at least one of the expander and pump of said heat engine is a double-acting reciprocating piston assembly.

4. The engine of claim 1,

further comprising a heat interchanger for pre-heating working fluid prior to being heated by the heat storage means using heat from working fluid exhausted from the expander.

5. The engine of claim 1,

further comprising a fluid reservoir for storing supercritically pressurized working fluid produced from the pump.

6. The engine of claim 1,

further comprising 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.

7. The engine of claim 1,

wherein said heat storage means comprises a thermal container and a mixture of lithium hydride and lithium metal contained therein.

8. The engine of claim 7,

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.

9. The engine of claim 7,

wherein said thermal container includes an inner containment shell structure and an outer vacuum shell supporting an evacuated space therebetween.

10. The engine of claim 9,

wherein said thermal container includes thermal battery insulation in said evacuated space comprising multiple layers of highly reflective material to shield against radiation.