Power plants – Fluid within expansible chamber heated or cooled – Special motive fluid
Reexamination Certificate
1999-07-02
2001-09-04
Nguyen, Hoang (Department: 3745)
Power plants
Fluid within expansible chamber heated or cooled
Special motive fluid
C060S515000
Reexamination Certificate
active
06282894
ABSTRACT:
TECHNICAL FIELD
This invention relates to engines, such as reciprocating engines and gas turbine engines driven by kinetic cooling resulting from absorption of laser radiation.
BACKGROUND ART
All motors and engines that perform useful work consume energy in one form or another. The energy used by an engine may be used in the same form as provided by the energy source, or may be utilized in a form converted from the energy source. For instance, even though some devices respond directly to sunlight, solar energy usually is harnessed by converting sunlight energy into electrical energy, and then utilizing the electrical energy to drive the engine. Some energy sources, such as solar, hydro and geothermal, are practically inexhaustible, while all more commonly used energy sources, particularly fossil fuels and derivatives thereof, are irreversibly depleted when used. The cost of putting a load into Earth orbit is about $40,000 per pound; therefore, a gallon of fossil fuel costs about $320,000 in space. As an example, while energy in many satellites is provided by the sun, most space vehicles utilize depleting energy sources, such as hydrogen and oxygen, to perform necessary work, such as generating electricity by means of fuel cells. To derive one megawatt of power from the sun requires a solar collector of 10,000 square meters (about twice the size of a football field). Similarly, in extremely remote areas having harsh topography, such as the Ural mountains or the Himalayas, the provision of reliable energy sources to perform work in isolated instances is formidable. Although pipes to supply fluidic fuel or wires to supply electrical power may be utilized, in many cases this is entirely impractical. Ocean-going vessels carry expensive fuel that accounts for a significant fraction of their tonnage. Equipment operating in space has an additional disadvantage related to the inefficiency of heat rejection because the only available technique is radiative heat rejection, which requires very large areas, just as do solar collectors.
DISCLOSURE OF INVENTION
Objects of the invention include provision of engines in which the on-site working fuel is not depleted, and the energy may be provided from an extremely remote source; engines which are not connected to an energy source by wires or pipes; engines which can be operated in the atmosphere, stratosphere or space in response to energy sources on earth; engines in which no heat rejection is required, and engines which can be operated in extremely remote, basically unaccessible regions without expending fuel on site.
According to the present invention, a confined gas, such as a mixture of carbon dioxide and nitrogen, is utilized as fuel, the energy in the fuel being supplied by absorption of laser radiation, such as 10.6 micron wavelength radiation from a carbon dioxide laser or radiation from quantum cascade laser diodes. The gas mixture is kinetically cooled by absorption of laser radiation, following which the gas undergoes adiabatic compression, and then it is allowed to warm up over a period of time, after which it performs work, such as on a piston or a turbine blade, in an adiabatic expansion, returning the gas to its original state. The absorption of laser radiation converts energy within the gas from thermal translational (thermal) energy into vibrational energy levels of the carbon dioxide and nitrogen, thus causing the gas to cool. When the vibrational energy levels relax, and the energy is again converted into translational energy, the gas is heated to an elevated temperature. The energy source is the laser which can be located as much as hundreds of thousands of miles from the engine, and the fuel on site, within the engine (the CO
2
/N
2
mixture) is used over and over again, and is never depleted. No waste heat has to be dissipated as in an ordinary engine controlled by the Carnot cycle.
According to the invention in one form, the gas, such as a mixture of carbon dioxide and nitrogen, is within a cylinder having a piston which recedes during the adiabatic expansion and advances into the cylinder during the adiabatic compression, and the energy is provided by pulses of laser radiation applied before the compression cycle. In accordance with the invention in another form, the engine is a turbine driven compressor in which the gas is cooled by absorption of laser radiation, is compressed to a higher pressure in the compressor, is allowed to relax and undergo an increase in temperature in a so-called “combustor” segment, and is then expanded in a turbine producing useful work in what may be called a “power cycle” or a “work cycle”, and the gas thereby returns to its initial state so the process may be repeated. The present invention utilizes, for example, the inverse of the laser transition in the carbon dioxide molecule to absorb laser light from the energy source, which is stored in the vibrationally excited upper laser level (001 level) of CO
2
and the v
1
level of N
2
. Because of the lifetime of the states and the kinetics leading to vibrational thermal equilibrium, the gas is actually cooled as the translational energy of the gas is converted into vibrational energy of the gas. When released, the stored vibrational energy being converted back to translational energy (heat) corresponds to the combustion leg of an Otto cycle or a Brayton cycle, which can be preceded by a compression portion of the cycle and followed by a work portion of the cycle.
Other objects, features and advantages of the present invention will become more apparent in the light of the following detailed description of exemplary embodiments thereof, as illustrated in the accompanying drawing.
REFERENCES:
patent: 4452047 (1984-06-01), Hunt et al.
patent: 5095699 (1992-03-01), Blackshear
patent: 5186001 (1993-02-01), Muntz et al.
Nguyen Hoang
Williams M. P.
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