Power plants – Motor operated by expansion and/or contraction of a unit of... – Unit of mass is a gas which is heated or cooled in one of a...
Reexamination Certificate
2000-09-05
2002-05-14
Nguyen, Hoang (Department: 3748)
Power plants
Motor operated by expansion and/or contraction of a unit of...
Unit of mass is a gas which is heated or cooled in one of a...
C060S522000, C060S526000
Reexamination Certificate
active
06385972
ABSTRACT:
BACKGROUND OF THE INVENTION
The subject invention originates from twenty-two years research by the inventor, into engines and resonators that operate on the principles of thermoacoustic physics. For purposes of this application for patent, the term “thermoacoustic” refers to traveling energy impulses, normally detected as pressure fluctuations, propagating along velocity vectors, that move thermal energy through an elastic medium that is typically a compressible working fluid. For purposes of this application for patent, thermoacoustic energy includes both shockwaves (supersonic and hypersonic pressure waves) and sound waves (pressure waves traveling at the sonic velocity of the working fluid under locally extant conditions).
The research background data in heat, acoustic wave phenomena and gas mechanics includes the shock tube research performed by government and institutional scientists during the 1950's and 1960's, relevant examples of which can be found in the
Proceedings of the Seventh International Shock Tube Symposium
, University of Toronto Press 1970, ISBN 0-8020-1729-0; as well as research into thermoacoustic waves generated by chemical explosives,
The Chemistry of Powder and Explosives
, Volume I, 1941, Volume II, 1943, by Tenney L. Davis, Ph.D., ISBN 0913022-00-4; published research in atmospheric physics, including
Lightning
, by Martin A Uman, McGraw-Hill 1969;
The Flight of Thunderbolts
, 2
nd
ed., B. F. J. Schonland, Clarendon Press 1964;
Graphic Survey of Physics
, by Alexander Taffel, Oxford Book Company 1960;
Matter and Motion
, by James Clerk Maxwell, 1877, Dover Publications 1991 (reprint);
Laboratory Exercises in Physics
, Fuller and Brownlee, Allyn and Bacon 1913;
Laboratory Experiments in Elementary Physics
, by Newton Henry Black, Macmillan Company, 1944;
Modern Physics
, by Williams, Metcalfe, Trinklein and Lefler, 1968, Holt, Rinehart and Winston Publishers;
Physics of Lightning
, D. J. Malan, The English Universities Press Ltd., 1963; which includes thermoacoustic phenomena generated by natural lightning and man-made electric arcs.
Other relevant published research includes work in pulse tube refrigeration, including
The Influence of heat Conduction on Acoustic Streaming
, Nikolaus Rott, Journal of Applied Mathematics and Physics (ZAMP), vol. 25, pp. 417-421, 1974;
A Review of Pulse Tube Refrigeration
, Ray Radebaugh, Cryogenic Engineering Conference, pp. 1-14, 1989;
Flow Patterns Intrinsic to the Pulse Tube Refrigerator
, J. M. Lee, P. Kittel, K. D. Timmerhaus, R. Radebaugh, National Institute of Standards and Technology, pp. 125-139, 1993. The cryogenics department at NASA-Ames is a premier focus of pulse tube refrigeration research. Pulse tubes differ from thermoacoustic devices in that they are typically non-resonant devices in which a mechanical piston, driven by an external power source, generates compression waves (pulses) that move in one direction through a series of heat exchangers, and cause thermal energy to be transported between those heat exchangers. Pulse tubes are typically used in cryogenic refrigeration applications. Pulse tubes are similar to thermoacoustic devices in that traveling pressure waves in a working fluid are the mode of operation.
The research history involving prime movers with associated thermoacoustic characteristics includes
Stirling Cycle Machines
, by Graham Walker, PhD, 1973, Oxford University Press; various Stirling engine technical research reports, 1937-1978, issued by The Philips Company Laboratories, Eindhoven, Netherlands; and Stirling Cycle Engines, by Andy Ross, 1977, published by Solar Engines, Phoenix, Ariz.
The device described herein is a traveling-wave Thermoacoustic Cycle (TAC) engine-generator set, herein referred to as a Thermoacoustic Resonator (TAR), comprised of an acoustically resonant cavity containing a multiplicity of thermally resonant heat exchangers and a compressible working fluid, in which a train of acoustic traveling waves is generated, and in which said acoustic traveling waves are amplified by a thermal gradient across the device, causing an increase in pressure and temperature amplitudes, and wave propagation velocity, and said acoustic traveling waves impinge upon a moveable piston-armature assembly, causing it to reciprocate within a magnetic field and generate electrical energy.
Thermoacoustic Cycle (TAC) engines are well known to acoustic science, are in USPTO Class 310 and International Class H01L 041/08, and have been explored extensively by Peter H. Ceperley, George Mason University; Steven Garrett of Penn State University and Gregory Swift of Los Alamos National Laboratory. Thermoacoustic related patents searched include:
6,054,775
Apr., 2000
Vocaturo
290/1R
6,032,464
Mar., 2000
Swift, et al
60/517
5,953,920
Sep., 1999
Swift, et al
60/520 X
5,892,293
Apr., 1999
Lucas
290/1R
5,673,561
Oct., 1997
Moss
62/6
5,659,173
Aug., 1997
Putterman, et al
250/361
5,647,216
Jul., 1997
Garrett
62/6
5,519,999
May., 1996
Harpole, et al
60/520 X
5,515,684
May., 1996
Lucas, et al
62/6
5,456,082
Oct., 1995
Keolian, et al
62/6
5,319,938
Jun., 1994
Lucas
62/6
5,303,555
Apr., 1994
Chrysler, et al
62/6
5,295,355
Mar., 1994
Zhou, et al
62/6
5,275,002
Jan., 1994
Inoue, et al
62/6
5,269,147
Dec., 1993
Ishizaki, et al
62/467
5,263,341
Nov., 1993
Lucas
62/6
5,165,243
Nov., 1992
Bennett
62/6
4,722,201
Feb., 1988
Hoffler, et al
62/467
4,686,407
Auq., 1987
Ceperley
60/721
4,599,551
Jui., 1986
Wheatley, et al
322/2R
4,398,398
Aug., 1983
Wheatley, et al
62/467
4,355,517
Oct., 1982
Ceperley
60/721
4,114,380
Sep., 1978
Ceperley
60/721
A Thermoacoustic Cycle engine is typically comprised of a resonant cavity in the approximate shape of a cylinder, tube or torus, in which a working fluid resides, and in which an applied difference in thermal potential, across internal isothermal heat exchangers that are separated by a regenerative heat exchanger (stack) and spaced along the length of the resonant cavity by a nominal wavelength or fraction thereof, produce and amplify acoustic waves which transport thermal energy from one heat exchanger to another, and maintain a state of oscillation, or periodic thermal and acoustic flux, in the working fluid. To extract useful work from the engine, the oscillating pressure component can be applied to a mechanical member, such as a piston, in order to perform reciprocating work, and thereby used to perform tasks such as pumping fluids or generating electrical energy. The maxima, or peak pressure points in the traveling thermoacoustic wave train, also transport thermal energy in accordance with the pressure-temperature relationship in a gas, as described in Charles Law, and this property can be employed in a reverse entropy cycle to produce refrigeration.
Thermoacoustic Cycle engines have been researched for several decades, and researchers at the Los Alamos National Laboratory, the Naval Post Graduate School, The University of Texas, Penn State University and other institutions have written numerous research papers on the genre, primarily concerning standing-wave thermoacoustic physics. A standing-wave thermoacoustic refrigerator developed by Steven Lurie Garrett was flown aboard the space shuttle
Discovery
in 1991 as an experimental package. It is mentioned (project 511) along with this inventor's Acoustic Cycle engine (project 503) in the
1993
Rolex Awards For Enterprise
, published December, 1992. Currently, there are approximately thirty relevant patents in the field.
The most significant problem with prior art thermoacoustic engines and refrigerators is that they have a very low power density. They are typically much larger and more massive for the amount of output work they produce, than other types of engines and refrigerators. Until 1998, in disregarding non-resonant pulse tubes, most researchers working in the field, including Gregory Swift's Los Alamos group, concentrated their efforts largely on thermoacoustic engines that employed standing wave physics. The power output of standing wave systems is limited by the inherent phy
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