US 6,385,972 B1Granted

Thermoacoustic resonator

OwnerOscar Lee Fellowsinventor

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Abstract

A Thermo-Acoustic Resonator (TAR) is a miniature thermoacoustic heat pump and thermal-electric generator that is typically imbedded in a thermoplastic or metal package. The TAR converts a thermal gradient into electrical energy. It can range in size from that of a microchip, upward. The operable principle is that sensible and latent heat in a material can be pumped most efficiently when pumped at intervals that are resonant with the natural period of the material at a given temperature, thereby increasing the energy density of the thermoacoustic engine. The normal period of the device is tailored to produce thermodynamic oscillation in the heat exchangers and working fluid, and thereby to cause a miniature armature to reciprocate within a magnetic field and generate alternating current. Power output depends on the amplitude and frequency of the thermal gradient, and the tailored energy flow rate through the device.

Claims20

Dependent claims

A miniature heat engine comprising:

a) a thermally conductive envelopment means including a housing for containing a compressible working fluid,
b) said compressible working fluid being capable of supporting propagation of periodic acoustical traveling waves,
c) a first heat exchange means for adding thermal energy to the working fluid in one section of the housing,
d) a second heat exchange means for removing thermal energy from the working fluid in another section of the housing,
e) a thermal insulating means comprising an intermediate substrate dividing said first and second heat exchange means, and for mounting component parts of the miniature heat engine,
f) an acoustical traveling wave generating means for causing periodic acoustical traveling waves to propagate on a path through the working fluid in communication between said first and second heat exchange means,
g) an acoustic wave guiding means, a wave-guide, contiguous with the acoustical traveling wave generating means and integral with the geometry of working fluid passages in the thermal insulating means and said first heat exchange means, by means of which the periodic acoustical traveling waves are vectored, thermally amplified, and acoustic-impedance-controlled,
h) an energy conversion means for converting the acoustical energy produced by said miniature heat engine into other forms of electrical and mechanical energy,
i) an inertance means, comprised of a planar baffle, for reducing the local propagation velocity of the acoustic traveling wave, and increasing the pressure gradient decay period during which energy is extracted from the working fluid by the energy conversion means and said second heat exchange means,
j) a metering means for causing the admittance of cooler working fluid from said second heat exchange means, through the energy conversion means, into the acoustical traveling wave generating means, thereby completing an acoustic and thermodynamic circuit in the working fluid.

7 more elements

A process comprising steps of:

a) using a new engineering craft, with unique formulae and terminology, for calculating, quantifying and evaluating thermodynamic coupling efficiency and thermoacoustic resonance in solid materials and compressible working fluids subjected to a periodic flow of thermal energy,
b) manipulating the elemental and geometric properties of said solid material so as to cause heat exchange means to resonate and couple thermodynamically with a compressible working fluid via a periodic thermal energy flux of specific frequency,
c) using a methodology for designing said heat exchange means, so as to cause an exchange of specific quantities of sensible and latent thermal energy between said heat exchange means and periodic acoustical traveling waves, thereby amplifying the pressure-temperature gradient of said periodic acoustical traveling waves with respect to the working fluid they are propagating through,
d) using a methodology for calculating, quantifying and evaluating periodic thermal energy transmission through said solid material, and between said heat exchange means and a working fluid, in order to design and test thermoacoustic engines,
e) determining a property of thermal impedance (Zt), expressed as a reciprocal power in Joules per centimeter per square centimeter per degree Kelvin, to quantify the flow of alternating energy per unit time with regard to impeding properties of a component or system,
f) determining a property of thermal capacitance (Ct), expressed in Joules per degree Kelvin, with regard to the quantity of thermal energy that can be stored in a component or system for a given amplitude of applied thermal energy,
g) determining a property of thermomotive force, thermal amplitude, the temperature gradient across a thermoacoustic engine or component thereof, the difference in maximum and minimum temperatures across said thermoacoustic engine or component thereof, expressed in degrees Kelvin,
h) determining a property of thermal reactance (Xt), expressed as a reciprocal power in Joules per second, with regard to the resistance of a component or system to a reversal in the direction of flow of thermal energy.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/655,521Filed 5 Sep 2000 · us provisional application
Priority: 30 Aug 1999
Granted: 14 May 2002
Term ends: Not estimatedThe source records don’t support an estimate.

Classification13 codes

H02K 7/1884
With reciprocating, linearly oscillating or vibrating parts: structurally associated with free piston engines
F02G 1/0435
The engine being operated by expansion and contraction of a mass of working gas which is heated and cooled in one of a plurality of constantly…:…
F03G 7/002
Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for: using the energy of…
F02G 2243/54
Having resonance tubes: thermo-acoustic