US 2003/0192324 A1 · Thermoacoustic device

Abstract

A thermocoustic device includes a housing with a thermal core supported in the housing and having a first and a second surface. The thermal core includes a first heat exchanger defining the first surface of the thermal core and a second heat exchanger defining the second surface of the thermal core. A main chamber is in fluid communication with the first surface of the thermal core and a secondary multiplier chamber is in fluid communication with the second surface of the thermal core. A working volume of a gaseous working fluid fills the main chamber, the multiplier chamber, and the thermal core at a pressure. An equilibrium pressure is defined as the pressure of the working volume of gaseous working fluids with the thermoacoustic device is in a non-operating mode. The main chamber includes a first oscillating member that is operable when the thermoacoustic device is in an operating mode to oscillate such that the pressure in both the main chamber and in the multiplier chamber is oscillated between a peak pressure greater than the equilibrium pressure and a minimum pressure less than the equilibrium pressure. A main pressure amplitude is defined as one-half of the difference between the peak pressure and the minimum pressure in the main chamber. The secondary multiplier chamber includes a second oscillating member that is operable when the thermoacoustic device is in the operating mode to oscillate such that the pressure in the multiplier chamber is oscillated between a peak pressure greater than the equilibrium pressure and a minimum pressure less than the equilibrium pressure. A multiplier pressure amplitude is defined as one-half of the difference between the peak pressure and the minimum pressure in the multiplier chamber. The first and second oscillating members oscillate at substantially the same frequency and such that the pressure oscillations in the main chamber and the multiplier chamber are substantially in phase with each other. The multiplier pressure amplitude is greater than the main pressure amplitude.

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Claims60

Dependent claims

A thermoacoustic device having an operating mode and a non-operating mode, the device comprising:

a housing;
a thermal core supported in the housing and having a first and a second surface, the thermal core including a first heat exchanger defining the first surface of the thermal core and a second heat exchanger defining the second surface of the thermal core;
a main chamber in fluid communication with the first surface of the thermal core;
a secondary multiplier chamber in fluid communication with the second surface of the thermal core;
a working volume of a gaseous working fluid filling the main chamber, the multiplier chamber, and the thermal core at a pressure, an equilibrium pressure being defined as the pressure of the working volume of gaseous working fluid when the thermoacoustic device is in the non-operating mode;
the main chamber including a first oscillating member, the first oscillating member being operable when the thermoacoustic device is in the operating mode to oscillate such that pressure in the multiplier chamber is oscillated between a peak pressure greater than the equilibrium pressure and a minimum pressure less than the equilibrium pressure, a main pressure amplitude being defined as one half of the difference between the peak pressure and the minimum pressure in the main chamber;
the secondary multiplier chamber including a second oscillating member, the second oscillating member being operable when the thermoacoustic device is in the operating mode to oscillate such that the pressure in the multiplier chamber is oscillated between a peak pressure greater than the equilibrium pressure and a minimum pressure less than the equilibrium pressure, a multiplier pressure amplitude being defined as one half of the difference between the peak pressure and the minimum pressure in the multiplier chamber;
wherein the first and second oscillating members oscillate at substantially the same frequency and such that the pressure oscillations in the main chamber and the multiplier chamber are substantially in phase with each other;
and
the multiplier pressure amplitude is greater than the main pressure amplitude.

7 more elements

A thermoacoustic device comprising:

a housing having a first end and a second end;
a cold head heat exchanger defining the first end of the housing, the cold head heat exchanger having an exterior heat exchange surface in thermal communication with an interior heat exchange surface;
a multiplier chamber disposed in the housing and having a multiplier volume defined therein, the multiplier chamber including a multiplier oscillating member, the multiplier oscillating member being movable such that the multiplier volume is increased and decreased;
a main chamber disposed in the housing and surrounding the multiplier chamber, the main chamber having a main volume defined between the multiplier chamber and the main chamber, the main chamber including a main oscillating member, the main oscillating member being movable such that the main volume is increased and decreased;
a support disposed in the housing adjacent the interior heat exchange surface of the cold head heat exchanger, the support defining a first passage between the multiplier volume and the interior heat exchange surface of the cold head heat exchanger and a second passage between the main volume and the interior heat exchange surface of the cold head heat exchanger, whereby the main volume and the multiplier volume are in fluid communication through the first and second passages;
a porous thermal storage element disposed in one of the passages, the thermal storage element having a first surface and a second surface, the first surface being adjacent the interior heat exchange surface of the cold head heat exchanger;
and a hot heat exchanger disposed adjacent the second surface of the thermal storage element.

4 more elements

A thermoacoustic device having an operating mode and a non-operating mode, the device comprising:

a housing;
a thermal core supported in the housing and having a first and a second surface, the thermal core including a first heat exchanger defining the first surface of the thermal core and a second heat exchanger defining the second surface of the thermal core;
a main chamber in fluid communication with the first surface of the thermal core;
a secondary multiplier chamber in fluid communication with the second surface of the thermal core;
a working volume of a gaseous working fluid filling the main chamber, the multiplier chamber, and the thermal core at a pressure, an equilibrium pressure being defined as the pressure of the working volume of gaseous working fluid when the thermoacoustic device is in the non-operating mode;
the main chamber including a first oscillating member, the first oscillating member being operable when the thermoacoustic device is in the operating mode to oscillate such that pressure in the multiplier chamber is oscillated between a peak pressure greater than the equilibrium pressure and a minimum pressure less than the equilibrium pressure, a main pressure amplitude being defined as one half of the difference between the peak pressure and the minimum pressure in the main chamber;
the secondary multiplier chamber including a second oscillating member, the second oscillating member being operable when the thermoacoustic device is in the operating mode to oscillate such that the pressure in the multiplier chamber is oscillated between a peak pressure greater than the equilibrium pressure and a minimum pressure less than the equilibrium pressure, a multiplier pressure amplitude being defined as one half of the difference between the peak pressure and the minimum pressure in the multiplier chamber;
wherein the first and second oscillating members oscillate at substantially the same frequency and such that the pressure oscillations in the main chamber and the multiplier chamber are substantially in phase with each other;
and
the multiplier pressure amplitude is less than the main pressure amplitude.

7 more elements

Dependencies are inferred from the claim text.

Description15,291 words

Summary3,579 words

#The present invention relates generally to thermoacoustic devices and, more specifically, to thermoacoustic engines and refrigeration pumps. However, the present invention has applicability outside the field of thermoacoustics, and is therefore not limited to thermoacoustic devices.

#During the past two decades, there has been an increasing interest in the development of thermoacoustical cooling engines (pumps) for a variety of commercial, military and industrial applications. Interest in thermoacoustic cooling has accelerated rapidly with the production ban of chlorofluorocarbons (CFC's). Thermoacoustic refrigerators can be constructed such that they use only inert gases, which are non-toxic and do not contribute to ozone depletion, nor to global warming. Exemplary prior art designs for thermoacoustic engines and refrigerators are shown in the following patents: U.S. Pat. Nos. 4,398,398; 4,489,553, 4,722,201, 5,303,555, 5,647,216, 5,953,921, 6,032,464, and 6,314,740.

#For a complete appreciation of the present invention, an understanding of earlier heat engines is beneficial.

Brief description of the drawings15 figures

#FIG. 1 is a cross-sectional view of a prior art thermoacoustic device;

#FIG. 2 is a cross-sectional view of another prior art thermoacoustic device;

#FIG. 3 is a cross-sectional view of yet another prior art thermoacoustic device;

Detailed description11,434 words

#The present invention provides a thermoacoustic device with a thermal core including a regenerator or other thermal storage medium sandwiched between first and second heat exchangers. A main volume is preferably defined by a compliant enclosure and is in fluid communication with one of the heat exchangers. A piston forms part of the compliant enclosure and oscillates so as to change the volume in the enclosure. A second multiplier chamber is in fluid communication with the other heat exchanger and also has an oscillatory member for oscillating the volume in the multiplier chamber. The piston and the oscillating member move approximately in phase with one another such that the pressure introduced to the chambers rises at approximately the same time and approximately in phase with one another. Using a thermoacoustic Stirling effect, the oscillating pressure waves pump heat from one of the heat exchangers to the other. Alternatively, heat may be provided to one of the heat exchangers and power extracted by attaching the piston to an alternator or some other means to produce electricity or by attaching the piston to some other device thereby providing energy in the form of reciprocating mechanical motion.

#First Preferred Embodiment—Overview

#FIG. 4 shows a cross-sectional side view of one preferred embodiment of a thermoacoustic device 110 according to the present invention. FIG. 5 shows the same thermoacoustic device 110 with portions cut away, and some components left out of the view for simplicity. This device 110 is designed to produce a refrigeration effect by absorbing heat through a unitized cold head heat exchanger 112 and delivering that heat at a lower temperature to a regenerator 114, contained in a thermally-insulated and thermally insulating support or platform 118. The energy in sound waves is used to pump that heat up to a higher temperature at the hot end of the regenerator 114. This heat, plus any acoustic energy deposited by the thermoacoustic heat pumping process, is deposited on the hot heat exchanger 116. The heat deposited on the hot heat exchanger 116 is exhausted from the system by hot heat exchange transport fluid that passes through the heat exchanger 116.

Thermoacoustic device

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Thermoacoustic device

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Abstract

Drawings

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Claims60

Description15,291 words

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Classification10 codes

Life of this patent

Description15,291 words