US20070193281A1 - Thermoacoustic apparatus and thermoacoustic system - Google Patents

Thermoacoustic apparatus and thermoacoustic system Download PDF

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Publication number
US20070193281A1
US20070193281A1 US10/594,278 US59427805A US2007193281A1 US 20070193281 A1 US20070193281 A1 US 20070193281A1 US 59427805 A US59427805 A US 59427805A US 2007193281 A1 US2007193281 A1 US 2007193281A1
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United States
Prior art keywords
stack
temperature
heat exchanger
side heat
thermoacoustic apparatus
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US10/594,278
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English (en)
Inventor
Yoshiaki Watanabe
Shinichi Sakamoto
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DOSHIHA
Doshisha Co Ltd
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DOSHIHA
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Assigned to THE DOSHISHA reassignment THE DOSHISHA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: WATANABE, YOSHIAKI, SAKAMOTO, SHINICHI
Publication of US20070193281A1 publication Critical patent/US20070193281A1/en
Priority to US13/441,264 priority Critical patent/US20120247569A1/en
Abandoned legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
    • F25B9/14—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the cycle used, e.g. Stirling cycle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2309/00—Gas cycle refrigeration machines
    • F25B2309/003—Gas cycle refrigeration machines characterised by construction or composition of the regenerator
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2309/00—Gas cycle refrigeration machines
    • F25B2309/14—Compression machines, plants or systems characterised by the cycle used 
    • F25B2309/1403—Pulse-tube cycles with heat input into acoustic driver
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2309/00—Gas cycle refrigeration machines
    • F25B2309/14—Compression machines, plants or systems characterised by the cycle used 
    • F25B2309/1404—Pulse-tube cycles with loudspeaker driven acoustic driver
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2309/00—Gas cycle refrigeration machines
    • F25B2309/14—Compression machines, plants or systems characterised by the cycle used 
    • F25B2309/1405—Pulse-tube cycles with travelling waves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2309/00—Gas cycle refrigeration machines
    • F25B2309/14—Compression machines, plants or systems characterised by the cycle used 
    • F25B2309/1415—Pulse-tube cycles characterised by regenerator details
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2309/00—Gas cycle refrigeration machines
    • F25B2309/14—Compression machines, plants or systems characterised by the cycle used 
    • F25B2309/1416—Pulse-tube cycles characterised by regenerator stack details
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/0318—Processes
    • Y10T137/0391—Affecting flow by the addition of material or energy

Definitions

  • the present invention relates to a thermoacoustic apparatus capable of cooling or heating an object through the use of thermoacoustic effect and a thermoacoustic system including the thermoacoustic apparatus.
  • thermoacoustic effect Known technologies of a heat exchanger through the use of thermoacoustic effect include the technologies described in the following Patent Document 1, Non-Patent Document 1, and the like.
  • the apparatus described in Patent Document 1 relates to a cooling apparatus through the use of thermoacoustic effect.
  • This apparatus is configured to include a first stack sandwiched between a high-temperature-side heat exchanger and a low-temperature-side heat exchanger and a regenerator sandwiched between a high-temperature-side heat exchanger and a low-temperature-side heat exchanger in the inside of a loop tube, in which a working fluid is enclosed, where an acoustic wave is generated through self excitation by heating the high-temperature-side heat exchanger on the first stack side, and the low-temperature-side heat exchanger on the regenerator side is cooled by a standing wave and a traveling wave based on the acoustic wave.
  • Non-Patent Document 1 discloses an experimental study of a cooling apparatus through the use of thermoacoustic effect.
  • the cooling apparatus used in this experiment is also configured to include a substantially rectangular cross-section loop tube formed from a metal, a first stack sandwiched between a heater (high-temperature-side heat exchanger) and a low-temperature-side heat exchanger, and a second stack disposed at a position opposite to the first stack.
  • a temperature gradient is generated in the first stack by heating the heater (high-temperature-side heat exchanger) disposed on the first stack side and, in addition, circulating running water in the low-temperature-side heat exchanger, and an acoustic wave is generated through self excitation in a direction opposite to the temperature gradient.
  • the resulting acoustic energy is transferred to the regenerator side through the loop tube, and on the second stack side, thermal energy is transferred in the direction opposite to the direction of the acoustic energy on the basis of the energy conservation law, so as to cool the vicinity of a thermometer on the other end side of the second stack.
  • a temperature reduction of about 16° C. has been ascertained under a predetermined condition at the portion where the thermometer has been disposed.
  • Patent Document 1 Japanese Unexamined Patent Application Publication No. 2000-88378
  • Non-Patent Document 1 Shinichi SAKAMOTO, Kazuhiro MURAKAMI, and Yoshiaki WATANABE, “Netsuonkyou Koukao Mochiita Onkyoureikyaku Genshouno Jikkenteki Kentou (Experimental Study of Acoustic Cooling Phenomenon Through the Use of Thermoacoustic Effect)”, The Institute of Electronics, Information and Communication Engineers, TECHNICAL REPORT OF IEICE. US2002-118 (2003-02)
  • thermoacoustic effect In the apparatus through the use of the above-described thermoacoustic effect, the time period from heating to generation of the standing wave and the traveling wave must be reduced. Furthermore, after the standing wave and the traveling wave are generated, the efficiency of heat exchange must be improved. In the case where the standing wave and the traveling wave are generated rapidly, it is necessary that, for example, the temperature gradient is formed in the stack as rapid as possible and the surface wavefront of the generated acoustic wave is stabilized as rapid as possible.
  • thermoacoustic apparatus including a loop tube, wherein a standing wave and a traveling wave are generated rapidly and, thereby, heat exchange is performed rapidly and efficiently.
  • thermoacoustic apparatus includes a first stack sandwiched between a first high-temperature-side heat exchanger and a first low-temperature-side heat exchanger and a second stack sandwiched between a second high-temperature-side heat exchanger and a second low-temperature-side heat exchanger in the inside of a loop tube, wherein a standing wave and a traveling wave are generated through self excitation by heating the above-described first high-temperature-side heat exchanger, the above-described second low-temperature-side heat exchanger is cooled by the standing wave and the traveling wave, or/and a standing wave and a traveling wave are generated through self excitation by cooling the above-described first low-temperature-side heat exchanger, and the above-described second high-temperature-side heat exchanger is heated by the standing wave and the traveling wave, and in the thermoacoustic apparatus, the above-described loop tube is configured to include a plurality of
  • the surface wavefront of the acoustic wave generated in the first stack can be stabilized in the linear tube portion set to be the longest, and the standing wave and the traveling wave can be generated rapidly. Since the first stack is disposed in the linear tube portion standing relative to the ground, the time until the acoustic wave is generated can be reduced through the use of an updraft or a downdraft generated on the first stack side. Furthermore, after the standing wave and the traveling wave are generated, the efficiency of heat exchange can be improved.
  • the lengths of the linear tube portion and the connection tube portion of the above-described loop tube are assumed to be La and Lb, respectively, the lengths are set in such a way as to satisfy 1:0.01 ⁇ La:Lb ⁇ 1:1.
  • the linear tube portion becomes relatively long, as in the above description, the surface wavefront of the acoustic wave can be stabilized. It is preferable that the linear tube portion is as long as possible, and when the lengths are set in such a way as to satisfy La:Lb ⁇ 1:0.5, the surface wavefront of the generated acoustic wave can be further stabilized.
  • the first stack is disposed below the center of the linear tube portion.
  • the first stack is disposed above the center of the linear tube portion.
  • low-temperature heat a large space for generation of a downdraft due to the heat at a low temperature (hereafter referred to as “low-temperature heat”) applied to the first low-temperature-side heat exchanger can be ensured in the downside, and the standing wave and the traveling wave can be generated rapidly through the use of the downdraft.
  • an intersection of the respective center axes is assumed to be a start point of a circuit, and an entire length of the circuit is assumed to be 1.00, the center of the first stack is set at a position corresponding to 0.28 ⁇ 0.05 relative to the entire length of the circuit.
  • the acoustic wave can be generated through self excitation more rapidly.
  • a first peak of the pressure variation of a working fluid along the circuit is present in the vicinity of the first stack, and a second peak is present at a position corresponding to about one-half the entire length of the circuit, the above-described second stack is disposed in such a way that the center of the second stack is positioned past the above-described second peak.
  • the cooling efficiency or the heating efficiency in the second stack can be increased.
  • An acoustic wave generator for generating the standing wave and the traveling wave is disposed on the outer perimeter portion or in the inside of the loop tube.
  • the standing wave and the traveling wave can be generated more rapidly not only by the acoustic wave through self excitation, but also by forced vibration from the acoustic wave generator.
  • the first stack or/and the second stack to be used include connection channels arranged in such a way that the inner diameters of individual connection channels are increased one after another as the position of the connection channel approaches the outside.
  • first stack or/and the second stack to be used include connection channels arranged in such a way that the inner diameters of individual connection channels are decreased one after another as the position of the connection channel approaches the outside.
  • first stack or/and the second stack to be used include meandering connection channels.
  • first stack or/and the second stack to be used include connection channels arranged in such a way that the flow path lengths of individual connection channels are decreased one after another as the position of the connection channel approaches the outside.
  • the flow path lengths of connection channels close to the boundary layer of the loop tube are decreased, the speed gradient can be made uniform and, thereby, the heat exchanger can be heated or cooled uniformly.
  • thermoacoustic apparatus in which a material for the first stack or/and the second stack is composed of at least one type of ceramic, sintered metal, gauze, and nonwoven metal fabric, and the ⁇ ( ⁇ : an angular frequency of the working fluid, ⁇ : temperature relaxation time) thereof is configured to become within the range of 0.2 to 20.
  • an acoustic wave can be generated through self excitation more rapidly and efficiently.
  • thermoacoustic apparatuses are disposed, wherein a second low-temperature-side heat exchanger in one thermoacoustic apparatus is connected to a first low-temperature-side heat exchanger in another thermoacoustic apparatus adjacent thereto, or a second high-temperature-side heat exchanger in one thermoacoustic apparatus is connected to a first high-temperature-side heat exchanger in another thermoacoustic apparatus adjacent thereto.
  • thermoacoustic apparatus since the temperature gradient in the first stack is increased one after another on an adjacent thermoacoustic apparatus basis, higher-temperature heat or lower-temperature heat can be output from the thermoacoustic apparatus on the end side.
  • thermoacoustic apparatus includes the first stack sandwiched between the first high-temperature-side heat exchanger and the first low-temperature-side heat exchanger and the second stack sandwiched between the second high-temperature-side heat exchanger and the second low-temperature-side heat exchanger in the inside of the loop tube, wherein a standing wave and a traveling wave are generated through self excitation by heating the above-described first high-temperature-side heat exchanger, the above-described second low-temperature-side heat exchanger is cooled by the standing wave and the traveling wave, or/and a standing wave and a traveling wave are generated through self excitation by cooling the above-described first low-temperature-side heat exchanger, and the above-described second high-temperature-side heat exchanger is heated by the standing wave and the traveling wave, and in the thermoacoustic apparatus, the above-described loop tube is configured to include a plurality of linear tube portions, which stand relative to the ground, and connection tube portions shorter than the linear
  • the surface wavefront of the acoustic wave generated in the first stack through self excitation can be stabilized in the long linear tube portion, and the standing wave and the traveling wave can be generated rapidly. Since the first stack is disposed in the standing linear tube portion, the time until the acoustic wave is generated can be reduced through the use of an updraft or a downdraft generated on the first stack side. Furthermore, after the acoustic wave is generated, the efficiency of heat exchange can be improved.
  • thermoacoustic apparatus 1 A first embodiment of a thermoacoustic apparatus 1 according to an aspect of the present invention will be described below with reference to drawings.
  • the thermoacoustic apparatus 1 in the present embodiment includes a first stack 3 a sandwiched between a first high-temperature-side heat exchanger 4 and a first low-temperature-side heat exchanger 5 and a second stack 3 b sandwiched between a second high-temperature-side heat exchanger 6 and a second low-temperature-side heat exchanger 7 in the inside of a loop tube 2 configured to take on a rectangular shape as a whole.
  • a standing wave and a traveling wave are generated through self excitation by heating the first high-temperature-side heat exchanger 4 on the first stack 3 a side, and the second low-temperature-side heat exchanger 7 disposed on the second stack 3 b side is cooled by propagating the standing wave and the traveling wave to the second stack 3 b side.
  • a pair of linear tube portions 2 a are disposed along the vertical direction (direction of gravity), connection tube portions 2 b shorter than these linear tube portions 2 a are disposed, and the first stack 3 a is disposed in the lower portion of one of the linear tube portions 2 a while being sandwiched between the first high-temperature-side heat exchanger 4 and the first low-temperature-side heat exchanger 5 .
  • the surface wavefront of the acoustic wave generated from the first stack 3 a must be stabilized as rapid as possible in order to generate a standing wave and a traveling wave.
  • the first stack 3 a is disposed in the longest linear tube portion 2 a in the loop tube 2 in order to stabilize the surface wavefront of the generated acoustic wave as rapid as possible.
  • the length of this linear tube portion 2 a is set to be longer than the length of the connection tube portion 2 b , and when the length of the linear tube portion 2 a is assumed to be La and the length of the connection tube portion 2 b is assumed to be Lb,
  • La and Lb are set within the range satisfying 1:0.01 ⁇ La:Lb ⁇ 1:1.
  • the linear tube portion 2 a is made as long as possible, and
  • La and Lb are set within the range satisfying 1:0.01 ⁇ La:Lb ⁇ 1:0.5.
  • connection tube portion 2 b connecting the linear tube portions 2 a is configured to have corner portions 20 b at both ends.
  • the acoustic wave propagated from the linear tube portion 2 a is reflected by the corner portion 20 b to the connection tube portion 2 b .
  • a structure shown in FIG. 2 is used.
  • FIG. 2 is a diagram showing a magnified corner portion 20 b in the upper end portion of the linear tube portion 2 a .
  • the corner portion 20 b is configured to have an inner diameter substantially equal to the inner diameter of the linear tube portion 2 a and have a diameter which is substantially equal to the inner diameter of the tube and which is centering the inside corner portion of the loop tube 2 . In this manner, all the acoustic energy transferred from the linear tube portion 2 a is reflected at the corner portion 20 b , and is transferred to the connection tube portion 2 b side without being returned to the linear tube portion 2 a .
  • the inner diameter of the corner portion 20 b is configured to become substantially equal to that of the linear tube portion 2 a and, thereby, the inner walls of the linear tube portion 2 a and the corner portion 20 b can be made smooth. Consequently, the acoustic energy is prevented from being lost, so that the acoustic energy can be transferred efficiently.
  • the shape of this corner portion 20 b is not limited to an arch shape, and a linear shape as shown in FIG. 3 can also be used.
  • FIG. 3 is a diagram showing a magnified corner portion 200 b in the upper end portion of the linear tube portion 2 a . In FIG.
  • the corner portion 200 b is disposed in such a way that the outside corner portion thereof takes on a shape of a straight line which forms an angle of about 45 degrees with the linear tube portion 2 a . Consequently, all the acoustic wave propagating in the linear tube portion 2 a is reflected at this linear corner portion to the connection tube portion 2 b side.
  • linear tube portion 2 a and connection tube portion 2 b are composed of metal pipes.
  • the material is not limited to the metal or the like, and may be transparent glass, a resin, or the like.
  • these portions are composed of a material, such as the transparent glass, the resin, or the like, positions of the first stack 3 a and the second stack 3 b can be checked and the status in the tube can easily be observed in an experiment or the like.
  • the first stack 3 a sandwiched between the first high-temperature-side heat exchanger 4 and the first low-temperature-side heat exchanger 5 and the second stack 3 b sandwiched between the second high-temperature-side heat exchanger 6 and the second low-temperature-side heat exchanger 7 are disposed.
  • This first stack 3 a is configured to take on a cylindrical shape which touches the inner wall of the loop tube 2 , and is formed from a material, e.g., ceramic, sintered metal, gauze, or nonwoven metal fabric, which has a large heat capacity.
  • the first stack 3 a is configured to have multiple holes penetrating in the axis direction of the loop tube. As shown in FIG. 4 and FIG.
  • a stack 3 c including a plurality of connection channels 30 arranged in such a way that the inner diameters of individual connection channels are increased one after another as the position of the connection channel approaches the outside from the center or a stack 3 d including connection channels 30 arranged in such a way that the inner diameters of individual connection channels are decreased one after another as the position of the connection channel approaches the outside from the center can be used in place of this first stack 3 a .
  • a stack 3 c including a plurality of connection channels 30 arranged in such a way that the inner diameters of individual connection channels are increased one after another as the position of the connection channel approaches the outside from the center
  • a stack 3 d including connection channels 30 arranged in such a way that the inner diameters of individual connection channels are decreased one after another as the position of the connection channel approaches the outside from the center can be used in place of this first stack 3 a .
  • a stack 3 e including meandering connection channels 30 (connection channel 30 indicated by a thick line) produced by laying, for example, a plurality of fine spherical ceramic or a stack 3 f including connection channels 30 arranged in such a way that the flow path lengths of individual connection channels are decreased one after another as the position of the connection channel approaches the inner perimeter surface of the loop tube 2 may be used.
  • Both the first high-temperature-side heat exchanger 4 and the first low-temperature-side heat exchanger 5 are composed of a thin metal, and are configured to include through holes for transmitting the standing wave and the traveling wave in the inside thereof.
  • the first high-temperature-side heat exchanger 4 is configured to be heated by an electric power supplied from the outside, waste heat, unused energy, or the like.
  • the first low-temperature-side heat exchanger 5 is set at a temperature relatively lower than that of the first high-temperature-side heat exchanger 4 by circulating water around it.
  • the first stack 3 a is disposed below the center of the linear tube portion 2 a , as described above, on the grounds that an acoustic wave is generated rapidly through the use of an updraft generated when the first high-temperature-side heat exchanger 4 is heated.
  • the first high-temperature-side heat exchanger 4 is disposed on the upper side on the grounds that a warm working fluid generated when the first high-temperature-side heat exchanger 4 is heated is prevented from entering the first stack 3 a and, thereby, a large temperature gradient is formed between the first low-temperature-side heat exchanger 5 and the first high-temperature-side heat exchanger 4 .
  • the acoustic wave can be generated through self excitation more rapidly and efficiently by setting the center of the first stack at a position corresponding to 0.28 ⁇ 0.05 relative to the entire length of the circuit in a counterclockwise direction from the start point X.
  • the second stack 3 b is configured to take on a cylindrical shape which touches the inner wall of the loop tube 2 , and is formed from a material, e.g., ceramic, sintered metal, gauze, or nonwoven metal fabric, which has a large heat capacity.
  • the second stack 3 b is configured to have multiple holes penetrating in the axis direction of the loop tube.
  • This second stack 3 b is disposed in such a way that when a first peak of the pressure variation of the working fluid along the loop tube 2 is present in the vicinity of the first stack 3 a , and a second peak is present at a position corresponding to about one-half the entire length of the circuit, the center of the second stack 3 b is positioned past the second peak. As shown in FIG. 4 and FIG.
  • a stack 3 c including a plurality of connection channels 30 arranged in such a way that the inner diameters of individual connection channels are increased one after another as the position of the connection channel approaches the outside from the center or a stack 3 d including connection channels 30 arranged in such a way that the inner diameters of individual connection channels are decreased one after another as the position of the connection channel approaches the outside from the center can be used in place of this second stack 3 b similarly to that for the first stack 3 a .
  • a stack 3 e including meandering connection channels 30 (connection channel 30 indicated by a thick line) produced by laying, for example, a plurality of fine spherical ceramic or a stack 3 f including connection channels 30 arranged in such a way that the flow path lengths of individual connection channels are decreased one after another as the position of the connection channel approaches the inner perimeter surface of the loop tube 2 may be used.
  • both the second high-temperature-side heat exchanger 6 and the second low-temperature-side heat exchanger 7 disposed on the second stack 3 b side are composed of a thin metal, and are configured to include through holes for transmitting the standing wave and the traveling wave in the inside thereof.
  • Water is circulated around the second high-temperature-side heat exchanger 6 and, in addition, an object of cooling is connected to the second low-temperature-side heat exchanger 7 . It is believed that the object of cooling is outside air, a heat-producing household electric appliance, a CPU of a personal computer, and the like. However, objects other than them may be cooled.
  • An inert gas e.g., helium or argon
  • An inert gas is enclosed in the inside of the thus configured loop tube 2 .
  • a working fluid e.g., nitrogen or air, may be enclosed. These working fluid is set at 0.1 MPa to 1.0 MPa.
  • helium having a small Prandtl number and a small specific gravity is enclosed in the loop tube 2 , and an acoustic wave is generated rapidly.
  • a gas e.g., argon
  • argon having a large Prandtl number and a large specific gravity is injected in order to reduce the sound velocity of the acoustic wave generated.
  • a gas injection apparatus 9 is disposed at the center portion of the connection tube portion 2 b disposed on the upper side, and argon is injected therefrom.
  • Argon is injected uniformly into the right and left linear tube portions 2 a and, thereby, argon having a relatively large specific gravity is allowed to flow downward, so that the gas in the inside is made homogeneous.
  • the procedure is not limited to the above-described case where helium is enclosed in advance and, thereafter, argon is injected. Conversely, argon may be enclosed in advance and, thereafter, helium may be injected. In this case, when the gas injection apparatus 9 is disposed at the center portion of the connection tube portion 2 b disposed on the lower side, and helium is injected therefrom, helium having a relatively small specific gravity is allowed to move upward, so that the gas is made homogeneous.
  • the pressures of these mixed gases are set at 0.01 MPa to 5 MPa, and in the case where the entire apparatus is miniaturized, the pressure is set at a relatively low level, for example, 0.01 MPa. In this manner, an influence of the viscosity in the miniaturized loop tube 2 can be reduced.
  • thermoacoustic apparatus 1 The operation state of the thus configured thermoacoustic apparatus 1 will be described below.
  • helium is enclosed in the loop tube 2 .
  • water is circulated around the first low-temperature-side heat exchanger 5 of the first stack 3 a and the second high-temperature-side heat exchanger 6 of the second stack 3 b .
  • a temperature gradient is generated in the first stack 3 a due to the temperature difference between the first high-temperature-side heat exchanger 4 and the first low-temperature-side heat exchanger 5 , and the working fluid begins wandering minutely. Subsequently, this working fluid begins vibrating largely and circulates in the loop tube 2 .
  • the linear tube portion 2 a including the first stack 3 a is set to be relatively long, the surface wavefront of the acoustic wave generated in the first stack 3 a is stabilized, and a standing wave and a traveling wave can be generated in a short time in the loop tube 2 .
  • the acoustic energy due to the standing wave and the traveling wave is generated in the direction opposite to the transfer direction (direction from the first high-temperature-side heat exchanger 4 toward the first low-temperature-side heat exchanger 5 ) of the thermal energy in the first stack 3 a , that is, in the direction from the first low-temperature-side heat exchanger 5 toward the first high-temperature-side heat exchanger 4 , on the basis of the energy conservation law.
  • the resulting acoustic energy is reflected efficiently at the corner portions 20 b of the loop tube 2 and the like and, thereafter, is transferred to the second stack 3 b side.
  • the working fluid is allowed to expand or shrink due to pressure variation and volume variation of the working fluid based on the standing wave and the traveling wave on the second stack 3 b side.
  • the thermal energy generated at that time is transferred in the direction opposite to the transfer direction of the acoustic energy, that is, from the second low-temperature-side heat exchanger 7 toward the second high-temperature-side heat exchanger 6 side. In this manner, the second low-temperature-side heat exchanger 7 is cooled and the intended object is cooled.
  • thermoacoustic apparatus 1 the acoustic wave is generated through self excitation by the temperature gradient provided in the first stack 3 a .
  • an acoustic wave generator 8 may be disposed.
  • This acoustic wave generator 8 is composed of a speaker, a piezoelectric element, or other devices which forcedly vibrate the working fluid from the outside, and is disposed along the outer perimeter surface of the loop tube 2 or in the inside of the loop tube 2 . It is preferable that the acoustic wave generator 8 is attached with a distance of one-half or one-quarter the wavelength of the standing wave and the traveling wave generated, and preferably, the acoustic wave generator 8 is disposed in such a way as to forcedly vibrate the working fluid in the axis direction of the loop tube 2 in correspondence with the movement direction of the standing wave and the traveling wave. As described above, when the acoustic wave generator 8 is disposed, the generation time of the standing wave and the traveling wave can be reduced, and the second low-temperature-side heat exchanger 7 can be cooled.
  • thermoacoustic system 100 in which a plurality of thermoacoustic apparatuses 1 are connected, as shown in FIG. 9 , may be used.
  • reference numerals 1 a , 1 b . . . and 1 n denote thermoacoustic apparatuses 1 configured as described above, and these first thermoacoustic apparatus 1 a , second thermoacoustic apparatus 1 b . . . and nth thermoacoustic apparatus 1 n are disposed adjacently in series. All first high-temperature-side heat exchangers 4 in these first thermoacoustic apparatus 1 a . .
  • thermoacoustic apparatus 1 a . . . are heated by heaters or the like.
  • respective second low-temperature-side heat exchangers 7 of thermoacoustic apparatus 1 a . . . are connected to first low-temperature-side heat exchangers 5 of thermoacoustic apparatus 1 b adjacent thereto.
  • the temperature gradient in the second thermoacoustic apparatus 1 b can be made larger than the temperature gradient of the first stack 3 a in the first thermoacoustic apparatus 1 a . Consequently, the temperature gradient of the thermoacoustic apparatus in can be increased one after another toward the downstream, and the last thermoacoustic apparatus in can output heat at a lower temperature.
  • thermoacoustic apparatuses 1 a . . . is allowed to generate an acoustic wave through self excitation, it takes significantly much time until a standing wave and a traveling wave are generated in the last thermoacoustic apparatus 1 n . Consequently, it is preferable that the time until a standing wave and a traveling wave are generated in each of the thermoacoustic apparatuses 1 a . . . is reduced by disposing acoustic wave generators 8 , in particular, on the outer perimeter surface or in the inside of the loop tube 2 .
  • thermoacoustic apparatus 1 in which the first stack 3 a side is heated and the second stack 3 b side is cooled. Conversely, the first stack 3 a side may be cooled and the second stack 3 b side may be heated.
  • FIG. 8 shows an example of this thermoacoustic apparatus 1 .
  • FIG. 10 the elements indicated by the same reference numerals as those in FIG. 1 to FIG. 8 are elements having the same structures as the elements set forth above.
  • a first stack 3 a is disposed above the center of a linear tube portion 2 a
  • a second stack 3 b is disposed at an appropriate position in the linear tube portion 2 a opposite thereto.
  • it is preferable that these are disposed at the positions at which the installation condition is the same as the condition in the above-described embodiment.
  • Low-temperature heat at minus several tens of degrees or lower is input into the first low-temperature-side heat exchanger 5 and, in addition, an antifreeze liquid is circulated in a first high-temperature-side heat exchanger 4 and a second low-temperature-side heat exchanger 7 . Consequently, an acoustic wave is generated through self excitation by the temperature gradient formed in the first stack 3 a on the basis of the principle of thermoacoustic effect, the surface wavefront is stabilized in the linear tube portion 2 a set to be relatively long, and a standing wave and a traveling wave are generated rapidly through the use of a downdraft of the low-temperature heat.
  • the acoustic energy of the standing wave and the traveling wave is generated in such a way that the movement direction thereof is a direction opposite to the transfer direction (direction from the first high-temperature-side heat exchanger 4 toward the first low-temperature-side heat exchanger 5 ) of the thermal energy in the first stack 3 a .
  • the acoustic energy due to the standing wave and the traveling wave is reflected efficiently at the corner portions 20 b of the loop tube 2 and the like and, thereafter, is transferred to the second stack 3 b side.
  • the working fluid is allowed to repeat expansion and shrinkage due to pressure variation and volume variation of the working fluid based on the standing wave and the traveling wave on the second stack 3 b side.
  • the thermal energy generated at that time is transferred in the direction opposite to the transfer direction of the acoustic energy, that is, from the second low-temperature-side heat exchanger 7 toward the second high-temperature-side heat exchanger 6 side. In this manner, the second high-temperature-side heat exchanger 6 is heated.
  • an acoustic wave generator 8 may be disposed on the outer perimeter surface or in the inside of the loop tube 2 .
  • the above-described thermoacoustic apparatuses 1 may be connected as shown in FIG. 9 , and higher-temperature heat may be output from the thermoacoustic apparatus 1 on the end side.
  • a pair of linear tube portions 2 a having the same length are disposed along the vertical direction, connection tube portions 2 b for connecting the linear tube portions 2 a are disposed, and the linear tube portions 2 b are set to be longer than the connection tube portions 2 b .
  • the first stack 3 a sandwiched between the first high-temperature-side heat exchanger 4 and the first low-temperature-side heat exchanger 5 is disposed in the linear tube portion 2 a . Consequently, the surface wavefront of the acoustic wave generated through self excitation in the first stack 3 a can be stabilized in the long linear tube portion 2 a .
  • the time until the acoustic wave is generated can be reduced through the use of an updraft or a downdraft generated on the first stack 3 a side. Furthermore, after the acoustic wave is generated, the efficiency of heat exchange can be improved.
  • La and Lb are set within the range satisfying “1:0.01 ⁇ La:Lb ⁇ 1:1”, more preferably, La and Lb are set within the range satisfying “La:Lb ⁇ 1:0.5”. Therefore, the surface wavefront of the generated acoustic wave can be stabilized more rapidly.
  • the first stack 3 a side is heated and the second stack 3 b side is cooled, the first stack 3 a is disposed below the center of the linear tube portion 2 a . Therefore, a space for generation of an updraft due to the heat applied to the first high-temperature-side heat exchanger 4 can be ensured, and the standing wave and the traveling wave can be generated rapidly through the use of the updraft.
  • the first stack 3 a side is cooled and the second stack 3 b side is heated, the first stack 3 a is disposed above the center of the linear tube portion 2 a . Therefore, a space for generation of a downdraft due to the low-temperature heat applied to the first low-temperature-side heat exchanger 5 can be ensured, and the standing wave and the traveling wave can be generated rapidly through the use of the downdraft.
  • the center of the first stack 3 a is set at a position corresponding to 0.28 ⁇ 0.05 relative to the entire length of the circuit. Consequently, the acoustic wave through self excitation can be generated more rapidly.
  • the second stack 3 b is disposed in such a way that the center of the second stack 3 b is positioned past the above-described second peak. Consequently, the cooling efficiency or the heating efficiency in the second stack 3 b can be increased.
  • the acoustic wave generator 8 for generating the standing wave and the traveling wave is disposed on the outer perimeter portion or in the inside of the loop tube 2 , the standing wave and the traveling wave can be generated more rapidly not only by the acoustic wave through self excitation, but also by forced vibration from the acoustic wave generator 8 .
  • the stack 3 c including connection channels 30 arranged in such a way that the inner diameters of individual connection channels are increased one after another as the position of the connection channel approaches the outside can also be used in place of the first stack 3 a and the second stack 3 b . Consequently, the inner diameters of the connection channels 30 in the vicinity of the boundary layer in the inside of the loop tube 2 can be increased, and the energy exchange in this portion can be performed efficiently.
  • the stack 3 d including connection channels 30 arranged in such a way that the inner diameters of individual connection channels are decreased one after another as the position of the connection channel approaches the outside, can also be used in place of the first stack 3 a and the second stack 3 b . Consequently, the inner diameters of the connection channels 30 in the center portion in the inside of the loop tube 2 can be increased, and the energy exchange in this portion can be performed efficiently.
  • the stack 3 e including meandering connection channels 30 can also be used in place of the first stack 3 a and the second stack 3 b . Consequently, large surface areas of the working fluid and the stack 3 e can be ensured, the heat exchange with the working fluid is facilitated and, thereby, higher-temperature heat can be output.
  • the stack 3 f including connection channels arranged in such a way that the flow path lengths of individual connection channels are decreased one after another as the position of the connection channel approaches the outside may be used in place of the first stack 3 a and the second stack 3 b . Consequently, the flow path lengths of connection channels close to the boundary layer of the loop tube 2 can be decreased, the speed gradient is made uniform as a whole and, thereby, the heat exchangers 4 , 5 , 6 , and 7 can be uniformly heated or cooled altogether.
  • the material used for the first stack 3 a and the second stack 3 b is composed of at least one type of ceramic, sintered metal, gauze, and nonwoven metal fabric, and the ⁇ ( ⁇ : an angular frequency of the working fluid, ⁇ : temperature relaxation time) thereof is set to become within the range of 0.2 to 20. Consequently, an acoustic wave can be generated through self excitation more rapidly and efficiently.
  • thermoacoustic apparatuses 1 are disposed, wherein a second low-temperature-side heat exchanger 7 in one thermoacoustic apparatus 1 is connected to a first low-temperature-side heat exchanger 5 in another thermoacoustic apparatus 1 adjacent thereto, or a second high-temperature-side heat exchanger 6 in one thermoacoustic apparatus 1 is connected to a first high-temperature-side heat exchanger 4 in another thermoacoustic apparatus 1 adjacent thereto. Consequently, the temperature gradient in the first stack 3 a can be increased one after another on an adjacent thermoacoustic apparatus 1 basis, higher-temperature heat or lower-temperature heat can be output from the thermoacoustic apparatus 1 on the end side.
  • bilaterally symmetric loop tube 2 is disposed.
  • an irregularly meandering loop tube may be used.
  • a first stack 3 a serving as an acoustic wave generation source is disposed in the longest linear tube portion.
  • linear tube portions 2 a along the vertical direction are disposed.
  • a linear tube portion slightly inclined relative to the ground may be disposed.
  • the positions of the above-described first stack 3 a and the second stack 3 b are not limited to the conditions set as described above, and they may be disposed at appropriately positions on the basis of various experiments or the like.
  • FIG. 1 is a schematic diagram of a thermoacoustic apparatus according to an embodiment of the present invention.
  • FIG. 2 is a diagram showing a magnified corner portion of a loop tube in the above-described embodiment.
  • FIG. 3 is a diagram showing the shape of a corner portion of a loop tube in another embodiment.
  • FIG. 4 is a diagram showing the shape of a stack in another embodiment.
  • FIG. 5 is a diagram showing the shape of a stack in another embodiment.
  • FIG. 6 is a diagram showing the shape of a stack in another embodiment.
  • FIG. 7 is a diagram showing the shape of a stack in another embodiment.
  • FIG. 8 is a schematic diagram of a thermoacoustic apparatus including an acoustic wave generator.
  • FIG. 9 is a schematic diagram of an acoustic heating system in which acoustic heating apparatuses are connected.
  • FIG. 10 is a schematic diagram of a thermoacoustic apparatus in another embodiment.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
US10/594,278 2004-03-26 2005-03-23 Thermoacoustic apparatus and thermoacoustic system Abandoned US20070193281A1 (en)

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PCT/JP2005/005220 WO2005093340A1 (ja) 2004-03-26 2005-03-23 熱音響装置及び熱音響システム

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US8443599B2 (en) 2006-09-02 2013-05-21 The Doshisha Thermoacoustic apparatus
JP2008249223A (ja) * 2007-03-30 2008-10-16 Doshisha スタック及びその製造方法
JP5299107B2 (ja) * 2009-06-16 2013-09-25 いすゞ自動車株式会社 熱音響機関
JP5310287B2 (ja) * 2009-06-16 2013-10-09 いすゞ自動車株式会社 熱音響機関
JP5532938B2 (ja) * 2010-01-13 2014-06-25 いすゞ自動車株式会社 熱音響機関
JP6482350B2 (ja) * 2015-03-26 2019-03-13 大阪瓦斯株式会社 気化設備
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JP2018071821A (ja) * 2016-10-25 2018-05-10 三菱電機株式会社 熱音響装置
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