U.S. patent application number 11/662297 was filed with the patent office on 2008-05-15 for thermoacoustic device.
This patent application is currently assigned to THE DOSHISHA. Invention is credited to Shinichi Sakamoto, Yoshiaki Watanabe.
Application Number | 20080110180 11/662297 |
Document ID | / |
Family ID | 36647495 |
Filed Date | 2008-05-15 |
United States Patent
Application |
20080110180 |
Kind Code |
A1 |
Watanabe; Yoshiaki ; et
al. |
May 15, 2008 |
Thermoacoustic Device
Abstract
A thermoacoustic device 1 for reliably generating standing and
traveling waves, which have a large sound pressure, in a loop tube,
has a loop tube 2 in which a working fluid is sealed; first stacks
3a, each of which has a plurality of communication paths 30 along a
heat transportation direction and is provided between a first
high-temperature side heat exchanger 4 and a first low-temperature
side heat exchanger 5, which are provided in this loop tube 2; and
a second stack 3b which has a plurality of communication paths 30
along a heat transportation direction and which is provided between
a second high-temperature side heat exchanger 6 and a second
low-temperature side heat exchanger 7, which are provided in the
loop tube 2, and in the thermoacoustic device 1, self-excited
standing and traveling waves are generated by heating the first
high-temperature side heat exchanger 4, so that the second
low-temperature side heat exchanger 7 is cooled by the standing and
traveling waves. The first stacks 3a each provided between the
first high-temperature side heat exchanger 4 and the first
low-temperature side heat exchanger 5 are provided at a plurality
of positions which are in the vicinities at which the phase of
change in acoustic particle velocity is the same as the phase of
change in sound pressure.
Inventors: |
Watanabe; Yoshiaki; (Kyoto,
JP) ; Sakamoto; Shinichi; (Osaka, JP) |
Correspondence
Address: |
WESTERMAN, HATTORI, DANIELS & ADRIAN, LLP
1250 CONNECTICUT AVENUE, NW, SUITE 700
WASHINGTON
DC
20036
US
|
Assignee: |
THE DOSHISHA
Kyoto
JP
|
Family ID: |
36647495 |
Appl. No.: |
11/662297 |
Filed: |
April 22, 2005 |
PCT Filed: |
April 22, 2005 |
PCT NO: |
PCT/JP05/07685 |
371 Date: |
March 9, 2007 |
Current U.S.
Class: |
62/6 ;
62/324.2 |
Current CPC
Class: |
F02F 3/003 20130101;
F02G 2243/54 20130101; F25B 2309/1403 20130101; F25B 9/145
20130101; F02G 1/02 20130101; F25B 2309/1405 20130101; F25B
2309/1416 20130101 |
Class at
Publication: |
62/6 ;
62/324.2 |
International
Class: |
F25B 9/00 20060101
F25B009/00; F25B 13/00 20060101 F25B013/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 7, 2005 |
JP |
2005-002624 |
Claims
1. A thermoacoustic device comprising: a tube in which a working
fluid is sealed; first stacks which each have a plurality of
communication paths along a heat transportation direction and which
are each provided between a first high-temperature side heat
exchanger and a first low-temperature side heat exchanger, which
are provided in the tube; and a second stack which has a plurality
of communication paths along a heat transportation direction and
which is provided between a second high-temperature side heat
exchanger and a second low-temperature side heat exchanger, which
are provided in the tube, in which self-excited standing and
traveling waves are generated by heating the first high-temperature
side heat exchanger, and the second low-temperature side heat
exchanger is cooled by the standing and traveling waves, or in
which self-excited standing and traveling waves are generated by
cooling the first low-temperature side heat exchanger, and the
second high-temperature side heat exchanger is heated by the
standing and traveling waves, wherein the first stacks each
provided between the first high-temperature side heat exchanger and
the first low-temperature side heat exchanger are provided at a
plurality of positions in the tube.
2. The thermoacoustic device according to claim 1, wherein the
first stacks each provided between the first high-temperature side
heat exchanger and the first low-temperature side heat exchanger
are provided in the vicinities of positions at which the phase of
change in acoustic particle velocity is the same as the phase of
change in sound pressure.
3. A thermoacoustic device comprising: a tube in which a working
fluid is sealed; an acoustic wave generator generating an acoustic
wave provided in the tube; and second stacks which each have a
plurality of communication paths along a heat transportation
direction and which are each provided between a second
high-temperature side heat exchanger and a second low-temperature
side heat exchanger, which are provided in the tube, in which
standing and traveling waves are generated in the tube by the
acoustic wave generator so that the second low-temperature side
heat exchanger is cooled or the second high-temperature side heat
exchanger is heated by the standing and traveling waves, and heat
obtained by the cooling or the heating is output outside, wherein
the second stacks each provided between the second high-temperature
side heat exchanger and the second low-temperature side heat
exchanger are provided at a plurality of positions in the tube.
4. The thermoacoustic device according to claim 3, wherein the
second stacks each provided between the second high-temperature
side heat exchanger and the second low-temperature side heat
exchanger are provided in the vicinities of positions at which the
phase of change in acoustic particle velocity is the same as the
phase of change in sound pressure.
5. A thermoacoustic device comprising: a tube in which a working
fluid is sealed; first stacks which each have a plurality of
communication paths along a heat transportation direction and which
are each provided between a first high-temperature side heat
exchanger and a first low-temperature side heat exchanger, which
are provided in the tube; and second stacks which each have a
plurality of communication paths along a heat transportation
direction and which are each provided between a second
high-temperature side heat exchanger and a second low-temperature
side heat exchanger, which are provided in the tube, in which
self-excited standing and traveling waves are generated by heating
the first high-temperature side heat exchanger, and the second
low-temperature side heat exchanger is cooled by the standing and
traveling waves, or in which self-excited standing and traveling
waves are generated by cooling the first low-temperature side heat
exchanger, and the second high-temperature side heat exchanger is
heated by the standing and traveling waves, wherein the first
stacks each provided between the first high-temperature side heat
exchanger and the first low-temperature side heat exchanger have
the same structure as the structure of the second stacks each
provided between the second high-temperature side heat exchanger
and the second low-temperature side heat exchanger, and the first
stacks and the second stacks, which have the same structure, are
provided at a plurality of positions in the tube.
Description
TECHNICAL FIELD
[0001] The present invention relates to a thermoacoustic device
capable of cooling an object to be cooled or of heating an object
to be heated using a thermoacoustic effect, and more particularly,
relates to a thermoacoustic device capable of amplifying acoustic
energy generated in a tube and of efficiently converting the
amplified acoustic energy to thermal energy.
BACKGROUND ART
[0002] Heat exchange devices using an acoustic effect have been
disclosed, for example, in the following Patent Document 1.
[0003] The device disclosed in Patent document 1 includes a
resonance tube in the form of a loop having a circumference of an
integral multiple of an acoustic wavelength, a plurality of
speakers disposed at intervals of an odd multiple of one fourth of
an acoustic wavelength, an acoustic wave generation control means
which changes the phases of acoustic waves generated from the
speakers by an odd multiple of one-fourth cycle, and a regenerative
member disposed at a predetermined position in the loop-shaped
resonance tube, and in this device, an acoustic wave traveling only
in one direction is allowed to remain in the resonance tube, so
that the amplitude of the acoustic wave is amplified as is the
resonance. According to this thermoacoustic device, when the
acoustic waves emitted from the speakers travel in two directions
in the loop-shaped resonance tube, acoustic waves traveling in one
direction are overlapped with each other by the intervals at which
the speakers are disposed and are amplified, and acoustic waves
traveling in the other direction are counteracted by waves having
an opposite phase; hence, an acoustic wave amplified only in one
direction can be generated.
[0004] [Patent Document 1] Japanese Unexamined Patent Application
Publication No. 10-325625
DISCLOSURE OF INVENTION
Problems to be Solved by the Invention
[0005] Since the device disclosed in Patent Document 1 is a device
to input acoustic waves using speakers, an object to be cooled
cannot be cooled using waste heat or the like. In addition, as the
case of the above Patent Document 1, when speakers are mounted to
the outside of a tube, acoustic waves emitted from the speakers are
reflected by an outer peripheral portion of the tube, and hence
stable acoustic waves cannot be input in the tube. In addition,
when speakers are mounted in the vicinity of the tube, the whole
tube also vibrates as the speakers vibrate, and hence acoustic
waves in the tube cannot be well counteracted with each other.
[0006] Accordingly, the present invention has been conceived in
consideration of the above problems, and an object of the present
invention is to provide a thermoacoustic device capable of reliably
generating large standing and traveling waves in a tube.
Means for Solving the Problems
[0007] In order to achieve the above object, in accordance with one
aspect of the present invention, there is provided a thermoacoustic
device including: a tube in which a working fluid is sealed; first
stacks which each have a plurality of communication paths along a
heat transportation direction and which are each provided between a
first high-temperature side heat exchanger and a first
low-temperature side heat exchanger, which are provided in the
tube; and a second stack which has a plurality of communication
paths along a heat transportation direction and which is provided
between a second high-temperature side heat exchanger and a second
low-temperature side heat exchanger, which are provided in the
tube, in which self-excited standing and traveling waves are
generated by heating the first high-temperature side heat
exchanger, and the second low-temperature side heat exchanger is
cooled by the standing and traveling waves, or self-excited
standing and traveling waves are generated by cooling the first
low-temperature side heat exchanger, and the second
high-temperature side heat exchanger is heated by the standing and
traveling waves. In the above thermoacoustic device, the first
stacks each provided between the first high-temperature side heat
exchanger and the first low-temperature side heat exchanger are
provided at a plurality of positions in the tube.
[0008] According to the structure described above, since an
acoustic wave is generated in the tube instead of inputting an
acoustic wave from the outside of the tube, the acoustic wave is
not reflected by the outside wall surface of the tube. In addition,
since the first stacks are provided at a plurality of positions,
the acoustic wave can be amplified, and at this stage, a
self-excited acoustic wave can be generated using heat; hence, for
example, an object to be cooled can be cooled by using waste
heat.
[0009] In addition, according to the present invention, the first
stacks each provided between the first high-temperature side heat
exchanger and the first low-temperature side heat exchanger are
preferably provided in the vicinities of positions at which the
phase of change in acoustic particle velocity is the same as the
phase of change in sound pressure.
[0010] According to the above structure, the acoustic wave
generated in each first stack can be reliably amplified.
[0011] In addition, in accordance with another aspect of the
present invention, there is provided a thermoacoustic device
including: a tube in which a working fluid is sealed; an acoustic
wave generator generating an acoustic wave provided in the tube;
and second stacks which each have a plurality of communication
paths along a heat transportation direction and which are each
provided between a second high-temperature side heat exchanger and
a second low-temperature side heat exchanger, which are provided in
the tube, in which standing and traveling waves are generated in
the tube by the acoustic wave generator so that the second
low-temperature side heat exchanger is cooled or the second
high-temperature side heat exchanger is heated by the standing and
traveling waves, and heat obtained by the cooling or the heating is
output outside. In the above thermoacoustic device, the second
stacks each provided between the second high-temperature side heat
exchanger and the second low-temperature side heat exchanger are
provided at a plurality of positions in the tube.
[0012] According to the structure described above, by the second
stacks provided at a plurality of positions in the tube, the
conversion efficiency from acoustic energy to thermal energy can be
improved.
[0013] In addition, as is the case described above, the second
stacks each provided between the first high-temperature side heat
exchanger and the first low-temperature side heat exchanger are
provided in the vicinities of positions at which the phase of
change in acoustic particle velocity is the same as the phase of
change in sound pressure.
[0014] According to the structure described above, the acoustic
energy generated in the tube can be efficiently converted to the
thermal energy, and an object to be cooled can be further
cooled.
[0015] Furthermore, the first high-temperature side heat exchanger,
the first low-temperature side heat exchanger, and the first stack
are formed to have the same structures as those of the second
high-temperature side heat exchanger, the second low-temperature
side heat exchanger, and the second stack, respectively.
[0016] Accordingly, when stacks each provided between a
high-temperature side heat exchanger and a low-temperature side
heat exchanger are provided beforehand at appropriate positions in
the tube, that is, are provided in the vicinities at which the
phase of change in acoustic particle velocity is the same as the
phase of change in sound pressure, the number of stacks at the
acoustic wave generation side and the number of stacks at the heat
output side can be increased or decreased only by selecting heat
input positions and heat output positions.
Advantages
[0017] According to one aspect of the present invention, the
thermoacoustic device has a tube in which a working fluid is
sealed; first stacks which each have a plurality of communication
paths along a heat transportation direction and which are each
provided between a first high-temperature side heat exchanger and a
first low-temperature side heat exchanger, which are provided in
the tube; and a second stack which has a plurality of communication
paths along a heat transportation direction and which is provided
between a second high-temperature side heat exchanger and a second
low-temperature side heat exchanger, which are provided in the
tube, in which self-excited standing and traveling waves are
generated by heating the first high-temperature side heat
exchanger, and the second low-temperature side heat exchanger is
cooled by the standing and traveling waves, or self-excited
standing and traveling waves are generated by cooling the first
low-temperature side heat exchanger, and the second
high-temperature side heat exchanger is heated by the standing and
traveling waves. In the above thermoacoustic device, since the
first stacks each provided between the first high-temperature side
heat exchanger and the first low-temperature side heat exchanger
are provided at a plurality of positions in the tube, compared to
the case in which an acoustic wave is input from the outside of the
tube using a speaker, the acoustic wave is not reflected by the
outside wall surface of the tube, and hence the acoustic wave can
be reliably amplified in the tube. In addition, at this stage,
since a self-excited acoustic wave is generated using heat, for
example, waste heat can be used.
[0018] According to another aspect of the present invention, the
thermoacoustic device has: a tube in which a working fluid is
sealed; an acoustic wave generator generating an acoustic wave
provided in the tube; and second stacks which each have a plurality
of communication paths along a heat transportation direction and
which are each provided between a second high-temperature side heat
exchanger and a second low-temperature side heat exchanger, which
are provided in the tube, in which standing and traveling waves are
generated in the tube by the acoustic wave generator so that the
second low-temperature side heat exchanger is cooled or the second
high-temperature side heat exchanger is heated by the standing and
traveling waves, and heat obtained by the cooling or the heating is
output outside. In the thermoacoustic device described above, since
the second stacks each provided between the second high-temperature
side heat exchanger and the second low-temperature side heat
exchanger are provided at a plurality of positions in the tube, the
conversion efficiency from acoustic energy to thermal energy can be
improved.
Best Mode for Carrying Out the Invention
[0019] Hereinafter, a first embodiment of a thermoacoustic device 1
according to the present invention will be described with reference
to figures.
[0020] As shown in FIG. 1, the thermoacoustic device 1 of this
embodiment includes a loop tube 2 having an approximately
rectangular shape as a whole, and in this loop tube 2, there are
provided first heat exchangers 300, each of which is composed of a
first high-temperature side heat exchanger 4, a first
low-temperature side heat exchanger 5, and a first stack 3a, and
second heat exchangers 310, each of which is composed of a second
high-temperature side heat exchanger 6, a second low-temperature
side heat exchanger 7, and a second stack 3b. By heating the first
high-temperature side heat exchangers 4 at the first heat exchanger
300 side, self-excited standing and traveling waves are generated,
and when acoustic energy by the standing and traveling waves is
transported to the second heat exchanger 310 side, it is converted
to thermal energy at the second heat exchanger 310 side so as to
cool the second low-temperature side heat exchangers 7.
[0021] In this embodiment, in order to generate standing and
traveling waves having a high sound pressure in the loop tube 2,
the first heat exchangers 300 are provided in the vicinities of
positions at which the phase of change in acoustic particle
velocity is the same as the phase of change in sound pressure, and
in order to improve conversion efficiency of acoustic energy of the
standing and traveling waves generated in the loop 2 to thermal
energy, the second heat exchangers 310 are disposed in the
vicinities of positions at which the phase of change in acoustic
particle velocity is the same as the phase of change in sound
pressure. Hereinafter, a particular structure of this
thermoacoustic device 1 will be described in detail.
[0022] The loop tube 2 forming the thermoacoustic device 1 is
formed of a pair of straight tube portions 2a and connection tube
portions 2b connecting therebetween so as to form a closed curved
line. Those straight tube portions 2a and the connection tube
portions 2b are formed of metal pipes; however, a material is not
limited to a metal, and for example, a transparent glass or resin
may also be used. When a transparent glass or resin is used, in an
experiment or the like, the positions of the first stack 3a and the
second stack 3b can be easily confirmed, and the state in the tube
can be easily observed.
[0023] In addition, in the loop tube 2 thus formed, there are
provided the first heat exchangers 300, each of which is composed
of the first high-temperature side heat exchanger 4, the first
low-temperature side heat exchanger 5, and the first stack 3a, and
the second heat exchangers 310, each of which is composed of the
second high-temperature side heat exchanger 6, the second
low-temperature side heat exchanger 7, and the second stack 3b. All
the first heat exchangers 300 have the same structure, and all the
second heat exchangers 310 also have the same structure.
[0024] The first high-temperature side heat exchanger 4 and the
first low-temperature side heat exchanger 5 are both formed, for
example, of a metal having a large heat capacity, and as shown in
FIG. 3, communication paths 30 having a small diameter are provided
inside each of the heat exchangers along the axial direction of the
loop tube 2. Of the heat exchangers 4 and 5, the first
high-temperature side heat exchanger 4 is mounted so as to be in
contact with an upper surface of the stack 3a and is heated to a
temperature relatively higher than that of the first
low-temperature side heat exchanger 5 by waste heat or the like
supplied from the outside. Alternatively, besides the waste heat,
this first high-temperature side heat exchanger 4 may be heated by
electric power or the like supplied from the outside.
[0025] In addition, as is the case described above, the first
low-temperature side heat exchanger 5 is mounted so as to be in
contact with a lower surface of the first stack 3a and is set to a
temperature, such as 15 to 16.degree. C., which is relatively lower
than that of the first high-temperature side heat exchanger 4, by
circulating water or the like in an outer peripheral portion of the
first low-temperature side heat exchanger 5.
[0026] The first stack 3a provided between the first
high-temperature side heat exchanger 4 and the first
low-temperature side heat exchanger 5 has a cylindrical shape in
contact with the inside wall surface of the loop tube 2 and, as
shown in FIG. 3, is formed of stack constituent elements 3eL and
3eH which are laminated together and which have different thermal
conductivities. Those stack constituent elements 3eL and 3eH are
formed using a material, such as a ceramic, a sintered metal, a
metal mesh, or a metal nonwoven cloth, and the stack constituent
element 3eL having a low thermal conductivity, the stack
constituent element 3eH having a high thermal conductivity, and the
stack constituent element 3eL having a low thermal conductivity are
disposed in that order from the first high-temperature side heat
exchanger 4 side. Of the stack constituent elements 3eL and 3eH,
the stack constituent element 3eH having a high thermal
conductivity is formed thicker than the stack constituent element
3eL having a relatively low thermal conductivity, and by the
structure described above, an area in which heat exchange can be
performed with a working fluid is increased. Inside those stack
constituent elements 3eL and 3eH, communication paths 30, which
penetrate therethrough and which have a small diameter, are
provided along the axial direction of the loop tube 2, as shown in
FIG. 2. Those stack constituent elements 3eL and 3eH are laminated
together in the top and down direction so as to be closely in
contact with each other. When those stack constituent elements 3eL
and 3eH are laminated together, and lamination is performed using
an adhesive, an adhesive which overflows may block the
communication paths 30 having a small diameter, provided in the
stack constituent elements 3eL and 3eH. Accordingly, without using
an adhesive, for example, the widths of the first high-temperature
side heat exchanger 4 and the first low-temperature side heat
exchanger 5 are set to be equal to a thickness width of the first
stack 3a, and the stack constituent elements 3eL and 3eH are
provided between the first high-temperature side heat exchanger 4
and the first low-temperature side heat exchanger 5 by a holding
force generated therebetween. Alternatively, when the first stack
3a is provided in the erected straight tube portion 2a of the loop
tube 2, the stack constituent elements 3eL and 3eH are disposed so
as to be closely in contact with each other by their own
weights.
[0027] In addition, the stack constituent elements 3eL and 3eH are
each formed, for example, from a single material so as to obtain a
constant thermal conductivity in a plane surface direction. When
the thermal conductivity is nonuniform in a plane surface
direction, the difference in temperature between the inside and the
outside of the first stack 3a is generated, and thereby a
nonuniform acoustic wave is generated; hence, the time for
generating standing and traveling waves is delayed, and as a
result, the heat exchange efficiency is degraded. Hence, the stack
constituent elements 3eL and 3eH are each formed of a single
material so as to obtain a constant thermal conductivity in a plane
surface direction.
[0028] In addition, while the first high-temperature side heat
exchangers 4 are disposed so as to face in the same direction, the
first heat exchangers 300 formed as described above, that is, the
first high-temperature side heat exchanger 4, the first
low-temperature side heat exchanger 5, and the first stack 3a, are
provided in the vicinities of positions in the tube 2 at which the
phase of change in acoustic particle velocity is the same as the
phase of change in sound pressure. FIG. 4 is a view showing the
tube 2 in an open state and shows the relationship of positions of
the first heat exchanger 300 and the second heat exchanger 310 with
positions at which the phase of change in acoustic particle
velocity is the same as the phase of change in sound pressure. In
general, properties of an acoustic wave are change, for example, by
the difference in temperature between the first high-temperature
side heat exchanger 4 and the first low-temperature side heat
exchanger 5 and the pressure in the loop tube 2. Hence, an
alterable mechanism for altering the position of the first heat
exchanger 300 or a pressure adjustment mechanism for adjusting the
wavelength of an acoustic wave by the pressure may be provided. As
the alterable mechanism, for example as shown in FIG. 5, a
mechanism may be conceived in which a part 20 of the loop tube, to
which the first heat exchanger 300 is fitted, is formed to be
slidably separated from a main frame of the loop tube 2, and the
part 20 thus separated is allowed to slide therealong to adjust the
position of the first heat exchanger 300. In addition, as the
pressure adjustment mechanism, gas injection devices 9aand 9b,
which will be described below, may also be conceived.
[0029] Next, operation of the first heat exchanger 300 thus formed
will be described. First, when the first high-temperature side heat
exchanger 4 of the first heat exchanger 300 is heated while the
first low-temperature side heat exchanger 5 is cooled, heat is
transported in the directions (axial direction) form the first
high-temperature side heat exchanger 4 to the first low-temperature
side heat exchanger 5. At this stage, heat at a temperature of
approximately 600.degree. C. obtained by heating in the first
high-temperature side heat exchanger 4 is transported to the first
low-temperature side heat exchanger 5 via the first stack 3a;
however, the heat transportation described above is inhibited by
the stack constituent elements 3eL having a low thermal
conductivity, which are provided at end portions of the first stack
3a. Hence, the heat is not transported to the first low-temperature
side heat exchanger 5, and as a result, the difference in
temperature between the first high-temperature side heat exchanger
4 and the first low-temperature side heat exchanger 5 can be
increased. In addition, the heat at a temperature of approximately
600.degree. C. obtained by heating in the first high-temperature
side heat exchanger 4 is transported to the first low-temperature
side heat exchanger 5 side via a working fluid present in the
communication paths 30 of the first stack 3a. As a result, the
temperature gradient between the first high-temperature side heat
exchanger 4 and the first low-temperature side heat exchanger 5 is
formed, and by this temperature gradient generated in this working
fluid, wobbling thereof is generated, so that an acoustic wave is
generated while heat exchange is performed with the first stack 3a.
At this stage, since large heat exchange is performed with the
stack constituent element 3eH having a relatively high thermal
conductivity, an acoustic wave is rapidly generated, and as a
result, the heat exchange efficiency can be improved.
[0030] The acoustic wave thus generated is turned into the standing
and traveling waves in the loop tube 2, is amplified by the first
heat exchangers 300 located at a plurality of positions, and is
then transported to the second heat exchanger 310 side as acoustic
energy having a high sound pressure.
[0031] This second heat exchanger 310 is formed of the second
high-temperature side heat exchanger 6, the second low-temperature
side heat exchanger 7, and the second stack 3b. The second
high-temperature side heat exchanger 6 and the second
low-temperature side heat exchanger 7 are both formed, for example,
of a metal having a large heat capacity and are provided at two
ends of the second stack 3b, as is the case of the first stack 3a,
and in addition, inside the heat exchangers 6 and 7, there are
provided communication paths 30 having a small diameter through
which the standing and traveling waves are allowed to pass. This
second high-temperature side heat exchanger 6 is set to a
temperature, such as 15 to 16.degree. C., by circulating water in
an outer peripheral portion of the second high-temperature side
heat exchanger 6. On the other hand, the second low-temperature
side heat exchanger 7 has a heat output portion and is designed to
cool an exterior object to be cooled. As the object to be cooled,
for example, ambient air, a home electric appliance which generates
heat, and a CPU of a personal computer may be mentioned. In
addition, the second stack 3b has the structure similar to that of
the first stack 3a. That is, three layers, a stack constituent
element 3eL having a low thermal conductivity, a stack constituent
element 3eH having a high thermal conductivity, and a stack
constituent element 3eL having a low thermal conductivity, are
provided in that order from the second high-temperature side heat
exchanger 6 side. In addition, the stack constituent element 3eH
having a high thermal conductivity is formed thicker than the stack
constituent element 3eL having a relatively low thermal
conductivity. The second heat exchanger 310 formed as described
above is provided in the vicinity of a position in the loop tube 2
at which the phase of change in acoustic particle velocity is the
same as the phase of change in sound pressure, as shown in FIG. 4.
In addition, as shown in FIG. 5, the second heat exchanger 310 is
mounted in a mechanism in which a part 20 of the loop tube, to
which the second heat exchanger 310 is fixed, is formed to be
slidably separated from a main frame of the loop tube 2, and the
part 20 thus separated is allowed to slide therealong to adjust the
position of the second heat exchanger 310.
[0032] Inside this loop tube 2, an inert gas, such as helium or
argon, is sealed. Besides the inert gases as mentioned above, a
working fluid, such as nitrogen or air, may also be sealed. The
pressure of the working fluid is set in the range of 0.01 to 5
MPa.
[0033] In the case in which the working fluid as described above is
sealed, when helium or the like, having a small Prandtl number and
also having a small specific gravity, is used, the time for
generating an acoustic wave can be decreased. However, when the
working fluid as described above is used, the acoustic velocity is
increased, and as a result, heat exchange with stack inside walls
cannot be well performed. On the other hand, when argon or the
like, having a large Prandtl number and also having a large
specific gravity, is used, since the viscosity is increased this
time, and as a result, an acoustic wave cannot be rapidly
generated. Hence, a mixed gas of helium and argon is preferably
used. The mixed gas mentioned above is sealed as described
below.
[0034] First, helium having a small Prandtl number and also having
a small specific gravity is sealed in the loop tube 2, so that an
acoustic wave is rapidly generated. Subsequently, in order to
decrease the acoustic velocity of the generated acoustic wave, a
gas, such as argon, having a large Prandtl number and also having a
large specific gravity is injected. When this argon is mixed, as
shown in FIG. 1, the helium gas injection device 9a and the argon
gas injection device 9b are provided at a central portion of the
connection tube portion 2b formed at an upper side, and argon is
injected therefrom. Accordingly, argon equally flows into the
right-side and the left-side straight tube portions 2a and are then
mixed with helium present inside. The pressure of the mixed gas
described above is set in the range of 0.01 to 5 MPa.
[0035] Next, an operation state of the thermoacoustic device 1 thus
configured will be described.
[0036] First, helium is sealed in the loop tube 2 using the helium
gas injection device 9a, and in this state, water is circulated in
an outer peripheral portion of the first low-temperature side heat
exchanger 5 of the first heat exchanger 300 and that of the second
high-temperature side heat exchanger 6 of the second heat exchanger
310. In the above state, the first high-temperature side heat
exchanger 4 of the first heat exchanger 300 is heated to
approximately 600.degree. C., and in addition, the first
low-temperature side heat exchanger 5 is set to approximately 15 to
16.degree. C. As a result, heat is transported from the first
high-temperature side heat exchanger 4 to the first low-temperature
side heat exchanger 5. At this stage, the heat from the first
high-temperature side heat exchanger 4 is transported to the first
low-temperature side heat exchanger 5 via a member of the first
stack 3a; however, this heat transportation is inhibited by the
presence of the stack constituent elements 3eL having a low thermal
conductivity. Hence, the difference in temperature between the
first high-temperature side heat exchanger 4 and the first
low-temperature side heat exchanger 5 can be increased. On the
other hand, the heat (600.degree. C.) of this first
high-temperature side heat exchanger 4 is transported to the first
low-temperature side heat exchanger 5 side by the working fluid
present in the communication paths 30 of the first stack 3a.
Accordingly, the temperature gradient is formed between the first
high-temperature side heat exchanger 4 and the first
low-temperature side heat exchanger 5, and by this temperature
gradient generated in this working fluid, wobbling thereof is
generated, so that an acoustic wave is generated while heat
exchange is performed with the first stack 3a. At this stage, large
heat exchange is performed with the stack constituent element 3eH
which is relatively thick and which has a high thermal
conductivity, and the acoustic wave is rapidly generated, so that
the heat exchange efficiency is improved. In addition, an acoustic
wave can also be generated in the other first heat exchanger 300 as
described above, and the acoustic wave can be amplified by the
first heat exchangers 300. The acoustic wave thus generated is
transported as acoustic energy by the standing and traveling waves
to the second heat exchanger 310 side. This acoustic energy is
transported based on the energy conservation law in a direction
opposite to that of transportation of the thermal energy in the
first heat exchanger 300 (from the first high-temperature side heat
exchanger 4 to the first low-temperature side heat exchanger 5),
that is, in a direction from the first low-temperature side heat
exchanger 5 to the first high-temperature side heat exchanger
4.
[0037] Subsequently, immediately after the standing and traveling
waves are generated, argon is injected from the argon gas injection
device 9b provided at the upper side of the connection tube portion
2b so that the pressure is set at a predetermined value, thereby
improving the heat exchange efficiency.
[0038] Next, at the second heat exchanger 310 side, based on the
standing and traveling waves, the working fluid in the
communication paths 30 of the second stack 3b is expanded and
contracted. Thermal energy which is heat-exchanged at this stage is
transported in a direction opposite to the transportation direction
of the acoustic energy, that is, in a direction from the second
low-temperature side heat exchanger 7 to the second
high-temperature side heat exchanger 6 side. At this stage, high
heat is accumulated at the second high-temperature side heat
exchanger 6 side, and low heat is accumulated at the second
low-temperature side heat exchanger 7 side. Subsequently, by the
difference in temperature described above, the high heat is
transported to the second low-temperature side heat exchanger 7
side via the second stack 3b; however, since the stack constituent
elements 3eL having a low thermal conductivity are provided at the
second high-temperature side heat exchanger 6 and the second
low-temperature side heat exchanger 7 sides, the heat
transportation is inhibited. Accordingly, the temperature of the
second low-temperature side heat exchanger 7 can be further
decreased, and hence an object to be cooled can be further
cooled.
[0039] In addition, acoustic energy which is not converted to
thermal energy in this second heat exchanger 310 passes through the
communication paths 30 thereof and is transported to the other
second heat exchanger 310 located next thereto. Subsequently, the
acoustic energy is converted to thermal energy in the manner as
described above, and the second low-temperature side heat exchanger
7 of the other second heat exchanger 310 is cooled.
[0040] According to the embodiment described above, in the
thermoacoustic device 1 including: the loop tube 2 in which a
working fluid is sealed; the first stacks 3a, each of which is
provided in this loop tube 2 and between the first high-temperature
side heat exchanger 4 and the first low-temperature side heat
exchanger 5 and has the communication paths 30 along the heat
transportation direction; and the second stacks 3b, each of which
is provided in this loop tube 2 and between the second
high-temperature side heat exchanger 6 and the second
low-temperature side heat exchanger 7 and has the communication
paths 30 along the heat transportation direction, self-excited
standing and traveling waves are generated by heating the first
high-temperature side heat exchanger 4, and by the standing and
traveling waves, the second low-temperature side heat exchanger 7
is cooled. In the thermoacoustic device 1 described above, since
the first stacks 3a each provided between the first
high-temperature side heat exchanger 4 and the first
low-temperature side heat exchanger 5 are provided at a plurality
of positions, compared to the case in which an acoustic wave is
input from the outside of the tube by a speaker, an acoustic wave
is not reflected by the outside wall surface of the loop tube 2,
and as a result, the acoustic wave can be reliably amplified in the
tube. In addition, at this stage, since the self-excited acoustic
wave is generated using heat, waste heat or the like can be
used.
[0041] In addition, since the first stack 3a provided between the
first high-temperature side heat exchanger 4 and the first
low-temperature side heat exchanger 5 is provided in the vicinity
of a position in the loop tube 2 at which the phase of change in
acoustic particle velocity is the same as the phase of change in
sound pressure, standing and traveling waves having a larger sound
pressure can be generated.
[0042] In addition, as is the case described above, at the second
heat exchanger 310 side at which acoustic energy is converted to
thermal energy, since the second stacks 3b each provided between
the second high-temperature side heat exchanger 6 and the second
low-temperature side heat exchanger 7 are provided at a plurality
of positions, the acoustic energy can be efficiently converted to
the thermal energy by the second stacks 3b.
[0043] In addition, as is the case described above, since the
second stack 3b provided between the second high-temperature side
heat exchanger 6 and the second low-temperature side heat exchanger
7 is provided in the vicinity of a position at which the phase of
change in acoustic particle velocity is the same as the phase of
change in sound pressure, the conversion efficiency from acoustic
energy to thermal energy can be improved, and an object to be
cooled can be further cooled.
[0044] The present invention is not limited to the above
embodiment, and various embodiments may be performed without
departing from the spirit and the scope of the present
invention.
[0045] For example, in the above embodiment, the thermoacoustic
device 1 in which the second stack 3b side is cooled by heating the
first stack 3a side is described by way of example; however, in a
manner opposite thereto, by cooling the first stack 3a side, the
second stack 3b side may be heated. An example of this
thermoacoustic device 1 is shown in FIG. 6.
[0046] In FIG. 6, the same reference numerals as in the above
embodiment indicate elements having the same structures as
described above. A thermoacoustic device 1b of this embodiment has
a plurality of the first heat exchangers 300 and a plurality of the
second heat exchangers 310 as is the first embodiment. In addition,
in this embodiment, the first low-temperature side heat exchanger 5
is cooled to minus several tens of degrees or less, and at the same
time, a nonfreezing solution is circulated in the first
high-temperature side heat exchanger 4 and the second
low-temperature side heat exchanger 7. As a result, by the law of
the thermoacoustic effect, a self-excited acoustic wave is
generated by the temperature gradient formed in the first stack 3a.
The traveling direction of acoustic energy of the standing and
traveling waves is opposite to the transportation direction
(direction from the first high-temperature side heat exchanger 4 to
the first low-temperature side heat exchanger 5) of thermal energy
in the first stack 3a, and the acoustic energy is amplified in the
other first heat exchanger 300. The acoustic energy by the standing
and traveling waves is transported to the second stack 3b side, and
at the second stack 3b side, a working fluid is repeatedly expanded
and contracted by the pressure change and the volume change of the
working fluid based on the standing and traveling waves.
Subsequently, thermal energy generated at this stage is transported
from the second low-temperature side heat exchanger 7 to the second
high-temperature side heat exchanger 6 side, that is, in a
direction opposite to the transportation direction of the acoustic
energy. As described above, the second high-temperature side heat
exchanger 6 is heated.
[0047] In addition, in another embodiment, when the first heat
exchanger 300 and the second heat exchanger 310 are formed to have
the same structure, the first heat exchanger 300 may also be used
as the second heat exchanger 310, and vice versa. In this case, the
first high-temperature side heat exchanger 4 and the first
low-temperature side heat exchanger 5 provided in the first heat
exchanger 300, and the second high-temperature side heat exchanger
6 and the second low-temperature side heat exchanger 7 provided in
the second heat exchanger 310 are not necessarily set beforehand to
be the high temperature side and the low temperature side, and when
metal plates of the heat exchangers 4, 5, 6, and 7 are selected to
be heated or cooled, the first high-temperature side heat exchanger
4, the first low-temperature side heat exchanger 5, the second
high-temperature side heat exchanger 6, and the second
low-temperature side heat exchanger 7 are set. Accordingly, when it
is desired to increase the sound pressure, a thermoacoustic device
1b having an increased number of the first heat exchangers 300,
that is, a thermoacoustic device 1b having three heat input
portions, may be formed, as shown in FIG. 7, and when the sound
pressure is sufficient, and a cooling temperature is not
sufficient, a thermoacoustic device 1c having an increased number
of the second heat exchangers 310, that is, a thermoacoustic device
1c having three cold-heat output portions, may be formed, as shown
in FIG. 8.
BRIEF DESCRIPTION OF THE DRAWINGS
[0048] FIG. 1 is a schematic view of a thermoacoustic device of one
embodiment according to the present invention.
[0049] FIG. 2 is a view of a stack according to the above
embodiment, when viewed along an axial direction.
[0050] FIG. 3 is a cross-sectional view of the stack according to
the above embodiment.
[0051] FIG. 4 is a view showing the positional relationship of a
standing wave with the first and the second heat exchangers
according to the above embodiment.
[0052] FIG. 5 is a view showing an alterable mechanism for a first
heat exchanger and a second heat exchanger according to the above
embodiment.
[0053] FIG. 6 is a schematic view of a thermoacoustic device
according to another embodiment.
[0054] FIG. 7 is a schematic view of a thermoacoustic device
according to another embodiment.
[0055] FIG. 8 is a schematic view of a thermoacoustic device
according to another embodiment.
REFERENCE NUMERALS
[0056] Accordingly, [0057] 1 . . . thermoacoustic device [0058] 2 .
. . loop tube [0059] 2a . . . straight tube portion [0060] 2b . . .
connection tube portion [0061] 3a . . . first stack [0062] 3b . . .
second stack [0063] 30 . . . communication path [0064] 3eL, 3eH . .
. stack constituent element [0065] 4 . . . first high-temperature
side heat exchanger [0066] 5 . . . first low-temperature side heat
exchanger [0067] 6 . . . second high-temperature side heat
exchanger [0068] 7 . . . second low-temperature side heat exchanger
[0069] 300 . . . first heat exchanger [0070] 310 . . . second heat
exchanger
* * * * *