JPH10325625A - Acoustic refrigerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a gas cycle similar to a Carnot cycle by a method wherein first and second sound wave generating devices are arranged with a distance therebetween an odd number times as large as the specified wavelength of the wavelength of a sound wave, a cold storage member is disposed in a given position, and a sound wave generation control device is provided to control the phases of first and second sound waves. SOLUTION: Speakers 2 and 3 serving as a sound wave generating device are attached to a pipe 1 relatively with a distance therebetween being an odd number times as large as the 1/4 wavelength of a sound wave. Further, a sound wave radiated from the speakers 2 and 3 are controlled by a sound wave generation control device 50 so that the phases are deviated from each other by a distance an odd number times as large as the 1/4 period of the period of a sound wave. In this constitution, from a relation between an arrangement distance between the speakers 2 and 3 and a phase difference, a sound wave progressing in only one-way remains. In this case, a compression stroke occurs in the progressing direction of a sound wave, and when thermal suction and thermal discharge are effected by using a storage coolant 20, heat is conveyed, in order, from a progressing direction to an opposite direction. This heat transfer stroke is reversible and efficiency is high.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic refrigeration apparatus, and more particularly to an acoustic refrigeration apparatus capable of realizing an ideal gas cycle close to a Carnot cycle.

[0002]

2. Description of the Related Art The structure and principle of a resonance tube refrigerator as one of acoustic refrigerators will be described with reference to FIGS. First, a basic structure of the resonance tube refrigeration apparatus 200 will be described with reference to FIG. A pipe 202 has a closed end 202A at one end and an open end 202B at the other end, and has a speaker 201 for generating sound and a stack 203 in which flat plates are arranged in a plurality of layers.

[0003] A speaker 201 has an open end 202 of a pipe.
It is installed to emit a sound wave from b to the closed end 202A, and is a driving unit of the resonance tube refrigerator 200. The stack 203 is disposed in the pipe 202 in parallel with the direction of sound wave propagation, and the flat plates are all arranged at equal intervals.

When a sound wave is generated from the speaker 201,
A temperature difference occurs at both ends of the stack 203, and the low-temperature end and the high-temperature end of the stack 203 cool the object and radiate heat to the outside via the heat exchangers. For this reason,
The stack 203 is made of nylon, polyester, or other material having low thermal conductivity.

[0005] The frequency of the current applied to the speaker 201 is
The sound waves are selected so as to resonate in the pipe 202. At this time, in the pipe 202, an antinode portion of the pressure having a large pressure fluctuation and a node portion of the pressure having no pressure fluctuation alternately occur. Antinodes and nodes of gas displacement also occur. Note that P in FIG. 9 indicates a fluctuation in pressure, and an arrow indicated by W indicates the amplitude of gas displacement.

The resonance tube refrigeration apparatus 200 having the above structure
Can be described by a gas cycle using a minute gas mass. FIG. 10 and FIG.
This will be described with reference to FIG.

[0007] The gas cycle in the resonance tube refrigerator 200 can be described as a Brayton cycle. When a minute gas mass moves most in the direction of the nodal point of displacement,
The gas mass changes adiabatically and the pressure becomes maximum, at which time the gas temperature becomes maximum. This process is described in FIG. 10 and FIG.
, The adiabatic compression stroke shown by G → E.

Next, the gas mass which has become high temperature is
Heat is released to the plate holding the temperature difference at 03 and the gas mass is cooled. At this time, the gas pressure changes slowly. This process is performed in FIG. 10 and FIG.
This is a constant pressure change process indicated by A.

Next, when the gas mass moves most in the direction of the antinode of displacement, the gas mass expands adiabatically and the pressure becomes minimum, and at this time the gas temperature becomes lowest. This process is an adiabatic expansion process indicated by A → F in FIGS.

Thereafter, the low-temperature gas mass absorbs heat from the stack 203. Also at this time, the pressure change of the gas mass is gradual. This step is a constant pressure change step indicated by F → G shown in FIGS. With the above gas cycle, heat can be transferred from the node direction of displacement to the antinode direction.

[0011]

Here, the amount of heat absorbed as the refrigerating capacity in the gas cycle of the above-mentioned resonance tube refrigerating apparatus is represented by the temperature-entropy diagram in FIG.
-The area enclosed by G, Sh, Sc. Therefore,
The heat absorption amount H, G, Sh, Sc, which is the refrigeration capacity of the Carnot cycle shown in FIG.
The area enclosed by is reduced. In addition, A.E.G.F representing the input work is also higher than H.G.
It can be seen that the area is larger by the area of F + A, D, and E, and the efficiency is considerably reduced. This is because the temperature Tc ′ when the gas mass is expanded and the temperature Tc
And the heat is radiated by the temperature difference between the temperature Th 'when the gas mass is compressed and the temperature Th of the stack 203, so that the thermal transfer process becomes irreversible. Because it is.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems, and an acoustic refrigerating apparatus in which a thermal transfer process is reversible and a gas cycle thereof is similar to a Carnot cycle which is an ideal gas cycle. Is to provide.

[0013]

According to the present invention, there is provided an acoustic refrigeration apparatus having a hollow annular conduit having a circumference equal to an integral multiple of the wavelength of a sound wave; A sound wave having a first sound wave generator for generating a first sound wave and a second sound wave generator for generating a second sound wave, which are arranged at an interval of an odd multiple of a quarter wavelength of the sound wave. A generator, a cold storage member disposed at a predetermined position in the resonance tube, the first sound wave and the second sound wave.
In order to generate a phase different from that of a sound wave by an odd multiple of a 1/4 cycle, a sound wave generation control device for controlling the first sound wave generator and the second sound wave generator is provided.

In the acoustic refrigerator having the above structure,
When sound waves are emitted from the first sound wave generator and the second sound wave generator into the resonance tube, the sound waves travel in two directions in the resonance tube. Thereafter, the phases of the sound waves generated from the first sound wave generator and the second sound wave generator advance in one direction from the arrangement interval between the first sound wave generator and the second sound wave generator and the phase of the generated sound waves. The sound waves are superimposed and amplified, and sound waves traveling in other directions are canceled. Therefore, only the sound wave traveling in one direction remains in the resonance tube, and furthermore, the sound wave having the same phase is superimposed after one rotation, so that the amplitude of the sound wave is always amplified as in the case of resonance. become.

When the sound wave thus formed traveling in only one direction passes through the regenerative member, the pressure and displacement of the minute gas mass located at each location have a phase shift depending on the position. As a result, the minute gas mass located at each location expands when located in the traveling direction of the sound wave, and compresses when located in the opposite direction from the center of the displacement. In the expansion stroke and the compression stroke, heat is absorbed and released, so that heat is sequentially transferred from the traveling direction of the sound wave to the opposite direction. As a result, the heat transfer process in the refrigeration cycle can be performed reversibly.

In the above-mentioned acoustic refrigeration apparatus, preferably, a plurality of the sound wave generators are arranged so as to be shifted by an odd number of 1/4 wavelength of the sound wave to reduce a load applied to each sound wave generator. It is possible to extend the life of the acoustic refrigerator. In addition, by providing a plurality of units, even if one of the units breaks down, for example, it is possible to perform interpolation by gradually increasing the output of another sound wave generator, thereby providing a highly reliable acoustic refrigerator. It becomes possible.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an acoustic refrigerator according to the present invention will be described below with reference to the drawings.
First, the basic structure and principle of the acoustic refrigerator will be described with reference to FIGS.

The pipe 1 through which the sound wave travels has a closed loop with a hollow annular pipe. The circumference of the pipe 1 is set to be an integral multiple of the wavelength of the sound wave. In addition,
In the embodiment, the length of the center line of the pipe 1 is defined as the circumference. The speakers 2 and 3 as sound wave generators are relatively separated by a distance equal to an odd multiple of 1/4 wavelength of the sound wave,
Attached to the pipe 1 so as to emit sound waves into the pipe 1.

The sound waves radiated from the speakers 2 and 3 are generated by using the sound wave generation control device 50 so that the phases of the sound waves generated by the speakers 2 and 3 are shifted by an odd multiple of 1/4 cycle of the sound waves. Controlled.

Next, the operation principle of the acoustic refrigerator having the above basic structure will be described with reference to FIG. The sound waves radiated from the speakers 2 and 3 respectively travel in two directions after entering the pipe 1. Thereafter, in the pipe 1, the sound waves radiated from the speakers 2 and 3 travel in the pipe 1 and overlap each other. As shown in FIG. 2, the sound waves 2L and 3L traveling in one direction have the same phase, are superposed and amplified, and the sound wave phase is superimposed on the other hand, as shown in FIG. Sound wave 2 traveling to
R and 3R have opposite phases and cancel each other out. As a result, only sound waves traveling in one direction remain. Furthermore, since the sound waves of the same phase are superimposed after one rotation of the pipe 1, the amplitude of the sound waves is always amplified as in the case of resonance.

Next, as shown in FIG. 3, the principle of refrigeration when the regenerative member 20 having good heat exchange property and low pressure loss is inserted into the pipe 1 of the acoustic refrigeration system having the above structure is shown in FIG. It will be described with reference to FIG. The traveling sound wave passing through the cold storage member 20 has a phase shift depending on its position, and when focusing on a minute gas mass located at a certain position, an expansion stroke occurs in the traveling direction of the sound wave at the center position as a boundary. In the opposite direction, a compression stroke occurs. When heat absorption and heat release are performed using the cold storage member 20 in the expansion stroke and the compression stroke, heat is sequentially transferred from the traveling direction of the sound wave to the opposite direction as shown in FIG. Since this heat transfer process is reversible, the efficiency is higher than that of the conventional resonance tube refrigeration system.

Here, a gas cycle of the acoustic refrigeration apparatus according to the present embodiment will be further described with reference to FIGS. First, the Carnot cycle, which is the most ideal gas cycle, will be briefly described with reference to FIG. This Carnot cycle is composed of an isothermal process and an adiabatic process, and is shown as a rectangular cycle diagram of A, H, G, and D in the TS diagram as shown in FIG. A → H indicates an adiabatic expansion stroke (constant entropy), H → G indicates an isothermal expansion stroke, G → D indicates an adiabatic compression stroke, and D → A indicates an isothermal expansion stroke.

The amount of heat absorbed indicating the refrigerating capacity is represented by the isothermal expansion stroke H
→ Rectangle HG Sh Sh surrounded by G and entropy diagram
It is represented by the area of Sc. Similarly, the amount of heat released to the outside is represented by the area of a rectangle D, A, Sc, Sh. The input work applied from the outside during this Carnot cycle is represented by the area of the difference rectangle A, H, G, D. Therefore, the efficiency is H · G for this A · H · G · D.
· It is expressed by the ratio of Sh · Sc.

Next, a gas cycle of the acoustic refrigeration apparatus according to the present embodiment will be described. When a sound wave traveling in one direction passes through the gas mass and the regenerative member 20 having good heat conductivity, the minute gas mass reciprocates and generates a pressure change at the same time. The pressure change is such that when the gas moves the most in the direction of sound wave propagation, the pressure rises quickly and is strongly compressed. At this time, since the cold storage member 20 has extremely good heat conductivity, an isothermal compression process is performed. This process is described in FIG. 5 and FIG.
, Is shown in the process of D → A.

Next, when the gas mass moves in the direction opposite to the traveling direction of the sound wave, heat is dissipated along the temperature gradient of the regenerative member 20 and is cooled by a substantially equal volume change. This process is illustrated in FIG.
And A → B in FIG.

Thereafter, at the end in the direction opposite to the direction in which the sound wave travels, the pressure decreases rapidly and expands strongly. At this time, an isothermal expansion process for absorbing heat from the cold storage member 20 is performed. This step is a step indicated by B → C in FIGS.

When the gas moves in the direction in which the sound wave travels, it undergoes an equal volume change that absorbs heat along the temperature gradient of the cold storage member 20. This process corresponds to C in FIGS.
→ The process shown in D is performed.

As described above, D → A → B → C → shown in FIG.
In one cycle of D, heat can be transferred in the direction opposite to the direction of sound wave propagation. Thus, the cycle constituted by the isothermal process and the isostatic process is called a Stirling cycle, and the adiabatic process of the Carnot cycle is an isostatic process. Further, the heat absorption indicating the refrigerating capacity in the Stirling cycle is BＢSc′Sh ・ C, which is equal to the heat absorption H ・ Sc ・ Sh ・ G in the Carnot cycle. Similarly, A, B, C, and D representing the input work are also equal to the Carnot cycle values A, H, G, and D, and the efficiency is also equal. Therefore, it can be seen that the sonic refrigerator according to the present embodiment has the same efficiency as the Carnot cycle.

The equation representing the theoretical efficiency is as follows. The refrigeration efficiency of the Carnot cycle (Stirling cycle) is ηst = 1 / (Th / Tc-1) The theoretical efficiency of the conventional resonance tube refrigeration system (Brayton cycle) is ηbr = 1 / (Th / Tc′-1) Therefore, when comparing the two, ηst> ηbr (Tc
> Tc ').

Here, in order to perform reversible heat exchange between the refrigerant and the regenerative member, the heat transfer between them must be performed much faster than the period of the sound wave. In order to lengthen the period, it is necessary to lengthen the wavelength, assuming that the sound speed is constant. Accordingly, the perimeter of the pipe of the acoustic refrigeration apparatus also needs to be increased (the minimum achievable pipe perimeter is one wavelength).

When a strong sound wave travels in the pipe, strong attenuation occurs due to friction between the pipe wall and the cold storage member. Therefore,
By generating a solitary wave that is transmitted very stably as a sound wave and by propagating the sound wave, it is possible to realize a large refrigeration capacity without abrupt attenuation. This solitary wave is a wave having a property that even if the amplitude of the sound wave is greatly affected and the nonlinearity is affected, the waveform is stably propagated without changing the waveform by setting the state to the dispersive state. As a method of generating a solitary wave, it is conceivable to add a plurality of relatively small volumes of space on the pipe side wall through which the sound wave propagates in a branch shape to add dispersibility. It is conceivable to appropriately select the volume of the loudspeaker to be used, or to install a small tank having an appropriate volume in a branch shape on a pipe (Reference: N. Sugimoto,
J. Fluid Mech. Vol. 244, pp55
-78, 1992).

(Specific Example) Next, a specific example of the acoustic refrigerator having the above-described configuration and principle will be described with reference to FIG. This acoustic refrigeration apparatus 100 has a hollow annular pipe 1. A flexible hose made of vinyl is used for the pipe 1 and its circumference is about 3.
4 m. This pipe 1 has joint joints 6
7, speakers 2 and 3 are provided. Rear covers 4 and 5 are attached to the speakers 2 and 3, respectively.

The speakers 2 and 3 are connected to the speakers 2 and 3, respectively.
An amplifier 1 for generating predetermined sound waves from 3
1. The phase adjuster 12 and the signal generator 13 are connected.

On the other hand, a microphone 8,
9 is provided at a predetermined position, and an oscilloscope 10 for observing signals obtained from the microphones 8 and 9 is connected. Further, a cold storage member 14 is provided on the pipe 1, and thermocouples 15 and 16 are attached to the cold storage member 14, and the thermocouples 15 and 16 are used to confirm a temperature difference obtained from the thermocouple. Oscillographic recorder 1
7 is connected.

In the acoustic refrigeration apparatus 100 having the above configuration, the driving frequency is 100 Hz, and the microphones are installed in the vicinity of the speaker 3 in the vicinity of the speaker 3 and in the direction opposite to the speaker 2 when the microphone 8 is viewed from the speaker 3. It is mounted at a location 1/4 wavelength away.

The thermocouple was attached to both ends of the cold storage member 14, and the distance between the speakers 2 and 3 was about 0.85 m. In the acoustic refrigeration apparatus having the above configuration, the performance was measured in the following procedure.

(1) A signal whose phase is shifted by the phase adjuster 12 is generated from the sine wave signal of the signal generator 13, and the original signal and the signal whose phase is shifted are amplified by the amplifier 11. Input to speakers 2 and 3.

(2) While observing signals from the microphones 8 and 9 with the oscilloscope 10, the speaker 2
And the phase of the sound wave radiated from the speaker 3 is shifted by 1/4 cycle. At this time, the output of the amplifier 11 is set so that the signal outputs of the microphones 8 and 9 are in a sinusoidal range.

(3) The temperature of both ends of the cold storage member 14 is monitored by the oscillographic recorder 17. Here, it is confirmed that a temperature difference has occurred.

(4) The output of the amplifier 11 is gradually increased,
The oscillographic recorder 17 confirms that the temperature difference increases. As a result, in the acoustic refrigerator described above, the following results were obtained.

High temperature part temperature 42 ° C. Low temperature part temperature 34 ° C. Temperature difference 8 ° C. Room temperature 26 ° C. From the above results, the refrigerating ability could not be confirmed, but it was confirmed that a temperature difference occurred in the cold storage member. Was.

In the above configuration, the case where two speakers are used has been described. For example, as shown in the acoustic refrigerator shown in FIG. 8, the speakers 10A, 10B,
By disposing the speakers 20A and 20B, the speakers 30A and 30B, the speakers 40A and 40B, the speakers 50A and 50B, and the speakers 60A and 60B, respectively, at an odd multiple of 1/4 wavelength of the sound wave, the load on each set of speakers is reduced. The size can be reduced, and the life of the acoustic refrigerator can be extended. Further, even if one of the sets of speakers breaks down, interpolation can be performed by gradually increasing the output of the other set of speakers, and a highly reliable system can be realized.

It should be understood that the embodiments disclosed this time are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0044]

According to the acoustic refrigerator according to the present invention, when sound waves are emitted from the first sound wave generator and the second sound wave generator into the resonance tube, the sound waves travel in two directions in the resonance tube. Thereafter, the phases of the sound waves generated from the first sound wave generator and the second sound wave generator advance in one direction from the arrangement interval between the first sound wave generator and the second sound wave generator and the phase of the generated sound waves. The sound waves are superimposed and amplified, and sound waves traveling in other directions are canceled.

For this reason, only the sound wave traveling in one direction remains in the resonance tube, and furthermore, the sound wave having the same phase is superimposed after one rotation, so that the amplitude of the sound wave is always amplified similarly to the resonance. Will be done.

When the sound wave formed in this way and traveling in only one direction passes through the cold storage member, the sound wave is
There is a phase shift depending on the position, and when focusing on a minute gas mass located at a certain position, expansion occurs in the traveling direction of the sound wave from the center position, and compression occurs in the opposite direction. In the expansion stroke and the compression stroke,
By performing heat absorption and heat release, heat is sequentially transferred from the traveling direction of the sound wave to the opposite direction. As a result, the heat transfer process can be performed reversibly.

In the above-mentioned acoustic refrigerator, preferably, a plurality of the sound wave generators are arranged at odd-numbered times of 1/4 wavelength of the sound wave so as to reduce a load applied to each sound wave generator. It is possible to extend the life of the acoustic refrigerator. In addition, by disposing a plurality of units, even if one of the units breaks down, for example, it is possible to supplement by gradually increasing the output of the other sound wave generators, and to provide a highly reliable acoustic refrigerator. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a first diagram illustrating a principle for generating a sound wave traveling in one direction of an acoustic refrigerator according to the present invention.

FIG. 2 is a second diagram illustrating a principle for generating a sound wave traveling in one direction of the acoustic refrigerator according to the present invention.

FIG. 3 is a schematic view showing a basic structure of an acoustic refrigerator according to the present invention.

FIG. 4 is a schematic diagram for explaining a heat transfer process of the acoustic refrigerator in the present invention.

FIG. 5 is a TS diagram of a refrigeration cycle of the acoustic refrigerator according to the present invention.

6 is a schematic diagram for explaining the refrigeration cycle shown in FIG.

FIG. 7 is a diagram showing a specific configuration of an acoustic refrigerator according to the present invention.

FIG. 8 is a schematic diagram for explaining another specific example of the acoustic refrigerator in the present invention.

FIG. 9 is a diagram for explaining a configuration and an operation principle of the resonance tube refrigerator.

FIG. 10 is a TS diagram for explaining a refrigeration cycle of the resonance tube refrigeration apparatus.

11 is a schematic diagram for explaining the refrigeration cycle shown in FIG.

[Explanation of symbols]

 1 pipe 2,3 speaker 14,20 cold storage member

Claims (2)

[Claims] 1. A resonance tube having a hollow annular conduit having a circumference equal to an integral multiple of the wavelength of a sound wave, and an odd multiple of a quarter wavelength of the wavelength of the sound wave in the resonance tube. Sound wave generating means having a first sound wave generator for generating a first sound wave and a second sound wave generator for generating a second sound wave arranged at intervals; and cold storage arranged at a predetermined position in the resonance tube. A member, and a sound wave generation control means for controlling the first sound wave generator and the second sound wave generator in order to generate the first sound wave and the second sound wave so that the phases thereof are different from each other by an odd number of 1/4 cycle. And an acoustic refrigeration apparatus comprising: 2. The acoustic refrigeration apparatus according to claim 1, wherein a plurality of said sound wave generators are arranged so as to be shifted by an odd number times a quarter wavelength of said sound wave.