JPH11344266A - Acoustic freezer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise the general heat efficiency in a freezing system which freezes the object, using an acoustic freezer. SOLUTION: A speaker 23 is arranged opposite to the duct line of an acoustic pipe 1, and also a cold accumulating member 4 is arranged in the specified position within the acoustic pipe 1. Moreover, plural pieces of thin pipes 6 are arranged in contact with each end face of the end face on low temperature side and the end face on high temperature side of a cold accumulating member 4, and these thin pipes 6 pierce the acoustic pipe, in the direction orthogonal to the axis of the pipe. Then, the cooling of a freezing chamber 8 is performed by the heat medium flowing in the thin pipe 6 opposite to the end on a low temperature side, and also the heat radiation to outside is performed by the heat medium flowing in the thin pipe 6 opposite to the end on a high temperature side. As a heat medium, ammonium or acetone is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic refrigeration system in which a sound wave generator is provided facing a pipe of an acoustic tube, and a regenerative member is provided at a predetermined position in the acoustic tube. The present invention relates to an acoustic refrigeration apparatus capable of efficiently cooling an object and radiating heat to the outside.

[0002]

2. Description of the Related Art Conventionally, there is known an acoustic refrigeration apparatus for refrigeration using sound waves (see, for example, Japanese Patent Publication No. 3-46745). For example, the acoustic refrigerator (200) shown in FIG.
02A) is closed, and the other end (202B) is provided with a resonance tube (202) having an opening, and a speaker (201) for generating sound is provided facing the open end (202B) of the resonance tube (202). ing. Also, the resonance tube (20
A cold storage member (203) called a stack is built in an appropriate place in 2). The cold storage member (203) is composed of a plurality of concentric cylinders made of nylon, polyester, or other material having low thermal conductivity, a single spiral plate, or a plurality of parallel plates.

Here, the frequency of the current applied to the speaker (201) is set to a value at which sound waves resonate in the resonance tube (202). From the speaker (203) to the closed end of the resonance tube (202)
When a sound wave is generated toward (202A), a pressure distribution P as shown in FIG. 11 is formed in the resonance tube (202), and an antinode part having a large pressure fluctuation and a node part having a small pressure fluctuation are formed. And occur alternately. Further, as shown by an arrow W in the figure, the gas displacement also has an antinode and a node. As a result, the regenerator (2
A temperature difference occurs at both ends of 03). Then, the low-temperature end and the high-temperature end of the regenerator (203) perform cooling of the object and heat radiation to the outside via a heat exchanger (not shown), respectively.

The above-described acoustic refrigeration apparatus (200) can be described by a Brayton cycle consisting of four steps of adiabatic compression, isobaric pressure change, adiabatic expansion, and isobaric pressure change of a minute gas mass. However, in the Brayton cycle constituted by the acoustic refrigerator (200),
Heat is absorbed by the difference between the temperature when the gas mass expands and the temperature of the regenerator (203), or heat is released by the difference between the temperature when the gas mass is compressed and the temperature of the regenerator (203). The thermal transfer process is irreversible,
There is a disadvantage that the thermal efficiency is lower than that of the Carnot cycle.

Therefore, the applicant has proposed an acoustic refrigeration apparatus in which the thermal transfer process is reversible and a gas cycle close to an ideal gas cycle, the Carnot cycle, can be realized (Japanese Patent Application No. Hei 9-1997). 134993). The basic structure and principle of the acoustic refrigerator will be described with reference to FIGS.

As shown in FIG. 5, an acoustic tube (1) through which a sound wave is to be transmitted forms a hollow annular closed-loop conduit. The circumference of the acoustic tube (1) is set to be an integral multiple of the wavelength of the sound wave. In the following example, the length of the center line of the acoustic tube (1) is defined as the circumference. Speaker as sound wave generator
(2) and (3) are attached to the acoustic tube (1) so as to emit acoustic waves into the acoustic tube (1) while being separated from each other by a distance equal to an odd multiple of 音波 wavelength of the acoustic wave. Also, speaker (2)
A sound wave generation control device (50) is connected to (3), and a speaker
(2) The phases of the sound waves emitted from (3) are 1 /
Drive control is performed so as to shift by an odd multiple of four wavelengths.

Next, the operation principle of the acoustic refrigerator is described.
This will be described with reference to FIG. The sound waves radiated from the speakers (2) and (3) enter the acoustic tube (1), branch in two directions, and travel in the acoustic tube (1). And both speakers (2)
Two sound waves emitted from (3) and traveling in the acoustic tube (1) overlap each other. Here, from the relationship between the arrangement intervals of the speakers (2) and (3) and the phase difference between the sound waves, the sound waves 2L and 3L traveling to the left in the drawing have the same phase, are superimposed on each other and amplified, and The sound waves 2R and 3R traveling in the directions have opposite phases and cancel each other. As a result, only the sound wave traveling in one direction (left direction) remains, and the sound wave further goes around in the acoustic tube (1) and is superimposed with the sound wave of the same phase, so that the amplitude is increased similarly to the resonance. Will be.

Next, as shown in FIG. 7, the principle of refrigeration when a regenerative member (40) having good heat exchange properties and a small pressure loss is arranged in an acoustic tube (1) of an acoustic refrigeration apparatus will be described with reference to FIG. This will be described with reference to FIG. The traveling sound wave passing through the cold storage member (40) 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. In the expansion step and the compression step, heat is absorbed and released using the cold storage member (40), so that heat is sequentially transferred in the direction opposite to the traveling direction of the sound wave. Since the heat transfer process is reversible, the heat efficiency is higher than that of the conventional acoustic refrigerator.

Further, the gas cycle of the acoustic refrigerator according to the present invention will be described with reference to FIGS. The Carnot cycle consists of an isothermal process and an adiabatic process.
As shown in the figure, the TS diagram shows a rectangular cycle diagram of A, H, G and D. Here, 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.

As shown in FIG. 10, when a sound wave passes in one direction through a regenerative member having good heat conductivity as a gas mass, the minute gas mass reciprocates and changes pressure at the same time. The pressure change is such that when the gas mass moves most in the direction of sound wave travel, the pressure rises rapidly and is strongly compressed. Here, since the heat storage member has good heat conductivity, isothermal compression is performed. This isothermal compression stroke is represented by D →
Indicated by A. Next, when the gas mass moves in the direction opposite to the sound wave traveling direction, heat is released along the temperature gradient of the cold storage member, and the gas mass is cooled by a substantially equal volume change. This process is indicated by AB in FIGS. 9 and 10.

Thereafter, at the end in the direction opposite to the traveling direction of the sound wave, the pressure decreases rapidly and expands strongly. At this time, an isothermal expansion process in which heat is absorbed from the cold storage member is performed.
This process is indicated by B → C in FIGS. 9 and 10. Even when the gas moves in the direction in which the sound wave travels, there is an equal volume change that absorbs heat along the temperature gradient of the cold storage member. This process is indicated by C → D in FIGS. 9 and 10.

As described above, D → A → B → C → shown in FIG.
One cycle of D makes it possible to transfer heat in the direction opposite to the direction of sound wave travel. Thus, a 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. Therefore, according to the acoustic refrigeration apparatus, efficiency equivalent to the Carnot cycle can be obtained.

[0013]

The overall thermal efficiency (system thermal efficiency) of a refrigeration system that freezes an object such as a freezer by the acoustic refrigerator is not only the thermal efficiency of a gas cycle using a cold storage member, Even if the heat efficiency of the gas cycle approaches the heat efficiency of the Carnot cycle, the low-temperature portion and the high-temperature portion of the cold storage member are also affected by the efficiency of heat exchange when cooling the object to be cooled and releasing heat to the outside, respectively. Unless the efficiency of heat exchange is improved, high system thermal efficiency cannot be obtained. However, in the conventional acoustic refrigerator, heat exchange between the cold storage member and the heat medium is performed via the wall of the acoustic tube,
The heat exchange efficiency when the low-temperature portion and the high-temperature portion of the cold storage member perform cooling of the object to be cooled and heat radiation to the outside, respectively, is low. In particular, FIG.
In the case of the acoustic refrigeration apparatus as described in 1, the acoustic tube and the cold storage member are formed of a material having low thermal conductivity, so that this problem has been extremely remarkable. Therefore, an object of the present invention is to provide an acoustic refrigeration apparatus capable of obtaining a higher system thermal efficiency than conventional ones.

[0014]

According to the acoustic refrigeration apparatus of the present invention, a sound wave generator is provided facing a pipe of an acoustic tube, and a cold storage member is provided at a predetermined position in the acoustic tube.
A temperature gradient is formed in the cool storage member by the sound waves emitted from the sound wave generator, and the low-temperature portion and the high-temperature portion of the cool storage member perform cooling of the object to be cooled and heat radiation to the outside world, respectively.
In the characteristic configuration, the acoustic tube is provided with a plurality of thin tubes penetrating the acoustic tube in a direction intersecting the tube axis at positions opposite to the low-temperature end and the high-temperature end of the regenerative member. The cooling target is cooled by the heat medium flowing through the thin tube facing the low-temperature side end, and heat is released to the outside world by the heat medium flowing through the thin tube facing the high-temperature end.

In the acoustic refrigeration apparatus of the present invention, since a plurality of thin tubes are disposed opposite to the low-temperature end and the high-temperature end of the cold storage member, the low temperature side of the cold storage member is provided. The heat exchange between the ends and the high-temperature side ends and the heat medium flowing through the plurality of thin tubes arranged opposite to each end is efficiently performed.

Specifically, each of the plurality of thin tubes is arranged in contact with the end face of the cold storage member. Therefore, the low-temperature end and the high-temperature end of the cold storage member and the plurality of thin tubes are in solid contact, and heat is transferred between the two by heat conduction. As a result, a high heat exchange rate is obtained.

In a specific configuration, an inlet chamber surrounding the acoustic tube and communicating with the inlets of the plurality of thin tubes and an outlet chamber communicating with the outlets of the plurality of thin tubes are formed.
The heat medium flows into the inlet chamber, and the heat medium flows out of the outlet chamber. In this specific configuration, since the entrance chamber and the exit chamber are formed so as to surround the acoustic tube, the end of the regenerative member, the entrance chamber, and the exit chamber are provided through the outer peripheral wall of the acoustic tube that contains the regenerative member. Performs heat exchange with the heat medium. Therefore,
Low heat loss and high heat exchange rate.

In still another specific configuration, water can be used as the heat medium flowing through the thin tube, and more preferably, a low-viscosity medium such as ammonia or acetone is used. Therefore, even if a very small circular tube having an inner diameter of 1 mm or less is used as the thin tube, the viscous resistance of the heat medium flowing through the thin tube is small and the power for circulating the heat medium is small.

[0019]

According to the acoustic refrigeration apparatus of the present invention, a high efficiency can be obtained as the heat exchange efficiency when the low-temperature portion and the high-temperature portion of the regenerative member perform cooling of the object to be cooled and heat radiation to the outside. Thus, the system thermal efficiency is improved as compared with the related art.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an acoustic refrigerator having a basic structure shown in FIG. 7 will be specifically described with reference to the drawings.

As shown in FIG. 1, a first loudspeaker (2) and a second loudspeaker, which are sound wave generating means, face a pipe of a hollow annular sound tube (1) whose circumference is an integral multiple of the wavelength of a sound wave. Speakers (3) are arranged at an interval of an odd multiple of 1/4 wavelength of the sound wave. A sound wave generation control circuit (not shown) is connected to both speakers (2) and (3), and the phases of the first sound wave emitted from the first speaker (2) and the second sound wave emitted from the second speaker (3) are determined. The operations of the two speakers (2) and (3) are controlled so that they differ by an odd multiple of １ ／ wavelength of the sound wave. In addition, a cool storage member (4) is built in an appropriate position of the acoustic tube (1).

When sound waves are radiated from the speakers (2) and (3) into the acoustic tube (1), the sound waves radiated from each speaker are branched in two directions in the acoustic tube (1) and proceed in one direction. A sound wave traveling in the other direction is generated. And the first speaker (2)
The first sound wave emitted from the first speaker and the second sound wave emitted from the second speaker (3) are superimposed on the sound wave traveling in one direction from the arrangement interval of the two speakers (2) and (3) and the phase of the generated sound wave. The sound wave that is amplified and propagates in the other direction is canceled. For this reason, only the sound wave traveling in one direction remains in the sound tube (1), and further goes around the sound tube (1) and is superimposed with the sound wave of the same phase, so that the amplitude is increased like resonance. Become

When the sound wave thus formed, which travels only in one direction, passes through the cold storage member 4, the pressure and displacement of the minute gas mass located at each location are shifted in phase depending on the location. Is generated. As a result, the 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 position of the displacement. In the expansion stroke and the compression stroke, heat is absorbed and released, so that heat is sequentially transferred in the direction opposite to the direction in which the sound wave travels. As a result, a temperature gradient is formed in the cold storage member (4), and one end has a high temperature and the other end has a low temperature.

The acoustic tube (1) of the above-mentioned acoustic refrigerator has the acoustic tube (1) perpendicular to the tube axis at a position in contact with each of the low-temperature side end and the high-temperature side end of the cold storage member (4). A plurality of thin tubes (6) penetrating in the direction in which the low temperature side heat exchanger (8) is disposed in a freezer (8) to be cooled is provided. 81), a heat medium circulation system S1 on the low temperature side is formed, and a thin tube facing the high temperature side end is formed.
(6) is a high temperature side heat exchanger for radiating heat to the outside world
A high-temperature side heat medium circulation system S2 is configured with (82). A pump (9) for circulating the heat medium is connected to each of the heat medium circulation systems S1 and S2 on the low temperature side and the high temperature side.

FIGS. 2 and 3 show a plurality of thin tubes arranged at each of a low-temperature end and a high-temperature end of the cold storage member.
The specific structure for connecting (6) to the heat medium circulation system is shown. As described above, the acoustic tube (1) is provided with a plurality of thin tubes (6) having an inner diameter of 1 mm each corresponding to each of the low-temperature side end and the high-temperature side end of the cold storage member (4). And a jacket (7) is provided surrounding the inlet and outlet of the capillary (6). The jacket
The inside of (7) is vertically partitioned by a partition plate (75) to form an inlet chamber (71) to which the inlet of the thin tube (6) is connected and an outlet chamber (72) to which the outlet of the thin tube (6) is connected. doing. Entrance room (71)
Is connected to the inlet pipe (73), and the inlet chamber (71) is connected to the outlet pipe (74).
Are connected, and an inlet pipe (73) and an outlet pipe (74) are connected to the heat medium circulating system.

The heat medium circulation system has a low viscosity such as water, preferably ammonia or acetone as a heat medium,
A natural refrigerant having a relatively low saturated vapor pressure is sealed in a slightly pressurized state. However, when using ammonia or acetone as the heat medium, these heat mediums are flammable and toxic, so it is necessary to reliably prevent the heat medium from leaking from the heat medium circulation system. .

Therefore, as a pump (9) for circulating such a heat medium, a closed type pump as shown in FIG. 4 is employed. In the pump (9), a housing (91) that rotatably accommodates a screw (94) is connected to a pipe (90) that constitutes a heat medium circulation system, and the housing (91) is surrounded by a stator ( 92) is deployed and the housing (9
In 1), a rotor (93) is fixed to an outer peripheral portion of a screw (94), and a drive motor is constituted by the stator (92) and the rotor (93). According to the pump (9), since the flow path of the heat medium is completely sealed, there is no possibility that the heat medium leaks from the heat medium circulation system.

According to the above acoustic refrigerator, the first speaker
By radiating sound waves from the second speaker (2) and the second speaker (3) into the acoustic tube (1), as described above, heat absorption and heat release are performed by the expansion process and the compression process occurring in the cold storage member, and the Carnot cycle is performed. A heat cycle close to is realized. As a result, higher refrigeration efficiency than the conventional acoustic refrigeration apparatus shown in FIG. 11 can be obtained.

Further, since the plural thin tubes (6) are arranged in contact with both end surfaces of the cold storage member (4), the cold storage member (4) and the plural thin tubes (6) come into solid contact with each other. Heat is transmitted between the two by heat conduction. Furthermore, since a plurality of thin tubes (6) having an inner diameter of 1 mm are employed, the heat transfer area is increased. As described above, by using ammonia or acetone as the heat medium, an increase in flow resistance due to the provision of the thin tube (6) is suppressed. As a result, heat exchange between the cold storage member (4) and the heat medium flowing through the plurality of thin tubes (6) is efficiently performed, and the overall system thermal efficiency in the system for freezing the freezer by the acoustic refrigerator is improved. Will be.
The use of natural refrigerants such as ammonia and acetone also avoids the problem of environmental pollution.

The configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims. For example, the present invention relates to FIGS.
The present invention is not limited to the acoustic refrigeration apparatus described above, but can be implemented in the conventional acoustic refrigeration apparatus shown in FIG. or,
The first and second loudspeakers (2) and (3) can be arranged at a plurality of positions shifted by an odd multiple of 音波 wavelength of the sound wave, thereby reducing the load applied to each loudspeaker. As a result, the life of the acoustic refrigerator can be extended. Further, the generation of the sound wave is not limited to the loudspeaker as described above, and a diaphragm driven by a linear motor,
A device using a piezoelectric element as a vibration source can be employed.

[Brief description of the drawings]

FIG. 1 is a system diagram of a refrigeration system using an acoustic refrigeration apparatus according to the present invention.

FIG. 2 is a perspective view showing a main part of the acoustic refrigerator according to the present invention in a cutaway manner.

FIG. 3 is a sectional view taken along a tube axis of the acoustic refrigerator.

FIG. 4 is a cross-sectional view of the hermetic pump.

FIG. 5 is a first diagram for explaining the operation principle of the acoustic refrigerator according to the proposal of the applicant.

FIG. 6 is a second diagram of the above.

FIG. 7 is a schematic diagram showing a basic structure of the acoustic refrigerator.

FIG. 8 is a view for explaining a heat transfer process of the acoustic refrigerator.

FIG. 9 shows a TS representing a refrigeration cycle of the acoustic refrigerator.
FIG.

FIG. 10 is a diagram for explaining the refrigeration cycle.

FIG. 11 is a sectional view of a conventional acoustic refrigerator.

[Explanation of symbols]

 (1) Acoustic tube (2) First speaker (3) Second speaker (4) Cold storage member (6) Thin tube (7) Jacket (71) Inlet room (72) Outlet room (73) Inlet tube (74) Outlet tube (75) Partition plate (8) Freezer (81) Low temperature heat exchanger (82) High temperature heat exchanger (9) Pump

Claims (4)

[Claims] A sound wave generator is provided facing a pipe of an acoustic tube, and a cool storage member is provided at a predetermined position in the sound tube, and a temperature gradient is applied to the cool storage member by sound waves emitted from the sound wave generator. A low-temperature part and a high-temperature part of the regenerator member cool and cool the object to be cooled and radiate heat to the outside, respectively. A plurality of thin tubes penetrating the acoustic tube in a direction intersecting with the tube axis are arranged at positions facing the portion, and the cooling target is cooled by a heat medium flowing through the thin tube facing the low-temperature side end, An acoustic refrigeration apparatus characterized in that heat is radiated to the outside by a heat medium flowing through a thin tube facing a high temperature side end. 2. The acoustic refrigeration apparatus according to claim 1, wherein each of the plurality of thin tubes is disposed in contact with an end face of the cold storage member. 3. An inlet chamber surrounding the acoustic tube and communicating with the inlets of the plurality of thin tubes, and an outlet room communicating with the outlets of the plurality of thin tubes are formed, and the heat medium is supplied to the inlet chamber. The acoustic refrigeration apparatus according to claim 1 or 2, wherein the heat medium flows out from the outlet chamber while flowing in. 4. The acoustic refrigerating apparatus according to claim 1, wherein water, ammonia, or acetone is used as the heat medium.