Thermoacoustic device and method for suppressing mass flow using thermoacoustic device

Abstract

To provide a thermoacoustic device that can suppress a mass flow generated from a thermoacoustic device while improving maintainability and durability as well as propagating a work flow, and to provide a method for suppressing a mass flow using a thermoacoustic device.SOLUTION: A thermoacoustic device 1 includes: a flow path 2 through which a working gas circulates; a heat accumulator 10 which is installed in the middle of the flow path and in which heat exchangers are installed to both ends; and a suppression part 20 for generating a suppression flow R for suppressing a mass flow M advancing through the flow path. The suppression part generates the suppression flow that moves the working gas, toward a direction suppressing the mass flow that varies in accordance with an output state of the heat accumulator.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a thermoacoustic device for suppressing a mass flow generated in an annular flow path and a method for suppressing a mass flow using the thermoacoustic device.

Background Art

[0002] A thermoacoustic device is a device that utilizes a thermoacoustic phenomenon capable of mutually converting thermal flow and working flow (acoustic power) to extract thermal energy or acoustic energy. The thermoacoustic device includes a regenerator that generates a thermoacoustic phenomenon and heat exchangers installed at both ends of the regenerator. In the regenerator, for example, a large number of capillary flow paths penetrating both ends are formed so that a working gas capable of propagating sound circulates.

[0003] For example, by providing a low-temperature heat exchanger on one end side of the regenerator and a high-temperature heat exchanger on the other end side, when heat is input to the regenerator to give a temperature gradient, a thermoacoustic engine that converts thermal energy into acoustic energy, generates, or amplifies a working flow can be configured. Since the conversion between thermal energy and acoustic energy in the regenerator is a reversible reaction, a thermoacoustic heat pump that outputs thermal energy by the heat pump effect can be configured by inputting a working flow to the regenerator. That is, according to the thermoacoustic device, it is also possible to configure a thermoacoustic heater that outputs high-temperature heat based on the input of a working flow, and it is also possible to configure a thermoacoustic cooler that outputs low-temperature heat.

[0004] According to the thermoacoustic device, it is also possible to configure a thermoacoustic generator that outputs electric power based on the input of thermal energy by providing a generator that operates based on a vibration flow such as sound as an output unit. According to the thermoacoustic device, an acoustically driven thermoacoustic heat pump that outputs thermal energy based on the input of a vibration flow can also be configured by providing an acoustic driver that generates a vibration flow in the thermoacoustic device. Further, according to the thermoacoustic device, it is also possible to combine a thermoacoustic engine and a thermoacoustic heat pump, and a thermoacoustic heat pump that operates based on the input of thermal energy can also be configured.

[0005] As heat sources for heat input to a thermoacoustic prime mover, various heat sources such as waste heat from factories, ships, etc. and heat collection from sunlight can be utilized. Therefore, the thermoacoustic device is expected to be used as a waste heat recovery device. Since a thermoacoustic heat pump can use gases such as air, argon, and helium that have no global warming potential as the working gas, an eco-friendly heat pump can be configured.

[0006] A general thermoacoustic device includes, for example, a tubular flow path formed in a loop shape and a regenerator provided in the middle of the flow path. On one end side of the regenerator, a high-temperature part is formed by a high-temperature heat exchanger. On the other end side of the regenerator, a low-temperature part is formed by a low-temperature heat exchanger. The high-temperature part of the regenerator is heated to a higher temperature than the low-temperature part, and a temperature gradient is generated inside the regenerator. In a thermoacoustic device having a flow path formed in a loop shape like this, in addition to the working flow, a mass flow (also called a Gedeon flow or an acoustic flow) generated in the annular flow path may flow in one direction in the flow path. The working flow propagates vibrations through the working gas, while the mass flow circulates in one direction in the loop pipe and moves the working gas.

[0007] When a mass flow occurs in a thermoacoustic device, part of the amount of heat to be input to the regenerator or the amount of heat to be output from the regenerator is transported outside the regenerator by the mass flow, and the thermal efficiency decreases. In addition, when a mass flow occurs in a thermoacoustic device configured as a thermoacoustic cooler, the amount of heat to be output from the low-temperature part side of the regenerator through the low-temperature heat exchanger is transported outside the output part formed in the cooler by the mass flow. When a mass flow occurs in a thermoacoustic device configured as a thermoacoustic heater, the amount of heat to be output from the high-temperature part side of the regenerator through the high-temperature heat exchanger is transported outside the output part formed in the heater by the mass flow. Therefore, in order to improve the thermal efficiency of the thermoacoustic device, it is desirable to suppress the mass flow generated from the regenerator as much as possible.

[0008] The mass flow rate increases or decreases depending on the increase or decrease of the working fluid flow rate in the thermoacoustic device. For example, in a thermoacoustic engine, if the temperature on the high-temperature side increases, the working fluid flow rate output from the thermoacoustic engine increases, and accordingly the mass flow rate increases. Conversely, if the temperature on the high-temperature side of the thermoacoustic engine decreases, the output working fluid flow rate decreases, and thus the mass flow rate decreases. Also, in a thermoacoustic refrigerator, it is necessary to increase the input amount of the working fluid flow rate in order to lower the temperature on the low-temperature side. Similarly, in a thermoacoustic heater, it is necessary to increase the input amount of the working fluid flow rate in order to raise the temperature on the heating side. In both the thermoacoustic refrigerator and the thermoacoustic heater, when the input amount of the working fluid flow rate increases, the mass flow rate also increases, and when the input amount of the working fluid flow rate decreases, the mass flow rate decreases. Therefore, in a thermoacoustic device, when attempting to improve the thermal efficiency, it is desirable to appropriately suppress the mass flow rate according to the working fluid flow rate.

[0009] As methods for suppressing the mass flow rate in a thermoacoustic device, there have been proposed a structure in which a film is provided in the middle of the flow path (see, for example, Non-Patent Document 1 and Non-Patent Document 2), and a structure in which a component called a jet pump is provided in the middle of the flow path (see, for example, Non-Patent Document 3 and Non-Patent Document 4). According to the thermoacoustic device having the film structure described in Non-Patent Document 1 and Non-Patent Document 2, a film formed of an elastic body such as rubber is provided so as to block the radial direction of the flow path. This film prevents the mass flow rate from moving into the flow path by blocking the mass flow rate while propagating the vibration of the working fluid flow in the flow path based on the vibration generated in itself. In this film structure, the cross-sectional area of the flow path may change at the installation position of the film.

[0010] The jet pump described in Non-Patent Document 3 and Non-Patent Document 4 has a structure in which the diameter decreases (or increases) along the axial direction of the tube in a tubular flow path and the inlet and outlet are asymmetric along the axial direction of the tube (hereinafter referred to as a jet flow path). The jet pump creates a flow that suppresses the mass flow rate by the differential pressure generated before and after the jet pump while propagating the working fluid flow into the flow path through the jet flow path.

Prior Art Documents

Patent Documents

[0011] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2022 - 065498 [Non - Patent Document]

[0012] [Non - Patent Document 1] E. C. Luo, W. Dai, Y. Zhang, and H. Ling, “Experimental investigation of a thermoacoustic - Stirling refrigerator driven by a thermoacoustic - Stirling heat engine,” Ultrasonics 44, e1531 - e1533 (2006). doi:10.1016 / j.ultras.2006.08.002 [Non - Patent Document 2] T. Biwa, “Double - loop Thermoacoustic Stirling Cooler - II. Measurements of Acoustic Streaming Velocity -,” TEION KOGAKU 43, 543 - 547 (2008). doi:10.2221 / jcsj.43.543 [Non - Patent Document 3] S. Backhaus and G. W. Swift, “A thermoacoustic - Stirling heat engine: Detailed study,” J. Acoust. Soc. Am. 107, (2000) 3148 - 3166. [Non - Patent Document 4] T. Biwa, Y. Tashiro, M. Ishigaki, Y. Ueda and T. Yazaki, “Measurements of acoustic streaming in a looped - tube thermoacoustic engine with a jet pump,” JOURNAL OF APPLIED PHYSICS 101, 064914 2007

Non-Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0013] In a thermoacoustic device to which a film structure is applied, when suppressing the mass flow, in order to increase the suppression effect of the mass flow, it is desirable that the film structure be installed as close as possible to the peak of the acoustic impedance (in many cases, near the regenerator). Acoustic impedance is a parameter given by the ratio of the pressure vibration to the volume flow velocity vibration. However, if a film structure formed of a rubber film is installed near a high-temperature heat exchanger or a low-temperature heat exchanger provided in the regenerator, the rubber film may come into contact with the heat exchanger, and the function of the film structure may be inhibited. Since the rubber film allows the mass flow to pass even if a small hole is opened, there is a risk that the performance will be significantly reduced.

[0014] In a thermoacoustic device to which a film structure is applied, when configured as a thermoacoustic heater, if the film structure is installed near the high-temperature heat exchanger provided in the regenerator, the rubber film may melt and the film structure may stop functioning. In a thermoacoustic device to which a film structure is applied, when configured as a thermoacoustic cooler, if the film structure is installed near the low-temperature heat exchanger provided in the regenerator, the rubber film may freeze and the film structure may stop functioning. Furthermore, since the film vibrates due to sound waves, deterioration occurs, and when used for a long period of time, it needs to be replaced regularly. In a thermoacoustic device to which a film structure is applied, if the rubber film is provided in the middle of the flow path, it is time-consuming to replace it, and there is a risk that the maintainability will decrease.

[0015] In a thermoacoustic device to which a jet pump is applied, it is necessary to form the jet pump into a specific shape based on the installation position of the jet pump and the amplitude of the assumed mass flow. Since the thermoacoustic device to which the jet pump is applied has a passive device configuration, it can suppress a mass flow with a predetermined amplitude. However, if the output state of the regenerator changes and a mass flow with an amplitude different from the predetermined amplitude occurs, there is a possibility that this mass flow cannot be suppressed.

[0016] Therefore, there was an essential problem that it was difficult to cope with practical use in which the waste heat temperature fluctuates. Further, the jet pump suppresses the mass flow by generating a differential pressure before and after the jet pump. At this time, the working flow decays. Therefore, there is also a problem that the installation of the jet pump itself leads to a decrease in the efficiency of the device. In previous studies, it was necessary to consider mutually the improvement of the thermal efficiency due to the suppression of the mass flow associated with the installation of the jet pump and the loss of the working flow associated with the installation of the jet pump.

[0017] An object of the present invention is to provide a thermoacoustic device that can suppress the mass flow generated in the annular flow path of the thermoacoustic device while propagating the working flow, while improving maintainability and durability, and a method for suppressing the mass flow using the thermoacoustic device.

Means for Solving the Problems

[0018] One aspect of the present invention includes a flow path through which a working gas flows, a regenerator provided in the middle of the flow path and having heat exchangers provided at both ends, and a suppression unit that generates a suppression flow for suppressing the mass flow that progresses in the flow path. The suppression unit is a thermoacoustic device that generates the suppression flow that moves the working gas in a direction to decelerate the mass flow that varies according to the output state of the regenerator.

Effects of the Invention

[0019] According to the present invention, it is possible to suppress the mass flow generated from the thermoacoustic device while propagating the working flow, while improving maintainability and durability.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0021] As shown in FIG. 1, the thermoacoustic device 1 includes a flow path 2 through which a working gas flows, a regenerator 10 provided in the middle of the flow path 2, a suppression unit 20 provided in the middle of the flow path 2, an output unit 30 connected to the flow path 2 and outputting a work flow as energy, a control device 40 for controlling each component in the device, and an adjustment unit 50 for adjusting the work flow generated in the flow path 2. The flow path 2 is formed by a pipe with a circular cross section, for example. The cross section of the flow path 2 may be formed in a shape other than circular. The flow path 2 is formed in a sealed state. The flow path 2 may be formed with a part open to the atmosphere.

[0022] Inside the flow path 2, a gas serving as the working gas is enclosed. The working gas is a gas that can transmit an oscillating flow, such as an inert gas composed of nitrogen, helium, argon, a mixed gas of helium and argon, and air. The working gas only needs to be able to transmit an oscillating flow, and is not limited to these gases, and other gases may be used, or it may have a liquid part such as water or ethanol instead of being limited to a gas. The working gas is enclosed, for example, at a predetermined pressure.

[0023] The flow path 2 is formed in an arbitrary shape, with an arbitrary pipe length, and an arbitrary pipe diameter. The flow path 2 may have a bent portion bent in an arbitrary direction at an arbitrary curvature at an arbitrary position. The flow path 2 is formed, for example, with a loop portion 3 formed in a loop shape. A regenerator 10 is provided in the middle of the loop portion 3. In the loop portion 3, a first flow path 3A connected to one end side of the regenerator 10 and a second flow path 3B connected to the other end side of the regenerator 10 are formed.

[0024] On the first flow path 3A side, a first branch pipe 4 branched from the loop portion 3 is formed. An output portion 30 is provided at the end of the first branch pipe 4. On the second flow path 3B side, a second branch pipe 5 branched from the loop portion 3 is formed. A suppression portion 20 is provided in the second branch pipe 5. A third branch pipe 6 is formed in the middle of the flow path 2. An adjustment portion 50 is provided at the end of the third branch pipe 6.

[0025] The regenerator 10 is formed by a thermoacoustic device that generates a thermoacoustic phenomenon. The regenerator 10 has one to countless fine tube channels 11 formed therein. The one to countless fine tube channels 11 are formed to penetrate from one end side on the downstream side to the other end side on the upstream side of the regenerator 10 along the streamline direction of the working gas (for example, the tube axis direction of the channel 2). The regenerator 10 is, for example, a honeycomb structure formed of ceramics. The regenerator 10 may have one to countless fine tube channels 11 formed by a structure in which a large number of stainless steel mesh thin plates are laminated. The regenerator 10 may be made of any material that can form fine tube channels 11 such as glass pipes and allow the oscillating flow to pass through, and is not limited to these. The regenerator 10 can apply, for example, the configuration described in Patent Document 1.

[0026] A first heat exchanger 12 for heat exchange on the low-temperature side is provided on one end side of the regenerator 10. The first heat exchanger 12 is configured to maintain, for example, one end side of the regenerator 10 in a normal temperature region (first temperature region) as the ambient temperature. The first heat exchanger 12 is appropriately set to utilize the normal temperature heat energy obtained in the environment where the thermoacoustic device 1 is installed. Here, the normal temperature is, for example, a temperature stably obtained by the surrounding environment such as the atmosphere, seawater, river water, lake water, pool water, and geothermal heat.

[0027] The first heat exchanger 12 exchanges heat with the normal temperature atmosphere through a heat medium, for example. The first heat exchanger 12 is controlled by the control device 40. The first heat exchanger 12 may be configured to operate in conjunction with the operation of the thermoacoustic device 1.

[0028] On the other end side of the heat accumulator 10, a second heat exchanger 13 for heat exchange on the high-temperature side is provided. The second heat exchanger 13 is configured to heat, for example, the other end side of the heat accumulator 10 via a heat medium to a high-temperature region (second temperature region) that is at a higher temperature than the normal-temperature region on one end side. The second heat exchanger 13 is appropriately set to utilize the thermal energy of the high-temperature region obtained in the environment where the thermoacoustic device 1 is installed. The second heat exchanger 13 may utilize, for example, unused thermal energy such as the exhaust heat of an internal combustion engine or factory exhaust heat. The second heat exchanger 13 is controlled by a control device 40.

[0029] With the above configuration, the heat accumulator 10 forms a temperature gradient between one end side maintained at the normal-temperature region by the first heat exchanger 12 and the other end side heated to the high-temperature region by the second heat exchanger 13, and is configured as a thermoacoustic device that generates or amplifies a working flow (acoustic power) based on an oscillating flow in the direction of the second flow path 3B from the other end side on the high-temperature side. The heat accumulator 10 only needs to be configured as a thermoacoustic device for prime mover use that utilizes the working flow. The heat accumulator 10 is configured as a thermoacoustic device for prime mover use that utilizes, for example, a standing-wave type oscillating flow, a traveling-wave type oscillating flow, a phase-change type oscillating flow, or the like.

[0030] The working flow generated from the heat accumulator 10 propagates in the flow path 2. Work can be extracted from the working flow propagating in the flow path 2 via an output unit 30 connected to the first branch pipe 4. The output unit 30 may be configured as, for example, a generator that outputs electric power. The output unit 30 is composed of, for example, a linear motor or a speaker that converts the working flow into electric power and outputs it. The output unit 30 converts the oscillating energy of the oscillating flow of the working flow propagated to the working gas into electric power and outputs it (see Patent Document 1). The output unit 30 may be composed of a heat accumulator (second heat accumulator) provided separately from the heat accumulator 10 (first heat accumulator). In this case, the output unit may be configured as a heat pump that outputs high-temperature thermal energy or a cooler that outputs low-temperature thermal energy (see Patent Document 1). The position and device configuration of the output unit 30 are not limited to the illustrated example and may be arbitrarily configured.

[0031] The working fluid flowing in the flow path 2 is adjusted by the adjustment unit 50. The adjustment unit 50 has a configuration proposed by the inventors and is configured to adjust both or either one of the working fluid of the oscillating flow and the sound field in the flow path 2 (see Patent Document 1). The adjustment unit 50 controls the sound field by operating as an acoustic driver that inputs the working fluid or as a generator that consumes the working fluid according to the sound field formed in the flow path 2. The adjustment unit 50 is composed of, for example, a linear motor, a speaker, etc. that apply pressure vibration into the flow path 2. The adjustment unit 50 is controlled by the control device 40 and adjusts the acoustic impedance of the sound field in the flow path 2 so that the output unit 30 operates (see Patent Document 1). The principle, operation, and control method of the adjustment unit 50 conform to, for example, the content described in Patent Document 1. When the flow path 2 is designed to satisfy the predetermined conditions of the acoustic impedance of the regenerator 10 and the output unit 30, the adjustment unit 50 may not be provided.

[0032] As described above, inside the thermoacoustic device 1, in addition to the working fluid, a mass flow Gedeon flow (mass flow M) generated in the annular flow path flows in one direction in the flow path 2. Different from the working fluid that propagates sound waves in the working gas, the mass flow M is accompanied by the movement of the working gas and travels in the loop portion 3. In the illustrated example, the mass flow M travels in the direction of the arrow (first direction) in the figure from the second flow path 3B toward the first flow path 3A along the tube axis direction of the loop portion 3. The mass flow M moves a part of the heat quantity given from the second heat exchanger 13 to the regenerator 10 into the flow path 2 through the working gas. Since the working gas is cooled in the first temperature region in the first heat exchanger 12, when the mass flow M occurs, a part of the heat quantity given to the second heat exchanger 13 is lost, and the thermal efficiency of the thermoacoustic device 1 decreases. In order to suppress the mass flow M, a suppression unit 20 is provided in the middle of the second flow path 3B.

[0033] The suppression unit 20 is provided at a position not affected by the high-temperature heat generated by the heat accumulator 10. It is desirable that the suppression unit 20 be composed of a device not affected by the high-temperature heat generated by the heat accumulator 10. It is desirable that the suppression unit 20 be configured as a device having durability such that part or all of it does not need to be replaced during the operation period of the thermoacoustic device 1, or even if it is replaceable, the replacement frequency is low.

[0034] As shown in FIG. 2, the suppression unit 20 includes a blade portion 21 that periodically operates to move the surrounding working gas, and a drive unit 25 that operates the blade portion 21. In the illustrated example, the blade portion 21 is formed as a rotary blade. The drive unit 25 is composed of, for example, a motor that operates based on electric power and its control circuit. The drive unit 25 is composed of, for example, a rotating device such as a brushless motor. The drive unit 25 rotates the blade portion 21 around the rotation axis L, for example. The drive unit 25 is controlled by the control device 40.

[0035] The blade portion 21 is formed, for example, in a propeller shape having a pair of blades 22. The pair of blades 22 are formed to be rotatable with respect to the rotation axis L. The pair of blades 22 are given a predetermined pitch angle with respect to the rotation axis L. The pair of blades 22 are formed to generate a pressure difference based on the rotation around the rotation axis L, move the working gas, and generate an air flow. The moving direction of the working gas changes according to design conditions such as the shape of the blade 22, the rotation direction of the blade 22, the shape of the second branch pipe 5 that houses the suppression unit 20, and the angle of the rotation axis L with respect to the tube axis direction of the loop portion 3.

[0036] The moving direction of the working gas is appropriately adjusted according to the design conditions of the suppression unit 20. In the illustrated example, the suppression unit 20 is configured to generate an air current in the flow path 2 by exhausting the working gas from the gap with the second branch pipe 5 while sucking the working gas. In the illustrated example, the suppression unit 20 is provided in the second branch pipe 5 so as to generate a suppression flow R that suppresses the mass flow M traveling in the flow path 2 based on the generated air current (see FIG. 1). The suppression unit 20 generates a suppression flow R in the second direction opposite to the first direction so as to suppress the mass flow M traveling in the first direction, for example. The suppression unit 20 is configured to generate the suppression flow R without blocking the waveguide in the flow path 2. The suppression unit 20 may be provided at any position in the flow path 2 as long as it can generate a suppression flow R that suppresses the mass flow M. One or more suppression units 20 may be provided in the flow path 2.

[0037] The illustrated wing part 21 is an example, and it may be formed not only as a propeller-shaped rotary wing but also as a centrifugal rotary wing, i.e., a sirocco fan. The wing part 21 may be formed not only as a rotary wing but also to generate a suppression flow R based on a reciprocating motion. The suppression unit 20 may be configured not only to generate a suppression flow R based on the operation of the wing part 21 but also by a device that injects or pumps the working gas to generate a suppression flow R. The suppression unit 20 may be of any type as long as it can move the working gas to generate a suppression flow R.

[0038] The suppression unit 20 is controlled by the control device 40 and generates a suppression flow R that moves the working gas in a direction to suppress the mass flow M that varies based on the output state of the regenerator 10. Here, the thermoacoustic device 1 may include a detection unit that detects the output state of the regenerator 10. The detection unit may be configured in any way as long as it can output a detection value for detecting the output state of the regenerator 10. The detection unit may be configured by a sensor that detects the mass flow M, such as an ultrasonic flowmeter or a laser flowmeter. The detection unit may be configured by each component of the thermoacoustic device 1, and the control value applied to each component may be used as the detection value, or the output value or measurement value of each component may be used as the detection value.

[0039] The detection unit may detect the temperature of the second heat exchanger 13. The detection unit may output the output value of the output unit 30. As will be described later, the detection unit may use any means as long as it can output a detection value for determining a control amount for controlling the suppression unit 20 to suppress the mass flow M. However, it is desirable that the detection unit be configured to be able to reduce the influence on the working flow in the flow path 2. The detection value is output to the control device 40. The control device 40 controls the suppression unit 20 based on the detection value to adjust the suppression flow R.

[0040] As shown in FIG. 3, the control device 40 includes, for example, a control unit 41 that executes processes for controlling each component, and a storage unit 42 that stores data and programs necessary for control. The control unit 41 is composed of a hardware processor such as at least one CPU (Central Processing Unit). The storage unit 42 is composed of a non-temporary storage medium such as a hard disk drive (HDD) or a solid state drive (SSD). The control unit 41 may be composed of a sequential circuit that operates according to conditions.

[0041] The control unit 41 controls the adjustment unit 50 based on the detection value of the detection unit to adjust the acoustic impedance of the sound field in the flow path 2 so that the output unit 30 operates (see Patent Document 1). The detection unit 60 may be configured to obtain a detection value composed of, for example, an output value, a control value, a measurement value, etc. used for the first heat exchanger 12, the second heat exchanger 13, the adjustment unit 50, and the output unit 30. The detection unit detects at least one detection value among, for example, the pressure amplitude of the working gas, the flow velocity amplitude of the working gas, the working flow of the working gas, the temperature of the regenerator, and the temperature of the heat exchanger provided in the regenerator. The detection unit 60 does not necessarily need to be able to obtain the detection value by using the configuration of the thermoacoustic device 1.

[0042] The control unit 41 adjusts the suppression unit 20 based on the detected value and generates a suppression flow R. The control unit 41 controls, for example, the rotation speed of the drive unit 25 of the suppression unit 20 based on the detected value to adjust the operation cycle (rotation cycle) of the wing unit 21, generate a suppression flow R, and suppress the mass flow M. The control unit 41 generates, for example, a suppression flow R in a second direction opposite to the first direction in which the mass flow M flows. The control unit 41 adjusts the suppression unit 20 so as to increase, for example, the output value of the output unit 30. The control unit 41 adjusts the suppression unit 20 to maximize, for example, the output value of the output unit 30. The control unit 41 may perform feedback control on the suppression unit 20 based on the detected value. The control unit 41 may adjust the suppression unit 20 based on the control amount data mapped in advance to be a control amount corresponding to the detected value and stored in the storage unit 42.

[0043] FIG. 4 shows an experimental apparatus 100 for measuring the change in the time-averaged flow velocity. The experimental apparatus 100 has a device configuration imitating the thermoacoustic device 1. In the following description, the same names and reference numerals are used for the same configurations as those of the thermoacoustic device 1, and redundant descriptions are omitted as appropriate. The experimental apparatus 100 uses the output unit 30 as an adjustment unit 50. The adjustment unit 50 is an acoustic driver that inputs sound into the flow path 2. Here, the propagation direction of the working flow is defined as positive. The flow path 2 of the experimental apparatus 100 is formed of a glass tube and a PVC tube. A third heat exchanger 14 for heat exchange in the normal temperature region is provided on the downstream side of the second heat exchanger 13 in the second flow path 3B. The third heat exchanger 14 may be omitted. In the middle of the flow path 2, a PIV (Particle Image Velocimetry) laser device 101 for visually measuring the movement of the working gas and an imaging device 102 for imaging the working gas irradiated with laser light are provided.

[0044] The experimental apparatus 100 measures the time-averaged flow velocity component of the mass flow (ρu) during the air column vibration in the flow path 2. The mass flow (ρu) is represented by the following formula (1). ρu = <ρ 1 u 1 > + ρ 0 u 2 (1) However, ρ represents the density fluctuation of the working gas, u represents the flow velocity fluctuation in the direction along the tube axis of the working gas. The subscript 0 indicates the average value in the non-vibrating state, the subscript 1 indicates the value that vibrates at the angular frequency ω and is time-dependent, and the subscript 2 indicates the value that is not time-dependent. < > represents the time-averaging operation. u 2 is the time-averaged flow velocity component of the mass flow (ρu). Here, u 2 is called the time-averaged flow velocity.

[0045] ρ 1 u 1 is a flow that moves spatially in the same direction as the propagation direction of the working flow. In the experiment, in the state where the wing part 21 is not driven, ρ 1 u 1 and ρ 0 u 2 were both confirmed to be in the positive direction (the propagation direction of the working flow). At this time, the end face temperature (T hot ) of the second heat exchanger 13 side of the regenerator 10 was 251 degrees, and the pressure amplitude of the working gas was approximately 1880 Pa (about 20 cm upstream from the first heat exchanger 12). A brushless DC motor was used for the drive unit 25 that drives the wing part 21, and the rotational speed was increased step by step to confirm that the propagation direction and magnitude of the time-averaged flow velocity u 2 could be changed. To control the rotational speed of the drive unit 25, an ESC (Electric Speed Controller) was connected to the brushless DC motor. In the experiment, the voltage applied to the ESC was fixed at 10 V, and the rotational speed was increased step by step by adjusting the ESC pulse signal with a servo tester connected to the ESC. The distribution of the time-averaged flow velocity u 2 was measured by PIV.

[0046] The conditions of the experimental apparatus 100 are as follows. Inner diameter of the flow path 2: 40 mm Flow path diameter of the capillary flow path of the regenerator 10: 0.67 mm Length of the capillary flow path of the regenerator 10 in the tube axis direction: 30 mm Flow path diameter of the first heat exchanger 12: 2 mm Length of the first heat exchanger 12 in the tube axis direction: 30 mm Flow path diameter of the second heat exchanger 13: 1.46 mm Length in the pipe axis direction of the second heat exchanger 13: 30 mm Flow path diameter of the third heat exchanger 14: 2 mm Length in the pipe axis direction of the third heat exchanger 14: 20 mm Length along the pipe axis direction of the second branch pipe 5: 70 mm Inner diameter of the second branch pipe 5: 48 mm Motor housed in the second branch pipe 5: A2212 / 13T (product name) Inner diameter of the third branch pipe 6: 40 mm Length along the pipe axis direction of the third branch pipe 6: 114 mm Pitch angle of the blade 22 with respect to the rotation axis L: 20 degrees Position of the imaging device 102 from the downstream side of the second heat exchanger 13: approximately 850 mm Vibration frequency of the working gas in the flow path 2 adjusted by the adjustment unit 50: 60 Hz

[0047] FIG. 5 shows an example of a motor control value for controlling the drive unit 25. The motor control value is, for example, the current value displayed on the monitor of the DC power supply connected to the ESC. This value changes as the ESC pulse signal is adjusted by the servo tester. Other values may be used as long as they can control the brushless DC motor.

[0048] FIGS. 6 and 7 show the measurement results of the time-averaged flow velocity u 2 measured at the position of the imaging device 102 in the flow path 2. FIGS. 6(a) to 6(d), and FIGS. 7(e) to 7(g) show the radial distribution of the time-averaged flow velocity u 2 . FIGS. 6(a) to 6(d), and FIGS. 7(e) to 7(g) correspond to the 7 patterns of measurements from measurement a) to measurement g) measured in FIG. 5. The vertical axis in each figure is the radial coordinate of the flow path 2. Centered on the radial center r = 0 of the flow path 2, r = -20 is taken in the direction of gravity and r = 20 is represented in the direction opposite to gravity. In each figure, the time-averaged flow velocity u 2 is obtained from the displacement of the tracer particles generated in two cycles, and the results u 2 (1) to u 2 (5) for a total of 5 times at different times are plotted. Furthermore, the average value u of the 5 measurements2 (ave.) is shown by a thick line.

[0049] As shown in the figure, when the current input to the motor is increased, the time-averaged flow velocity u 2 decreases in magnitude. The measurement result of the time-averaged flow velocity u 2 when the motor is not driven is shown in measurement a). At this time, the value of the time-averaged flow velocity u 2 (ave.) was approximately 0.037 m / s at r = 0. The measurement results of the time-averaged flow velocity u 2 when the motor is operating and the rotational speed is gradually increased are shown in b) to g). The value of the time-averaged flow velocity u 2 (ave.) at r = 0 was approximately 0.023 m / s in measurement b), approximately 0 m / s from measurement c) to measurement e), approximately -0.041 m / s in measurement f), and approximately -0.047 m / s in measurement g). In measurements a) and b), the time-averaged flow velocity u 2 is in the positive direction throughout the radial direction, but in measurement b) compared to measurement a), the value of the time-averaged flow velocity u 2 decreases. Taking measurements d) and e) as the boundary, after measurement f), u 2 reverses to the negative direction throughout the radial direction, and it was confirmed that in measurement g), the value of ρu 2 further increases in the negative direction.

[0050] According to the experimental apparatus 100, by providing the suppression unit 20 in the flow path 2, ρ 1 u 1 and ρ 0 u 2 which are components of the mass flow M, can be changed from both being in the positive direction to the positive and negative of u 2 and its magnitude. This indicates that the mass flow M can be suppressed by the suppression flow R generated by the suppression unit 20.

[0051] FIG. 8 shows a method for suppressing the mass flow M using the thermoacoustic device 1 to suppress the mass flow M by the thermoacoustic device 1. In the thermoacoustic device 1, a detected value of the mass flow M traveling in the flow path 2 is detected (step S10). As the detected value, a sensor value for measuring each component of the thermoacoustic device 1, a control value applied to each component, an output value of each component, etc. can also be used as the detected value. Based on the detection result of the detected value, the suppression unit 20 is adjusted, and a suppression flow R for moving the working gas is generated in a direction to suppress the mass flow M that varies based on the output state of the regenerator 10 (step S20). Each step of the method for suppressing the mass flow M may be executed by a computer program installed in the storage unit 42 for controlling the control unit 41 of the computer mounted on the control device 40.

[0052] As described above, according to the thermoacoustic device 1, by providing the suppression unit 20 capable of generating the adjustable suppression flow R in the flow path 2, the mass flow M generated in the flow path 2 can be suppressed. According to the thermoacoustic device 1, the mass flow M that varies according to the temperature fluctuations of the regenerator 10 and the heat exchanger can be suppressed by actively adjusting the suppression unit 20 and generating the suppression flow R. According to the thermoacoustic device 1, when configuring a thermoacoustic prime mover, it is possible to prevent the amount of heat that should be input to the high-temperature side heat exchanger from being transported outside the regenerator by the mass flow M generated in the flow path 2, and improve the thermal efficiency of the device.

[0053] According to the thermoacoustic device 1, when configuring a thermoacoustic cooler, it is possible to prevent the amount of heat output from the low-temperature side heat exchanger from being transported outside the regenerator by the mass flow M generated in the flow path 2, and improve the thermal efficiency of the device. According to the thermoacoustic device 1, when configuring a thermoacoustic heater, it is possible to prevent the amount of heat output through the high-temperature side heat exchanger of the regenerator 10 from being transported into the flow path 2 by the mass flow M generated in the flow path 2, and improve the thermal efficiency of the device.

[0054] In the conventional membrane structure, the flow path 2 is blocked, and when propagating sound waves, it passes through an elastic body having an attenuation element, so that the working flow is attenuated. Also, the jet pump attenuated the working flow by generating a differential pressure. According to the thermoacoustic device 1, by providing the suppression unit 20, it is possible to suppress the mass flow while reducing the attenuation of the working flow as compared with the membrane structure and the jet pump of the prior art. According to the thermoacoustic device 1, by providing the suppression unit 20, it is possible to actively control the mass flow as compared with the membrane structure and the jet pump of the prior art. According to the thermoacoustic device 1, by providing the suppression unit 20, it is possible to improve the durability and maintainability as compared with the membrane structure of the prior art.

[0055] Hereinafter, a modified example of the thermoacoustic device 1 will be described. In the following description, the same names and reference numerals are used for the same configurations as those in the above embodiment, and overlapping descriptions are omitted as appropriate.

[0056] FIG. 9 shows a thermoacoustic device 1A according to a modified example. The thermoacoustic device 1A includes a suppression unit 80 that generates a suppression flow R based on an ionic wind in the working gas. The suppression unit 80 is provided in the second flow path 3B. The suppression unit 80 includes, for example, a first electrode 81 for discharge and a second electrode 82 on the ground side. A power supply unit V that outputs a direct current is connected to the first electrode 81. The power supply unit V is controlled by the control unit 41.

[0057] The first electrode 81 is linearly formed by a conductor such as a metal wire having conductivity along the tube axis direction in the flow path 2. The first electrode 81 is disposed, for example, on the downstream side of the second electrode 82 in the flow path 2. The tip of the first electrode 81 is disposed to face the second electrode 82. When the first electrode 81 is energized from the power supply unit V, a corona discharge is generated from the tip toward the second electrode 82. The suppression unit 80 generates an ionic wind in the flow path 2 that moves the working gas from the first electrode 81 side to the second electrode 82 side based on the corona discharge.

[0058] That is, the suppression unit 80 generates a suppression flow R that suppresses the mass flow M in the flow path 2 based on the ionic wind. The control unit 41 can adjust the suppression unit 80 by adjusting the output of the power supply unit V to generate a suppression flow R corresponding to the mass flow M. The suppression unit 80 may not only continuously generate the suppression flow R but also generate a pulse wave of the suppression flow R.

[0059] The arrangement relationship between the first electrode 81 and the second electrode 82 in the suppression unit 80 described above is an example. As long as the suppression unit 80 can suppress the mass flow M, the first electrode 81 and the second electrode 82 may be configured with other arrangement relationships. For example, the first electrode 81 and the second electrode 82 may be arranged in a direction orthogonal to the tube axis direction of the flow path, and the suppression flow R may be generated as an air curtain with respect to the mass flow M to suppress the mass flow M. Further, the second electrode 82 may be constituted by a heat exchanger used in the thermoacoustic device. The second electrode 82 may be constituted by, for example, any one of the first heat exchanger 12, the second heat exchanger 13, and the third heat exchanger 14. The first electrode 81 and the second electrode 82 may be arranged not only inside the flow path 2 but also outside the flow path 2, and a suppression flow R based on the ionic wind may be generated inside the flow path 2.

[0060] As long as the suppression unit 80 can generate a suppression flow R that moves the working gas in a direction to decelerate the mass flow M that varies based on the output state of the regenerator 10, the first electrode 81 and the second electrode 82 may be arranged at arbitrary positions, and the power supply unit V may input a direct current, a pulse current, or an alternating current to the first electrode 81 or the second electrode 82. The power supply unit V may adjust the current input to the first electrode 81 according to the vibration frequency of the mass flow M.

[0061] Based on the thermoacoustic device 1 having the suppression unit 20 described above or the thermoacoustic device 1A having the suppression unit 80, another regenerator may be arranged in the output unit 30 to constitute a thermoacoustic temperature riser, or a thermoacoustic cooler may be constituted. The output unit 30 may be constituted by another loop unit different from the loop unit 3 of the flow path 2, and the suppression unit 20 or the suppression unit 80 may be arranged in the other loop unit.

[0062] The output unit 30 may be provided in the loop unit 3, or may constitute a thermoacoustic heater or a thermoacoustic cooler. In this case, the suppression unit 20 may be arranged to generate the suppression flow R from a branch pipe branched from the loop unit 3, or the suppression unit 80 may be provided in the loop unit 3.

[0063] When the working gas is a magnetic fluid, the suppression unit may generate the suppression flow R by applying a magnetic field to the working gas. In this case, the suppression unit may generate the suppression flow R by adjusting the intensity of the magnetic field by the control unit 41, or may generate the suppression flow R by adjusting the intensity of the magnetic field using a permanent magnet. The suppression unit may be provided in the flow path 2 and may be constituted by a one-way valve such as a Tesla valve that suppresses the flow in the other direction while allowing the working gas to flow in one direction without blocking the flow path 2.

[0064] In addition, one or more valve devices (see, for example, Non-Patent Document 5) capable of arbitrarily adjusting the opening area based on an openable and closable shutter structure may be applied to the suppression unit. The suppression unit may actively generate a suppression flow R with a controllable discharge amount in the flow path 2 by a combination of the above-described valve device and a device that generates an air flow. As the valve device, a butterfly valve or a slide valve capable of arbitrarily adjusting the opening area may be used. The valve device may be one that arbitrarily adjusts the opening area by deforming so as to crush the flexible flow path 2. That is, any suppression unit may be used as long as it can generate a suppression flow R that moves the working gas in a direction to decelerate the mass flow M that varies based on the output state of the regenerator 10.

[0065] In the above-described embodiment, the computer program executed in the control device 40 may be provided in a form recorded on a computer-readable portable recording medium such as a semiconductor memory, a magnetic recording medium, or an optical recording medium.

Explanation of Reference Numerals

[0066] 1. 1A thermoacoustic device, 2 flow path, 3 loop section, 3A first flow path, 3B second flow path, 4 first manifold, 5 second manifold, 6 third manifold, 10 regenerator, 11 capillary flow path, 12 first heat exchanger, 13 second heat exchanger, 14 third heat exchanger, 20 suppression section, 21 wing section, 22 blade, 25 drive section, 30 output section, 40 control device, 41 control section, 42 memory section, 50 adjustment section, 60 detection section, 80 suppression section, 81 first electrode, 82 second electrode, 100 experimental device, 101 PIV laser device, 102 imaging device, L rotation axis, M mass flow, R suppression flow

Claims

1. A flow path through which a working gas flows, a regenerator provided in the middle of the flow path and having heat exchangers provided at both ends, a suppression unit that generates a suppression flow for suppressing a mass flow advancing in the flow path, wherein the suppression unit generates the suppression flow that moves the working gas in a direction to suppress the mass flow that varies according to the output state of the regenerator, a thermoacoustic device.

2. The suppression unit adjusts the output of the suppression flow based on a detection value obtained by detecting the output state, The thermoacoustic device according to Claim 1.

3. The suppression unit includes a wing portion that operates periodically to move the working gas, and adjusts the momentum of the wing portion according to the detection value to generate the suppression flow, The thermoacoustic device according to Claim 2.

4. The suppression unit includes an ion wind generation unit that generates an ion wind in the working gas, and adjusts the output of the ion wind according to the detection value to generate the suppression flow, The thermoacoustic device according to Claim 2.

5. a detection unit that outputs the detection value, wherein the detection unit detects at least one of the detection values of the pressure amplitude of the working gas, the flow velocity amplitude of the working gas, the work flow of the working gas, the temperature of the regenerator, and the temperature of the heat exchanger provided at both ends of the regenerator, The thermoacoustic device according to Claim 2.

6. In a thermoacoustic device including a flow path through which a working gas flows, a regenerator provided in the middle of the flow path and having heat exchangers provided at both ends, and a suppression unit that generates a suppression flow for moving the working gas, a mass flow advancing in the flow path is detected, the suppression unit is adjusted based on the detection result, and the suppression flow that moves the working gas is generated in a direction to suppress the mass flow that varies according to the output state of the regenerator, A method for suppressing a mass flow using a thermoacoustic device.

Images