Thermoacoustic device

Abstract

To provide a thermoacoustic device capable of efficiently performing transformation between heat and a sound wave.SOLUTION: In a thermoacoustic device 1, a thermoacoustic transform unit 12 includes a heat accumulator 2, a high-temperature side heat exchanger 31, a low-temperature side heat exchanger 32, and a housing 4. The housing 4 accommodates the heat accumulator 2, the high-temperature side heat exchanger 31, and the low-temperature side heat exchanger 32 therein, and is connected to a fluid pipe 11. The heat accumulator 2 is sandwiched between the high-temperature side heat exchanger 31 and the low-temperature side heat exchanger 32 in an arrangement direction Z of the low-temperature side heat exchanger 32, the heat accumulator 2, and the high-temperature side heat exchanger 31. In at least one of the high-temperature side heat exchanger 31 and the low-temperature side heat exchanger 32, a ratio of a length of a fluid flow path to a hydraulic diameter of the fluid flow path is 5 or more.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to thermoacoustic devices. [Background technology]

[0002] For example, a known thermoacoustic device includes a heat accumulator, a high-temperature side heat exchanger that heats one end of the heat accumulator, and a low-temperature side heat exchanger that cools the other end of the heat accumulator, as disclosed in Patent Document 1. The thermoacoustic device described in Patent Document 1 attempts to obtain a sufficient thermoacoustic effect by setting the hydraulic diameter, opening ratio, etc. of the pores in the heat accumulator that generates the thermoacoustic effect within predetermined ranges. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-70214 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the thermoacoustic device described in Patent Document 1 takes into consideration the pores of the heat accumulator to obtain a sufficient thermoacoustic effect, but does not sufficiently consider the fluid flow paths of the heat exchanger. As a result, there is a risk that the vibration speed and phase of the gas molecules, which are the medium, may be shifted in the sound waves propagating from each fluid flow path of the heat exchanger to the pores of the heat accumulator, and there is a risk that the conversion between heat and sound waves may not be performed efficiently. Therefore, it can be said that there is room for further improvement in terms of the conversion efficiency between heat and sound waves.

[0005] The present invention has been made in view of the above-mentioned problems, and aims to provide a thermoacoustic device that can efficiently convert between heat and sound waves. [Means for solving the problem]

[0006] One aspect of the present invention is a thermoacoustic device (1) that utilizes the thermoacoustic phenomenon to convert between heat and sound waves, The device comprises a fluid pipe (11) filled with a working fluid, and a thermoacoustic converter (12) provided in the fluid pipe, The thermoacoustic converter is a heat accumulator (2) having a large number of pores (20) into which the working fluid is introduced; a high-temperature side heat exchanger (31) disposed at one end of the heat accumulator and having a number of fluid flow paths (310) into which the working fluid is introduced; a low-temperature side heat exchanger (32) disposed at the other end of the heat accumulator and having a number of fluid flow paths (320) into which the working fluid is introduced; a housing (4) that houses the heat accumulator, the high-temperature side heat exchanger, and the low-temperature side heat exchanger therein and is connected to the fluid piping; the heat accumulator is sandwiched between the high-temperature side heat exchanger and the low-temperature side heat exchanger in an arrangement direction (Z) of the low-temperature side heat exchanger, the heat accumulator, and the high-temperature side heat exchanger, At least one of the high-temperature side heat exchanger and the low-temperature side heat exchanger is in a thermoacoustic device, wherein the ratio of the length of the fluid flow path to the hydraulic diameter of the fluid flow path is 5 or greater. [Effects of the Invention]

[0007] In the thermoacoustic device, at least one of the high-temperature side heat exchanger and the low-temperature side heat exchanger has a ratio of the length of the fluid flow path to the hydraulic diameter of the fluid flow path of 5 or more. Therefore, in the sound waves propagating from each fluid flow path of at least one of the high-temperature side heat exchanger and the low-temperature side heat exchanger to the pores of the heat accumulator, the vibration velocity and phase shift of the molecules of the working fluid, which is the medium, can be suppressed. As a result, the conversion between heat and sound waves can be performed efficiently.

[0008] As described above, according to the above aspect, it is possible to provide a thermoacoustic device that can efficiently convert between heat and sound waves. In addition, the symbols in parentheses in the claims and the means for solving the problems indicate the correspondence with the specific means described in the embodiments described below, and do not limit the technical scope of the present invention. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of a thermoacoustic device according to a first embodiment. [Figure 2] 1 is a cross-sectional view of a thermoacoustic device according to a first embodiment, taken along the arrangement direction. [Figure 3] 3 is a plan view of the high-temperature side heat exchanger in the first embodiment, seen from the arrangement direction, and viewed from the arrow III in FIG. 4. FIG. [Figure 4] 4 is a cross-sectional view taken along line IV-IV in FIG. 3. [Figure 5] FIG. 3 is a plan view of the high-temperature side heat exchanger in the first embodiment, seen from the arrangement direction, and is an enlarged plan view of the vicinity of the fluid flow path. [Figure 6] 8 is a plan view of the low-temperature side heat exchanger in the first embodiment, seen from the arrangement direction, taken along the arrow VI in FIG. 7. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. [Figure 8] FIG. 3 is a plan view of the low-temperature side heat exchanger in the first embodiment, seen from the arrangement direction, and is an enlarged plan view of the vicinity of the fluid flow path. [Figure 9] FIG. 3 is a plan view of the heat accumulators in the first embodiment, viewed from the arrangement direction. [Figure 10] FIG. 3 is a plan view of the heat accumulators as seen from the arrangement direction, and is an enlarged plan view of the vicinity of the pores in the first embodiment. [Figure 11] 1 is a graph showing the relationship between the values of "LH1 / DH1" and "LH2 / DH2" and the thermoacoustic conversion efficiency in Experimental Example 1. [Figure 12] 10 is a graph showing the relationship between the hydraulic diameter Dh of the heat accumulator and the thermoacoustic conversion efficiency in Experimental Example 2. [Figure 13] 10 is a graph showing the relationship between the values of "DH1 / Dh" and "DH2 / Dh" and the thermoacoustic conversion efficiency in Experimental Example 3. [Figure 14]10 is a graph showing the relationship between the values of "DH1 / Dh" and "DH2 / Dh" and the viscous loss ratio in Experimental Example 4. [Figure 15] 10 is a graph showing the relationship between the values of "DH1 / Dh" and "DH2 / Dh" and the thermoacoustic conversion efficiency in Experimental Example 5. [Figure 16] 10 is a graph showing the relationship between the value of the product of the opening ratio R1 of the heat accumulator and the opening ratio R2 of the high-temperature side heat exchanger and the thermoacoustic conversion efficiency in Experimental Example 6. [Figure 17] FIG. 10 is a schematic diagram of a thermoacoustic device according to a second embodiment. [Figure 18] FIG. 10 is a schematic diagram of a thermoacoustic device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Embodiment 1) An embodiment of a thermoacoustic device will be described with reference to FIGS. The thermoacoustic device 1 of this embodiment converts heat to sound waves by utilizing the thermoacoustic phenomenon. As shown in Fig. 1, the thermoacoustic device 1 includes a fluid pipe 11 filled with a working fluid and a thermoacoustic converter 12 provided in the fluid pipe 11.

[0011] As shown in FIG. 2, the thermoacoustic converter 12 includes a heat accumulator 2, a high-temperature side heat exchanger 31, a low-temperature side heat exchanger 32, and a housing 4. As shown in FIGS. 9 and 10, the heat accumulator 2 has a large number of pores 20 into which the working fluid is introduced. As shown in FIG. 2, the high-temperature side heat exchanger 31 is disposed at one end of the heat accumulator 2, and has a large number of fluid flow paths 310 into which the working fluid is introduced, as shown in FIGS. 3 to 5. As shown in FIG. 2, the low-temperature side heat exchanger 32 is disposed at the other end of the heat accumulator 2, and has a large number of fluid flow paths 320 into which the working fluid is introduced, as shown in FIGS. 6 to 8. As shown in FIG. 2, the housing 4 accommodates the heat accumulator 2, the high-temperature side heat exchanger 31, and the low-temperature side heat exchanger 32 therein, and is connected to the fluid piping 11.

[0012] The heat accumulator 2 is sandwiched between the high-temperature side heat exchanger 31 and the low-temperature side heat exchanger 32 in the arrangement direction Z of the low-temperature side heat exchanger 32, the heat accumulator 2, and the high-temperature side heat exchanger 31. At least one of the high-temperature side heat exchanger 31 and the low-temperature side heat exchanger 32 has a ratio of the length of the fluid flow paths 310, 320 to the hydraulic diameter of the fluid flow paths 310, 320 of 5 or more. Furthermore, at least one of the high-temperature side heat exchanger 31 and the low-temperature side heat exchanger 32 has a ratio of the length of the fluid flow paths 310, 320 to the hydraulic diameter of the fluid flow paths 310, 320 of 6 or more. Furthermore, in the thermoacoustic device 1 of this embodiment, in the high-temperature side heat exchanger 31, the hydraulic diameter D H1 4. The length L of the fluid flow path 310 shown in FIG. H1 The ratio of the hydraulic diameter D H2 7. The length L of the fluid flow path 320 shown in FIG. H2 The ratio is 5 or more.

[0013] The thermoacoustic converter 12 of the thermoacoustic device 1 can be configured to convert heat into sound waves by, for example, creating a temperature gradient in the heat accumulator 2 using heat exchangers 31 and 32. Alternatively, the thermoacoustic converter can be configured to convert sound waves output by a sound wave generator (not shown) provided in the fluid piping into cold heat. In this embodiment, the thermoacoustic converter 12 is used to amplify sound waves circulating in the fluid piping 11 filled with a working fluid. Specifically, the thermoacoustic converter 12 can generate and amplify sound waves by vibrating the working fluid using the temperature difference between both ends of the heat accumulator 2 (see FIG. 2). Some of the sound waves generated and amplified by the thermoacoustic converter 12 circulate in the annular piping 111. The working fluid of the thermoacoustic device 1 can be, for example, air, helium, argon, or the like. In this embodiment, the working fluid is compressed helium gas.

[0014] The thermoacoustic device 1 of this embodiment can be used as a power generation means that uses exhaust gas discharged from an industrial furnace (not shown) or the like as a heat source. Industrial furnaces include heating furnaces, baking furnaces, drying furnaces, and exhaust gas treatment furnaces that heat an object to be heated or atmospheric gas by burning fuel. As shown in FIG. 1 , the fluid piping 11 of the thermoacoustic device 1 of this embodiment is a loop type having an annular piping 111 formed in a ring shape and a branch piping 112 branching from the annular piping 111. The thermoacoustic converter 12 is configured to convert the heat of the exhaust gas into sound waves. One or more thermoacoustic converters 12 can be installed, for example, along the fluid piping 11. In this embodiment, one thermoacoustic converter 12 is installed along the annular piping 111.

[0015] The thermoacoustic device 1 also has a sound wave utilization device 13. In this embodiment, the sound wave utilization device 13 is a generator. The generator 13 is provided at the end of the branch pipe 112 and is configured as a linear generator that converts vibrations caused by sound waves into electricity using electromagnetic induction. The sound waves amplified by the thermoacoustic conversion unit 12 are used by the generator 13 and converted into electricity. The sound wave utilization device may be various other devices besides the generator 13, for example, a device that performs heating or cooling.

[0016] The high-temperature side heat exchanger 31 heats one end surface 21 of the heat accumulator 2 in the arrangement direction Z. In this embodiment, the high-temperature side heat exchanger 31 has a cylindrical shape as shown in Figs. 3 and 4. The high-temperature side heat exchanger 31 may be made of a metal such as stainless steel. In addition, in the arrangement direction Z, the side of the high-temperature side heat exchanger 31 on which the low-temperature side heat exchanger 32 is arranged is referred to as the front side Z1, and the opposite side is referred to as the rear side Z2.

[0017] The high-temperature side heat medium introduced into the high-temperature side heat exchanger 31 circulates between the high-temperature side heat exchanger 31 and an exhaust gas heat exchanger (not shown), which exchanges heat with exhaust gas discharged from an industrial furnace or the like. The high-temperature side heat medium transfers the heat of the exhaust gas recovered by the exhaust gas heat exchanger to the regenerator 2 and the working fluid via the high-temperature side heat exchanger 31, thereby heating the regenerator 2 and the working fluid. The temperature of the high-temperature side heat medium sent from the exhaust gas heat exchanger to the high-temperature side heat exchanger 31 can be, for example, about 300°C. Various heat transfer oils are used as the high-temperature side heat medium. Examples of the heat transfer oil that can be used include synthetic heat transfer oils, paraffinic polymer oils, diphenyl heat transfer oils, and synthetic heat transfer oils.

[0018] As shown in FIGS. 3 to 5 , the high-temperature side heat exchanger 31 has a number of fluid flow paths 310 through which sound waves propagate, and heat medium flow paths 319 through which a high-temperature side heat medium flows, which are formed around the fluid flow paths 310 via heat transfer walls 318. The high-temperature side heat exchanger 31 also has a flow path forming section 15 that is a structure for promoting heat exchange and that forms the fluid flow paths 310. The fluid flow paths 310 are formed by being surrounded by the flow path forming section 15 and the heat transfer walls 318. In this embodiment, the flow path forming section 15 is a fin with a corrugated shape. The flow path forming section 15 is joined by brazing to the heat transfer walls 318 that form the heat medium flow paths 319. In the fluid flow paths 310, the working fluid is heated by the high-temperature side heat medium flowing in the heat medium flow paths 319, via the flow path forming section 15 and the heat transfer walls 318.

[0019] As shown in FIG. 4, in the high-temperature side heat exchanger 31, the length L H1 has a length equal to the length L1 in the arrangement direction Z of the high-temperature side heat exchanger 31. In other words, the fluid flow path 310 passes through the high-temperature side heat exchanger 31 in the arrangement direction Z.

[0020] 2, a fixing portion 314 that is fixed to the housing 4 is provided on the outer peripheral surface of the high-temperature side heat exchanger 31. The high-temperature side heat exchanger 31 and the fixing portion 314 are fixed to each other by welding.

[0021] The fixed portion 314 has an annular portion 315 fixed to the high-temperature side heat exchanger 31 so as to cover the outer peripheral surface of the high-temperature side heat exchanger 31, and a protruding flange portion 316 protruding from the center of the annular portion 315 in the arrangement direction Z toward the outer peripheral side. The annular portion 315 and the protruding flange portion 316 are integrally formed. Furthermore, as will be described later, the protruding flange portion 316 is fixed to the housing 4.

[0022] Two communication holes 317 are formed in the fixed part 314 to communicate between the high-temperature side heat exchanger 31 and the outside. A high-temperature side inlet pipe 312 that introduces a high-temperature side heat medium into the high-temperature side heat exchanger 31 is inserted into one of the communication holes 317, and a high-temperature side outlet pipe 313 that discharges the high-temperature side heat medium from the high-temperature side heat exchanger 31 to the outside is inserted into the other communication hole 317. The high-temperature side inlet pipe 312 and the high-temperature side outlet pipe 313 are fixed to the fixed part 314 by welding while inserted into the communication holes 317.

[0023] The low-temperature side heat exchanger 32 cools the end surface 21 on the front side Z1 of the heat accumulator 2. In this embodiment, the low-temperature side heat exchanger 32 has a cylindrical shape as shown in Figures 6 and 7. The low-temperature side heat exchanger 32 may be made of a metal such as stainless steel.

[0024] The low-temperature side heat medium, which is the heat medium introduced into the low-temperature side heat exchanger 32, is used to cool the regenerator 2 and the working fluid via the low-temperature side heat exchanger 32. The low-temperature side heat medium can be various fluids whose temperatures are lower than the exhaust gas and the high-temperature side heat medium. In this embodiment, the low-temperature side heat medium is circulating water used in the factory.

[0025] As shown in FIGS. 6 to 8 , the low-temperature side heat exchanger 32 has a number of fluid flow paths 320 through which sound waves pass and refrigerant flow paths 329 through which a low-temperature side heat medium flows, which are formed around the fluid flow paths 320 via heat transfer walls 328. Similarly to the high-temperature side heat exchanger 31, the low-temperature side heat exchanger 32 also has a flow path forming portion 16 that is a structure for promoting heat exchange and that forms the fluid flow paths 320. The fluid flow paths 320 are formed by being surrounded by the flow path forming portion 16 and the heat transfer walls 328. In this embodiment, the flow path forming portion 16 is a fin having a corrugated shape. The flow path forming portion 16 is joined to the heat transfer walls 328 that form the refrigerant flow paths 329 by brazing. In the fluid flow paths 320, the working fluid is cooled by the low-temperature side heat medium flowing through the refrigerant flow paths 329 via the flow path forming portion 16 and the heat transfer walls 328. The flow path forming portions 15, 16 may have various shapes used in known heat exchangers, in addition to a corrugated shape. The flow path forming portions 15 and 16 may be made of, for example, stainless steel.

[0026] As shown in FIG. 7, in the low-temperature side heat exchanger 32, the length L H2 has a length equal to the length L2 in the arrangement direction Z of the low-temperature side heat exchanger 32. In other words, the fluid flow path 320 penetrates the low-temperature side heat exchanger 32 in the arrangement direction Z.

[0027] 2, an annular outer peripheral portion 324 is provided on the outer peripheral surface of the low-temperature side heat exchanger 32. The low-temperature side heat exchanger 32 and the outer peripheral portion 324 are fixed to each other by welding. Two communication holes 325 are formed in the outer peripheral portion 324. One communication hole 325 connects the low-temperature side heat exchanger 32 to the low-temperature side inlet pipe 322, and the other communication hole 325 connects the low-temperature side heat exchanger 32 to the low-temperature side outlet pipe 323. The low-temperature side inlet pipe 322 is a pipe that introduces the low-temperature side heat medium into the low-temperature side heat exchanger 32, and the low-temperature side outlet pipe 323 is a pipe that discharges the low-temperature side heat medium from the low-temperature side heat exchanger 32 to the outside. The low-temperature side inlet pipe 322 and the low-temperature side outlet pipe 323 are inserted into the front ends of the communication holes 325 and fixed to the outer peripheral portion 324 by welding.

[0028] As shown in FIG. 9 , the heat accumulator 2 has a skin portion 23 constituting an outer wall portion and segments 22 provided on the inner circumferential side of the skin portion 23. As shown in FIGS. 9 and 10 , the segments 22 are formed with a large number of pores 20 penetrating the segments 22 along the arrangement direction Z. In the segments 22, the cell walls 24 forming the pores 20 can be formed as walls having, for example, a lattice shape, a honeycomb shape, or a cylindrical shape. Sound waves propagate through the pores 20 separated by the cell walls 24. The heat accumulator 2 can amplify sound waves by vibrating the working fluid in the pores 20 using the temperature difference between both ends of the arrangement direction Z. The heat accumulator 2 can be made of, for example, a metal material such as stainless steel or ceramic. In this embodiment, the heat accumulator 2 is made of ceramic such as alumina. In this embodiment, the heat accumulator 2 has a cylindrical shape.

[0029] The heat accumulator 2 is sandwiched and fixed between the high-temperature side heat exchanger 31 and the low-temperature side heat exchanger 32 in the arrangement direction Z. As shown in Fig. 2, the low-temperature side heat exchanger 32 is pressed toward the rear side Z2 by a pressing member 5 provided on the housing 4. An end face 321 on the rear side Z2 of the low-temperature side heat exchanger 32 is in pressure contact with an end face 21 on the front side Z1 of the heat accumulator 2, and the end face 21 on the rear side Z2 of the heat accumulator 2 is in pressure contact with an end face 311 on the front side Z1 of the high-temperature side heat exchanger 31. As shown in Fig. 9, the end face 21 on the high-temperature side heat exchanger 31 side of the heat accumulator 2 has a plurality of heat transfer surfaces 211 that are in pressure contact with a heat transfer wall 318 that forms a heat medium flow path 319 of the high-temperature side heat exchanger 31. The end face 21 (not shown) of the heat accumulator 2 on the low-temperature side heat exchanger 32 side also has a plurality of heat transfer surfaces 211 that are brought into pressure contact with the heat transfer wall 328 that forms the heat medium flow path 319 of the low-temperature side heat exchanger 32. The end face 21 of the heat accumulator 2 on the high-temperature side heat exchanger 31 side and the end face 21 of the heat accumulator 2 on the low-temperature side heat exchanger 32 side have similar structures.

[0030] 2, the thermoacoustic device 1 includes a housing 4 that houses the heat exchangers 31 and 32 and the heat accumulator 2 to prevent leakage of the working fluid to the outside. In this embodiment, the housing 4 has a first housing section 41 that houses the low-temperature side heat exchanger 32 and the heat accumulator 2 therein, and a second housing section 42 that is provided so as to have a substantially symmetrical shape to the first housing section 41.

[0031] The first accommodating portion 41 and the second accommodating portion 42 each have a cylindrical outer peripheral portion 411, 421 that covers the accommodating space 40, which is the space inside the housing 4, from the outer peripheral side, and a flange portion 412, 422 that protrudes outer peripherally from one end of the outer peripheral portions 411, 421 in the arrangement direction Z. The first accommodating portion 41 and the second accommodating portion 42 also have a connecting portion 413, 423 that is provided at the other end of the outer peripheral portions 411, 421 in the arrangement direction Z and is connected to the fluid pipe 11. Specifically, the flange portion 412 protrudes outer peripherally from an end of the outer peripheral portion 411 of the first accommodating portion 41 on the rear side Z2, and the flange portion 422 protrudes outer peripherally from an end of the outer peripheral portion 421 of the second accommodating portion 42 on the front side Z1. The connecting portion 413 is provided at an end of the outer circumferential portion 411 on the front side Z1, and the connecting portion 423 is provided at an end of the outer circumferential portion 421 on the rear side Z2.

[0032] The protruding flange 316 of the fixing portion 314 fixed to the high-temperature side heat exchanger 31 is fastened to the housing 4 in a state where it is sandwiched in the arrangement direction Z by the flange portion 412 of the first housing portion 41 and the flange portion 422 of the second housing portion 42. Specifically, the flange portions 412, 422 and the protruding flange 316 each have a through hole (not shown) that penetrates along the arrangement direction Z. Bolts 191, which are fastening members, are inserted into the through holes, and the flange portions 412, 422 and the protruding flange 316 are fastened to each other by the bolts 191 and nuts 192. The flange portions 412, 422 and the protruding flange 316 are fastened to each other by the fastening members 191, 192 at multiple locations in the circumferential direction of the housing 4.

[0033] Furthermore, fluid pipes 11 are connected to the connecting portions 413, 423 of the housing 4, respectively. Specifically, an annular pipe flange 113 that protrudes outward is formed at the end of the fluid pipe 11. The pipe flange 113 and the connecting portions 413, 423 of the housing 4 are fastened and fixed to each other in the arrangement direction Z by bolts (not shown).

[0034] Furthermore, a first fluid communication hole 402 is formed in the connecting portion 413 of the first accommodating portion 41, penetrating in the arrangement direction Z and connecting the accommodating space 40 to the inside of the fluid pipe 11. With the first fluid communication hole 402 formed in the housing 4, sound waves can propagate between the accommodating space 40 and the fluid pipe 11 fixed to the connecting portion 413 via the working fluid. Furthermore, a second fluid communication hole 404 is formed in the connecting portion 423 of the second accommodating portion 42, and is configured to propagate between the accommodating space 40 and the fluid pipe 11 fixed to the connecting portion 423 via the working fluid. The second fluid communication hole 404 penetrates the connecting portion 423 of the second accommodating portion 42 in the arrangement direction Z and connecting the accommodating space 40 to the inside of the fluid pipe 11.

[0035] Next, the hydraulic diameter D of the pores 20 of the heat accumulator 2 h The relationship between the hydraulic diameter D of the pores 20 of the heat accumulator 2 and the hydraulic diameter D of the fluid flow paths 310, 320 of the heat exchangers 31, 32 will be described. h The ratio of the hydraulic diameter D of the fluid flow paths 310, 320 in at least one of the high-temperature side heat exchanger 31 and the low-temperature side heat exchanger 32 to the hydraulic diameter D is 30 or less. h The hydraulic diameter D of the fluid flow path 310 in the high-temperature side heat exchanger 31 H1 The ratio is 30 or less. h The hydraulic diameter D of the fluid flow passage 320 in the low-temperature side heat exchanger 32 H2 The ratio of hydraulic diameter D is also less than 30. h can be set to, for example, 0.1 to 0.5 mm.

[0036] Also, hydraulic diameter Dh The ratio of the hydraulic diameter of the fluid flow paths 310, 320 in at least one of the high-temperature side heat exchanger 31 and the low-temperature side heat exchanger 32 to the hydraulic diameter D is 1 or more. h Hydraulic diameter D H1 The ratio of the hydraulic diameter D h hydraulic diameter D H2 The ratio of the hydraulic diameter D h hydraulic diameter D H1 The ratio is preferably 2 or more, and the hydraulic diameter D h hydraulic diameter D H2 The ratio is also preferably 2 or more.

[0037] Hydraulic diameter D h The ratio of the hydraulic diameter of the fluid flow paths 310, 320 in at least one of the high-temperature side heat exchanger 31 and the low-temperature side heat exchanger 32 to the hydraulic diameter D is 10 or more. h hydraulic diameter D H1 The ratio is 10 or more. In this embodiment, the hydraulic diameter D h hydraulic diameter D H2 The ratio is also 10 or more.

[0038] Next, the relationship between the aperture ratio R1 of the heat accumulator 2 and the aperture ratios of the heat exchangers 31 and 32 will be described. In this embodiment, the product of the aperture ratio R1 and the aperture ratio R2 is 0.15 or more, and the product of the aperture ratio R1 and the aperture ratio R3 is 0.15 or more. The aperture ratio R1 is the aperture ratio at each end face 21 in the arranging direction Z of the heat accumulator 2, and the aperture ratio R2 is the aperture ratio at each end face 311 in the arranging direction Z of the high-temperature side heat exchanger 31. The aperture ratio R3 is the aperture ratio at each end face 321 in the arranging direction Z of the low-temperature side heat exchanger 32. Furthermore, the product of the aperture ratio R1 of the heat accumulator 2 and the aperture ratio R2 of the high-temperature side heat exchanger 31 is 0.5 or less, and the product of the aperture ratio R1 of the heat accumulator 2 and the aperture ratio R3 of the low-temperature side heat exchanger 32 is 0.5 or less. Furthermore, it is preferable that the product of the aperture ratio R1 and the aperture ratio R2, and the product of the aperture ratio R1 and the aperture ratio R3 are each 0.3 to 0.4.

[0039] The aperture ratio R1 means the aperture ratio of the region of the end surface 21 of the heat accumulator 2 that overlaps with the heat exchangers 31, 32 when viewed from the arrangement direction Z. More specifically, when calculating the product of the aperture ratio R1 and the aperture ratio R2, the aperture ratio R1 means the aperture ratio of the heat storage high temperature side region, which is the region of the end surface 21 of the heat accumulator 2 that overlaps with the high temperature side heat exchanger 31 when viewed from the arrangement direction Z. Furthermore, when calculating the product of the aperture ratio R1 and the aperture ratio R3, the aperture ratio R1 means the aperture ratio of the heat storage low temperature side region, which is the region of the end surface 21 of the heat accumulator 2 that overlaps with the low temperature side heat exchanger 32 when viewed from the arrangement direction Z. Furthermore, the aperture ratio R2 means the aperture ratio of the high temperature overlap region, which is the region of the end surface 311 of the high temperature side heat exchanger 31 that overlaps with the heat accumulator 2 when viewed from the arrangement direction Z. Moreover, the opening ratio R3 means the opening ratio of the low-temperature overlapping region, which is the region that overlaps with the heat accumulator 2, on the end face 321 of the low-temperature side heat exchanger 32 when viewed from the arrangement direction Z.

[0040] Furthermore, the opening ratio R1 is the ratio of the total opening area of all the openings 201 to the area obtained by adding the area of the end face 21 in the heat storage high temperature side region or the heat storage low temperature side region to the total opening area of all the openings 201 (see FIG. 10) of the pores 20 that open to the end face 21. For example, when the area of the end face 21 and the total opening area of all the openings 201 are the same in the heat storage high temperature side region or the heat storage low temperature side region, the opening ratio R1 is 0.5. The area of the end face 21 is the area of the end face 21 of the cell wall portion 24 plus the area of the heat transfer surface 211, and means the area excluding the area of the end face in the arrangement direction Z of the skin portion 23 (see FIG. 9) and the area of the openings 201.

[0041] The opening ratio R2 is the ratio of the total opening area of all openings 300 to the area obtained by adding the area of end face 311 in the high-temperature overlap region to the total opening area of all openings 300 (see FIG. 5) of fluid flow channels 310 that open to end face 311. For example, when the area of end face 311 and the total opening area of all openings 300 in the high-temperature overlap region are the same, the opening ratio R2 is 0.5. Note that the area of end face 311 does not include the area of openings 300.

[0042] The opening ratio R3 is the ratio of the total opening area of all the openings 301 to the area obtained by adding the area of the end face 321 in the low-temperature overlap region to the total opening area of all the openings 301 (see FIG. 8) of the fluid flow channels 320 that open to the end face 321. Note that the area of the end face 321 does not include the area of the openings 301.

[0043] For example, if the aperture ratio R1 is 0.5 and the aperture ratio R2 is 0.5, the product of the aperture ratios R1 and R2 is 0.25. Also, for example, if the aperture ratio R1 is 0.4 and the aperture ratio R3 is 0.5, the product of the aperture ratios R1 and R3 is 0.2. The aperture ratios R1, R2, and R3 can be the same value or different values.

[0044] Next, the effects of this embodiment will be described. In the thermoacoustic device 1, at least one of the high-temperature side heat exchanger 31 and the low-temperature side heat exchanger 32 has a ratio of the length of the fluid flow paths 310, 320 to the hydraulic diameter of the fluid flow paths 310, 320 of 5 or more. Therefore, in the sound waves propagating from the fluid flow paths 310, 320 of at least one of the high-temperature side heat exchanger 31 and the low-temperature side heat exchanger 32 to the pores 20 of the heat accumulator 2, the vibration velocity of the molecules of the working fluid (hereinafter referred to as fluid vibration velocity) and phase shift can be suppressed. Therefore, the phase shift of the sound waves output from the heat accumulator 2 can be suppressed. As a result, the conversion between heat and sound waves can be performed efficiently. Note that the above "molecules of the working fluid" also includes monatomic molecules that constitute the working fluid.

[0045] Generally, when sound waves propagate from a fluid pipe with a relatively large opening area to a fluid flow path in a heat exchanger with a relatively small opening area, the working fluid transmitting the sound waves may be disturbed by colliding with a flow path forming portion or the like. This can result in variations in the fluid vibration velocity and phase of the sound waves propagating through each fluid flow path in the heat exchanger. That is, for example, in sound waves propagating from a fluid pipe to a fluid flow path, variations in the fluid vibration velocity and phase may occur between sound waves that collide with a flow path forming portion or the like and sound waves that propagate without colliding with a flow path forming portion or the like. Here, assume that the ratio of the length of the fluid flow path to the hydraulic diameter of the fluid flow path in a heat exchanger is too low. In this case, if sound waves with a shifted fluid vibration velocity or phase propagate through the fluid flow path of the heat exchanger, the sound waves may not be sufficiently rectified in the fluid flow path of the heat exchanger, and sound waves with a shifted fluid vibration velocity or phase may propagate to the heat storage unit. This may cause the fluid vibration velocity and phase of the sound waves amplified by the heat accumulator to shift, and when sound waves from each pore of the heat accumulator converge, sound waves with different phases may cancel each other out. As a result, the thermal-acoustic conversion efficiency, which is the conversion efficiency between heat and sound waves, may not be sufficiently ensured. Therefore, in this embodiment, the ratio of the length of the fluid flow paths 310, 320 to the hydraulic diameter of at least one of the high-temperature side heat exchanger 31 and the low-temperature side heat exchanger 32 is set to 5 or more. As a result, even if sound waves with different fluid vibration velocity or phases propagate through the fluid flow paths 310, 320 of the heat exchangers 31, 32, the sufficient length of the fluid flow paths 310, 320 ensures that the sound waves are easily rectified as they propagate through the fluid flow paths 310, 320 of the heat exchangers 31, 32. Therefore, rectified sound waves with stable fluid vibration velocity and phase can be propagated to the heat accumulator 2. Therefore, it is possible to suppress the phase shift between the sound waves coming out of each pore 20 of the heat accumulator 2, and it is possible to improve the energy of the sound waves when the sound waves coming out of the heat accumulator 2 join together. As a result, it is possible to improve the heat-sound conversion efficiency.

[0046] Furthermore, in this embodiment, in both the high-temperature side heat exchanger 31 and the low-temperature side heat exchanger 32, the ratio of the length of the fluid flow paths 310, 320 to the hydraulic diameter of the fluid flow paths 310, 320 is 5 or more. Therefore, it is possible to sufficiently rectify both the sound waves propagating to the fluid flow path 310 of the high-temperature side heat exchanger 31 and the sound waves propagating to the fluid flow path 320 of the low-temperature side heat exchanger 32. Therefore, it is possible to suppress the fluid vibration velocity and phase shift in both the sound waves propagating from the fluid flow path 310 of the high-temperature side heat exchanger 31 to the pores 20 of the heat accumulator 2 and the sound waves propagating from the fluid flow path 320 of the low-temperature side heat exchanger 32 to the pores 20 of the heat accumulator 2. Therefore, it is possible to further suppress the phase shift between the sound waves output from each pore 20 of the heat accumulator 2, and to further improve the heat-to-sound conversion efficiency.

[0047] Furthermore, it is preferable that the ratio of the length of the fluid flow paths 310, 320 to the hydraulic diameter of the fluid flow paths 310, 320 of the heat exchangers 31, 32 is equal to or greater than 6. In this case, the fluid vibration velocity and phase shift of the sound waves propagating from the fluid flow paths 310, 320 of the heat exchangers 31, 32 to the pores 20 of the heat accumulator 2 can be further suppressed.

[0048] Hydraulic diameter D of the pores 20 of the heat accumulator 2 h The ratio of the hydraulic diameter of the fluid flow paths 310, 320 in at least one of the high-temperature side heat exchanger 31 and the low-temperature side heat exchanger 32 to the hydraulic diameter D is 30 or less. Therefore, it is possible to suppress temperature variations in the fluid flow paths 310, 320. As a result, heat can be transferred relatively evenly between the heat exchangers 31, 32 and the heat accumulator 2. Therefore, it is possible to suppress temperature variations at the ends of the heat accumulator 2 on the heat exchanger 31, 32 side. As a result, it is possible to suppress the occurrence of phase shifts of sound waves in the heat accumulator 2. In other words, when heat is converted into sound waves in the heat accumulator 2, the phase of the sound waves propagating through the pores 20 changes. The amount of change in the phase of the sound waves changes depending on the amount of heat when heat is converted into sound waves in the heat accumulator 2, i.e., the temperature of the heat accumulator 2. Therefore, in this embodiment, the hydraulic diameter D hThe ratio of the hydraulic diameter of the fluid flow paths 310, 320 in at least one of the high-temperature side heat exchanger 31 and the low-temperature side heat exchanger 32 to the hydraulic diameter is set to 30 or less. Therefore, as described above, heat can be transferred relatively evenly between the heat exchangers 31, 32 and the heat accumulator 2. As a result, the occurrence of phase shift of sound waves in the heat accumulator 2 can be suppressed. Furthermore, the speed and phase shift of sound waves propagating through the fluid flow paths 310, 320 can also be suppressed. That is, the speed of sound waves varies depending on the temperature of the working fluid. Therefore, if there is a temperature variation in each fluid flow path in the heat exchanger, phase shift may occur between sound waves passing through the fluid flow paths. Specifically, if the hydraulic diameter of the fluid flow path is too large, a temperature difference may occur in each fluid flow path, for example, between the temperature of the working fluid near the flow path forming portion and the temperature of the working fluid near the center of the flow path forming portion. This may cause a difference in speed between the sound waves propagating through the working fluid with a relatively high temperature and the sound waves propagating through the working fluid with a relatively low temperature. h By setting the ratio of the hydraulic diameter of the fluid flow paths 310, 320 to the diameter of the fluid flow paths 310, 320 to 30 or less, the hydraulic diameters of the fluid flow paths 310, 320 are prevented from becoming too large. This makes it easy to maintain a relatively uniform temperature of the working fluid in each of the fluid flow paths 310, 320. Therefore, it is easy to maintain a relatively uniform speed of sound waves propagating through the fluid flow paths 310, 320. Furthermore, as described above, it is easy to maintain a uniform amount of heat when heat is converted to sound waves in the heat accumulator 2. This further reduces the deviation in speed and phase of sound waves propagating from the heat exchangers 31, 32 to the heat accumulator 2 and the deviation in speed and phase of sound waves propagating from the heat exchangers 31, 32 to the fluid piping 11. As a result, the heat-to-sound conversion efficiency can be further improved.

[0049] Hydraulic diameter D hThe ratio of the hydraulic diameter of the fluid flow paths 310, 320 in at least one of the high-temperature side heat exchanger 31 and the low-temperature side heat exchanger 32 to the hydraulic diameter D is 1 or more. Therefore, the attenuation of sound waves can be suppressed in the heat exchangers 31, 32. In other words, in general, to improve the heat exchange performance of a heat exchanger, it is preferable that the hydraulic diameter of the fluid flow path is small. However, if the hydraulic diameter of the fluid flow path is too small, attenuation of sound waves is likely to occur due to the viscosity of the working fluid when the sound waves propagate within the fluid flow path. Therefore, in this embodiment, the hydraulic diameter D h The ratio of the hydraulic diameter of the fluid flow paths 310, 320 in at least one of the high-temperature side heat exchanger 31 and the low-temperature side heat exchanger 32 to the hydraulic diameter is set to be 1 or more. This makes it possible to suppress the attenuation of sound waves caused by the viscosity of the working fluid. As a result, it is possible to ensure sufficient thermal sound conversion efficiency.

[0050] Hydraulic diameter D h The ratio of the hydraulic diameter of the fluid flow passages 310, 320 in at least one of the high-temperature side heat exchanger 31 and the low-temperature side heat exchanger 32 to the hydraulic diameter D is 10 or more. h The hydraulic diameter of the fluid flow paths 310, 320 can be made sufficiently large with respect to the above. Therefore, it is possible to suppress unintended conversion between heat and sound waves in the fluid flow paths 310, 320. In other words, in order to efficiently perform the thermal acoustic conversion, which is the conversion between heat and sound waves in the heat accumulator 2, the hydraulic diameter D hIt is important to propagate sound waves tuned to the heat accumulator 2 in accordance with the frequency and other conditions required for efficient thermal acoustic conversion in the heat accumulator. However, if sound waves with the conditions, such as frequency, required for efficient thermal acoustic conversion in the heat accumulator are also likely to be converted into thermal acoustics in the fluid flow path of the heat exchanger, the conditions of the sound waves propagating to the heat accumulator may deviate from the desired conditions. As a result, efficient thermal acoustic conversion may not be possible in the heat accumulator 2. Furthermore, it is possible to design the hydraulic diameter of the fluid flow path on the assumption that thermal acoustic conversion will occur in the heat exchanger, but if the temperature or flow rate of the heat medium introduced into the heat exchanger changes, there is a risk that the intended thermal acoustic conversion may not be sufficient in the fluid flow path. In other words, the amount of thermal acoustic conversion in the heat exchanger is likely to change depending on changes in conditions such as the temperature and flow rate of the heat medium introduced into the heat exchanger, making adjustment difficult. Therefore, in this embodiment, the hydraulic diameter D h The ratio of the hydraulic diameter of the fluid flow paths 310, 320 in at least one of the high-temperature side heat exchanger 31 and the low-temperature side heat exchanger 32 to the hydraulic diameter D is set to 10 or more. h The hydraulic diameter of the fluid flow paths 310 and 320 is set to be 10 times or more larger than that of the pore 20. h This can sufficiently prevent sound waves tuned to the desired conditions from being converted into heat sound in the fluid flow paths 310, 320. Therefore, sound waves of desired conditions can be propagated from the heat exchangers 31, 32 to the heat accumulator 2. As a result, the heat sound conversion efficiency can be further improved. In addition, sound waves that meet the conditions for efficient use in the generator 13 can be output from the heat sound conversion unit 12 to the generator 13, thereby improving the power generation efficiency.

[0051] The product of the opening ratio R1 of the heat accumulator 2 and the opening ratio R2 of the high-temperature side heat exchanger 31 is 0.15 or more, and the product of the opening ratio R1 and the opening ratio R3 of the low-temperature side heat exchanger 32 is 0.15 or more. Therefore, it is possible to ensure a sufficient number of pores 20 in the heat accumulator 2 while ensuring a large hydraulic diameter in the fluid flow paths 310, 320. Therefore, it is possible to suppress attenuation of sound waves caused by the viscosity of the working fluid in the fluid flow paths 310, 320 while ensuring a sufficient amount of thermal acoustic conversion in the heat accumulator 2. As a result, it is possible to further improve the thermal acoustic conversion efficiency.

[0052] The product of the opening ratio R1 and the opening ratio R2 is 0.5 or less, and the product of the opening ratio R1 and the opening ratio R3 is 0.5 or less. Therefore, the area of the end face 21 of the heat accumulator 2 and the area of the end faces 311 and 321 of the heat exchangers 31 and 32 can be sufficiently secured. Therefore, the area where the end faces 21 and 311 and 321 are in pressure contact with each other can be sufficiently secured, thereby reducing the thermal resistance between the heat accumulator 2 and the heat exchangers 31 and 32. Therefore, the amount of heat transfer between the heat exchangers 31 and 32 and the heat accumulator 2 can be sufficiently secured, and a sufficient temperature difference between both ends of the heat accumulator 2 can be created. As a result, the thermal-acoustic conversion efficiency can be sufficiently improved. Furthermore, the surface areas of the heat exchangers 31 and 32 and the heat accumulator 2 that exchange heat with the working fluid can be increased. Therefore, the temperatures of the working fluid in the fluid flow paths 310 and 320 and the working fluid in the pores 20 can be easily uniformed. Therefore, it is easy to make the speed of the sound waves propagating through the fluid flow paths 310, 320 relatively uniform, and further it is easy to make the amount of heat when heat is converted into sound waves uniform within the heat accumulator 2. As a result, it is possible to further suppress deviations in the speed and phase of the sound waves.

[0053] As described above, according to this embodiment, it is possible to provide a thermoacoustic device 1 that can efficiently convert between heat and sound waves.

[0054] In the first embodiment described above, sound waves are amplified by the heat accumulator 2. However, for example, a configuration can be adopted in which sound waves from a sound wave generator (not shown) are propagated to the heat accumulator to generate a temperature difference between both ends of the heat accumulator. In other words, a configuration can be adopted in which the temperature difference formed in the heat accumulator is utilized to cool an object to be cooled via a heat exchanger. Even in this case, sound waves with a uniform fluid vibration velocity and phase can be propagated to the heat accumulator due to the rectification effect of sound waves in the fluid flow path of the heat exchanger, and efficient thermal sound conversion can be achieved. Therefore, a temperature difference can be efficiently created in the heat accumulator.

[0055] In the first embodiment, the flange portions 412, 422 and the fixing portion 314 are fastened and fixed to each other by fastening members 191, 192. However, the flange portions and the fixing flange portion can also be fixed to each other by welding, for example.

[0056] (Experimental Example 1) In this example, as shown in FIG. 11, in a thermoacoustic device having the same basic structure as in the first embodiment, the hydraulic diameter D H1 The length of the fluid flow path L H1 The ratio of (hereinafter referred to as "L H1 / D H1 "), and the hydraulic diameter D of the fluid flow path of the low-temperature heat exchanger H2 The length of the fluid flow path L H2 The ratio of (hereinafter referred to as "L H2 / D H2 The heat-sound conversion efficiency was calculated by thermal fluid analysis while changing the value of "L H1 / D H1 " and "L H2 / D H2 The relationship between the variation in the fluid vibration velocity of the sound waves propagating from the fluid flow path of the heat exchanger to the pores of the heat storage device and the thermal acoustic conversion efficiency was analyzed by changing the value of "L H1 / D H1 " value and "L H2 / D H2 The analysis was performed assuming that the values of " and " were the same.

[0057] As shown in Figure 11, H1 / D H1 " and "L H2 / D H2 The larger the value of ", the smaller the variation in the fluid vibration velocity of the sound waves propagating from the fluid flow path of the heat exchanger to the pores of the heat accumulator, and the higher the thermal acoustic conversion efficiency. H1 / D H1 " and "L H2 / D H2 If the value of " is 5 or more, "L H1 / D H1 " and "L H2 / D H2 The heat-sound conversion efficiency is significantly higher than when the value of "L" is lower than 5. H1 / D H1 " and "L H2 / D H2 When the value of "L" is 6 or more, the heat-sound conversion efficiency is even higher. H1 / D H1 " and "L H2 / D H2 By setting the value of "L" to 5 or more, it is thought that the length of the fluid flow path is sufficiently secured, and the sound waves are rectified when they propagate through the fluid flow path of the heat exchanger. Therefore, it is thought that rectified sound waves with stable fluid vibration velocity and phase can be propagated from the fluid flow path to the heat accumulator, improving the thermal sound conversion efficiency. Therefore, it is thought that "L" H1 / D H1 " value and "L H2 / D H2 The thermoacoustic device of embodiment 1, in which at least one of the values of " is 5 or greater, can suppress the variation in the fluid vibration velocity and phase shift of the sound waves propagating from the fluid flow path of the heat exchanger to the pores of the heat accumulator, and can be said to be able to improve the thermal acoustic conversion efficiency.

[0058] (Experimental Example 2) In this example, as shown in FIG. 12, in a thermoacoustic device having the same basic structure as in the first embodiment, the hydraulic diameter D h While changing the hydraulic diameter D hThe relationship between the hydraulic diameter D and the heat-sound conversion efficiency was obtained by thermal fluid analysis. In this example, the hydraulic diameter D h The relationship between the heat-sound conversion efficiency and the heat-sound conversion efficiency was analyzed.

[0059] As shown in Figure 12, the hydraulic diameter D h When the hydraulic diameter D is between 0.35 and 0.45 mm, the thermal acoustic conversion efficiency is relatively high for sound waves with frequencies of 60 Hz, 90 Hz, and 120 Hz. h When the hydraulic diameter D is 0.8 mm or more, sound waves with frequencies of 90 Hz, 120 Hz, and 150 Hz are hardly converted into heat or sound. h As the hydraulic diameter D increases from 0.6 mm, the thermoacoustic conversion efficiency decreases. h The ratio of the hydraulic diameter of the fluid flow path in at least one of the high-temperature side heat exchanger and the low-temperature side heat exchanger to the hydraulic diameter is 10 or more. That is, in the thermoacoustic device of the first embodiment, the hydraulic diameter of the heat exchanger is large enough to make it difficult to convert sound waves of the frequency shown in FIG. 12 into thermoacoustic waves. As a result, as will be described in Experimental Example 5 below, it is thought that thermoacoustic conversion can be suppressed in the fluid flow path of the heat exchanger, and deviations in the conditions for sound waves propagating to the heat accumulator can be suppressed. Therefore, it can be said that the thermoacoustic device of the first embodiment can improve thermoacoustic conversion efficiency.

[0060] (Experimental Example 3) In this example, in a thermoacoustic device having the same basic structure as in the first embodiment, the hydraulic diameter D h hydraulic diameter D H1 The ratio of (hereinafter referred to as "D H1 / D h ") and hydraulic diameter D h hydraulic diameter D H2 The ratio of (hereinafter referred to as "D H2 / D h The heat-sound conversion efficiency was calculated by thermo-fluid analysis while changing the hydraulic diameter D his set as a constant value, and the hydraulic diameter D H1 and hydraulic diameter D H2 While changing the value of "D H1 / D h " and "D H2 / D h The relationship between the value of " and the thermal acoustic conversion efficiency was analyzed. H1 / D h " value and "D H2 / D h The analysis was performed assuming that the values of " and " were the same.

[0061] As shown in Figure 13, "D H1 / D h " and "D H2 / D h It can be seen that the smaller the value of "D", the higher the thermal acoustic conversion efficiency. H1 / D h " and "D H2 / D h " becomes smaller, that is, the hydraulic diameter of the fluid flow path of the heat exchanger becomes smaller, it is thought that it is easier to make the temperature of the working fluid in each fluid flow path of the heat exchanger relatively uniform. Therefore, it is thought that it is possible to transfer heat relatively uniformly between the heat exchanger and the heat accumulator, and it is easier to make the amount of heat when heat is converted into sound waves in each pore of the heat accumulator uniform. Therefore, it is thought that it is possible to suppress the occurrence of phase shift of sound waves in the heat accumulator. Therefore, in this example, "D H1 / D h " and "D H2 / D h It is considered that the smaller the value of ", the higher the thermal acoustic conversion efficiency. Also, the speed of sound waves varies depending on the temperature of the working fluid. Therefore, if the temperature of the working fluid is made uniform in each fluid flow path of the heat exchanger, the speed of sound waves propagating through the fluid flow path of the heat exchanger will be relatively uniform compared to when the temperature of the working fluid varies within the fluid flow path. This is considered to be able to suppress the deviation in speed and phase of sound waves propagating from the heat exchanger to the heat accumulator. Therefore, in this example, "D H1 / D h " and "D H2 / D h It is considered that the smaller the value of "D" is, the higher the thermal acoustic conversion efficiency is. In particular, looking at the graph in Figure 13, the thermal acoustic conversion efficiency is H1 / D h " and "D H2 / D h The value of "D" changes significantly at the boundary of 30. H1 / D h " and "D H2 / D h The thermoacoustic device of embodiment 1, in which the value of " is 30 or less, can sufficiently suppress the velocity and phase shift of the sound waves, and can further improve the thermoacoustic conversion efficiency.

[0062] (Experimental Example 4) In this example, as shown in FIG. 14, in a thermoacoustic device having the same basic structure as in the first embodiment, H1 / D h " and "D H2 / D h The ratio of the viscous loss of the heat exchanger to the viscous loss of the heat accumulator was calculated by thermal fluid analysis while changing the value of "D H1 / D h " and "D H2 / D h The relationship between the value of " and the ratio of the amount of attenuation of sound waves caused by the viscosity of the working fluid in the pores of the heat accumulator to the amount of attenuation of sound waves caused by the viscosity of the working fluid in the fluid flow path of the heat exchanger (hereinafter referred to as the viscous loss ratio) was analyzed. In this example, the hydraulic diameter D of the pores of the heat accumulator h is set as a constant value, and the hydraulic diameter D H1 and hydraulic diameter D H2 While changing the value of "D H1 / D h " and "D H2 / D h The relationship between the value of " and the viscous loss ratio was analyzed. H1 / D h " value and "D H2 / D h The analysis was performed assuming that the values of " and " were the same.

[0063] As shown in Figure 14, "D H1 / D h " and "D H2 / D h When the value of " is 1 or more, "D H1 / D h " and "D H2 / D h It can be seen that the value of the viscous loss ratio is significantly lower than when the value of "D" is smaller than 1. H1 / D h " and "D H2 / D h When the value of "D" is 2 or more, the value of the viscous loss ratio is lower. H1 / D h " and "D H2 / D h When the value of "D" is set to 1 or more, the value of the viscous loss ratio is 1 or less, so it is thought that the attenuation of sound waves in the heat exchanger can be prevented from becoming greater than the attenuation of sound waves in the heat accumulator. H1 / D h " and "D H2 / D h The thermoacoustic device of the first embodiment, in which the value of "D" is 1 or more, can sufficiently reduce the amount of attenuation of sound waves in the fluid flow path of the heat exchanger, and can improve the thermoacoustic conversion efficiency. H1 / D h " and "D H2 / D h When the value of " is set to 2 or more, the viscous loss ratio approaches 0, which suggests that the attenuation of sound waves in the fluid flow path of the heat exchanger can be significantly reduced.

[0064] (Experimental Example 5) In this example, as shown in FIG. 15, in a thermoacoustic device having the same basic structure as in the first embodiment, H1 / D h " and "D H2 / D h While changing the value of "D H1 / D h " and "D H2 / D h The relationship between the value of " and the heat-sound conversion efficiency was obtained by thermal fluid analysis. In this example, the hydraulic diameter Dh is set as a constant value, and the hydraulic diameter D H1 and hydraulic diameter D H2 While changing the value of "D H1 / D h " and "D H2 / D h The relationship between the value of " and the thermal acoustic conversion efficiency was analyzed. H1 / D h " value and "D H2 / D h The analysis was performed assuming that the values of " and " were the same.

[0065] As shown in Figure 15, "D H1 / D h " and "D H2 / D h " is 10 or more and 30 or less, "D H1 / D h " and "D H2 / D h It can be seen that the heat-sound conversion efficiency is higher than when the value of "D" is less than 10 or greater than 30. This is because, as explained in Experimental Example 2, H1 / D h " and "D H2 / D h It is believed that by setting the value of "D" to 10 or more, it was possible to suppress the occurrence of thermoacoustic conversion in the fluid flow path of the heat exchanger. Also, as explained in Experimental Example 3, H1 / D h " and "D H2 / D h By setting the value of "D" to 30 or less, it is possible to make the temperature of the working fluid in the fluid flow path of the heat exchanger relatively uniform, and it is thought that this has made it possible to suppress the speed and phase shift of the sound waves. H1 / D h " and "D H2 / D h It can be said that the thermoacoustic device of embodiment 1, in which the value of "Ratio of Heat Transfer Rate" is 10 or more and 30 or less, can improve the thermoacoustic conversion efficiency.

[0066] (Experimental Example 6) In this example, in a thermoacoustic device having the same basic structure as in embodiment 1, the thermoacoustic conversion efficiency was determined by thermal fluid analysis while changing the product of the opening ratio R1 of the heat accumulator and the opening ratio R2 of the high-temperature side heat exchanger (hereinafter referred to as "R1 x R2") and the product of the opening ratio R1 of the heat accumulator and the opening ratio R3 of the low-temperature side heat exchanger (hereinafter referred to as "R1 x R3"). In this example, the analysis was performed with the values of "R1 x R2" and "R1 x R3" set to the same value.

[0067] As shown in Figure 16, when the values of "R1 × R2" and "R1 × R3" are 0.15 or greater and 0.5 or less, respectively, the thermal-acoustic conversion efficiency is higher than when the values of "R1 × R2" and "R1 × R3" are less than 0.15 and greater than 0.5, respectively. This is thought to be because, by setting the values of "R1 × R2" and "R1 × R3" to 0.15 or greater, it is possible to ensure a sufficient number of pores in the heat accumulator and also to ensure a large hydraulic diameter in the fluid flow path of the heat exchanger. In other words, it is thought that the thermal-acoustic conversion efficiency can be improved by suppressing the attenuation of sound waves due to the viscosity of the working fluid in the fluid flow path of the heat exchanger while ensuring a sufficient thermal-acoustic conversion capacity in the heat accumulator. Furthermore, by setting the values of "R1 × R2" and "R1 × R3" to 0.5 or less, the area of the end face of the heat accumulator and the area of the end face of the heat exchanger can be sufficiently secured, thereby reducing the thermal resistance between the heat accumulator and the heat exchanger. In other words, a sufficient temperature difference can be achieved between the two ends of the heat accumulator, thereby improving the thermal-acoustic conversion efficiency. Furthermore, the surface area of the heat exchanger and the heat accumulator that exchange heat with the working fluid can be increased, thereby uniforming the temperature of the working fluid in the fluid flow path and the working fluid in the pores. Therefore, the speed of sound waves propagating through the fluid flow path becomes relatively uniform, and the amount of heat generated when heat is converted into sound waves in the heat accumulator is also relatively uniform. As a result, the thermal-acoustic conversion efficiency can be improved. Therefore, the thermoacoustic device of embodiment 1, in which the values of "R1 × R2" and "R1 × R3" are 0.15 or more and 0.5 or less, respectively, can be said to have improved thermal-acoustic conversion efficiency.

[0068] (Embodiment 2) In this embodiment, as shown in FIG. 17, both the thermoacoustic converting section 12 and the generator 13 are provided in the annular pipe 111 of the fluid pipe 11.

[0069] In this embodiment, the generator 13 is provided in the vicinity of the thermoacoustic converter 12 in the annular piping 111, as shown in Fig. 17. The distance from the generator 13 to the high-temperature side heat exchanger 31 is shorter than the distance from the generator 13 to the low-temperature side heat exchanger 32. Other configurations and effects are the same as those of embodiment 1. Note that, among the symbols used in embodiment 2 and onwards, the same symbols as those used in the previous embodiments represent the same components, etc. as those in the previous embodiments, unless otherwise specified.

[0070] (Embodiment 3) In this embodiment, as shown in FIG. 18, two thermoacoustic converters 12 and two generators 13 are provided in an annular pipe 111.

[0071] In this embodiment, the two thermoacoustic converting units 12 are provided at positions spaced apart from each other in the annular piping 111. A generator 13 is provided near each of the two thermoacoustic converting units 12. In this embodiment, sound waves amplified in one thermoacoustic converting unit 12 are propagated to the generator 13 provided near that thermoacoustic converting unit 12 to generate power, and the sound waves that have passed through the generator 13 are propagated to the other thermoacoustic converting unit 12. Then, after the sound waves are amplified again by the other thermoacoustic converting unit 12, the sound waves are propagated to the generator provided near the other thermoacoustic converting unit 12 and are used to generate power. The rest is the same as in the second embodiment.

[0072] In this embodiment, two thermoacoustic converters 12 and two generators 13 are provided in the annular piping 111. This makes it possible to further improve the power generation efficiency. In addition, the same effects as those of the second embodiment are achieved.

[0073] In the third embodiment, two thermoacoustic converters 12 and two generators 13 are provided in the annular piping 111. However, three or more thermoacoustic converters and generators may be provided in the annular piping. In this case, the power generation efficiency can be further improved.

[0074] The present invention is not limited to the above-described embodiments, and can be applied to various embodiments within the scope of the present invention.

[0075] <Other> The features of the present invention are as follows. [Section 1] A thermoacoustic device (1) that converts between heat and sound waves using the thermoacoustic phenomenon, The device comprises a fluid pipe (11) filled with a working fluid, and a thermoacoustic converter (12) provided in the fluid pipe, The thermoacoustic converter is a heat accumulator (2) having a large number of pores (20) into which the working fluid is introduced; a high-temperature side heat exchanger (31) disposed at one end of the heat accumulator and having a number of fluid flow paths (310) into which the working fluid is introduced; a low-temperature side heat exchanger (32) disposed at the other end of the heat accumulator and having a number of fluid flow paths (320) into which the working fluid is introduced; a housing (4) that houses the heat accumulator, the high-temperature side heat exchanger, and the low-temperature side heat exchanger therein and is connected to the fluid piping; the heat accumulator is sandwiched between the high-temperature side heat exchanger and the low-temperature side heat exchanger in an arrangement direction (Z) of the low-temperature side heat exchanger, the heat accumulator, and the high-temperature side heat exchanger, A thermoacoustic device, wherein at least one of the high-temperature side heat exchanger and the low-temperature side heat exchanger has a ratio of the length of the fluid flow path to the hydraulic diameter of the fluid flow path of 5 or more. [Section 2] The hydraulic diameter D of the pores of the heat accumulator hItem 2. The thermoacoustic device according to item 1, wherein the ratio of the hydraulic diameter of the fluid flow path in at least one of the high-temperature side heat exchanger and the low-temperature side heat exchanger to the hydraulic diameter is 30 or less. [Section 3] The hydraulic diameter D of the pores of the heat accumulator h Item 3. The thermoacoustic device according to item 1 or 2, wherein the ratio of the hydraulic diameter of the fluid flow path in at least one of the high-temperature side heat exchanger and the low-temperature side heat exchanger to the hydraulic diameter is 1 or more. [Section 4] The hydraulic diameter D of the pores of the heat accumulator h Item 4. The thermoacoustic device according to item 3, wherein the ratio of the hydraulic diameter of the fluid flow path in at least one of the high-temperature side heat exchanger and the low-temperature side heat exchanger to the hydraulic diameter is 10 or more. [Section 5] 5. The thermoacoustic device according to any one of items 1 to 4, wherein the product of the opening ratio R1 of the heat accumulator at each end face (21) in the arrangement direction and the opening ratio R2 of the high-temperature side heat exchanger at each end face (311) in the arrangement direction is 0.15 or more, and the product of the opening ratio R1 of the heat accumulator at each end face (321) in the arrangement direction of the low-temperature side heat exchanger is 0.15 or more. [Section 6] 6. The thermoacoustic device according to any one of items 1 to 5, wherein the product of the opening ratio R1 of the heat accumulator at each end face (21) in the arrangement direction and the opening ratio R2 of the high-temperature side heat exchanger at each end face (311) in the arrangement direction is 0.5 or less, and the product of the opening ratio R1 of the heat accumulator and the opening ratio R3 of the low-temperature side heat exchanger at each end face (321) in the arrangement direction is 0.5 or less. [Explanation of symbols]

[0076] 1...thermoacoustic device, 2...heat accumulator, 4...housing, 11...fluid piping, 12...thermoacoustic conversion section, 20...pores, 31...high-temperature side heat exchanger, 32...low-temperature side heat exchanger, 310...fluid flow path, 320...fluid flow path, Z...arrangement direction

Claims

1. A thermoacoustic device (1) that converts between heat and sound waves using the thermoacoustic phenomenon, The device comprises a fluid pipe (11) filled with a working fluid, and a thermoacoustic converter (12) provided in the fluid pipe, The thermoacoustic converter is a heat accumulator (2) having a large number of pores (20) into which the working fluid is introduced; a high-temperature side heat exchanger (31) disposed at one end of the heat accumulator and having a number of fluid flow paths (310) into which the working fluid is introduced; a low-temperature side heat exchanger (32) disposed at the other end of the heat accumulator and having a number of fluid flow paths (320) through which the working fluid is introduced; a housing (4) that houses the heat accumulator, the high-temperature side heat exchanger, and the low-temperature side heat exchanger therein and is connected to the fluid piping; the heat accumulator is sandwiched between the high-temperature side heat exchanger and the low-temperature side heat exchanger in an arrangement direction (Z) of the low-temperature side heat exchanger, the heat accumulator, and the high-temperature side heat exchanger, A thermoacoustic device, wherein at least one of the high-temperature side heat exchanger and the low-temperature side heat exchanger has a ratio of the length of the fluid flow path to the hydraulic diameter of the fluid flow path of 5 or more.

2. The hydraulic diameter D of the pores of the heat accumulator ｈ 2. The thermoacoustic device of claim 1, wherein a ratio of a hydraulic diameter of the fluid flow path in at least one of the high-temperature side heat exchanger and the low-temperature side heat exchanger to a hydraulic diameter of the fluid flow path in the high-temperature side heat exchanger is 30 or less.

3. The hydraulic diameter D of the pores of the heat accumulator ｈ The thermoacoustic device according to claim 1 or 2, wherein a ratio of a hydraulic diameter of the fluid flow path in at least one of the high-temperature side heat exchanger and the low-temperature side heat exchanger to a hydraulic diameter of the fluid flow path in the high-temperature side heat exchanger is 1 or greater.

4. The hydraulic diameter D of the pores of the heat accumulator ｈ The thermoacoustic device of claim 3 , wherein a ratio of a hydraulic diameter of the fluid flow path in at least one of the high-temperature side heat exchanger and the low-temperature side heat exchanger to a hydraulic diameter of the fluid flow path in the high-temperature side heat exchanger is 10 or greater.

5. 3. The thermoacoustic device according to claim 1, wherein the product of the opening ratio R1 at each end face (21) of the heat accumulator in the arrangement direction and the opening ratio R2 at each end face (311) of the high-temperature side heat exchanger in the arrangement direction is 0.15 or more, and the product of the opening ratio R1 of the heat accumulator and the opening ratio R3 at each end face (321) of the low-temperature side heat exchanger in the arrangement direction is 0.15 or more.

6. 3. The thermoacoustic device of claim 1, wherein the product of the opening ratio R1 at each end face (21) of the heat accumulator in the arrangement direction and the opening ratio R2 at each end face (311) of the high-temperature side heat exchanger in the arrangement direction is 0.5 or less, and the product of the opening ratio R1 of the heat accumulator and the opening ratio R3 at each end face (321) of the low-temperature side heat exchanger in the arrangement direction is 0.5 or less.

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