Thermoacoustic device and fluid supply method

Abstract

This thermoacoustic device is provided with: an energy converter which is provided with a heat accumulator, a first heat exchanger provided with a first flow path, and a second heat exchanger provided with a second flow path; an accommodation pipe in which the first heat exchanger is accommodated; a connection pipe which is connected to the accommodation pipe; a resin heat insulation member which is interposed between the accommodation pipe and the connection pipe; and a temperature sensor which is attached between the first heat exchanger and the heat insulation member in the accommodation pipe and which detects the temperature of the accommodation pipe; a first transport device which transports a first fluid to the first flow path; and a control unit which controls transport of the first fluid. When the temperature detected by the temperature sensor is equal to or higher than a preset reference temperature, the control unit executes at least one of: a flow rate reduction process that is for controlling the first transport device so as to reduce the flow rate of the first fluid transported to the first flow path; and a transport stop process that is for stopping the transport of the first fluid to the first flow path.

Description

Thermoacoustic device and fluid supply method

[0001] The technology disclosed in this specification relates to a thermoacoustic device and a method for supplying a fluid to a thermoacoustic device.

[0002] A thermoacoustic engine (thermoacoustic device) includes a pipe filled with a working gas that propagates sound waves and a prime mover (energy converter) incorporated in the pipe. The energy converter includes a heat accumulator and a heater and a cooler (heat exchanger) disposed at both ends of the heat accumulator. Such an energy converter can be used, for example, as a thermoacoustic engine that converts thermal energy into acoustic energy (sound waves) by self-excited oscillation of the working gas due to a temperature gradient generated between both ends of the heat accumulator.

[0003] In general, the greater the temperature gradient between the two ends of the heat accumulator, the higher the efficiency of converting thermal energy into acoustic energy. However, heat transfer between the heat exchanger and the piping can reduce the temperature gradient between the two ends of the heat accumulator, resulting in a decrease in energy conversion efficiency. To solve this problem, a configuration has been proposed in which an insulating member is interposed between two connected piping (see Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2017-3136

[0005] In the above configuration, if the temperature of the pipe becomes close to or higher than the heat resistance temperature of the heat insulating member, there is a concern that the heat insulating member may be damaged by heat.

[0006] This specification discloses a technique that can solve the above-mentioned problems.

[0007] The technology disclosed in this specification can be realized, for example, in the following forms.

[0008] (1) A thermoacoustic device disclosed in this specification includes an energy converter including: a heat accumulator having one surface and another surface and having a plurality of through passages penetrating from the one surface to the other surface; a first heat exchanger disposed opposite the one surface of the heat accumulator and having a first flow path through which a first fluid can flow; and a second heat exchanger disposed opposite the other surface of the heat accumulator and having a second flow path through which a second fluid having a lower temperature than the first fluid can flow; and a piping that accommodates the energy converter and can be filled with a working gas, the piping including an accommodation piping that accommodates the first heat exchanger inside and a connection piping that is connected to the accommodation piping; The system comprises a resin insulating member interposed between a pipe and the connecting pipe, a temperature sensor attached to the containing pipe between the first heat exchanger and the insulating member to detect the temperature of the containing pipe, a first transport device that transports the first fluid to the first flow path, and a control unit that controls the transport of the first fluid, wherein the control unit executes at least one of a flow rate reduction process that controls the first transport device to reduce the flow rate of the first fluid transported to the first flow path when the temperature detected by the temperature sensor is equal to or higher than a predetermined reference temperature, and a transport stop process that stops the transport of the first fluid to the first flow path.

[0009] According to the above configuration, when the temperature detected by the temperature sensor is equal to or higher than the reference temperature, the flow rate of the first fluid is reduced or the supply of the first fluid is stopped, thereby reducing the temperature of the containing pipe, thereby suppressing damage to the insulating member due to heat transmitted from the containing pipe.

[0010] (2) In the thermoacoustic device described in (1) above, the control unit may execute the flow rate reduction process when the temperature detected by the temperature sensor is equal to or higher than the reference temperature, and may execute the transport stop process when the temperature detected by the temperature sensor after executing the flow rate reduction process is equal to or higher than the reference temperature.

[0011] With this configuration, it is possible to prevent the operation of the thermoacoustic device from being stopped as much as possible, while suppressing damage to the heat insulating member.

[0012] (3) In the thermoacoustic device described in (1) or (2) above, the control unit may execute either the flow rate reduction process or the transport stop process when both the first temperature detected by the temperature sensor and the second temperature detected by the temperature sensor a certain time after the first temperature is detected are equal to or higher than the reference temperature.

[0013] For example, if the temperature detected by the temperature sensor temporarily rises due to some unexpected factor, but then immediately drops, it is unlikely that the heat insulating member will be damaged. With the above configuration, in such a case, the flow rate reduction process or transport stop process is not executed, thereby preventing unnecessary output reduction.

[0014] (4) In the thermoacoustic device described in any one of (1) to (3) above, the control unit may execute either the flow rate reduction process or the transport stop process when the temperature sensor detects a temperature equal to or higher than the reference temperature for a certain period of time.

[0015] With this configuration, it is possible to prevent the operation of the thermoacoustic device from being stopped as much as possible, while suppressing damage to the heat insulating member.

[0016] (5) In the thermoacoustic device described in any one of (1) to (4) above, a second transport device may be further provided to transport the second fluid to the second flow path, and the control unit may further perform a flow rate increase process to control the second transport device to increase the flow rate of the second fluid transported to the second flow path when the temperature detected by the temperature sensor is equal to or higher than the reference temperature.

[0017] According to this configuration, by also using a process for increasing the flow rate of the second fluid, it is possible to lower the temperature of the portion of the piping that is close to the second flow path, and to lower the temperature of the heat insulating member through the piping, thereby more effectively suppressing damage to the heat insulating member.

[0018] (6) In the thermoacoustic device described in any one of (1) to (5) above, the connecting pipe includes a first connecting pipe connected to one end of the accommodating pipe and a second connecting pipe connected to the other end of the accommodating pipe, the insulating member includes a first insulating member interposed between the accommodating pipe and the first connecting pipe and a second insulating member interposed between the accommodating pipe and the second connecting pipe, the temperature sensor includes a first temperature sensor attached between the first heat exchanger and the first insulating member and a second temperature sensor attached between the first heat exchanger and the second insulating member, and the control unit may perform at least one of the flow rate reduction process and the transport stop process when the temperature detected by at least one of the first temperature sensor and the second temperature sensor is equal to or higher than the reference temperature.

[0019] According to the above configuration, in the case where heat insulating members are arranged on both ends of the containing pipe, damage to these heat insulating members can be more effectively suppressed.

[0020] (7) A liquid supply method disclosed in the present specification includes an energy converter including: a heat accumulator having one surface and another surface and having a plurality of through passages penetrating from the one surface to the other surface; a first heat exchanger disposed opposite to the one surface of the heat accumulator and having a first flow path through which a first fluid can flow; and a second heat exchanger disposed opposite to the other surface of the heat accumulator and having a second flow path through which a second fluid having a temperature lower than that of the first fluid can flow; and a pipe inside which the energy converter is accommodated and in which a working gas can be sealed, the pipe including an accommodation pipe inside which the first heat exchanger is accommodated, and a connecting pipe connected to the accommodation pipe. A fluid supply method for supplying the first fluid and the second fluid to a thermoacoustic device having a pipe and a resin insulating member interposed between the storage pipe and the connecting pipe, the method comprising: a first determination step for determining whether the temperature of a portion of the storage pipe between the first heat exchanger and the insulating member is equal to or higher than a predetermined reference temperature; and a step for performing at least one of a flow rate reduction process for reducing the flow rate of the first fluid transported to the first flow path and a transport stop process for stopping the transport of the first fluid to the first flow path when it is determined in the first determination step that the temperature is equal to or higher than the reference temperature.

[0021] According to the above configuration, when it is determined that the temperature of the containing pipe is equal to or higher than the reference temperature, the flow rate of the first fluid is reduced or the supply of the first fluid is stopped, thereby reducing the temperature of the containing pipe, thereby suppressing damage to the insulating member due to heat transmitted from the containing pipe.

[0022] (8) In the fluid supply method described in (7) above, the method may include a step of executing the flow rate reduction process when it is determined in the first determination step that the temperature is equal to or higher than the reference temperature; a second determination step of determining whether the temperature of the portion of the containing pipe between the first heat exchanger and the insulating member is equal to or higher than the reference temperature after the flow rate reduction process is executed; and a step of executing the transport stop process when it is determined in the second determination step that the temperature is equal to or higher than the reference temperature.

[0023] With this configuration, it is possible to prevent the operation of the thermoacoustic device from being stopped as much as possible, while suppressing damage to the heat insulating member.

[0024] The technology disclosed in this specification can be realized in various forms, for example, a thermoacoustic device, a method for operating the same, and a method for supplying fluid to a thermoacoustic device.

[0025] 2A and 2B are perspective views of a thermoacoustic device according to a first embodiment, with a portion cut away; FIG. 1B is a cross-sectional view of the thermoacoustic device according to the first embodiment, taken along the line II-II in FIG. 1; FIG. 2C is a partially enlarged cross-sectional view of the inside of a circle R1 in FIG. 2A; FIG. 2D is a partially enlarged cross-sectional view of the inside of a circle R2 in FIG. 2B; FIG. 2E is a schematic diagram showing the configuration of a first heat exchanger according to the first embodiment; FIG. 2F is a schematic diagram showing the configuration of a second heat exchanger according to the first embodiment;

[0026] A. First Embodiment: A first embodiment will be described with reference to Figures 1 to 9. A thermoacoustic device 100A of this embodiment is a cooling device that uses acoustic energy to maintain the temperature of an object at a temperature lower than room temperature.

[0027] 1, 2, and 8, the thermoacoustic device 100A includes a pipe 200, two heat insulating members 350 and 360 disposed along the pipe 200, a prime mover 400 (an example of an energy converter) and a cooler 500 disposed within the pipe 200, a water jacket 600 for cooling the pipe 200, two temperature sensors TS1 and TS2 for measuring the temperature of the pipe 200, two pumps PN1A and PN2A and two inverters In1 and In2 for transporting a heat medium (an example of a first fluid) and a refrigerant (an example of a second fluid) to the prime mover 400, and a control unit 800 for controlling the transport of the heat medium and the refrigerant. The prime mover 400 includes a heat accumulator 410, a first heat exchanger 420 through which the heat medium flows, and a second heat exchanger 430 through which the refrigerant flows. The first pump PN1A and the first inverter In1 constitute the first transport device 700A1, and the second pump PN2A and the second inverter In2 constitute the second transport device 700A2. In Fig. 8, the thick solid lines indicate the piping 200, the thin solid lines indicate the flow of signals between the control unit 800 and the temperature sensors TS1 and TS2, and the transport devices 700A1 and 700A2, the thick dashed dotted lines indicate the flow paths of the heat medium, and the thick dashed two-dotted lines indicate the flow paths of the refrigerant.

[0028] 1 , the piping 200 includes a plurality of main pipes 210, 220, 230, and 240, a plurality of diffusers 250 and 260, a prime mover pipe 270, and a chiller pipe 280. In this embodiment, the main pipes 210, 220, 230, and 240, the diffusers 250 and 260, the prime mover pipe 270, and the chiller pipe 280 are made of metal. A prime mover 400 is housed inside the prime mover pipe 270, and a chiller 500 is housed inside the chiller pipe 280.

[0029] The main pipes 210, 220, 230, 240, the diffusers 250, 260, the motor pipe 270, and the cooling machine pipe 280 form a loop-shaped pipe 290. The pipe 290 can be filled with a working gas. There are no particular restrictions on the working gas as long as it is a gas that can transmit sound waves, and the preferred working gas is helium, argon, or an inert gas such as a mixture of helium and argon, or air.

[0030] The multiple main pipes 210, 220, 230, 240 each have a constant inner diameter and are pipes of the same diameter. The main pipe 210 is a pipe that connects the motor pipe 270 and the diffuser pipe 250. The main pipe 220 is a pipe that connects the two diffuser pipes 250, 260. The main pipe 230 is a pipe that connects the diffuser pipe 260 and the chiller pipe 280. The main pipe 240 is a pipe that connects the chiller pipe 280 and the motor pipe 270.

[0031] As shown in FIG. 1, the two expansion pipes 250 and 260 are pipes that have openings at both ends and have a larger inner diameter in the central portion between the ends than the main pipes 210, 220, 230 and 240.

[0032] As shown in FIG. 2 , the motor piping 270 is composed of a high-temperature piping 271 (an example of a housing piping) that houses the first heat exchanger 420 and a low-temperature piping 275 (a connecting piping, an example of a second connecting piping) that houses the second heat exchanger 430, and the inner diameter of the central portion between both ends is larger overall than that of the main pipes 210, 220, 230, and 240.

[0033] As shown in FIG. 2 , the high-temperature pipe 271 is a pipe having openings at both ends, and includes a small straight pipe section 272 , a tapered section 273 , a large straight pipe section 274 , a small flange 310 , and a large flange 320 .

[0034] The small straight pipe section 272 is a short, straight pipe section disposed at one end 271E1 of the high-temperature pipe 271, and has approximately the same outer and inner diameters as the main pipes 210, 220, 230, and 240. The large straight pipe section 274 is a short, straight pipe section disposed at the other end 271E2 of the high-temperature pipe 271, and has a larger inner diameter than the small straight pipe section 272. The tapered section 273 connects the small straight pipe section 272 and the large straight pipe section 274, and is a tubular section whose diameter decreases from the large straight pipe section 274 toward the small straight pipe section 272.

[0035] As shown in Figures 2 and 3, the small flange 310 is an annular portion extending outward from one end 271E1 of the high-temperature pipe 271. As shown in Figure 3, the small flange 310 has a seal groove 311 and a plurality of bolt insertion holes 312. The seal groove 311 is an annular groove disposed on the surface of the small flange 310 facing away from the small straight pipe section 272. An annular seal ring SR1 is disposed inside the seal groove 311. The seal ring SR1 is made of, for example, rubber. The bolt insertion holes 312 are through holes through which bolts B can be inserted.

[0036] As shown in Figures 2 and 4, the large flange 320 is an annular portion extending outward from the other end 271E2 of the high-temperature pipe 271. As shown in Figure 4, the large flange 320 has a seal groove 321 and a plurality of bolt insertion holes 322. The seal groove 321 is an annular groove disposed on the surface of the large flange 320 facing away from the large straight pipe section 274. An annular seal ring SR2 is disposed inside the seal groove 321. The seal ring SR2 is made of, for example, rubber. The bolt insertion holes 322 are through holes through which bolts B can be inserted.

[0037] Similar to the high-temperature pipe 271, the low-temperature pipe 275 includes a small straight pipe section 276, a tapered section 277, a large straight pipe section 278, a small flange (not shown), and a large flange 340. The large flange 340 has a seal groove 341 and a plurality of bolt insertion holes 342, and a seal ring SR2 is disposed inside the bolt insertion holes 342. Each portion of the low-temperature pipe 275 has the same shape as the corresponding portion of the high-temperature pipe 271.

[0038] The configuration of the chiller piping 280 is similar to that of the motor piping 270, and therefore a description thereof will be omitted.

[0039] Of the multiple main pipes 210, 220, 230, and 240, the first main pipe 210 (connecting pipe, an example of a first connecting pipe) connected to the high-temperature pipe 271 has a main pipe flange 211, as shown in Figures 2 and 3. The main pipe flange 211 is an annular portion extending outward from one end of the first main pipe 210, and has an outer diameter approximately equal to that of the small flange 310.

[0040] As shown in Figure 3, the main pipe flange 211 has a seal groove 212 and a plurality of bolt insertion holes 213. The seal groove 212 is an annular groove disposed on the surface of the main pipe flange 211 facing the high-temperature piping 271. An annular seal ring SR1 is disposed inside the seal groove 212. The bolt insertion holes 213 are through holes through which bolts B can be inserted, and are disposed in positions that align with the bolt insertion holes 312 of the small flange 310.

[0041] (Insulating Members 350, 360) The first insulating member 350 is a member for suppressing heat radiation from the high-temperature pipe 271 to the first main pipe 210, and is annular with a central hole 351, as shown in FIG. 3 . The outer diameter of the first insulating member 350 is equal to or slightly smaller than the outer diameters of the main pipe flange 211 and the small flange 310, and the inner diameter of the first insulating member 350 is approximately equal to the inner diameters of the first main pipe 210 and the small straight pipe section 272. The first insulating member 350 has a plurality of bolt insertion holes 352. The bolt insertion holes 352 are through-holes through which bolts B can be inserted, and are positioned to align with the bolt insertion holes 213, 312 of the main pipe flange 211 and the small flange 310.

[0042] The second insulating member 360 is a member for suppressing heat radiation from the high-temperature pipe 271 to the low-temperature pipe 275, and is annular with a central hole 361, as shown in Figure 4. The outer diameter of the second insulating member 360 is equal to or slightly smaller than the outer diameter of the large flanges 320, 340, and the inner diameter is approximately equal to the inner diameter of the large straight pipe sections 274, 278. The second insulating member 360 has a plurality of bolt insertion holes 362. The bolt insertion holes 362 are through-holes through which bolts B can be inserted, and are positioned to align with the bolt insertion holes 322, 342 of the large flanges 320, 340.

[0043] The first main pipe 210 is connected to one end 271E1 of the high-temperature pipe 271, and a first insulating member 350 is interposed between the high-temperature pipe 271 and the first main pipe 210. As shown in Figure 3, bolts B are inserted into bolt insertion holes 213, 352, 312, and nuts N are screwed onto the tips of the bolts B, thereby fastening the main pipe flange 211, the first insulating member 350, and the small flange 310 together. Seal rings SR1 seal the gaps between the first insulating member 350 and the main pipe flange 211, and the gaps between the first insulating member 350 and the small flange 310, respectively, preventing leakage of the working gas to the outside.

[0044] The low-temperature pipe 275 is connected to the other end 271E2 of the high-temperature pipe 271, and a second insulating member 360 is interposed between the high-temperature pipe 271 and the low-temperature pipe 275. As shown in Fig. 4, bolts B are inserted into the bolt insertion holes 322, 362, 342, and nuts N are screwed onto the tips of the bolts B, thereby fastening the two large flanges 320, 340 and the second insulating member 360 together. Seal rings SR2 seal the gaps between the second insulating member 360 and the two large flanges 320, 340, respectively, to prevent the working gas from leaking to the outside.

[0045] The heat insulating members 350, 360 are made of resin and have a lower thermal conductivity than the motor piping 270 and the first main pipe 210, which are made of metal. A suitable resin for the heat insulating members 350, 360 is, for example, a super engineering plastic that can function for a long period of time in a high-temperature environment of 150°C or higher. Examples of suitable super engineering plastics include PEEK (polyether ether ketone), which has a continuous use temperature (the upper limit temperature at which 50% or more of the strength is maintained after a long period of time (40,000 hours)) of approximately 200-250°C, and PTFE (polytetrafluoroethylene), which has a continuous use temperature of approximately 260°C. Other examples include PAI (polyamideimide), PEI (polyetherimide), PES (polyethersulfone), and PPS (polyphenylene sulfide).

[0046] (Prime mover 400) Prime mover 400 is a device for converting thermal energy into acoustic energy (sound waves), and is disposed inside prime mover piping 270. As shown in Figures 1 and 2, prime mover 400 includes a heat accumulator 410, a first heat exchanger 420, and a second heat exchanger 430. The first heat exchanger 420, the heat accumulator 410, and the second heat exchanger 430 are disposed side by side in this order.

[0047] (First Heat Exchanger 420, Second Heat Exchanger 430) As shown in FIG. 2, the first heat exchanger 420 is disposed inside the high-temperature piping 271. More specifically, the first heat exchanger 420 is disposed inside the large straight pipe section 274 in an orientation perpendicular to the axial direction of the motor piping 270. As shown in FIG. 5, the first heat exchanger 420 may be a known heat exchanger including a first heat transfer tube 421 (an example of a first flow path) and fins (not shown) disposed around the first heat transfer tube 421. A high-temperature heat medium can flow inside the first heat transfer tube 421, and heat exchange occurs between the working gas near the first heat exchanger 420 and the heat medium. For example, heat transfer oil heated by waste heat from a factory may be used as the heat transfer medium. The temperature of the heat transfer oil is, for example, approximately 200-400°C.

[0048] As shown in FIG. 2 , the second heat exchanger 430 is disposed inside the low-temperature pipe 275. More specifically, the second heat exchanger 430 is disposed inside the large straight pipe section 278 in an orientation perpendicular to the axial direction of the motor pipe 270. As shown in FIG. 6 , a known heat exchanger including a second heat transfer tube 431 (an example of a second flow path) and fins (not shown) disposed around the second heat transfer tube 431 can be used as the second heat exchanger 430. A refrigerant having a lower temperature than the heat transfer medium flowing inside the first heat transfer tube 421 can flow inside the second heat transfer tube 431, and the working gas near the second heat exchanger 430 has a temperature lower than that of the heat transfer medium. In this embodiment, room-temperature water is used as the refrigerant supplied to the second heat transfer tube 431.

[0049] (Heat accumulator 410) The heat accumulator 410 has a thick disk shape with one surface 410F1 (the surface on the right side in FIG. 2) and the other surface 410F2 (the surface on the left side in FIG. 2). As shown in FIG. 2, the heat accumulator 410 is disposed between the first heat exchanger 420 and the second heat exchanger 430, with the one surface 410F1 facing the first heat exchanger 420 and the other surface 410F2 facing the second heat exchanger 430.

[0050] As shown in FIG. 7 , the heat storage device 410 includes a stack 412 in which multiple circular metal meshes 411 are stacked in a compressed state, and a fixing member 413 fixed to the outer circumferential surface of the stack 412. The metal mesh 411 is a mesh-like member formed by weaving multiple thin metal wires. The multiple metal meshes 411 have substantially the same outer shape and are stacked with their outer edges aligned. The stack 412 is formed by the interconnection of the meshes (gaps between the thin wires) of the multiple metal meshes 411, and has numerous fine through-holes 414 that penetrate from one surface 410F1 to the other surface 410F2 of the stack 412. The fixing member 413 is fixed to the outer circumferential surface of the stack 412 and serves to keep the outer edges of the multiple metal meshes 411 from separating from each other.

[0051] (Chiller 500) Chiller 500 is a heat pump that generates a temperature gradient by inputting acoustic energy generated by motor 400 and maintains the temperature of an object at a temperature lower than room temperature, and is disposed inside chiller piping 280 as shown in FIG. 1 . Chiller 500 includes a heat accumulator 510 and a first heat exchanger 520 and a second heat exchanger 530 disposed on either side of heat accumulator 510. The heat accumulator 510 and the heat exchangers 520, 530 provided in chiller 500 have the same configurations as the heat accumulator 410 and the heat exchangers 420, 430 provided in motor 400. A medium at a constant temperature (water at room temperature in this embodiment) can flow inside the heat transfer tube provided in first heat exchanger 520, and the working gas near first heat exchanger 520 reaches a temperature approximately at room temperature. The heat transfer tubes provided in the second heat exchanger 530 are connected to a heat exchanger provided in an external cooling facility, and a refrigerant can circulate inside the heat transfer tubes.

[0052] (Water jacket 600) The water jacket 600 is a member disposed on the outer periphery of the first main pipe 210 and for cooling the first main pipe 210. As shown in FIGS. 1 and 2 , the water jacket 600 is an annular member having an inner diameter substantially equal to the outer diameter of the first main pipe 210, and has a flow groove 601. The flow groove 601 is disposed on the inner circumferential surface of the water jacket 600 and allows a refrigerant for cooling the first main pipe 210 to flow therethrough. The water jacket 600 is made of, for example, metal and is joined to the outer circumferential surface of the first main pipe 210 by welding.

[0053] 2, the water jacket 600 is connected to the second heat transfer pipe 431 by a connecting pipe 610. The refrigerant that has passed through the second heat transfer pipe 431 is supplied to the water jacket 600 through the connecting pipe 610.

[0054] (Temperature Sensors TS1, TS2) One of the two temperature sensors TS1, TS2 is a first temperature sensor TS1 that is attached to a portion of the high-temperature pipe 271 between the first heat exchanger 420 and the first insulating member 350 and detects the temperature of that portion. In order to effectively prevent damage to the first insulating member 350 due to heat, the first temperature sensor TS1 is preferably attached as close as possible to the first insulating member 350. In this embodiment, as shown in FIGS. 2 and 3 , the first temperature sensor TS1 is attached to the outer surface of the high-temperature pipe 271 adjacent to the small flange 310. The other of the two temperature sensors TS1, TS2 is a second temperature sensor TS2 that is attached to a portion of the high-temperature pipe 271 between the first heat exchanger 420 and the second insulating member 360 and detects the temperature of that portion. In order to effectively prevent damage to the second insulating member 360 due to heat, the second temperature sensor TS2 is preferably attached as close as possible to the second insulating member 360. In this embodiment, as shown in Figures 2 and 4, the second temperature sensor TS2 is attached to the outer surface of the high-temperature pipe 271 adjacent to the large flange 320. Known sensors such as thermocouples can be used as the temperature sensors TS1 and TS2.

[0055] (First Transport Device 700A1, Second Transport Device 700A2) As described above, the first pump PN1A and the first inverter In1 constitute the first transport device 700A1, and the second pump PN2A and the second inverter In2 constitute the second transport device 700A2 (see FIG. 8). The first pump PN1A is connected to the first heat transfer tube 421 and transports the heat medium to the first heat transfer tube 421. The second pump PN2A is connected to the second heat transfer tube 431 and transports the refrigerant to the second heat transfer tube 431. Known pumps capable of flow rate control using inverters can be used as the first pump PN1A and the second pump PN2A. The first inverter In1 controls the rotation speed of the first pump PN1A, and the second inverter In2 controls the rotation speed of the second pump PN2A.

[0056] (Control Unit 800) As the control unit 800, for example, a known PLC (programmable logic controller) can be used.

[0057] When the control unit 800 receives temperature information from the temperature sensors TS1 and TS2, it outputs control signals to the inverters In1 and In2 based on the temperature information to control the rotation speeds of the pumps PN1A and PN2A. The inverters In1 and In2 output AC currents in accordance with the input control signals. The frequency of the output AC current controls the rotation speeds of the pumps PN1A and PN2A, thereby controlling the flow rates of the heat transfer medium and refrigerant.

[0058] A-2. Operation of the thermoacoustic device 100A: When the thermoacoustic device 100A is operated, a heat medium is caused to flow through the first heat transfer tube 421. Then, heat exchange occurs between the heat medium and the working gas near the one surface 410F1 of the heat accumulator 410. As a result, the temperature of the working gas near the one surface 410F1 of the heat accumulator 410 is adjusted to approach the temperature of the heat medium. In addition, room-temperature water is caused to flow as a refrigerant through the second heat transfer tube 431. Then, heat exchange occurs between the working gas near the other surface 410F2 of the heat accumulator 410 and the room-temperature water. As a result, the temperature of the working gas near the other surface 410F2 of the heat accumulator 410 is adjusted to approach room temperature.

[0059] The action of the heat exchangers 420 and 430 creates a temperature gradient between the first surface 410F1 and the second surface 410F2 of the heat accumulator 410. This causes the working gas inside the through-passage 414 to become unstable and begin to vibrate. This vibration generates acoustic energy (sound waves). The generated acoustic energy is output from the first surface 410F1 of the heat accumulator 410, transmitted through the working gas sealed inside the duct 290, and reaches the cooler 500 (see the arrow in FIG. 1 ).

[0060] When acoustic energy transmitted by the working gas is input to the heat accumulator 510 provided in the cooling device 500, a temperature gradient occurs between one surface facing the first heat exchanger 520 and the other surface facing the second heat exchanger 530. Because room temperature water flows through the first heat exchanger 520, which is arranged on the acoustic energy input side of the cooling device 500, the temperature of the working gas in the heat accumulator 510 near the second heat exchanger 530 is adjusted to a temperature lower than room temperature by the amount of the temperature gradient that occurs. Heat exchange occurs between this working gas, which is lower than room temperature, and the refrigerant, and the cooled refrigerant is supplied to external cooling equipment to cool the target object.

[0061] When heat from the heat medium passing through the first heat transfer pipe 421 is transferred to the high-temperature pipe 271 and then moves to the adjacent first main pipe 210 and low-temperature pipe 275, the temperature difference between both ends of the heat accumulator 410 becomes smaller, which may reduce the efficiency of conversion from thermal energy to acoustic energy by the motor 400. To avoid this, heat insulating members 350, 360 are provided on both ends of the high-temperature pipe 271. The heat insulating members 350, 360 prevent the heat transferred to the high-temperature pipe 271 from being transferred to the low-temperature pipe 275 and first main pipe 210, thereby preventing a decrease in the efficiency of conversion from thermal energy to acoustic energy.

[0062] A-3. Heat Transfer Medium and Coolant Transport Control Procedure: The process of controlling the flow rates of the heat transfer medium and coolant during operation of the thermoacoustic device 100A described above for the purpose of protecting the heat insulating members 350, 360 will be described with reference to Figure 9. Note that the control procedure based on the temperature detected by the first temperature sensor TS1 and the control procedure based on the temperature detected by the second temperature sensor TS2 are similar, so the former will be described in detail below, and the latter will not be described.

[0063] When control by the control unit 800 begins, the first temperature sensor TS1 continuously detects the temperature of the high-temperature pipe 271, and a signal corresponding to the detected temperature is sent to the control unit 800. The control unit 800 determines whether the first temperature T1 detected by the first temperature sensor TS1 is equal to or higher than a predetermined reference temperature T0 (step S10). If the control unit 800 determines that the first temperature T1 is lower than the reference temperature T0, it repeats step S10.

[0064] If the control unit 800 determines that the first temperature T1 is equal to or higher than the reference temperature T0, the control unit 800 executes step S20. In step S20, the control unit 800 uses a timer (not shown) built into the control unit 800 to measure a fixed time from time t1 when the first temperature T1 is detected. The "fixed time" is, for example, one minute. After measuring the fixed time, the control unit 800 executes the process of step S30.

[0065] In step S30, the control unit 800 determines whether the temperature (second temperature T2) detected by the first temperature sensor TS1 at time t2, a certain time after time t1 when the first temperature T1 is detected, is higher than or equal to the reference temperature T0 (first determination step).

[0066] If the control unit 800 determines that the second temperature T2 is lower than the reference temperature T0, the process returns to step S10 and repeats the process.

[0067] If the control unit 800 determines that the second temperature T2 is equal to or higher than the reference temperature T0, the control unit 800 executes step S40. In step S40, the control unit 800 notifies the user by means of an alarm device (for example, a rotating light with a buzzer function; not shown) that the heat medium flow control has been switched to the "protection mode."

[0068] Next, the control unit 800 executes step S50. In step S50, the control unit 800 performs a flow rate reduction process to control the first transport device 700A1 to reduce the flow rate of the heat medium transported through the first heat transfer tube 421. Specifically, the control unit 800 sets a target flow rate value so that the flow rate of the heat medium is reduced compared to before the flow rate reduction process began, and outputs a control signal corresponding to the set target value to the first inverter In1. Upon receiving the control signal, the first inverter In1 outputs an AC current having a frequency corresponding to the target flow rate value based on the control signal. The rotation speed of the first pump PN1A is controlled in accordance with the frequency of the output AC current, thereby reducing the flow rate of the heat medium.

[0069] Next, the control unit 800 executes the process of step S60. In step S60, the control unit 800 counts a fixed time from the start of the flow rate reduction process using a timer (not shown) built into the control unit 800. After counting the fixed time, the control unit 800 executes the process of step S70.

[0070] In step S70, the control unit 800 determines whether the temperature (third temperature T3) detected by the first temperature sensor TS1 at time t3, a certain time after the start of the flow rate reduction process, is equal to or higher than the reference temperature T0.

[0071] If the control unit 800 determines that the third temperature T3 is lower than the reference temperature T0, it executes step S130. In step S130, the control unit 800 executes a cancellation process to cancel the flow rate reduction process. More specifically, the control unit 800 sets a target flow rate value so that the flow rate of the heat transfer medium returns to the level before the flow rate reduction process began, and outputs a control signal corresponding to the set target value to the first inverter In1. Upon receiving the control signal, the first inverter In1 outputs an AC current having a frequency corresponding to the target flow rate value based on the control signal. The rotation speed of the first pump PN1A is controlled in accordance with the frequency of the output AC current, and the flow rate of the heat transfer medium is restored.

[0072] Next, the control unit 800 executes step S140. In step S140, the control unit 800 causes the notification device to notify that the flow rate reduction process has been canceled.

[0073] After executing step S140, the control unit 800 returns to step S10 and repeats the process.

[0074] If the control unit 800 determines in step S70 that the third temperature T3 is equal to or greater than the reference temperature T0, it executes step S80. In step S80, the control unit 800 performs a flow rate increase process to control the second transport device 700A2 to increase the flow rate of the refrigerant to the second heat transfer tube 431 and the water jacket 600. Specifically, the control unit 800 sets a target flow rate value so that the refrigerant flow rate is increased compared to before the flow rate decrease process began, and outputs a control signal corresponding to the set target value to the second inverter In2. Upon receiving the control signal, the second inverter In2 outputs an AC current having a frequency corresponding to the target flow rate value based on the control signal. The rotation speed of the second pump PN2A is controlled in accordance with the frequency of the output AC current, thereby increasing the flow rate of the refrigerant.

[0075] Next, the control unit 800 executes the process of step S90. In step S90, the control unit 800 measures a fixed time from the start of the flow rate increasing process using a timer (not shown) built into the control unit 800. After measuring the fixed time, the control unit 800 executes the process of step S100.

[0076] In step S100, the control unit 800 determines whether the temperature (fourth temperature T4) detected by the first temperature sensor TS1 at time t4, a certain time after the start of the flow rate increase process, is higher than or equal to the reference temperature T0 (second determination step).

[0077] If the control unit 800 determines that the fourth temperature T4 is lower than the reference temperature T0, it executes step S150. In step S150, the control unit 800 executes a cancellation process to cancel the flow rate reduction process and the flow rate increase process. More specifically, the control unit 800 sets a target flow rate value so that the flow rate of the heat transfer medium returns to the level before the flow rate reduction process was started, and outputs a control signal corresponding to the set target value to the first inverter In1. The first inverter In1, which has received the control signal, outputs an AC current having a frequency corresponding to the target flow rate value based on the control signal. The rotation speed of the first pump PN1A is controlled in accordance with the frequency of the output AC current, thereby restoring the flow rate of the heat transfer medium. The control unit 800 also sets a target flow rate value to the second inverter In2 so that the flow rate of the refrigerant returns to the level before the flow rate increase process was started, and outputs a control signal corresponding to the set target value. The second inverter In2, which has received the control signal, outputs an AC current having a frequency corresponding to the target flow rate value based on the control signal. The rotational speed of the second pump PN2A is controlled in accordance with the frequency of the output AC current, and the flow rate of the refrigerant returns to the original level.

[0078] Next, the control unit 800 executes step S160. In step S160, the control unit 800 causes the notification device to notify that the flow rate reduction process and the flow rate increase process have been canceled.

[0079] After executing step S160, the control unit 800 returns to step S10 and repeats the process.

[0080] If the control unit 800 determines in step S100 that the fourth temperature T4 is equal to or higher than the reference temperature T0, the control unit 800 executes step S110. In step S110, the control unit 800 performs a transport stop process to control the first transport device 700A1 to stop transport of the heat medium to the first heat transfer tube 421. Specifically, the control unit 800 outputs a control signal to the first inverter In1 to stop outputting AC current. Upon receiving the control signal, the first inverter In1 stops outputting AC current based on the control signal. This stops the first pump PN1A, and transport of the heat medium is stopped.

[0081] Next, the control unit 800 executes step S120. In step S120, the control unit 800 causes the notification device to notify that the transport of the heat medium has been stopped.

[0082] If the determinations of whether the temperatures detected by the two temperature sensors TS1 and TS2 are equal to or greater than the reference temperature T0 differ, the control unit 800 executes the next step if the temperature detected by either of the two temperature sensors TS1 and TS2 is equal to or greater than the reference temperature T0. For example, in step S10, if either of the temperatures detected by the two temperature sensors TS1 and TS2 is equal to or greater than the reference temperature T0, the control unit 800 executes step S20. The same applies to steps S30, S70, and S100.

[0083] Here, the high-temperature pipe 271 may reach a high temperature close to the temperature of the heat medium due to the heat transfer from the heat medium. Therefore, for example, if the temperature of the high-temperature pipe 271 reaches a temperature close to or exceeds the heat resistance temperature of the resin that constitutes the heat insulating members 350, 360, there is a concern that the heat insulating members 350, 360 in contact with the high-temperature pipe 271 may be damaged by the heat. If the heat insulating members 350, 360 are damaged, there is a risk that the working gas may leak outside the pipe 200.

[0084] In this embodiment, as described above, when the temperatures T1 and T2 detected by the first temperature sensor TS1 are equal to or higher than the reference temperature T0, the flow rate of the heat transfer medium is reduced. When the third temperature T3 detected by the first temperature sensor TS1 is equal to or higher than the reference temperature T0, the flow rate of the coolant is increased. When the fourth temperature T4 detected by the first temperature sensor TS1 is equal to or higher than the reference temperature T0, the supply of the heat transfer medium is stopped. The same applies to the second temperature sensor TS2. This reduces the temperature of the high-temperature pipe 271 and prevents damage to the heat insulating members 350 and 360 due to heat transferred from the high-temperature pipe 271.

[0085] A-4. Advantages of this embodiment: As described above, thermoacoustic device 100A of this embodiment includes: heat accumulator 410 having one surface 410F1 and the other surface 410F2 and having a plurality of through-paths 414 penetrating from one surface 410F1 to the other surface 410F2; a first heat exchanger 420 disposed opposite one surface 410F1 of heat accumulator 410 and including a first heat transfer tube 421 through which a heat medium can flow; and a second heat exchanger 430 disposed opposite the other surface 410F2 of heat accumulator 410 and including a second heat transfer tube 431 through which a refrigerant having a lower temperature than the heat medium can flow; and piping 200 accommodating motor 400 therein and capable of sealing a working gas, including high-temperature piping 271 accommodating first heat exchanger 420 therein and a first heat transfer tube 431 connected to high-temperature piping 271. The system includes a piping (200) having a main pipe (210) and a low-temperature pipe (275), a first insulating member (350) made of resin interposed between a high-temperature pipe (271) and the first main pipe (210), and a second insulating member (360) made of resin interposed between the high-temperature pipe (271) and the low-temperature pipe (275), a first temperature sensor (TS1) attached to the high-temperature pipe (271) between the first heat exchanger (420) and the first insulating member (350) to detect the temperature of the high-temperature pipe (271), a second temperature sensor (TS2) attached to the high-temperature pipe (271) between the first heat exchanger (420) and the second insulating member (360) to detect the temperature of the high-temperature pipe (271), a first transport device (700A1) that transports a heat medium to the first heat transfer pipe (421), and a control unit (800) that controls the transport of the heat medium. The control unit 800 executes a flow rate reduction process to control the first transport device 700A1 to reduce the flow rate of the heat medium transported to the first heat transfer tube 421 when the temperatures T1, T2 detected by at least one of the temperature sensors TS1, TS2 are equal to or higher than a predetermined reference temperature T0.

[0086] Furthermore, the fluid supply method of this embodiment is a method for supplying a heat transfer medium and a refrigerant to the thermoacoustic device 100A having the above-described configuration, and includes a first determination step for determining whether the temperatures T1 and T2 of the portion of the high-temperature piping 271 between the first heat exchanger 420 and the first insulating member 350, or the portion between the first heat exchanger 420 and the second insulating member 360, are equal to or higher than a reference temperature T0, and a flow rate reduction process for reducing the flow rate of the heat transfer medium transported to the first heat transfer tube 421 if it is determined in the first determination step that the temperatures T1 and T2 are equal to or higher than the reference temperature T0.

[0087] According to the above configuration, when the temperatures T1, T2 detected by the temperature sensors TS1, TS2 are equal to or higher than the reference temperature T0, the flow rate of the heat transfer medium is reduced, thereby reducing the temperature of the high-temperature pipe 271. This makes it possible to prevent damage to the heat insulating members 350, 360 due to heat transferred from the high-temperature pipe 271.

[0088] In addition, after performing the flow rate reduction process, the control unit 800 performs a second judgment process to determine whether the fourth temperature T4 detected by the temperature sensors TS1 and TS2 is equal to or higher than the reference temperature T0, and if the fourth temperature T4 is equal to or higher than the reference temperature T0, it executes a transport stop process.

[0089] With this configuration, it is possible to prevent the thermal insulating members 350 and 360 from being damaged while avoiding the operation of the thermoacoustic device 100A from being stopped as much as possible.

[0090] In addition, the control unit 800 executes a flow rate reduction process when both the first temperature T1 detected by the first temperature sensor TS1 and the second temperature T2 detected by the temperature sensors TS1 and TS2 after a certain time has elapsed since the time t1 at which the first temperature T1 was detected are equal to or higher than the reference temperature T0.

[0091] For example, if the temperatures detected by the temperature sensors TS1 and TS2 temporarily rise due to some unexpected factor but then immediately drop, it is unlikely that this will damage the heat insulating members 350 and 360. With the above configuration, in such a case, the flow rate reduction process is not executed, thereby preventing unnecessary output reduction.

[0092] Note that "when both the first temperature T1 and the second temperature T2 are equal to or higher than the reference temperature T0" includes a case where a temperature equal to or higher than the reference temperature T0 is detected continuously for a certain period of time from time t1 to time t2, and a case where there is a time period between time t1 and time t2 where the temperature temporarily drops below the reference temperature T0. Furthermore, "when both the first temperature T1 and the second temperature T2 are equal to or higher than the reference temperature T0" includes a case where T1=T2, a case where T1<T2, and a case where T1>T2.

[0093] The thermoacoustic device 100A further includes a second transport device 700A2 that transports the refrigerant to the second heat transfer tube 431. The control unit 800 further executes a flow rate increase process to control the second transport device 700A2 to increase the flow rate of the refrigerant transported to the second heat transfer tube 431 when the third temperature T3 detected by the temperature sensors TS1 and TS2 is equal to or higher than the reference temperature T0.

[0094] According to this configuration, by also using a process for increasing the flow rate of the refrigerant, it is possible to lower the temperature of the portion of the piping 200 that is close to the second heat transfer pipe 431, and to lower the temperatures of the heat insulating members 350, 360 via the piping 200. This makes it possible to more effectively prevent damage to the heat insulating members 350, 360.

[0095] B. Second Embodiment: A second embodiment will be described with reference to Fig. 10. A thermoacoustic device 100B of this embodiment differs from the first embodiment in the configurations of a first transport device 700B1 and a second transport device 700B2, and in part of the transport control procedure.

[0096] B-1. Configuration of the thermoacoustic device 100B: The first transport device 700B1 includes a first pump PN1B and a first flow rate control valve BL1. The second transport device 700B2 includes a second pump PN2B and a second flow rate control valve BL2. The first pump PN1B is connected to the first heat transfer tube 421 and transports the heat medium to the first heat transfer tube 421. The second pump PN2B is connected to the second heat transfer tube 431 and transports the refrigerant to the second heat transfer tube 431. The pumps PN1B and PN2B of this embodiment do not have to be pumps whose flow rates can be controlled by an inverter.

[0097] The first flow control valve BL1 is disposed midway in the piping connecting the first pump PN1B and the first heat transfer pipe 421. The second flow control valve BL2 is disposed midway in the piping connecting the second pump PN2B and the second heat transfer pipe 431. As the flow control valves BL1 and BL2, known valves that can control the flow rate by controlling the valve opening, such as linear solenoid valves, proportional valves, and pressure control valves, can be used.

[0098] 10, the thick solid lines indicate the piping 200, the thin solid lines indicate the flow of signals between the control unit 800 and the temperature sensors TS1 and TS2, and the transport devices 700B1 and 700B2, the thick dashed dotted lines indicate the flow paths of the heat medium, and the thick dashed two-dot lines indicate the flow paths of the refrigerant.

[0099] B-2. Procedure for transport control of heat transfer medium and refrigerant: Next, the procedures for transport control of heat transfer medium and refrigerant in this embodiment that differ from those in the first embodiment will be described, and explanations of the same procedures will be omitted. As in the first embodiment, the processing procedures are the same when it is determined that the temperature T1 detected by the first temperature sensor TS1 is equal to or higher than the reference temperature T0 and when it is determined that the temperature T2 detected by the second temperature sensor TS2 is equal to or higher than the reference temperature T0. Therefore, the following will describe in detail the former, and omit explanations of the latter.

[0100] In step S50, the control unit 800 outputs a control signal corresponding to the set target value of the flow rate to the first flow control valve BL1. Upon receiving the control signal, the first flow control valve BL1 reduces its opening so as to correspond to the target value of the flow rate based on the control signal. The flow rate of the heat medium transported to the first heat transfer tube 421 decreases in accordance with the opening degree of the first flow control valve BL1.

[0101] Furthermore, in step S80, the control unit 800 outputs a control signal corresponding to the set target value of the flow rate to the second flow control valve BL2. The second flow control valve BL2, which has received the control signal, increases its opening degree to correspond to the target value of the flow rate based on the control signal. The flow rate of the refrigerant transported to the second heat transfer pipe 431 and the water jacket 600 increases in accordance with the opening degree of the first flow control valve BL1.

[0102] In step S110, the control unit 800 outputs a control signal to the first flow control valve BL1 to close the valve. Upon receiving the control signal, the first flow control valve BL1 closes the valve based on the control signal. This stops the transport of the heat medium to the first heat transfer tube 421.

[0103] Furthermore, in step S130, the control unit 800 outputs a control signal corresponding to the set target value to the first flow control valve BL1. Upon receiving the control signal, the first flow control valve BL1 increases its opening degree to correspond to the target flow rate value based on the control signal. The flow rate of the heat medium transported to the first heat transfer tube 421 is restored in accordance with the opening degree of the first flow control valve BL1.

[0104] Furthermore, in step S150, the control unit 800 outputs a control signal corresponding to the set target value to the first flow control valve BL1. The first flow control valve BL1, which has received the control signal, increases its opening degree to correspond to the target value of the flow rate based on the control signal. The flow rate of the heat medium transported to the first heat transfer tube 421 is restored in accordance with the opening degree of the first flow control valve BL1. The control unit 800 also outputs a control signal corresponding to the set target value of the flow rate to the second flow control valve BL2. The second flow control valve BL2, which has received the control signal, decreases its opening degree to correspond to the target value of the flow rate based on the control signal. The flow rate of the refrigerant transported to the second heat transfer tube 431 is restored in accordance with the opening degree of the second flow control valve BL2.

[0105] B-3. ​​Effects of this embodiment: According to this embodiment, the same effects as those of the first embodiment are achieved.

[0106] C. Third Embodiment A third embodiment will be described with reference to Fig. 11. A thermoacoustic device 100C of the third embodiment differs from the first embodiment in the configurations of a first transport device 700C1 and a second transport device 700C2, and in part of the transport control procedure.

[0107] C-1. Configuration of the first transport device 700C1 and the second transport device 700C2: The first transport device 700C1 includes a first pump PN1B and a first switch SW1. The second transport device 700C2 includes a second pump PN2B and a second switch SW2. As in the second embodiment, the first pump PN1B and the second pump PN2B do not have to be pumps capable of flow rate control by an inverter. The first switch SW1 controls the supply of electricity to the first pump PN1B. The second switch SW2 controls the supply of electricity to the second pump PN2B. As the switches SW1 and SW2, for example, known electromagnetic switches can be used.

[0108] 11, the thick solid lines indicate the piping 200, the thin solid lines indicate the flow of signals between the control unit 800 and the temperature sensors TS1 and TS2, and the transport devices 700C1 and 700C2, the thick dashed dotted lines indicate the flow paths of the heat medium, and the thick dashed two-dot lines indicate the flow paths of the refrigerant.

[0109] C-2. Procedure for transport control of heat transfer medium and refrigerant: Next, the procedures for transport control of heat transfer medium and refrigerant in this embodiment that differ from those in the first embodiment will be described, and explanations of the same procedures will be omitted. As in the first embodiment, the processing procedures are the same when it is determined that the temperature T1 detected by the first temperature sensor TS1 is equal to or higher than the reference temperature T0 and when it is determined that the temperature T2 detected by the second temperature sensor TS2 is equal to or higher than the reference temperature T0. Therefore, the following will describe in detail the former, and omit explanations of the latter.

[0110] If the control unit 800 determines in step S30 that the second temperature T2 is equal to or higher than the reference temperature T0, the process skips steps S40 to S100 and proceeds to step S110, where the process stops the transport. In step S100, the control unit 800 outputs a control signal to the first switch SW1 to stop the supply of power to the first pump PN1B. The first switch SW1 receives the control signal and stops the supply of power based on the control signal. This stops the first pump PN1B and stops the transport of the heat medium.

[0111] C-3. Advantages of this embodiment: According to this embodiment, when the temperatures detected by the temperature sensors TS1 and TS2 are equal to or higher than the reference temperature T0, the supply of heat transfer medium is stopped, thereby lowering the temperature of the high-temperature pipe 271. This makes it possible to prevent damage to the heat insulating members 350 and 360 due to heat transferred from the high-temperature pipe 271.

[0112] D. Reference Example A reference example will be described with reference to FIGS.

[0113] D-1. Configuration of the thermoacoustic device 100D: The thermoacoustic device 100D includes a pressure sensor PS, as shown in Fig. 12. The pressure sensor PS is a sensor that detects the pressure inside the high-temperature pipe 271, and is attached inside the high-temperature pipe 271. As the pressure sensor PS, a known sensor such as a resistive film type, a capacitance type, or a piezoelectric element type can be used.

[0114] The first transport device 700D1 includes a first pump PN1B and a switch SW3. A second pump PN2B is connected to the second heat exchanger 430. As in the second embodiment, the first pump PN1B and the second pump PN2B do not have to be pumps whose flow rates can be controlled by an inverter. The switch SW3 controls the supply of electricity to the first pump PN1B.

[0115] 12, the thick solid lines indicate the piping 200, the thin solid lines indicate the flow of signals between the control unit 800 and the temperature sensors TS1 and TS2, the pressure sensor PS, and the transport device 700D1, the thick dashed dotted lines indicate the flow path of the heat medium, and the thick dashed two-dotted lines indicate the flow path of the refrigerant.

[0116] D-2. Procedure for controlling transport of heat medium: Next, the procedure for controlling transport of heat medium in this embodiment will be described with reference to FIG. 13. When control by the control unit 800 begins, the pressure sensor PS continuously detects the pressure inside the high-temperature pipe 271, and a signal corresponding to the detected pressure is sent to the control unit 800. The control unit 800 determines whether the pressure P1 detected by the pressure sensor PS is equal to or greater than a predetermined reference pressure P0 (step S210). If the control unit 800 determines that the pressure P1 is equal to or greater than the reference pressure P0, it repeats step S210.

[0117] If the control unit 800 determines that the pressure P1 is less than the reference pressure P0, it executes step S220. In step S220, the control unit 800 outputs a control signal to the switch SW3 to stop the supply of power to the first pump PN1B. Upon receiving the control signal, the switch SW3 stops the supply of power based on the control signal. This stops the first pump PN1B and stops the transport of the heat medium.

[0118] D-3. Advantages of this Reference Example: When a drop in pressure P1 is detected, there is concern that damage to the heat insulating members 350, 360 has begun, and that the working gas is beginning to leak outside the pipe 210. According to this reference example, when the pressure P1 detected by the pressure sensor PS is lower than the reference pressure P0, the supply of heat medium is stopped, thereby lowering the temperature of the high-temperature pipe 271. This makes it possible to prevent the spread of damage to the heat insulating members 350, 360 caused by heat transferred from the high-temperature pipe 271.

[0119] E. Modifications: The technology disclosed in this specification is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit and scope of the present invention. For example, the following modifications are also possible. (1) In the above-described embodiments, the thermoacoustic devices 100A, 100B, and 100C each include a water jacket 600. However, the thermoacoustic device may not include a water jacket. (2) In the above-described embodiments, the insulating members 350 and 360 are disposed at both ends of the high-temperature pipe 271. However, the insulating members may be disposed at only one end of the containing pipe. (3) In the above-described embodiments, the flow rate reduction process or the transport stop process is executed when both the first temperature T1 and the second temperature T2 detected a certain time after the first temperature T1 is detected are equal to or higher than the reference temperature T0. However, when it is determined that the first temperature is equal to or higher than the reference temperature, the flow rate reduction process or the transport stop process may be executed without detecting the second temperature. (4) In the first and second embodiments, an example was described in which the flow rate increase process was executed when it was determined that the temperature T3 detected after the flow rate reduction process was executed was equal to or greater than the reference temperature T0. However, the flow rate increase process does not necessarily have to be executed. For example, if it is determined that the temperature detected by the temperature sensor after the flow rate reduction process is not below the reference temperature, the transport stop process may be executed without executing the flow rate increase process. (5) In the first and second embodiments, an example was described in which the flow rate increase process was executed when it was determined that the temperature T3 detected after the flow rate reduction process was executed was equal to or greater than the reference temperature T0. However, for example, if it is determined that the first temperature is equal to or greater than the reference temperature, the flow rate decrease process and the flow rate increase process may be executed simultaneously. (6) In the above embodiments, an example was described in which the control unit executed both the flow rate reduction process and the transport stop process, and an example in which the control unit executed only the transport stop process. However, it is also possible for the control unit to execute only the flow rate reduction process, or to execute both the transport reduction process and the transport increase process, without executing the transport stop process. For example, if the control unit executes the flow rate reduction process and the temperature detected by the temperature sensor thereafter does not fall below the reference temperature, the transport device may be stopped manually by an operator.Alternatively, the control unit may perform the flow rate reduction process and the flow rate increase process, and if the temperature detected by the temperature sensor does not subsequently fall below the reference temperature, the operator may manually stop the transport device. (7) In the third embodiment, an example was shown in which the control unit performs only the transport stop process without performing the flow rate reduction process or the flow rate increase process. However, even when using a thermoacoustic device having the configuration of the third embodiment, the control unit may perform one or both of the flow rate reduction process and the flow rate increase process. Alternatively, the control unit may perform only the flow rate reduction process, or the transport reduction process and the transport increase process, without performing the transport stop process. (8) In the above embodiment, a rotating light was used as an example of an alarm device that notifies the operator that the heat medium flow control has been switched to the "protection mode," that the heat medium transport has been stopped, or that the flow rate reduction process has been canceled. However, the operator may also be notified by displaying a warning on a touch panel, for example. Alternatively, such a display or notification may not be provided. (9) In the above embodiment, the temperature of the high-temperature pipe 271 is continuously detected by the first temperature sensor TS1. However, for example, the temperature of the high-temperature pipe may be detected at regular intervals. The same applies to the second temperature sensor.

[0120] 100A, 100B, 100C: thermoacoustic device 200: piping 210: first main pipe (connecting pipe, first connecting pipe) 270: prime mover pipe (accommodating pipe) 280: cooler pipe (connecting pipe, second connecting pipe) 330: first heat insulating member (heat insulating member) 340: second heat insulating member (heat insulating member) 400: prime mover (energy converter) 410: heat accumulator 410F1: one surface 410F2: other surface 414: through passage 420: first heat exchanger 421: first heat transfer tube (first flow path) 430: second heat exchanger 431: second heat transfer tube (second flow path) TS1: first temperature sensor (temperature sensor) TS2: second temperature sensor (temperature sensor) 700A1, 700B1, 700C1: First transport device 700A2, 700B2, 700C2: Second transport device 800: Control unit

Claims

a first heat exchanger disposed opposite the first surface of the heat accumulator and having a first flow path through which a first fluid can flow, and a second heat exchanger disposed opposite the other surface of the heat accumulator and having a second flow path through which a second fluid having a lower temperature than the first fluid can flow; an energy converter comprising: a piping in which the energy converter is housed and in which a working gas can be sealed, the piping comprising: an accommodation piping in which the first heat exchanger is housed; and a connection piping connected to the accommodation piping; a resin insulating member interposed between the accommodation piping and the connection piping; a temperature sensor attached to the accommodation piping between the first heat exchanger and the insulating member to detect the temperature of the accommodation piping; a first transport device for transporting the first fluid to the first flow path; and a control unit for controlling the transport of the first fluid, A thermoacoustic device which, when the temperature detected by the temperature sensor is equal to or higher than a predetermined reference temperature, executes at least one of a flow rate reduction process which controls the first transport device to reduce a flow rate of the first fluid transported to the first flow path, and a transport stop process which stops the transport of the first fluid to the first flow path.

2. The thermoacoustic device of claim 1, wherein the control unit executes the flow rate reduction process when the temperature detected by the temperature sensor is equal to or higher than the reference temperature, and executes the transport stop process when the temperature detected by the temperature sensor after execution of the flow rate reduction process is equal to or higher than the reference temperature.

3. A thermoacoustic device as described in claim 1 or claim 2, wherein the control unit executes either the flow rate reduction process or the transport stop process when both a first temperature detected by the temperature sensor and a second temperature detected by the temperature sensor a certain time after the first temperature is detected are equal to or higher than the reference temperature.

4. A thermoacoustic device as described in any one of claims 1 to 3, wherein the control unit executes either the flow rate reduction process or the transport stop process when a temperature equal to or higher than the reference temperature is detected by the temperature sensor for a certain period of time.

5. A thermoacoustic device as described in any one of claims 1 to 4, further comprising a second transport device that transports the second fluid to the second flow path, and the control unit further executes a flow rate increase process that controls the second transport device to increase the flow rate of the second fluid transported to the second flow path when the temperature detected by the temperature sensor is equal to or higher than the reference temperature.

6. A thermoacoustic device as described in any one of claims 1 to 5, wherein the connecting pipe includes: a first connecting pipe connected to one end of the accommodating pipe; and a second connecting pipe connected to the other end of the accommodating pipe; the insulating member includes: a first insulating member interposed between the accommodating pipe and the first connecting pipe; and a second insulating member interposed between the accommodating pipe and the second connecting pipe; the temperature sensors include: a first temperature sensor attached between the first heat exchanger and the first insulating member; and a second temperature sensor attached between the first heat exchanger and the second insulating member; and the control unit executes at least one of the flow rate reduction process and the transport stop process when a temperature detected by at least one of the first temperature sensor and the second temperature sensor is equal to or higher than the reference temperature.

7. A fluid supply method for supplying the first fluid and the second fluid to a thermoacoustic device comprising: a heat accumulator having one side and another side and having a plurality of through passages penetrating from the one side to the other side; a first heat exchanger arranged opposite to the one side of the heat accumulator and having a first flow path through which a first fluid can flow; and a second heat exchanger arranged opposite to the other side of the heat accumulator and having a second flow path through which a second fluid having a lower temperature than the first fluid can flow; and a piping in which the energy converter is housed and in which a working gas can be sealed, the piping comprising: an accommodation piping in which the first heat exchanger is housed; a connection piping connected to the accommodation piping; and a resin insulating member interposed between the accommodation piping and the connection piping, the method comprising: a first determination step of determining whether a temperature of a portion of the accommodation piping between the first heat exchanger and the insulating member is equal to or higher than a predetermined reference temperature; and when it is determined in the first determination step that the temperature is equal to or higher than the reference temperature, performing at least one of a flow rate reduction process for reducing a flow rate of the first fluid transported to the first flow path and a transport stop process for stopping the transport of the first fluid to the first flow path.

8. A fluid supply method as described in claim 7, comprising: a step of executing the flow rate reduction process when it is determined in the first determination step that the temperature is equal to or higher than the reference temperature; a second determination step of determining whether or not the temperature of a portion of the containing piping between the first heat exchanger and the insulating member is equal to or higher than the reference temperature after the flow rate reduction process is executed; and a step of executing the transport stop process when it is determined in the second determination step that the temperature is equal to or higher than the reference temperature.

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