JP7476732B2 - Thermoacoustic Device - Google Patents

Description

This disclosure relates to a thermoacoustic device.

Thermoacoustic devices are known that include a stack that uses vibration energy to generate a temperature gradient based on the thermoacoustic effect. The thermoacoustic device described in Patent Document 1 includes a heat pump that includes a stack provided within a tube, a first heat exchanger (second low-temperature side heat exchanger) that is arranged at one end of the stack and cooled by the temperature gradient, and a second heat exchanger (second high-temperature side heat exchanger) that is arranged at the other end of the stack and keeps the temperature of the other end of the stack constant. In the first heat exchanger, a flow path for a fluid that cools an object to be cooled is provided so as to surround the outer circumferential surface of the tube. Heat transfer occurs between the fluid and the tube, and the fluid is cooled. The cooled fluid cools the object to be cooled.

JP 2018-25340 A JP 2019-173687 A JP 2019-163924 A

In general, in a heat exchanger, the amount of energy that can be exchanged can be increased by increasing the contact surface area where heat transfer occurs. However, increasing the axial dimension of the stack of heat exchanger fins arranged in the flow path increases the resistance in the flow path. As a result, thermoacoustic phenomena become less likely to occur. It is also possible to widen the width of the heat exchanger flow path surrounding the tube in the axial direction of the stack, but in such an embodiment, the part of the tube that additionally comes into contact with the flow path is a part where a part that is higher in temperature than the end of the stack that is the coldest is arranged. This reduces the efficiency of heat exchange of the fluid.

This disclosure can be realized in the following forms:

(1) According to one embodiment of the present disclosure, there is provided a thermoacoustic device. The thermoacoustic device includes a stack that generates a temperature gradient using vibration energy supplied via a first fluid, a first heat exchanger that is arranged at one end of the stack and is cooled via the first fluid, and a second heat exchanger that is arranged at the other end of the stack and maintains a constant temperature of the first fluid near the other end of the stack. The first heat exchanger has an inlet pipe through which a second fluid flows into the first heat exchanger, an outlet pipe through which the second fluid flows out of the first heat exchanger, a first flow path portion that is provided to surround at least a part of a side surface of the first heat exchanger in a circumferential direction and is connected to the inlet pipe, and through which the second fluid circulates, a second flow path portion that is provided at a position farther from the one end than the first flow path portion and is provided to surround at least a part of a side surface of the first heat exchanger in a circumferential direction and is connected to the outlet pipe, and one or more branch flow path portions that connect the first flow path portion and the second flow path portion.
In this embodiment, the second fluid repeatedly circulates through the first flow path, so that a larger amount of heat can be transferred between the first heat exchanger and the second fluid without lengthening the flow path in the axial direction, and the object can be cooled by the second fluid flowing out of the second flow path, thereby improving the efficiency of energy conversion in the thermoacoustic device.
(2) In the thermoacoustic device of the above embodiment, the one or more branch flow passage sections may include a first branch flow passage section and a second branch flow passage section that is provided at a position farther from the connection portion of the inlet piping than the first branch flow passage section in the direction in which the second fluid circulates within the first flow passage section and has a cross-sectional area perpendicular to the direction in which the second fluid circulates that is different from that of the first branch flow passage section.
By changing the cross-sectional area, the flow rate of the second fluid circulating through the first flow path portion and the flow rate of the second fluid flowing into the second flow path portion can be changed, so the cross-sectional size of each branch flow path portion can be determined according to the desired temperature.
(3) In the thermoacoustic device of the above aspect, an area of the cross section of the second branch flow path portion may be larger than an area of the cross section of the first branch flow path portion.
In this embodiment, a small amount of less cooled fluid flows from the first branch flow path portion closer to the inlet pipe to the second flow path portion, and a large amount of cooled fluid flows from the second branch flow path portion closer to the outlet pipe to the first flow path portion, thereby allowing fluid at a desired temperature to flow out of the outlet pipe.
(4) In the thermoacoustic device of the above aspect, an area of the cross section of the second branch flow path portion may be smaller than an area of the cross section of the first branch flow path portion.
In this embodiment, a large amount of less cooled fluid flows from the first branch flow path portion close to the inlet pipe to the second flow path portion, and a small amount of cooled fluid flows from the second branch flow path portion close to the outlet pipe to the first flow path portion, thereby allowing a fluid at a desired temperature to flow out of the outlet pipe.
(5) In the thermoacoustic device of the above embodiment, the second branch flow path section may be configured such that the inclination of the second fluid section in the first flow path section with respect to the flow direction of the second fluid section is different from the inclination of the first branch flow path section, and the inclinations of the first branch flow path section and the second branch flow path section are both 90 degrees or less.
By changing the inclination, the flow rate of the second fluid circulating through the first flow path portion and the flow rate of the second fluid flowing into the second flow path portion can be changed. Therefore, the inclination of each branch flow path portion can be determined according to a desired temperature.
(6) In the thermoacoustic device of the above aspect, the first flow path portion may be disposed so as to surround the one end of the stack.
In this embodiment, the second fluid circulates through the same cross section at one end of the stack. In other words, the first flow path portion is disposed to surround the one end of the stack that is the coldest, thereby improving the efficiency of energy conversion in the thermoacoustic device.

The present disclosure can also be realized in various forms other than a thermoacoustic device. For example, it can be realized in the form of a heat exchanger for a thermoacoustic device, a heat pump equipped with a heat exchanger for a thermoacoustic device, a manufacturing method thereof, etc.

1 is an explanatory diagram showing a schematic configuration of a thermoacoustic device according to a first embodiment; FIG. 1 is an explanatory diagram showing a schematic configuration of a heat pump. FIG. 4 is an explanatory diagram showing a schematic configuration of a jacket of a first heat exchanger. 4 is a plan view of the first flow path portion as viewed along the axial direction of the stack. FIG. FIG. 4 is an explanatory diagram showing FIG. 3 cut along the line VV and developed; FIG. 11 is a plan view showing a schematic configuration of a first heat exchanger in another embodiment.

A. Embodiments:
Fig. 1 is an explanatory diagram showing a schematic configuration of a thermoacoustic device TA according to a first embodiment. Note that Fig. 1 does not accurately show the shapes of each component of the thermoacoustic device TA. The thermoacoustic device TA is a loop-tube type thermoacoustic device. The thermoacoustic device TA is connected to a heat source HS and a cooling target CO. The thermoacoustic device TA is supplied with thermal energy from the heat source HS and can cool the cooling target CO.

The thermoacoustic device TA includes a prime mover PM, a heat pump HP, and loop pipes LT1 and LT2. One end of the prime mover PM and one end of the heat pump HP are connected by the loop pipe LT1. The other end of the prime mover PM and the other end of the heat pump HP are connected by the loop pipe LT2. As a result, the prime mover PM, the heat pump HP, and the loop pipes LT1 and LT2 form a ring-shaped piping structure PA. This ring-shaped piping structure PA is filled with a first fluid FL1. In this embodiment, the first fluid FL1 is air. The ring-shaped piping structure PA is configured so that the first fluid FL1 inside can flow within the ring-shaped piping structure PA.

The prime mover PM receives thermal energy from the heat source HS and generates sound waves (see the lower left part of Figure 1). The prime mover PM includes a fourth heat exchanger 40, a third heat exchanger 20, and a stack 30.

In FIG. 1, the direction in which the fourth heat exchanger 40, the stack 30, and the third heat exchanger 20 are aligned is shown as the Z-axis direction. In addition, two directions perpendicular to the Z-axis direction and perpendicular to each other are shown as the X-axis direction and the Y-axis direction in FIG. 1. The X-axis, Y-axis, and Z-axis shown in FIG. 2 and subsequent figures correspond to the X-axis, Y-axis, and Z-axis shown in FIG. 1.

The fourth heat exchanger 40 is connected to a loop pipe LT1 at one end of the prime mover PM so that the first fluid FL1 can flow through it. The fourth heat exchanger 40 is further connected to a heat source HS. In this embodiment, the heat source HS is, for example, a rod-shaped heater that uses a resistance heating method. The fourth heat exchanger 40 is supplied with heat from the heat source HS and imparts heat to the first fluid FL1 in the piping structure PA, which is in contact with the fourth heat exchanger 40.

The third heat exchanger 20 is connected to the loop pipe LT2 at the other end of the prime mover PM so that the first fluid FL1 can flow through it. The third heat exchanger 20 is equipped with a chiller (not shown). The temperature of the third heat exchanger 20 is kept constant by the chiller. The third heat exchanger 20 controls the temperature of the first fluid FL1 in the piping structure PA, which is in contact with the third heat exchanger 20, to a predetermined range.

The stack 30 is installed in a location between the fourth heat exchanger 40 and the third heat exchanger 20. The stack 30 has a large number of through holes. These through holes form a flow path 32 through which the first fluid FL1 flows. The stack 30 is connected to the fourth heat exchanger 40 and the third heat exchanger 20 so that the first fluid FL1 can flow through it. The stack 30 creates a temperature gradient and generates sound waves within the piping structure PA.

The prime mover PM operates as follows. The first fluid FL1 heated by the fourth heat exchanger 40 provides heat to one end 38 of the stack 30 and the surrounding area, causing the area near the one end 38 of the stack 30 to become hot. The third heat exchanger 20 causes the area near the other end 39 of the stack 30 to become colder than the area near the one end 38. As a result, a temperature gradient is formed in the stack 30. The stack 30 then undergoes thermoacoustic self-excited vibration, generating standing waves in the piping structure PA. The sound energy generated by the stack 30 is transmitted from one end of the prime mover PM to one end of the heat pump HP via the first fluid FL1 in the loop pipe LT1 (see arrow K1 in FIG. 1).

Figure 2 is an explanatory diagram showing the schematic configuration of the heat pump HP. Note that Figure 2 does not accurately show the shape of each component of the heat pump HP. The heat pump HP is supplied with sound waves, which are vibration energy, from the prime mover PM, and cools the object to be cooled CO (see the upper right part of Figure 1). The heat pump HP includes a second heat exchanger 90, a first heat exchanger 70, and a stack 80.

The second heat exchanger 90 is connected to a loop pipe LT1 at one end of the heat pump HP so that the first fluid FL1 can flow through it (see the upper right part of Figure 1). The second heat exchanger 90 is equipped with a chiller (not shown). The second heat exchanger 90 has a fluid circulated through it by the chiller, so that the temperature is kept constant. The second heat exchanger 90 controls the temperature of the first fluid FL1 in the piping structure PA, which is in contact with the second heat exchanger 90, to a predetermined range.

The second heat exchanger 90 includes a jacket 93 and a fin module 94 (see the lower part of FIG. 2). The jacket 93 is an annular structure that constitutes a flow path 96 through which the third fluid FL3 flows. The jacket 93 is connected to a chiller, and the chiller causes the third fluid FL3 to flow through the jacket 93. The fin module 94 is disposed in a hole in the center of the jacket 93. The fin module 94 includes a large number of fins. The gaps between adjacent fins in the fin module 94 constitute a flow path 92 through which the first fluid FL1 flows. The fin module 94 exchanges heat with the jacket 93. The jacket 93 and the fin module 94 are controlled to a temperature within a predetermined range by the flow of the third fluid FL3 through the chiller. As a result, the first fluid FL1 flowing through the flow path 92 near the other end 88 of the stack 80 is controlled to a temperature within a predetermined range.

The first heat exchanger 70 is connected to a loop pipe LT2 at the other end of the heat pump HP so that the first fluid FL1 can flow therethrough (see the upper right part of FIG. 1). The first heat exchanger 70 is further connected to the object to be cooled CO. The first heat exchanger 70 absorbs heat from the first fluid FL1 in the piping structure PA that is in contact with the first heat exchanger 70, and absorbs heat from the object to be cooled CO. As a result, the object to be cooled CO is cooled. The detailed configuration and function of the first heat exchanger 70 will be described later.

The first heat exchanger 70 includes a jacket 73 and a fin module 74 (see the upper part of FIG. 2). The jacket 73 circulates the second fluid FL2 flowing through the jacket 73 between the second fluid FL2 and the object to be cooled CO. The detailed configuration and function of the jacket 73 will be described later. The fin module 74 is disposed in a hole in the center of the jacket 73. The fin module 74 includes a large number of fins. The gaps between adjacent fins in the fin module 74 form a flow path 72 through which the first fluid FL1 flows. The fin module 74 exchanges heat with the jacket 73. If the fin module 74 has a large number of fins, the resistance to the vibration of the first fluid FL1 increases, so the number of fins may be small or may be absent.

The stack 80 is installed between the first heat exchanger 70 and the second heat exchanger 90 (see the upper right part of FIG. 1 and FIG. 2). The stack 80 is housed in a tube LT3 and has a number of through holes. These through holes form a flow path 82 through which the first fluid FL1 flows. The stack 80 is connected to the first heat exchanger 70 and the second heat exchanger 90 so that the first fluid FL1 can flow through it. The stack 80 generates a temperature gradient using vibration energy, which is a standing wave of sound waves transmitted through the first fluid FL1 in the loop tube LT1.

The heat pump HP operates as follows. In the flow path 82 of the stack 80, the first fluid FL1 oscillates with a standing wave. When the first fluid FL1 moves in a direction from near one end 89 of the stack 80 toward near the other end 88, the first fluid FL1 undergoes adiabatic expansion. As a result, the temperature of the first fluid FL1 decreases. In the vicinity of the other end 88 of the stack 80, the first fluid FL1 absorbs heat from the first heat exchanger 70. The object to be cooled, CO, is cooled via the first heat exchanger 70.

When the first fluid FL1 moves from near the other end 88 of the stack 80 toward near one end 89, the first fluid FL1 is adiabatically compressed. As a result, the temperature of the first fluid FL1 rises. The first fluid FL1 provides heat to the second heat exchanger 90 near one end 89 of the stack 80. The heat provided to the second heat exchanger 90 is released to the outside via the chiller of the second heat exchanger 90. As a result, the vicinity of one end 89 of the stack 80 is cooled by the transfer of heat due to the vibration of the first fluid FL1. Then, the cooling target CO is cooled via the first heat exchanger 70.

Figure 3 is an explanatory diagram showing the schematic configuration of the jacket 73 of the first heat exchanger 70. For convenience of illustration, the fin module 74 is omitted in Figure 3. The first heat exchanger 70 has an inlet pipe 75, an outlet pipe 79, a first flow path section 76, a second flow path section 78, a first branch flow path section 77a, and a second branch flow path section 77b.

The inlet pipe 75 is a pipe through which the second fluid FL2 flows into the first heat exchanger 70. The outlet pipe 79 is a pipe through which the second fluid FL2 flows out of the first heat exchanger 70.

The first flow path section 76 is an annular structure that constitutes the flow path 26 through which the second fluid FL2 flows. The first flow path section 76 is a pipe connected to the inlet pipe 75, and is a flow path through which the second fluid FL2 circulates. The first flow path section 76 is provided so as to surround at least a portion of the side surface of the first heat exchanger 70 in the circumferential direction. In this embodiment, the first flow path section 76 is disposed so as to surround one end 89 of the stack 80 (see the upper part of FIG. 2). The first flow path section 76 is in contact with the fin module 74. As a result, heat exchange is performed between the first fluid FL1 in the fin module 74 and the second fluid FL2 in the first flow path section 76 through the wall of the first flow path section 76 and the fin module 74.

The second flow path section 78 is an annular structure that constitutes the flow path 26 through which the second fluid FL2 flows. The second flow path section 78 is a pipe connected to the outlet pipe 79, and is provided so as to surround at least a part of the side of the first heat exchanger 70 in the circumferential direction at a position farther from the one end 89 than the first flow path section 76 (see the upper part of FIG. 2). In this embodiment, the second flow path section 78 is provided at a position farther from the one end 89 on the opposite side to the stack 80 than the first flow path section 76 (see the upper part of FIG. 2 and FIG. 3). The second flow path section 78 is provided away from the wall of the loop pipe LT2 through which the first fluid FL1 flows and the fin module 74. As a result, heat exchange is not performed between the first fluid FL1 in the loop pipe LT2 and the fin module 74 and the second fluid FL2 in the first flow path section 76.

The branch flow path section 77 has a first branch flow path section 77a and a second branch flow path section 77b. In this embodiment, the first branch flow path section 77a and the second branch flow path section 77b are collectively referred to simply as the "branch flow path section 77". The branch flow path section 77 is a flow path that connects the first flow path section 76 and the second flow path section 78. The second branch flow path section 77b is provided at a position farther from the connection part between the first flow path section 76 and the inlet pipe 75 than the first branch flow path section 77a in the direction in which the second fluid FL2 circulates in the first flow path section 76. The "position farther from the connection part of the inlet pipe 75" is measured from the connection part of the inlet pipe 75 along the direction in which the second fluid FL2 circulates in the first flow path section 76.

Figure 4 is a plan view of the first flow path section 76 when viewed along the axial direction (Z-axis direction) of the stack 80. The second fluid FL2 flows in from the inlet pipe 75 and circulates in the first flow path section 76 in the direction of the arrow K2. In this embodiment, the inlet pipe 75 is provided at a position where the second fluid FL2 flows in from the tangential direction of the first flow path section 76. This makes it easier to generate a flow in which the second fluid FL2 circulates in the first flow path section 76.

Figure 5 is an explanatory diagram showing the jacket 73 shown in Figure 3 cut at position V-V and developed. The flow of the second fluid FL2 circulating in the first flow path section 76 and the second flow path section 78 is shown as flowing to the right in Figure 5. For convenience of illustration, the outlet pipe 79 is shown by a dotted line at the right end of the second flow path section 78, not above the inlet pipe 75. In this embodiment, the second branch flow path section 77b has a different cross-sectional area perpendicular to the direction A2 in which the second fluid FL2 flows than the first branch flow path section 77a. The cross-sectional area of the second branch flow path section 77b is larger than the cross-sectional area perpendicular to the direction A1 in which the second fluid FL2 flows in the first branch flow path section 77a. By making the cross-sectional area of the second branch flow path section 77b larger than the cross-sectional area of the first branch flow path section 77a, the flow rate of the second fluid FL2 flowing from the first flow path section 76 to the second flow path section 78 via the second branch flow path section 77b becomes greater than the flow rate of the second fluid FL2 flowing from the first flow path section 76 to the second flow path section 78 via the first branch flow path section 77a.

The inclination of the first branch flow path section 77a with respect to the direction of flow of the second fluid FL2 in the first flow path section 76 and the inclination of the second branch flow path section 77b with respect to the direction of flow of the second fluid FL2 in the first flow path section 76 are both 90 degrees or less. The inclination d2 in the second branch flow path section 77b is smaller than the inclination d1 in the first branch flow path section 77a. By making the inclination d2 in the second branch flow path section 77b smaller than the inclination d1 in the first branch flow path section 77a, the flow rate of the second fluid FL2 flowing from the first flow path section 76 to the second flow path section 78 via the second branch flow path section 77b becomes greater than the flow rate of the second fluid FL2 flowing from the first flow path section 76 to the second flow path section 78 via the first branch flow path section 77a.

The first heat exchanger 70 in this embodiment has a first flow path section 76 connected to the inlet pipe 75 and through which the second fluid FL2 circulates, a second flow path section 78 connected to the outlet pipe 79, and one or more branch flow path sections 77 connecting the first flow path section 76 and the second flow path section 78. In this embodiment, the second fluid FL2 repeatedly circulates through the first flow path section 76, so that a larger amount of heat can be transferred between the first heat exchanger 70 and the second fluid FL2 without lengthening the flow path in the axial direction (Z-axis direction) of the stack 80, and the object can be cooled by the second fluid FL2 flowing out of the second flow path section 78. Therefore, the efficiency of energy conversion of the thermoacoustic device can be improved.

In addition, in this embodiment, the second branch flow path section 77b has a cross-sectional area perpendicular to the direction in which the second fluid FL2 flows that is different from that of the first branch flow path section 77a. By changing the cross-sectional area of each branch flow path section 77, the flow rate of the second fluid FL2 circulating through the first flow path section 76 and the second fluid FL2 flowing into the second flow path section 78 can be changed. Therefore, the cross-sectional size of each branch flow path section 77 can be determined according to the desired temperature. As a result, the temperature of the second fluid FL2 in the second flow path section 78 can be set to the desired temperature.

In addition, in this embodiment, the inclination d2 of the second branch flow path portion 77b is different from the inclination d1 of the first branch flow path portion 77a. By changing the inclination of each branch flow path portion 77, the flow rate of the second fluid FL2 circulating through the first flow path portion 76 and the second fluid FL2 flowing into the second flow path portion 78 can be changed. Therefore, the inclination of each branch flow path portion 77 can be determined according to the desired temperature. As a result, the temperature of the second fluid FL2 in the second flow path portion 78 can be set to the desired temperature.

The first flow path section 76 is also arranged to surround one end 89 of the stack 80. Therefore, the second fluid FL2 circulates through the same cross section on the one end 89 side of the stack 80. In other words, the first flow path section 76 is arranged to surround the one end 89 of the stack 80, which is the coldest, thereby improving the efficiency of thermal energy transfer in the thermoacoustic device.

B. Other embodiments:
(B1) In the above embodiment, the second flow path portion 78 is provided at a position farther away from the one end 89 on the opposite side to the stack 80 than the first flow path portion 76. In other words, it is provided on the +Z axis side than the first flow path portion 76. However, the second flow path portion 78 may be provided at a position farther away from the one end 89 on the stack 80 side (−Z axis side) than the first flow path portion 76, or may be provided on the outer periphery of the first flow path portion 76.

(B2) FIG. 6 is a plan view showing a schematic configuration of the first heat exchanger 70 in another embodiment. In the above embodiment, the first heat exchanger 70 may have a parallel plate PP instead of the fin module 74 as shown in FIG. 6. The parallel plate PP forms the first flow path portion 76 in the pipe axial cross section. The first heat exchanger 70 may also have a fin module 74 and a parallel plate PP provided as part of the fins in the fin module 74. This extends the length over which the second fluid FL2 circulates in the first flow path portion 76, allowing a greater amount of heat to be transferred between the first heat exchanger 70 and the second fluid FL2.

(B3) In the above embodiment, the first heat exchanger 70 has two branch flow passage sections 77. This is not limited to the above, and the first heat exchanger 70 may have three or more branch flow passage sections 77, such as four. Also, the first heat exchanger 70 may have only one branch flow passage section 77.

(B4) In the above embodiment, the cross-sectional area of the second branch flow path portion 77b is larger than the cross-sectional area of the first branch flow path portion 77a. Not limited to this, the cross-sectional area of the second branch flow path portion 77b may be smaller than or the same as the cross-sectional area of the first branch flow path portion 77a. Also, in the above embodiment, the inclination d2 of the second branch flow path portion 77b is smaller than the inclination d1 of the first branch flow path portion 77a. Not limited to this, the inclination d2 of the second branch flow path portion 77b may be larger than or the same as the inclination d1 of the first branch flow path portion 77a.

(B5) In the above embodiment, the branch flow path section 77 may be provided with a flow rate control valve. With this configuration, the first heat exchanger 70 can determine the flow rate of the second fluid FL2 circulating through the first flow path section 76 and the second fluid FL2 flowing into the second flow path section 78.

The present disclosure is not limited to the above-described embodiments, and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features of the embodiments corresponding to the technical features in each form described in the Summary of the Invention column can be replaced or combined as appropriate to solve some or all of the above-described problems or to achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate.

20...third heat exchanger, 30...stack, 32...flow path, 38...one end, 39...other end, 40...fourth heat exchanger, 70...first heat exchanger, 72...flow path, 73...jacket, 74...fin module, 75...inlet piping, 76...first flow path section, 77...branch flow path section, 77a...first branch flow path section, 77b...second branch flow path section, 78...second flow path section, 79...outlet piping, 80...stack, 82...flow path, 88...other end, 89...one end, 90...second heat exchanger, 92...flow path, 93...jacket, 94...fin module, 96...flow path, CO...cooling target, FL1...first fluid, FL2...second fluid, FL3...third fluid, HP...heat pump, HS...heat source, LT1, LT2...loop tube, PA...piping structure, PM...motor, PP...parallel plate, TA...thermoacoustic device

Claims (6)

1. A thermoacoustic device comprising:
a stack that generates a temperature gradient using vibration energy supplied via a first fluid;
a first heat exchanger disposed at one end of the stack and cooled via the first fluid;
a second heat exchanger disposed at the other end of the stack and configured to maintain a constant temperature of the first fluid near the other end of the stack;
The first heat exchanger is
an inlet pipe through which a second fluid flows into the first heat exchanger;
an outlet pipe through which the second fluid exits the first heat exchanger;
a first flow path portion provided to circumferentially surround at least a portion of a side surface of the first heat exchanger and connected to the inlet pipe, through which the second fluid circulates;
a second flow path portion provided to surround at least a portion of a side surface of the first heat exchanger in a circumferential direction at a position farther from the one end than the first flow path portion and connected to the outlet pipe;
A thermoacoustic device having one or more branch flow path sections connecting the first flow path section and the second flow path section. 2. The thermoacoustic device of claim 1,
The one or more branch flow path portions are
A first branch flow path portion;
a second branch flow path section that is provided at a position farther from the connection portion of the inlet piping than the first branch flow path section in the direction in which the second fluid circulates within the first flow path section, and has a cross-sectional area perpendicular to the direction in which the second fluid circulates that is different from that of the first branch flow path section. 3. The thermoacoustic device according to claim 2,
A thermoacoustic device, wherein the cross-sectional area of the second branch passage portion is larger than the cross-sectional area of the first branch passage portion. 3. The thermoacoustic device according to claim 2,
A thermoacoustic device, wherein the cross-sectional area of the second branch passage portion is smaller than the cross-sectional area of the first branch passage portion. A thermoacoustic device according to any one of claims 2 to 4,
the second branch flow path portion has an inclination with respect to a flow direction of the second fluid in the first flow path portion different from the inclination with respect to the flow direction of the second fluid in the first branch flow path portion,
A thermoacoustic device, wherein the inclinations of the first branch flow path section and the second branch flow path section are both 90 degrees or less. A thermoacoustic device according to any one of claims 1 to 5,
A thermoacoustic device, wherein the first flow path portion is arranged to surround the one end of the stack.

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