JP5786658B2 - Thermoacoustic engine - Google Patents

Description

  The present invention relates to a thermoacoustic engine capable of improving the engine output of a thermoacoustic engine by reducing the amount of reflection of sound waves at a connection portion between a heat exchanger used as a heater and a cooler of a thermoacoustic engine and a resonance unit. About.

  Recently, research and development of thermoacoustic engines using thermoacoustic phenomena have been progressing. This thermoacoustic engine utilizes a thermoacoustic phenomenon in which the oscillating fluid in the narrow channel with a temperature gradient performs a thermodynamic process of compression, expansion, heating, and cooling, as shown in FIG. The thermoacoustic engine 10 includes a resonating unit 11 such as a loop tube, a regenerator 12 formed of an aggregate (stack) of thin tube channels, and a heater 13 and a cooler 14 disposed at both ends of the regenerator 12, respectively. And a working fluid G such as air, nitrogen, or helium, and can convert energy between heat and sound waves with a remarkably simple structure.

  8 to 10 show the structures of the heater 13X and the cooler 14X of the first thermoacoustic engine 10X of the prior art. The heater 13X includes a wall surface 13a of the tubular body of the heater 13X, outer peripheral fins 13b, and inner peripheral fins 13c. The wall surface 13a of the tubular body is formed in a cylindrical shape with the same diameter as the resonance portion 11, and the outer peripheral fins 13b are formed of concentric circular ring-shaped thin plates. The wall surface 13a of the tubular body is formed outside the wall surface 13a of the tubular body. Are arranged in a row in the axial direction. The inner peripheral fins 13c are formed of flat thin plates arranged in parallel with a gap in the wall surface 13a of the tubular body, and are arranged in parallel extending in the axial direction of the wall surface 13a of the tubular body.

  Similarly to the heater 13X, the cooler 14X is formed by including a wall surface 14a of the tubular body, outer peripheral fins 14b, and inner peripheral fins 14c, and has the same structure as the heater 13X. Between the heater 13X and the cooler 14X, a regenerator 12X formed by a heat accumulator (stack) such as a laminated wire mesh is disposed.

  In this thermoacoustic engine 10X, in the heater 12X, the outer peripheral fin 13a receives heat from the outside, and the inner peripheral fin 13b transfers heat to the working fluid G. On the other hand, in the cooler 14X, heat is received from the working fluid G by the inner peripheral fins 13a and radiated by the outer peripheral fins 13b.

  In the thermoacoustic engine 10X having the configuration shown in FIGS. 8 to 10, the cross-sectional area of the flow path is reduced by the inner peripheral fins 13c and 14c. Therefore, as shown in the lower part of FIG. The cross-sectional area of the flow path is reduced at P1, the cross-sectional area of the flow path is slightly increased at the part P2 entering the regenerator 12X from the heater 13X, and the cross-sectional area of the flow path is reduced at the part P4 entering the cooler 14X from the regenerator 12. The cross-sectional area of the flow path becomes large at the portion P2 entering the resonance portion 11 from the cooler 14X. That is, there is a large change in the cross-sectional area of the flow path between the portion P1 entering the heater 13X from the resonance portion 11 and the portion P2 entering the resonance portion 11 from the cooler 14X.

  If there is a large change in the cross-sectional area of the flow path in the part P1 entering the heater 13X from the resonance part 11 and the part P2 entering the resonance part 11 from the cooler 14X, many sound waves are reflected by the parts P1 and P2. Therefore, there is a problem that the output of the thermoacoustic engine 10X is lowered.

  In other words, in the thermoacoustic engine, when a sound wave is reflected, a standing wave is excited from the traveling wave, while the thermodynamic cycle of the thermoacoustic engine is realized by the traveling wave. When the ratio is lowered due to the generation of the standing wave, the output of the thermoacoustic engine 10Y is lowered.

  On the other hand, as shown in FIGS. 11 to 13, in order to reduce the change in the cross-sectional area at the connection portions P <b> 1 and P <b> 2 between the heater 13 </ b> Y or the cooler 14 </ b> Y and the resonance unit 11, The thermoacoustic engine 10Y that reduces the cross-sectional area change by enlarging the inner diameters of the 12Y and the cooler 14Y has been considered. The configurations of the regenerator 12Y, the heater 13Y, and the cooler 14Y of the conventional thermoacoustic engine 10Y are the same as those of the regenerator 12X, the heater 13X, and the cooler 14X of the conventional thermoacoustic engine 10X of FIGS. Although it is the same as a structure, the internal diameter is large.

  Therefore, in the thermoacoustic engine 10Y configured as shown in FIGS. 11 to 13, the flow path cross-sectional area is reduced by the inner peripheral fins 13c and 14c, but the inner diameter is increased, so as shown in the lower part of FIG. The flow path cross-sectional area is slightly increased at the part P1 entering the heater 13Y from the resonance unit 11, and the flow path cross-sectional area is further increased at the part P3 entering the regenerator 12Y containing the heat accumulator, from the regenerator 12Y to the cooler 14Y. The flow path cross-sectional area becomes smaller at the portion P4 that enters, and the flow path cross-sectional area that further enters the resonance portion 11 from the cooler 14Y becomes smaller.

  That is, a large change in the flow path cross-sectional area still occurs in the portion P1 entering the heater 13X from the resonance portion 11 and the portion P2 entering the resonance portion 11 from the cooler 14X. Therefore, many sound waves are reflected by these parts P1 and P2, and the problem that the output of the thermoacoustic engine 10Y falls remains unsolvable.

  In connection with this problem, in order to provide a thermoacoustic engine having a small change in the cross-sectional area of the flow path, the present inventors have provided the opposite side of the cooler from the heater connection where the heater is connected to the acoustic cylinder. The flow path of the working fluid is formed with a plurality of thin tubes up to the cooler connection part to which the acoustic cylinder is connected, and a plurality of thin tubes are arranged at intervals from the heater to the regenerator to the cooler. In the heater connection portion and the cooler connection portion, the interval between the plurality of thin tubes is gradually narrowed toward the acoustic tube, and the plurality of thin tubes are arranged in close contact with each other until reaching the acoustic tube. A thermoacoustic engine has been proposed in which the difference between the flow path cross-sectional area and the total flow cross-sectional area of the plurality of thin tubes is equal to or less than a predetermined value (see, for example, Patent Document 1).

JP 2011-122567 A

  The present invention has been made in view of the above situation, and its purpose is to prevent a change in the flow path cross-sectional area from increasing at the connecting portion between the heater or cooler of the thermoacoustic engine and the resonance portion. Thus, an object of the present invention is to provide a thermoacoustic engine that can reduce the amount of sound waves reflected at the connecting portion and suppress a decrease in output of the thermoacoustic engine due to reflection of sound waves.

  The thermoacoustic engine of the present invention for achieving the above object is a thermoacoustic engine comprising a heater, a cooler, a regenerator, a resonance part, and a working fluid. And forming a wall surface on which the inner peripheral fins of the heater are arranged in a tapered shape so as to be arranged between the resonance unit and the regenerator, The wall surface on which the inner peripheral fins of the cooler are arranged is formed in a tapered shape and is arranged between the regenerator and the resonance unit.

  According to this configuration, it is possible to prevent a change in the cross-sectional area of the flow path from becoming large at the connection portion between the heater or the cooler of the thermoacoustic engine and the resonance portion, thereby reducing the amount of sound waves reflected at this connection portion. It is possible to suppress a decrease in the output of the thermoacoustic engine due to the reflection of sound waves.

  Furthermore, since the shape of the heater in which the inner peripheral fin is arranged becomes a tapered shape, the area of connection or contact between the heating surface and the inner peripheral fin increases, and the shape of the cooler in which the inner peripheral fin is arranged is also increased. Because of the tapered shape, the area of connection or contact between the cooling surface and the inner peripheral fins increases, and the efficiency of heat transfer increases.

  In the above-described thermoacoustic engine, the outer peripheral wall surface to which the inner peripheral fin of the heater is connected or contacted is formed in a tapered shape, and the inner side of the inner peripheral fin assembly is a cone having a tapered large diameter side as a tip. In addition to forming the shape of the tapered shape on the small diameter side, the outer peripheral wall surface to which the inner peripheral fin of the cooler is connected or in contact is formed in a tapered shape, and the inner side of the inner peripheral fin assembly is If the conical shape with the tapered diameter on the large-diameter side is formed into a shape that is hollowed out to the small-diameter side of the tapered shape, the cross-sectional area of the flow path changes inside the heater and the cooler with a relatively simple configuration. Can be suppressed.

  In the thermoacoustic engine, if a cooling jacket is provided on the outer periphery of the cooler, the cooler can be cooled with a relatively simple configuration.

  According to the thermoacoustic engine of the present invention, it is possible to prevent a change in the flow path cross-sectional area from increasing at the connection portion between the heater or cooler of the thermoacoustic engine and the resonance portion, and to be reflected at this connection portion. The amount of sound waves can be reduced, and a decrease in output of the thermoacoustic engine due to reflection of sound waves can be suppressed.

It is a figure which shows the structure of a thermoacoustic engine. It is a figure which shows the external shape of the thermoacoustic engine of embodiment which concerns on this invention. It is a cross-sectional view which shows the structure inside the thermoacoustic engine of FIG. It is an assembly drawing which shows the structure of the thermoacoustic engine of FIG. It is a figure which shows the raw material of the heat exchanger used as the heater or cooler of the thermoacoustic engine of FIG. It is a figure which shows the inner peripheral fin of the heat exchanger of FIG. It is a figure which shows the structure of the thermoacoustic engine of FIG. 2, and the change of flow-path cross-sectional area. It is a perspective view which shows the structure of the thermoacoustic engine of a prior art. It is a cross-sectional view showing the configuration of the inner peripheral fins of the heater and cooler of the thermoacoustic engine of FIG. It is a figure which shows the structure of the thermoacoustic engine of FIG. 8, and the change of a flow-path cross-sectional area. It is a perspective view which shows the structure of the other thermoacoustic engine of a prior art. It is a cross-sectional view which shows the structure of the inner peripheral fin of the heater and cooler of the thermoacoustic engine of FIG. It is a figure which shows the structure of the thermoacoustic engine of FIG. 11, and the change of a flow-path cross-sectional area.

  Hereinafter, a thermoacoustic engine according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the thermoacoustic engine 10 includes a resonance unit 11 formed by a loop tube or the like, a regenerator 12, a heater 13 and a cooler 14 disposed at both ends of the regenerator 12, and It is composed of a working fluid G such as air, nitrogen, helium, or argon, and performs energy conversion between heat and sound waves by a thermoacoustic phenomenon with a remarkably simple structure.

  The inside of the resonance unit 11 is filled with the working fluid G, and the length and diameter of the resonance unit 11 are determined so as to resonate with the self-excited vibration of the enclosed gaseous working fluid G. In addition, the regenerator 12 is formed of a stack of heat accumulators such as an assembly of thin tube flow paths or a wire mesh. The heater 13 is configured as a heat exchanger for receiving the heat from the outside of the thermoacoustic engine 10 and heating the working fluid G, and the cooler 14 releases the heat to the outside of the thermoacoustic engine 10 to generate the working fluid G. It is configured as a heat exchanger for cooling.

  In this thermoacoustic engine 10, the air column in the narrow channel of the regenerator 12 is locally heated by the heater 13 or locally cooled by the cooler 14, and the temperature of the air column in the regenerator 12 is increased. When a gradient is generated, a part of thermal energy is converted into dynamic sound wave (vibration) energy by a thermoacoustic phenomenon in which the air column causes self-excited vibration. In other words, the working fluid G in the stack of the regenerator 12 experiences a thermodynamic process such as heating by the heater 13, cooling by the cooler 14, and self-excited oscillation of expansion and compression, thereby causing a heat called a Stirling cycle. By repeating the mechanical cycle, heat energy is converted into sonic energy. This sound wave energy resonates in the resonance part 11 and is stored in the resonance part 11 as a standing wave.

  In the present invention, as shown in FIGS. 2 to 7, the cross-sectional area inside the regenerator 12 is formed larger than the cross-sectional area inside the resonance part 11. With this configuration, the flow path cross-sectional area R12 of the regenerator 12 and the flow path cross-sectional area R11 of the resonance unit 11 are made substantially the same, preferably the same. At the same time, the wall surface 13 a on which the inner peripheral fins 13 c of the heater 13 are disposed is formed in a tapered shape and disposed between the resonance unit 11 and the regenerator 12. Further, the wall surface 14 a on which the inner peripheral fin 14 c of the cooler 14 is disposed is formed in a tapered shape, and is disposed between the regenerator 12 and the resonance unit 11.

  Further, a cooling jacket 15 is provided around the cooler 14 so that cooling water (heat medium) W flows around the outer periphery of the cooler 14, and heat is exchanged between the working fluid G and the cooling water W. Configured as follows. The cooling water W that has risen in temperature due to heat exchange of the cooler 14 goes to a radiator (not shown) via a circulation path 15b connected to the circulation port 15a, and exchanges heat between the cooling water W and outside air. To do. Thereby, the cooler 14 can be cooled with a relatively simple configuration.

  Furthermore, as shown in FIGS. 2 to 4, the outer peripheral wall surface 13 a to which the inner peripheral fin 13 c of the heater 13 is connected (or contacted) is formed in a tapered shape. Further, the inner side of the aggregate of the inner peripheral fins 13c is formed in a shape in which a conical shape having a tapered large diameter side as a tip is hollowed out to a small diameter side of the tapered shape.

  Moreover, the outer peripheral wall surface 14a to which the inner peripheral fin 14c of the cooler 14 is connected (or contacted) is formed in a tapered shape. Further, the inner side of the aggregate of the inner peripheral fins 14c is formed in a shape in which a conical shape having a tapered large diameter side as a tip is hollowed out to a small diameter side of the tapered shape.

  The structure of the heat exchanger 16 of the heater 13 and the cooler 14 is such that the outer peripheral surface 16d having a truncated cone shape as shown in FIG. 5 and a conical shape having a tapered large-diameter side B at the tip are tapered small diameters. As shown in FIG. 6, a gap through which the working fluid G can circulate is provided by using a material 16 having an inner peripheral surface 16 e cut out on the side A and using a wire cutter or the like. Thereby, the inner peripheral fin 16c is formed. That is, a plurality of sets (eight sets in FIG. 6) of the inner peripheral fins 16c arranged in parallel and having the large-diameter side B fixed thereto are arranged in the circumferential direction R.

  With this configuration, the heat exchanger 16 (13, 14) allows the small diameter side A and the large diameter side B to communicate with each other through a gap provided between the inner peripheral fins 16c (13c, 14c). Can be distributed. At the same time, heat is transferred between the working fluid G and the inner peripheral fin 16c, and in the heater 13, heat is transferred from the inner peripheral fin 16c (13c) to the working fluid G. The heat is transferred from the working fluid G to the inner peripheral fins 16c (14c).

  At the same time, with respect to the cross-sectional area of the flow path, the tip end side of the inner peripheral fin 16c is on the small diameter side A, and here, the total F (a) of the cross sectional area of the inner peripheral fin 16c is zero. The total cross-sectional area F (x) of the inner peripheral fin 16c increases toward the large-diameter side B, and the total cross-sectional area F (b) of the inner peripheral fin 16c reaches the base side of the inner peripheral fin 16c. Is the maximum.

  On the other hand, the outer peripheral wall surface of the heat exchanger 16 is tapered, and the outer peripheral surface 16d of the aggregate of the inner peripheral fins 16c is also tapered, so that the cross-sectional area of the heat exchanger 16 is on the small diameter side A. The cross-sectional area S (a) is minimized, the cross-sectional area S (x) increases from the small-diameter side A toward the large-diameter side B, and the cross-sectional area S (b) becomes the base side of the inner peripheral fin 16c. Maximum.

  Since the difference between the two is the flow path cross-sectional area R (x) (= S (x) −F (x)), the difference between the two (S (x) −F (x)) is constant. Thus, by setting the width of the gap and the tapered shape of the outer peripheral surface 16d and the inner peripheral surface 16e, the flow path cross-sectional area R (x) can be made constant.

  For example, if the ratio of the clearance in the cross-sectional area is Y% and the ratio of the inner peripheral fin 16 is (100−Y)%, the radius of the small diameter side A is r1 and the radius of the large diameter side B is r2. For example, the cross-sectional areas are “S (a) = π × r1 × r1 / 4” and “S (b) = π × r2 × r2 / 4”, and “S (b) × (1−Y / 100). ) = S (a) ”becomes“ r2 = r1 / SQRT (1-Y / 100) ”.

  Thus, it is possible to suppress the flow path cross-sectional area R (x) from changing inside each of the heater 13 and the cooler 14 with a relatively simple configuration.

  Moreover, since the shape of the heater 13 in which the inner peripheral fins 13c are arranged becomes a tapered shape, the area where the wall surface 13a serving as the heating surface and the inner peripheral fins 13c are connected (or contacted) increases, and the inner periphery Since the shape of the cooler 14 in which the fins 14c are arranged is also tapered, the area where the wall surface 14a serving as the cooling surface and the inner peripheral fin 14c are connected (or contacted) increases, and the efficiency of heat transmission increases. .

Further, the flow path cross-sectional area R (b) on the small diameter side A of the heat exchanger 16 (13, 14) is made the same as the flow path cross sectional area R11 of the resonance portion 11, and the flow path on the large diameter side B The cross-sectional area R (a) is formed to be the same as the flow path cross-sectional area R12 of the regenerator 12. Thus, when the radius r1 of the small diameter side A and the radius r2 of the large diameter side B are determined, the ratio Y (%) of the cross-sectional area occupied by the gap between the inner peripheral fins 16c is “Y = 100 × ( 1- (r1 / r2) ² ) ".

  According to this configuration, as shown in FIG. 7, it is possible to prevent a change in the flow path cross-sectional area from increasing at the connection portions P <b> 1 and P <b> 2 between the heater 13 or the cooler 14 of the thermoacoustic engine 10 and the resonance portion 11. Thus, it is possible to reduce the amount of the sound wave reflected by the connection portions P1 and P2, and to suppress a decrease in the output of the thermoacoustic engine 10 due to the reflection of the sound wave.

  The thermoacoustic engine of the present invention prevents the change in the cross-sectional area of the flow path from becoming large at the connection portion between the heater or cooler of the thermoacoustic engine and the resonance portion, and the amount of sound waves reflected at this connection portion. Can be used in many thermoacoustic engines.

DESCRIPTION OF SYMBOLS 10 Thermoacoustic engine 11 Resonance part 12 Regenerator 13 Heater 13a Wall surface 13b Outer peripheral fin 13c Inner peripheral fin 14 Cooler 14a Outer surface fin 14c Inner peripheral fin 15 Cooling jacket G Working fluid W Cooling water

Claims (3)

  In a thermoacoustic engine including a heater, a cooler, a regenerator, a resonance part, and a working fluid, a cross-sectional area inside the regenerator is formed larger than a cross-sectional area inside the resonance part, and the heater The wall surface on which the inner peripheral fin is disposed is formed in a taper shape, and is disposed between the resonance portion and the regenerator, and the wall surface on which the inner peripheral fin of the cooler is disposed is formed in a taper shape. The thermoacoustic engine is disposed between the regenerator and the resonance unit.   The outer peripheral wall surface to which the inner peripheral fin of the heater is connected or brought into contact is formed in a tapered shape, and the inner side of the inner peripheral fin assembly is formed in a tapered shape on the small diameter side with a tapered large diameter side at the tip. In addition, the outer peripheral wall surface to which the inner peripheral fin of the cooler is connected or in contact is formed in a tapered shape, and the inner side of the aggregate of the inner peripheral fin is the tip of the tapered large diameter side 2. The thermoacoustic engine according to claim 1, wherein the conical shape is formed into a shape in which the tapered shape is hollowed out toward the small diameter side.   The thermoacoustic engine according to claim 1, wherein a cooling jacket is provided on an outer peripheral portion of the cooler.

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