JP5446498B2 - Thermoacoustic engine - Google Patents

Description

  The present invention relates to a loop tube type thermoacoustic engine, and more particularly to a thermoacoustic engine that can excite a large amount of acoustic intensity in a loop tube and has a small oscillation temperature difference.

  In order to extract energy from waste heat, research and development of Stirling engines have been actively conducted. There are various types of Stirling engines, such as α type, β type, γ type, and free piston type. On the other hand, recently, research and development of a thermoacoustic engine having a simple structure and no moving parts such as pistons has been actively conducted mainly in the United States.

  If a regenerator with thin plates or thin tubes bundled in a tube and a heater or cooler is installed at each end to give a temperature difference (the air column in the tube is heated or cooled locally), heat energy Is converted into mechanical energy, the air column in the tube undergoes self-excited vibration, and sound waves (acoustic vibration) are generated. This action can be seen thermodynamically as a prime mover. A thermoacoustic engine uses this phenomenon.

  Conversely, when a sound wave is applied to one end of the tube, a temperature difference occurs between both ends of the regenerator sandwiched between the heater and the cooler. By utilizing this phenomenon, it is possible to realize a refrigeration apparatus (cooling apparatus) and a temperature raising apparatus.

  As shown in FIG. 3, a conventional thermoacoustic engine 31 includes a prime mover 35 including a cooler (low temperature side heat exchanger) 32, a regenerator (heat accumulator, stack) 33, and a heater (high temperature side heat exchanger) 34. Is generally included in the loop pipe 36 (see, for example, Patent Documents 1 and 2). When a passive machine (refrigerator, cooler) that converts vibrations of the air column into heat energy is incorporated in the thermoacoustic engine 31, a thermoacoustic refrigerator is configured.

  The thermoacoustic engine is applied to a cooling device for a living room and a refrigeration / freezing device for articles in a building or a moving body. For example, when the thermoacoustic engine 31 is mounted on a vehicle, the engine exhaust heat is supplied to the heater 34 of the prime mover 35 as a high temperature source, the atmosphere is supplied to the cooler 32 of the prime mover 35 as a low temperature source, and the passive machine By supplying air to the high temperature side heat exchanger as a high temperature source, it is possible to extract a cold output having a temperature lower than that of the atmosphere from the low temperature side heat exchanger side of the passive device. Using this cold output, for example, various coolers mounted on the vehicle (for example, a cooling air conditioner, an oil cooler, a canister, etc.) can be functioned.

Japanese Patent No. 3050543 JP 2006-149176 A

  However, in the loop tube type thermoacoustic engine 31 as shown in FIG. 3, the heat exchanger (cooler 32, heater 34), which is a sound wave generation source, is always located at the antinode of the sound pressure (the antinode of the standing wave). Resulting in. At the antinode of sound pressure, large heat exchange cannot be performed because the fluid displacement is minute. Therefore, the conventional thermoacoustic engine 31 formed only by the loop tube 36 cannot exert a large output.

  Further, in order to generate self-excited oscillation by the prime mover 35 in the thermoacoustic engine 31, when the low temperature source supplied to the cooler 32 is the atmosphere, a heat source of about 300 ° C. is required as the high temperature source supplied to the heater 34. Become. However, considering the use of a low-temperature heat source, it is desirable that the oscillation temperature difference is small. The oscillation temperature difference is a temperature difference between the cooler 32 and the heater 34 when the prime mover 35 generates self-excited oscillation.

  Accordingly, an object of the present invention is to provide a thermoacoustic engine that can excite a large amount of acoustic intensity in a loop tube and has a small oscillation temperature difference.

  The present invention was devised to achieve the above object, and a thermoacoustic provided with a prime mover comprising a heater, a heat accumulator, and a cooler that converts thermal energy into acoustic energy in the loop tube. The engine is a thermoacoustic engine in which a reduction pipe is provided in the loop pipe.

  The contraction pipe may be provided at a position of 30 to 35% or 80 to 85% of the total length of the loop pipe from the heater side of the prime mover starting from a position where the prime mover of the loop pipe is provided. .

  The vibration mode is n-order (n is a natural number of 1 or more), and the reduction tube divides the loop tube into n equal parts starting from the position where the prime mover of the loop tube is provided. It may be provided at a position of 30 to 35% or 80 to 85% from the heater side of the prime mover.

  According to the present invention, it is possible to provide a thermoacoustic engine that can excite a large amount of acoustic intensity in a loop tube and has a small oscillation temperature difference.

It is a figure which shows the thermoacoustic engine which concerns on one embodiment of this invention, (a) is a block diagram, (b) is the expanded view. In this invention, it is a graph which shows the change of the oscillation temperature difference when the position of a reduction tube is changed. It is a block diagram of the conventional thermoacoustic engine.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

  Fig.1 (a) is a block diagram of the thermoacoustic engine which concerns on this Embodiment.

  As shown in FIG. 1A, the thermoacoustic engine 1 is provided with a prime mover 3 that converts thermal energy into acoustic energy in the loop tube 2 in the loop tube 2.

  The prime mover 3 includes a cooler 4, a regenerator 5, and a heater 6 arranged in the tube axis direction of the loop tube 2. Since the detailed structures of the cooler 4, the regenerator 5, and the heater 6 belong to the prior art, they are omitted here.

  In the thermoacoustic engine 1, a reduction tube 7 is provided in the loop tube 2. The diameter of the reduction tube 7 is formed smaller than the diameter of the loop tube 2, and is formed, for example, about half the diameter of the loop tube 2. Both end portions of the reduction tube 7 are formed in a tapered shape so that the diameter gradually increases toward the connection portion with the loop tube 2.

  The reduction pipe 7 starts from the position where the prime mover 3 of the loop pipe 2 is provided (the center position in the pipe axis direction of the regenerator 5), and is 30 to 35% of the total length of the loop pipe 2 from the heater 6 side of the prime mover 3. It is provided at position A or position B of 80 to 85%. FIG. 1A shows a case where the reduction tube 7 is provided at a position B that is 80 to 85% of the entire length of the loop tube 2.

  The length of the reduction tube 7 (the length in the tube axis direction) is, for example, about 3% of the entire length of the loop tube 2. The contraction tube 7 is provided in the loop tube 2 so that the center in the tube axis direction is the positions A and B described above.

  In the thermoacoustic engine 1 of FIG. 1A, a development view in which the loop tube 2 is developed linearly is shown in FIG. In FIG. 1B, the reduction tube 7 is omitted.

  As shown in FIG. 1B, the reduction tube 7 has a range of 6/20 to 7/20 from the position where the prime mover 3 is provided to the heater 6 side when the loop tube 2 is divided into 20 in the tube axis direction. Is located at either position A or position B in the range of 16/20 to 17/20. It should be noted that only one reduction tube 7 has to be attached at either position A or B.

  Here, the reason why the position where the reduction tube 7 is provided is 30 to 35% of the total length of the loop tube 2 or 80 to 85% of the position B will be described.

  The oscillation temperature when the total length of the loop tube 2 is about 3000 mm, the position at which the reduction tube 7 is provided (reduction tube position; distance from the center position of the regenerator 5) is changed, and the reduction tube 7 is provided at each position. The difference (temperature difference between the cooler 4 and the heater 6 when the prime mover 3 generates self-excited oscillation) was measured. The measurement results are shown in FIG.

  As shown in FIG. 2, it can be seen that the oscillation temperature difference becomes the smallest when the reduction tube 7 is provided at a position of about 1000 mm from the center position of the regenerator 5 or at a position of 2500 mm. That is, when the reduction tube 7 is provided at the position A of 30 to 35% of the entire length of the loop tube 2 or the position B of 80 to 85%, the oscillation temperature difference becomes the smallest.

  As described above, in the thermoacoustic engine 1 according to the present embodiment, the position where the prime mover 3 of the loop pipe 2 is provided as a starting point, and 30 to 35% of the total length of the loop pipe 2 from the heater 6 side of the prime mover 3. The contraction tube 7 is provided at the position A or 80 to 85% of the position B.

  As described above, in the conventional thermoacoustic engine, the heat exchanger, which is a sound wave generation source, is always located at the antinode of the sound pressure, and thus it has not been possible to perform large heat exchange with the heat exchanger.

  In the thermoacoustic engine 1, the reduction tube 7 is provided at any one of the above-described positions A and B of the loop tube 2, so that the flow velocity of the working fluid enclosed in the loop tube 2 is only at the portion where the reduction tube 7 is provided. Get faster. As a result, the phase of the sound pressure in the steady state (the phase of the standing wave) changes, and the heat exchanger (the cooler 4 and the heater 6) is not positioned at the antinode of the sound pressure (the antinode of the standing wave). . That is, it is possible to maintain an appropriate fluid displacement in the heat exchangers 4 and 6, and the fluid displacement of the working fluid in the heat exchangers 4 and 6 increases. Therefore, large heat exchange can be performed in the heat exchanger, energy conversion efficiency is improved, and a large amount of acoustic intensity can be excited in the loop tube 2.

  Therefore, when a passive machine is incorporated in the thermoacoustic engine 1 and used as a thermoacoustic refrigeration apparatus, a low temperature can be realized as compared with the conventional one. Further, when a generator for converting acoustic energy into electric energy is incorporated in the thermoacoustic engine 1 and used as a thermoacoustic power generator, the amount of power generation can be improved as compared with the conventional case.

  Further, according to the thermoacoustic engine 1, since the reduction tube 7 is provided at any one of the above-described positions A and B of the loop tube 2, it is possible to greatly reduce the oscillation temperature difference, and with a small amount of input energy. Oscillation is possible. Therefore, the entire apparatus can be reduced in size, and the volume of the entire apparatus can be reduced.

  In the above embodiment, the case where the vibration mode is the first order has been described. However, when the vibration mode is used in the first or higher order n order (n is a natural number of 1 or more), the position where the prime mover 3 of the loop pipe 2 is provided. The loop tube 2 is divided into n equal to the starting point, and the reduced tube 7 may be provided at a position of 30 to 35% or 80 to 85% from the heater 6 side of the prime mover 3 of the divided loop tube 2. . The reduction tube 7 does not need to be provided for each of the divided loop tubes 2 and may be provided for the entire loop tube 2.

1 Thermoacoustic engine 2 Loop pipe 3 Motor 4 Cooler 5 Regenerator 6 Heater 7 Reduced pipe

Claims (2)

In a thermoacoustic engine provided with a prime mover composed of a heater, a heat accumulator, and a cooler that converts heat energy into acoustic energy in the loop tube,
A reduction pipe is provided in the loop pipe ,
The contraction pipe is provided at a position of 30 to 35% or 80 to 85% of the total length of the loop pipe from the heater side of the prime mover starting from the position where the prime mover of the loop pipe is provided. A thermoacoustic engine. In a thermoacoustic engine provided with a prime mover composed of a heater, a heat accumulator, and a cooler that converts heat energy into acoustic energy in the loop tube,
A reduction pipe is provided in the loop pipe,
The vibration mode is n-order (n is a natural number of 1 or more),
The reduction pipe divides the loop pipe into n starting from the position where the prime mover of the loop pipe is provided, and is 30 to 35%, or 80 to 85% from the heater side of the prime mover of the divided loop pipe. A thermoacoustic engine provided at a position.

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