Traveling Wave Thermoacoustic Engine in a Looped Tube

Yazaki, Taichi; Iwata, Atsunobu; Maekawa, Takuya; Tominaga, Akira

doi:10.1103/physrevlett.81.3128

Cited by 350 publications

(229 citation statements)

References 16 publications

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“…For the convenience of further discussions the mean pressure corresponding to the minimum ΔT onset will be denoted P m,opti . For the left branch of the minimum onset temperature difference curve, the regenerator operates in the near-isothermal zone [11,27]. The mean pressure is relatively low, and the thermal penetration depth is much higher than the hydraulic radius.…”

Section: Onset Temperature Difference Studiesmentioning

confidence: 99%

“…Onset temperature difference, understood as the minimum difference between the temperatures of the hot and cold ends of the regenerator necessary to induce the engine's self-oscillations, is one of the basic parameters for thermoacoustic engines [11]. The onset temperature can be plotted as a function of the mean pressure of the working gas, which is the classic stability curve for the thermoacoustic engines [26,27].…”

Section: Onset Temperature Difference Studiesmentioning

confidence: 99%

“…Secondly, in the regenerator, the heat contact between the gas and the solid material determines the thermodynamic process. For the travelling wave thermoacoustic engine, a near isothermal condition is required in the regenerator [11]. To achieve this condition, hydraulic radius, r h , defined as the ratio of the total gas volume to the gas-solid interface area, should be much smaller than the thermal penetration depth to ensure a very good heat contact between the gas and the solid material.…”

mentioning

confidence: 99%

“…Yazaki et al [11] or Yu and Jaworski [12]). Backhaus and Swift [13] developed a somewhat different concept of a travelling wave engine, where a torus resonator was connected to a standing wave resonator, which defined the operating frequency, while de Blok [14] proposed a novel hybrid configuration with a travelling wave feedback waveguide.…”

mentioning

confidence: 99%

“…To complete the thermodynamic process in the regenerator, the acoustic power has to be supplied to the ambient (cold) end of the regenerator with a near travellingwave phasing. Therefore, either an external acoustic source [16,17] or a feedback mechanism needs to be designed [11,13,18] to feed the acoustic power into the ambient end of the regenerator. The characteristics of the regenerator determine the performance of the travelling-wave thermoacoustic engine in two respects.…”

mentioning

confidence: 99%

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Selection and experimental evaluation of low-cost porous materials for regenerator applications in thermoacoustic engines

Abduljalil

Jaworski

2011

Materials & Design

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This paper aims at evaluating three selected low-cost porous materials from the point of view of their suitability as regenerator materials in the design of thermoacoustic travelling wave engines.The materials tested include: a cellular ceramic substrate with regular square channels; steel "scourers"; and stainless steel "wool". Comparisons are made against a widely used regenerator material: stainless steel woven wire mesh screen. For meaningful comparisons, the materials are selected to have similar hydraulic radii. One set of regenerators was designed around the hydraulic radius of 200 μm. This included the ceramic substrate, steel "scourers", stainless steel "wool" and stacked wire screens (as a reference). This set was complemented by steel "scourers" and stacked wire screens (as a reference) with hydraulic radii of 120 μm. Therefore six regenerators were produced to carry out the testing. Initial tests were made in a steady air flow to estimate their relative pressure drop due to viscous dissipation. Subsequently, they were installed in a looped-tube travelling-wave thermoacoustic engine to test their relative performance. Testing included the onset temperature difference, the maximum pressure amplitude generated and the acoustic power output as a function of mean pressure between 0 and 10 bar above atmospheric. It appears that the performance of regenerators made out of "scourers" and steel "wool" is much worse than their mesh-screen counterparts of the same hydraulic radius. However cellular ceramics may offer an alternative to traditional regenerator materials to reduce the overall system costs. Detailed discussions are provided.

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Section: Onset Temperature Difference Studiesmentioning

confidence: 99%

Section: Onset Temperature Difference Studiesmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Selection and experimental evaluation of low-cost porous materials for regenerator applications in thermoacoustic engines

Abduljalil

Jaworski

2011

Materials & Design

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The performance improvement of a cascade thermoacoustic engine by adjusting the acoustic impedance in the regenerator

Dhuchakallaya

Saechan

Rattanadecho

2016

Int. J. Energy Res.

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Summary A novel cascade configuration consisting of one standing wave unit and one travelling wave unit arranged in series is studied in this paper. Theoretically, a straight‐line cascade engine provides an efficient energy conversion, reduces the difficulties of fabrication and allows no Gedeon streaming. In order to achieve such a powerful cascade thermoacoustic engine, the regenerator of the travelling wave unit must be operated in high impedance and travelling wave phasing region. Various techniques of phase adjustment by modifying the configurations and geometrical dimensions of the system are investigated both numerically and experimentally in order to adjust the position of the sweet spot as well as to promote the acoustic impedance in the regenerator. It is found that the effective tuning methods with less modification here are accomplished by changing the volume of down‐cavity and reducing the flow area of down‐resonator by inserting the pencil. The exploration also shows that the acoustic field in the system is quite sensitive to the effect of down‐resonator length. The performance of the proposed system is clearly improved after the phase‐adjustment schemes are completely implemented, in which the regenerator works within the sweep spot zone with high acoustic impedance. Copyright © 2016 John Wiley & Sons, Ltd.

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Design and experimental evaluation of a travelling-wave thermoacoustic refrigerator driven by a cascade thermoacoustic engine

Dhuchakallaya

Saechan

2017

Int J Energy Res

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Summary A travelling‐wave thermoacoustic refrigerator driven by a cascade thermoacoustic engine is evaluated experimentally in this paper. A prototype is developed under the constraint of a low‐cost and less complicated device. In order to reduce the total budget, commercial materials and standard parts are selected, and air at atmospheric pressure is used as working fluid in the system. The thermoacoustic coupled engine‐refrigerator system consists of 1 standing‐wave unit, 1 travelling‐wave unit, and 1 travelling‐wave refrigerator arranged in a linear configuration. A resonator‐tube is connected at each end of the thermoacoustic core. The effects of the length and hydraulic radius of the regenerator in the refrigerator on the cooling performance are investigated at different levels of input power. In the experimental results, the maximum temperature difference of 17.6°C was realised at the no‐load condition. The maximum coefficient of performance relative to Carnot (COPR) of 2.4% was accomplished at the cooling load of 13 W.

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Traveling Wave Thermoacoustic Engine in a Looped Tube

Cited by 350 publications

References 16 publications

Selection and experimental evaluation of low-cost porous materials for regenerator applications in thermoacoustic engines

Selection and experimental evaluation of low-cost porous materials for regenerator applications in thermoacoustic engines

The performance improvement of a cascade thermoacoustic engine by adjusting the acoustic impedance in the regenerator

Design and experimental evaluation of a travelling-wave thermoacoustic refrigerator driven by a cascade thermoacoustic engine

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