Environmentally Sound: High Performance, Compact Thermoacoustic Refrigeration

环境无害：高性能，紧凑的热声制冷本提案的重点是研究将推进高效热声斯特林发动机的发展，用于一系列小规模应用。当玻璃吹风机注意到玻璃管道在生产过程中一端发热而另一端冷却时会发出噪音时，热声效应首次被发现。直到1978年，塞珀利通过制造行波热机将热声效应与斯特林循环联系起来，现代热声学才诞生。热声学这一新兴领域被分为两部分：驻波（声波波峰似乎是固定的）和行波（声波波峰似乎是移动的）发动机。后者更复杂，但也更有效。这种复杂性是行波技术在很大程度上被忽视的原因之一，这使得这项技术及其在广泛基础上的影响取得了重大进展。热声发动机通常由环形振荡器和谐振管组成。两个热交换器和一个蓄热器位于环形振荡器内部。两个热交换器作为热源和水槽，蓄热器允许工作气体从冷侧温度逐渐改变温度到热侧温度。热声发动机利用自振荡施加在系统上的热量增加到热侧。在几个工作循环的过程中，振荡的振幅不断增加，最终达到能量可以用于后续设备（如热声制冷机）的水平。热声斯特林过程的一个优点是它能够通过工作气体的外部加热来供电，使其成为由太阳能和废热供电的主要应用。我们提出通过将谐振管盘绕起来来实现热声斯特林热机的小型化，从而大大提高发动机的效率。将对发动机的部件进行计算分析，主要集中在谐振管和蓄热器上。详细了解在这些成分中发生的潜在物理现象是对热声学领域的重大贡献。这种分析将优化管柱的几何形状，并支持每个组件的有效缩小尺寸。实验原型的建造将包括热交换器和蓄热器的微加工。热声制冷相对于传统制冷的主要优点之一，也是这项工作的主要动机之一，是它不使用有害的制冷剂，如氟氯化碳或氟氯烃。研究表明，热声制冷可以显著降低制冷对环境的影响。改进和缩小的装置的广泛应用可以包括建筑物和车辆的冰箱和空调。以目前的尺寸，高效行波热声制冷机在这些领域的实施是不可行的。这项工作将用于推广热声学作为一种无害环境和发达的技术。此外，拟议的工作将通过少数民族学生推广，课堂演示和本科生研究来支持热力学，流体力学和声学领域的教育。

Environmentally Sound: High Performance, Compact Thermoacoustic RefrigerationThe focus of this proposal is research that will advance the development of an efficient thermoacoustic Stirling engine for a range of small-scale applications. The thermoacoustic effect was first discovered when glass blowers noticed that glass pipes emitted a noise during production when one end was hot and the other had cooled. It was not until Ceperley connected the thermoacoustic effect with the Stirling cycle by building a traveling wave heat engine in 1978 that modern thermoacoustics was born.The young field of thermoacoustics is divided into two parts: standing wave (where the crests of the sound waves appear to be fixed) and traveling wave (where the crests of the sound waves appear to move) engines. The latter is more complex but also more efficient. This complexity is one of the reasons why traveling wave technology has been largely overlooked, which allows for significant advances to be made both to this technology and its impact on a widespread basis.A thermoacoustic engine is commonly comprised of a looped oscillator and a resonator tube. Two heat exchangers and a regenerator are located inside the looped oscillator. The two heat exchangers serve as a heat source and sink, and the regenerator allows the working gas to gradually change temperature from the cold side temperature to the hot side temperature. Thermoacoustic engines utilize the self oscillation imposed on the system by the addition of heat to the hot side. Over the course of several work cycles, the amplitude of the oscillations is continuously increased, eventually reaching a level where the energy can be used in a subsequent device (such as a thermoacoustic refrigerator). One advantageous facet of the thermoacoustic Stirling process is its ability to be powered through external heating of the working gas, rendering it a prime application to be powered by solar heat and waste heat.We propose to achieve a smaller scale for a thermoacoustic Stirling heat engine by coiling the resonator tube and to drastically improve the engine's efficiency. A computational analysis of the engine's components will be conducted, focusing primarily the resonator tube and regenerator. A detailed understanding of the underlying physical phenomena occurring in these components is a significant contribution to the field of thermoacoustics. This analysis will result in an optimized tube geometry and will support the efficient downsizing of each component. The construction of an experimental prototype will incorporate the use of microfabrication for the heat exchangers and regenerators.One of the major advantages of thermoacoustic refrigeration over conventional refrigeration and a primary motivation for this work is that it does not utilize harmful refrigerants such as CFCs or HCFCs. It will be shown that thermoacoustic refrigeration can significantly decrease the environmental impact of refrigeration. Broad applications of the improved and downsized units could include refrigerators and air-conditioners for both buildings and vehicles. At the current size, efficient traveling wave thermoacoustic refrigerators are not feasible for implementation in these fields. This work will be used to promote thermoacoustics as an environmentally sound and well-developed technology. Also, the proposed work will support education in the fields of thermodynamics, fluid mechanics and acoustics through minority student outreach, classroom demonstrations, and undergraduate research.