Numerical analysis on a four-stage looped thermoacoustic Stirling power generator for low temperature waste heat
Numerical analysis on a four-stage looped thermoacoustic Stirling power generator for low temperature waste heat
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DOI：
10.1016/j.enconman.2017.03.023
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发表时间：
2017-10
影响因子：
10.4
通讯作者：
Kai Wang;L. Qiu
中科院分区：
文献类型：
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作者：
Kai Wang;L. Qiu
热声技术的最新发展表明，多级环形热声斯特林发动机将是收集废热的有前途的选择。以往对多级环路热声系统的研究主要集中在热驱动制冷或热泵方面，而在发电尤其是回收低温热量方面的工作较少。在这项工作中，系统地研究了一种利用 300°C 低温废热发电的四级回路热声斯特林发电机。建立了数值模型，然后在实验性四级环形热声斯特林发动机上进行了验证。在经过验证的模型的基础上，数值研究了线性交流发电机的耦合位置和再生器位置对发电系统的声学特性和性能的影响。针对三种代表性耦合模式，给出并分析了沿回路的声场分布，包括压力幅值、体积流量、相位角、比声阻抗和声功率。当线性交流发电机耦合在谐振器上热声芯的冷端附近时，可以实现卓越的效率，同时在热端产生更多的电力。当线性交流发电机连接在谐振器中间时，预计性能最差。通过分析不同耦合模式下的声场特征和输出声阻抗，进一步详细解释了其基本机制。此外，发现热声芯中回热器的位置对输出电功率有显着影响，而对效率则不太重要。优化的四级环形热声斯特林发电机能够提供最大1223W的电功率，最高相对卡诺效率约为0.20。这项工作深入了解了环形热声斯特林发电机的工作原理，并将有助于未来类似余热回收系统的发展。
Recent developments in thermoacoustic technologies have demonstrated that multi-stage looped thermoacoustic Stirling engine would be a promising option for harvesting waste heat. Previous studies on multi-stage looped thermoacoustic systems were mainly focused on heat-driven refrigeration or heat pumping, while much fewer work were done on power generations, especially those for recovering low temperature heat. In this work, a four-stage looped thermoacoustic Stirling power generator for generating electricity from low temperature waste heat at 300 °C is systematically studied. A numerical model is built and then validated on an experimental four-stage looped thermoacoustic Stirling engine. On the basis of the validated model, the effects of the coupling position for the linear alternators and the regenerator position on the acoustic characteristics and performances of the power generation system are numerically investigated. The distributions of the acoustic fields along the loop, including the pressure amplitude, volume flow rate, phase angle, specific acoustic impedance and acoustic power, are presented and analysed for three representative coupling modes. Superior efficiency is achieved when the linear alternators are coupled near the cold ends of the thermoacoustic cores on the resonators, while more electric power is generated at the hot ends. The worst performance is expected when the linear alternators are connected at the middle of the resonators. The underling mechanisms are further explained detailedly by analysing the characteristics of the acoustic fields and output acoustic impedances for different coupling modes. Furthermore, the regenerator position in the thermoacoustic cores is found to have a remarkable influence on the output electric power, while it is less important for the efficiency. The optimized four-stage looped thermoacoustic Stirling power generator is able to provide a maximum electric power of 1223 W with a highest relative Carnot efficiency of around 0.20. This work provides in-depth insights into the operation principle of the looped thermoacoustic Stirling power generator and will be helpful for future developments of similar waste heat recovery systems.