使用濕蓄熱器與液柱之行波型熱聲引擎

中文摘要

為呼應我國能源發展政策，本研究計畫旨在開發一可汲取利用低溫廢熱（230℃以下）之熱聲引擎系統。本計畫重點為整合濕蓄熱器與氣液柱耦合振動於同一熱聲引擎：蓄熱器為熱聲引擎能量轉換之關鍵部件，濕蓄熱器因有相變化的潛熱參與，可降低引擎工作臨界發振溫度；液體密度高於氣體，相較於純氣柱熱聲引擎，使用液柱可縮小引擎體積。 為個別釐清濕蓄熱器和液柱特性，與掌握整合效果，本計劃分三年實行。第一年度為掌握濕蓄熱器的基礎熱聲特性，以施加強制振盪的方式，實驗調查聲波傳遞於濕蓄熱器後的聲功率變化與振動流引起之熱傳率等性質。第二年度在純氣柱的環形熱聲引擎中測試濕蓄熱器，在對蓄熱器兩端施加急遽溫度差、觸發引擎自激振盪的情況下，調查水蒸氣質量不同對引擎臨界發振閾值的影響以求得穩定特性曲線， 並量測聲場狀態探究振幅成長特性。第三年度計畫開發一裝設複數蓄熱器（乾、濕蓄熱器）和氣液柱耦合之熱聲引擎，測試其性能並與線性熱聲理論之預測做比較對照。

ABSTRACT

To follow the policy of energy development of Taiwan, this project aims to develop a thermoacoustic heat engine capable to utilize low-grade heat (below 230\textcelsius) for practical use. The main focus is to integrate a wet regenerator and gas-liquid column oscillation in a thermoacoustic engine system. The regenerator is a key component for energy conversion. By adding water to the regenerator, the latent heat of phase change contributes to the reduction of the onset temperature of the engine. The density of a liquid column is larger than a gas column. Comparing to the thermoacoustic engine only with the gas column, adding the liquid column to the thermoacoustic engine can help to lower the volume of the engine system. For recognization of characteristics of wet regenerator and liquid column, and clarification of the integration effects, this project is divided into three years. In the first year, the wet regenerator will be tested for the realization of the basic thermoacoustic characteristics. By imposing forced oscillation to the wet regenerator, the experiments will measure the acoustic power changes and oscillation-induced heat flow rates transmitted through the wet regenerator. In the second year, the wet regenerator will be tested in a looped tube thermoacoustic engine. The hot end of the wet regenerator will be heated to exceed a critical value for inducing spontaneous oscillation. The stability curve will be experimentally obtained by adding different water mass on the regenerator. Also, by measuring acoustic states inside of the engine, the evolution of the oscillation amplitude of saturation caused by increasing input heat power will be discussed. In the third year, this project develops a looped thermoacoustic engine that uses the multiple regenerators (wet and dry) and spontaneous oscillations of liquid and gas columns, based on the result accomplished in previous years. The performance of the heat engine will be discussed under the framework the linear thermoacoustic theory.