結合史特靈引擎與可變式電容的能量蒐集器

Energy Harvester Combining Stirling Engine and Variable Capacitance

施華儒(Hua-Ju Shih)

指導教授 ： 陳國慶

國立臺灣大學/工學院/應用力學研究所/博士(2022年)

https://doi.org/10.6342/NTU202200701

摘要

廢熱蒐集是一個具發展潛力的課題。其不僅能將熱能回收利用，還能減緩環境的暖化。提到熱轉換，史特靈引擎是效率僅次於卡諾機的熱機。在應用方面，史特靈引擎有三項優勢。第一，外燃機的特性使得史特靈引擎可適應於任何型式的熱源；第二，安靜且穩定；第三，屬於綠能的一種。

史特靈引擎能將熱能轉換成力學能，而力學能轉換成電能的方法有很多種，如透過電磁感應、摩擦起電效應、壓電效應以及可變式電容等手段。以微型能量蒐集器的角度來看，可變式電容器方式比起其他三者更具優勢，它比電磁感應機制更容易微小化、比摩擦起電方式更不易受環境濕度影響、比壓電材料更具韌性。運作原理上，可變式電容器較其他三者簡單。相鄰的兩個帶異相電荷導體所形成的類電容環境，藉由兩者相對位置的改變造成電容值的變化，電容器自身便會進行充電與放電的行為，達到能量蒐集的目的。

本文將結合史特靈引擎與可變式電容器能量蒐集器，將環境中的廢熱轉化為電能，並提出相關數學模型分析之。我們將目標設定在低溫差(10℃~30℃)的廢熱，因而選擇啟動溫度差較低的Gamma型史特靈引擎。另外，還提出一款鍍有指叉環狀電極的圓形薄模能量蒐集器，試圖藉者薄膜的振動來蒐集能量。

關鍵字

廢熱蒐集 ； Gamma型史特靈引擎 ； 可變式電容器 ； 微機電系統 ； 指叉環狀電極

並列摘要

Waste heat recovery is a topic with high development potential. It not only recovers heat energy, but also curb global warming. For the thermal converter, the heat conversion efficiency of the Stirling engine is second only to the Carnot engine. In application of the waste heat recovery, Stirling engine has three advantages. Firstly, the engine can be applied to any form of heat source. Secondly, the engine is quiet and stable. Thirdly, the engine is one of the green energies.

The Stirling engine can convert thermal energy into mechanical energy. Then, there are many methods that can convert mechanical energy into electrical energy. Such as the electromagnetic generator, the piezoelectric generator, the triboelectric generator, and the electrostatic generator (variable capacitance). From the view of the micro energy generator, the electrostatic type is easier to miniaturize than the electromagnetic type, it is more resilient than the piezoelectric type, and it is less affected by humidity factor than the triboelectric type. Furthermore, the electrostatic type harveste the energy with a variable capacitor. When the capacitance changes due to external force, the capacitor achieves charge-discharge behavior.

In this study, we propose two mathematical models to estimate the ability of the harvesters. One is the model which combines the Gamma-type Stirling engine and the variable capacitor (temperature difference between 10℃~30℃); Other one is an analytical model for an interdigitated ring electrode on a circular elastic membrane, which can accumulate ambient vibrational energy from the environment.

並列關鍵字

waste heat recovery ； Gamma-type Stirling engine ； variable capacitance ； MEMS ； interdigitated ring electrode

參考文獻

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