以往之相關文獻大部分只著重於分析史特林引擎冷、熱端之溫差值以及幾何參數對於整體引擎效能之影響。事實上，史特林引擎移汽缸壁面之溫度分佈往往因選用之材料以及冷、熱兩端之結構等等而有很大的不同。有鑒於此，本論文以計算流體力學方法（CFD）對於不同移汽缸壁面溫度分佈於一中溫差(工作溫度150-500°C) γ-型雙動力缸史特林引擎引擎效能之影響進行數值模擬分析以及探討。除此之外，也進一步運用兩種熱傳增益方法對於此γ-型史特林引擎之整體效能影響進行模擬研究及探討分析。計算之結果包含引擎輸出功率、引擎效率、整體熱傳率及移汽缸各壁面之個別熱傳率。
本論文主要分為兩大部分。第一部分先透過比較絕熱以及線性溫度分佈之移汽缸側壁面來驗證史特林引擎缸體壁面之溫度分佈對於引擎整體效能的影響以及其重要性，並且進一步探討將熱端溫度TH及冷端溫度TL延伸至部份移汽缸之側壁面對於引擎之輸出功率及輸出效率之影響。另外，本文亦簡單探討冷熱端溫差值(TH - TL) 以及引擎速度對於引擎效能之影響。第二部分除了延伸熱端溫度及冷端溫度至部份移汽缸之側壁面外，進一步加入了肋條凹槽於移汽缸體壁面不同位置進行熱傳增益之研究。本部分對於肋條凹槽之位置以及數量對於整體引擎輸出功率及熱效率的影響亦做了系統性的分析和比較。
由研究結果顯示，移汽缸體側壁面之溫度分佈對於整體引擎效能以及熱傳現象有著很顯著的影響。將熱端溫度TH及冷端溫度TL延伸至部份移汽缸之側壁面可以增加引擎之輸出功率，但卻也同時造成了輸出效率的減少。而將肋條凹槽加工於熱端及冷端溫度延伸之移汽缸體側壁面帶來了正面熱傳之提升卻也同時提升了負面熱傳，因此對於整體引擎效能造成了好處及壞處二者相互牽制之混合情況。相較之下，將肋條凹槽加工於熱端及冷端溫度延伸之移汽缸體之上下壁面提升了正面熱傳也同時帶來了負面熱傳之減少。因此在此情況下，引擎輸出功率以及輸出效率同時在肋條凹槽數量增加時獲得了提升，也證明了此熱傳增益方法能夠有效提升引擎之整體效能。此外，本研究之結果證實了傳統熱力學分析對於引擎效能與熱傳面積成正比此假設並非事實。

In terms of parametric studies of Stirling Engines, the majority of the studies in previous literature lay emphasis merely on the magnitude of temperature difference between the hot end and cold end or the geometric parameters of the engine itself. As a matter of fact, thermal conditions on displacer cylinder wall boundaries of Stirling Engines can vary greatly according to different materials and heat source/sink configurations adopted.
The first focus of this thesis aims at understanding the effects of thermal conditions of displacer cylinder wall on the overall engine performance through analyzing various displacer cylinder wall temperature conditions of a MTD (150-500°C) Twin-Power-Piston γ type Stirling Engine using Computational Fluid Dynamics (CFD) approach.
It is confirmed by the results that not merely the magnitude of temperature difference between heat source and heat sink, but also the thermal conditions on the circumferential wall of the displacer cylinder has a significant impact on engine performance. Within the ranges investigated in this study, extending the coverage of heat source and heat sink on this wall boundary results in an increase in indicated power but with the penalty of reducing thermal efficiency, which is due to inadequate heat transfer.
For the second focus of this study, the effects of heat transfer enhancement on engine performance by machining slot grooves on walls of the displacer cylinder of the same engine model have been investigated. Three types of groove arrangements, namely circumferential, vertical and top/bottom, are added to the smooth wall engine model with heat source and heat sink extension on the displacer cylinder’s circumferential wall and the effects of each on the overall engine performance are compared in detail.
From the results it is found that adding slot grooves on the circumferential wall enhances both positive and inadequate heat transfer, hence resulting in a situation in which the negative effects competes with the positive effects. In contrast, adding slot grooves on top and bottom walls mainly enhances positive heat transfer thus yields an improvement in both indicated power and thermal efficiency as the number of grooves increases. By extending the hot- and cold-end temperatures on the circumferential wall region together with adding grooves on the top and bottom walls, the indicated power is increased by 30%. However, the thermal efficiencies of the two cases with and without adopting the two heat transfer enhancement methods are both at around 1.94 %. This further proves that this is an effective method for improving the performance of the engine model. In addition, it is proven by the results in this study that engine performance is actually not proportional to heat transfer area, which an assumption often is made in thermodynamic analyses.

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