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|其他題名: ||A Study on the Characteristics of a Pressurized medium -temperature-differential Gamma-Type Stirling Engine|
King-Leung Wong;Wen-Lih Chen
Impingement heat transfer;Computational fluid dynamics（CFD）;Stirling engine;walking beam
|Issue Date: ||2016-03-23 15:36:35 (UTC+8)|
|Abstract: ||本研究先以自行開發之計算流體力學（computational fluid mechanics；CFD）程式，模擬中溫γ型史特林引擎整體循環過程中複雜之熱傳機制，其結果涵蓋等溫線、速度向量、平均溫度、引擎輸出、輸入功率變化及重要時間點上沿固體邊緣之局部熱通量分布情形。研究發現衝擊熱傳導為膨脹與壓縮腔體之主要熱傳機制，引擎運轉過程中，腔體內任一時間狀態下，溫度與壓力皆為不均的分佈。在設計、開發與製造階段，首先採用樑結構設計取代原有之傳動方式，避免側向分力造成動力活塞刮損及減少摩擦損失，並驗證增加工作氣體質量、冷熱端溫差、壓縮比之自然對數及換用高氣體常數之氫氣作為工作氣體使用，均能有效提升引擎輸出功率。我們發現每部史特林引擎在某個熱端溫度下，存在著性能最佳之參數組合。經實驗結果表明，採用樑結構設計之中溫γ型史特林引擎，當動力活塞外徑匹配內徑80mm之汽缸、再生器內填充銅網32片、填充6bar加壓氫氣作為工作氣體、負載齒輪比為60：15等固定參數條件，在移氣缸熱端溫度為671K時，可獲得最佳輸出功率 383.29W。|
In this study on a pressurized medium-temperature-differentialγ- type Stirling engine, the design of geometric parameters and dimensions were first guided by using an in-house computational fluid mechanics （CFD） program to learn the physical phenomena in Stirling engine cycles. The simulation results were used to improve the engine’s output efficiency to meet future market requirement and application. The CFD results include temperature contours, velocity vectors, and distributions of local heat flux along solid boundaries at several important time steps as well as variation of average temperatures, integrated rates of heat input, heat output, and engine power. It is found that impingement heat transfer is the major heat transfer mechanism in the expansion and compression chambers; additionally, the temperature and pressure distribution is highly non-uniform across the engine volume at any given moment during the entire engine cycle. In design, development, and manufacturing stages, the original driving mechanism was replaced by walking beam structure to avoid power piston damages caused by lateral force and to reduce output power loss caused by friction. Meanwhile, it has been verified that increasing working gas mass, the temperature difference between cold and hot ends and the natural logarithm of compression ratio, and using hydrogen which has a high gas constant as the working gas can improve the engine power output effectively. We found that every Stirling engine has an optimal combination of parameters that produces the best performance at a certain hot-end temperature. When the temperature of the hot end is at 671 K, the experimental results show that the current Stirling engine produces the best output power of 383.29 W using the following parameters: power piston and the cylinder diameter 80 mm, filled with 32 sheets copper mesh within the regenerator, filled with 6 bar hydrogen as the working gas, and loading gear ratio of 60:15.
|Appears in Collections:||[機械與能源工程研究所(博士班)] 博士論文|
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