本研究以改善γ型史特林引擎的熱傳效益為目的，史特林引擎的上板為冷端而底板為熱端，透過設計不同的針狀鰭片，像是長方形、圓形、菱形、錐形等不同的鰭片，安置在史特林引擎的上板與下板，藉此提升其熱傳增益。為了瞭解上述設計所帶來的物理現象，本研究使用了CD-adapco所開發的數值分析軟體STAR-CCM+來分析史特林引擎的內部流場。在分析流場前，本研究會先進行網格獨立測試與時間獨立測試，並從測試結果中得到適合的網格與時間步數後，再進行絕熱驗證。藉由絕熱驗證所得到的壓力與體積帶入關係式中，來增加使用CFD軟體的可信度。
模擬結果會以鰭片高度做為區隔分開探討，其分別為圓形、長方形、菱形2mm高頂板與底板針狀鰭片，另一部分為圓形、長方形、菱形、錐形3mm高頂板與底板針狀鰭片。從模擬結果中可發現移氣器與移氣器汽缸的衝擊氣流和管狀再生器的衝擊氣流會撞擊底板及頂板，使氣體能夠更有效率的加熱與冷卻史特林引擎的內部氣體；模擬結果也發現在2mm高底板與頂板針狀鰭片中，圓形2mm高針狀鰭片在轉速60rpm、180rpm、300rpm下都有最好的表現，原因是由於其阻擋效應小，使衝擊氣流撞擊到鰭片能夠更有效率的加熱與冷卻氣體；在3mm高底板與頂板針狀鰭片中，圓形3mm高針狀鰭片在轉速60rpm、180rpm、300rpm下有最好的性能表現，由於其阻擋效應較小，衝擊氣流撞擊到鰭片時能夠使鰭片更充分的加熱與冷卻氣體，進而達到最好的性能，但若綜合性能與成本因素，在所有針狀鰭片設計中，圓形3mm高針狀鰭片會是最好的選擇。

In this study, the gamma type Stirling engine top plate and bottom plate were
designed with different pin fin shapes, such as rectangular, circular, diamond,
and conical, to enhance thermal efficiency. In order to research the physical
phenomenon accompanied by pin fin in the Stirling engine, this study used
commercial software STAR-CCM+ to analyze the flow field in the Stirling
engine. Before analyzing the flow field, the first validation was to conduct
the grid-independent test and the time-step independent test and obtain the
appropriate mesh and time-step for numerical analysis; then, the second
validation was to make all walls of the Stirling engine set in an adiabatic
process. According to the aforementioned steps, the validation showed that
pressure(p) and volume(V) would follow the theoretical relation of
pV1.4 = C , and could prove the accuracy of the current CFD approach. The
simulation results would be discussed separately with different pin fin height
as the segment. There are circular, rectangular, and diamond in 2mm height
pin fin in Stirling engine top plate and bottom plate, and the other apart are
circular, rectangular, diamond, and conical shapes in 3mm height pin fin in
Stirling engine top plate and bottom plate. It could be found that impinging
jets were created by the displacer gap channel and regenerator tube, and made
the heat exchange in the Stirling engine more efficient. The result also found
among the 2mm height pin fin, circular pin fin have the best performance,
due to the smallest blockage effect, on the other hand, among the 3mm height
pin fin circular pin fin have the best performance, due to smallest blockage
effect. However, considering the cost and feasibility, circular shape pin fin in
3mm height will be the best option to use.

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