本研究以再生器的孔隙率梯度對自由活塞式史特靈引擎的效能之影響分析為主軸，透過建立熱力模式及動力模式，並於MATLAB軟體環境下自行編寫數值模擬運算程式，目的是為了解再生器孔隙率梯度對自由活塞式史特靈引擎效能的影響。本研究透過熱力模式求得自由活塞式史特靈引擎內部工作流體的壓力、溫度與質量的變化；同時利用動力模式推算移氣器與動力活塞的位移與速度的變化。由於自由活塞式史特靈引擎的運作區間固定且操作範圍小，各項參數之間的關係緊密且複雜，本研究亦針對溫度、壓力、移氣器及動力活塞的質量與彈簧常數等對自由活塞式史特靈引擎的效能的影響作探討。而透過將再生器分作多段作計算，可以降低計算的誤差，且有利於調整再生器孔隙率梯度，而孔隙率梯度的設計，應參考再生器內部各段工作流體的密度變化，以達自由活塞式史特靈引擎的最佳效能。

This study focuses on the effect of porosity gradient of the regenerators on the performance of the free-piston Stirling engine. The purpose of this study is to analysis the porosity gradient of the regenerators through the self-developed numerical simulation program under MATLAB software environment, which combined the theoretical and dynamic model. The changes in the internal pressure of working fluid, temperatures of working fluid and mass of working fluid in separated chambers of a free-piston Stirling engine were calculated by using thermodynamic module. At the same time, the displacement and velocity changes of the displacer and the power piston are estimated by using the dynamic module. Because of the free-piston Stirling engine can only operate within a narrow and specific range, the relationships between the parameters are close and complicated. The adjustment of the porosity gradient of the regenerator can be achieved by dividing multiple sections in regenerator, and it also performs the benefit of calculation error reduction. The porosity gradient should refer to the density changes of the working fluid inside the regenerators in order to reach the best performance of the free-piston Stirling engine.

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