與一般以電能作為主要輸入能源的冷凍機械不同，維勒米爾式冷凍機熱驅動的特性，使其於近期開始得到研究者的關注，許多理論模型與參數分析的相關文獻也在近幾年陸續發表。回熱式機械中的再生室由於其兩端之間所存在的溫差，溫度梯度的產生是為必然，往復流動於其中的工作流體因溫度梯度而形成不同的物理狀態及熱力性質。本研究為因應此特性，欲在再生通道的設計上產生孔隙率梯度，使系統得以更高的效率運用外部提供之能量，藉此擁有更好的表現。以現有研究室所開發之維勒米爾式冷凍機為原型機基礎，除了為增進性能與配合實驗而進行設計改動外，針對改變內部再生室之孔隙率分布，配置具孔隙率梯度之再生室，建立實驗並探討比較其性能。建構一熱力分析之理論模型預測相同條件下之實驗結果，以更改配置後之實驗數據與理論模型之參數分析等討論不同工作條件下適宜之孔隙率分布。

Among all types of refrigerators, Vuilleumier refrigerator is distinguished for its ability to covert external heat source into cooling power. As a member of regenerative type machines, Vuilleumier refrigerator has two regenerators that effect the performance of refrigerator at its respective sub-systems. Working fluid flow through regenerators would have variant physical and thermal properties due to temperature differences that inevitably occurred along regenerators. In the present study, porosity gradient is obtained theoretically and experimentally to adapt properties changes along regenerators. Comparing results of refrigerator with uniform porosity and porosity gradient setups, improvements of refrigerator performance occurred in porosity gradient setups under various working conditions. Validated with experiment results, theoretical model shows potential to predict desirable value and range of porosity gradient setups under different working conditions.

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