本研究主體為無油渦卷式空壓機之散熱設計，其固定及繞動渦卷間的密閉腔體因往復進行壓縮產生熱能，使得整體系統溫度提高，為克服此散熱需求在轉動軸上安置風機以提供冷卻氣流；而空壓機的驅動馬達可供給空壓機及散熱風機轉動動能，以同時達到高壓輸出及散熱的功能。本案將藉由提升風機流量以及改變介於風機及空壓機間的分流擋板，使其氣流量能平均分配於前、後半部以吹向鰭片間。藉由CFD進行流場及溫度場的模擬分析後得知，問題點為前方出口排出風量不足，故吾人使用兩種改善方案，第一個規劃將分流擋板穿孔，並比較不同的數量及孔徑做評估分析；第二個是將原先的垂直式風向擋板改為平行式風向擋板，再依據觀察的流場適度地調整擋板外殼做改良設計，最後擇優進行實體製作以及溫度量測以驗證其成效。
數值模擬結果顯示，打孔式分流擋板之出口質量流率由原本的0.120 增加至0.146 ，整體散熱量由573.4w增加至627.7w，前後出口排熱差距為132.7w，而溫度量測於中心溫度下降8.0°C，週圍點溫度下降約1~6°C；平行式分流擋板之出口處質量流率由原本的0.120 增加至0.152 ，整體散熱量由573.4w增加至729.1w，前後出口排熱差距也由133.6w縮小至0.7w，而溫度量測於中心溫度下降8.5°C，週圍點溫度下降約2~8°C。因平行分流擋板的改良方式在質量流率、整體散熱量以及前後出口排熱差距皆優於打孔組，故以此模組進行實體製造以及量測。經實驗比對後得知整體溫度和模擬結果比較之誤差於7％以內，且經由修正模型可將誤差再縮至5%以內。本研究經由模擬量測各空壓機出風口質量流率以及入、出風口的溫度差後估計出模型散熱程度，再藉由流場可視化修改在分流擋板、散熱鰭片以及風扇外殼模型後，修正了原始模型在分流擋板處的迴流現象，不僅增加了出口處的總質量流率及整體系統的散熱量，也縮短前、後出風口處的質量流率差距，成功找出改善渦卷式空壓機散熱效益的方式，最後進行實驗證實其可行度。

This study intends to analyze and improve the cooling performance of the oil-free scroll compressor by integrating efforts from numerical simulation, mockup fabrication, and experimental verification. The operating procedure of compressor shows that the chambers between fixed and driving scrolls are keeping compressed and heating by the frictional dissipation energy. Thus, a centrifugal fan is installed on the compressor axis to generate airstream for transporting heat and cooling down the scroll temperature. Flow pattern inside the compressor is simulated by using the CFD code Fluent for design a superior fan. Also, the block board between the fan and compressor is redesigned and installed in parallel to ensure a uniform flow-rate distribution. In addition, the compressor cover is reshaped to a smaller size for guiding and increasing the cooling air flow. As a result, mass flow rate of the best model enlarges from the original 0.120 to 0.152 , which causes an extra 155.7w heat flux. And the highest temperature of scroll is reduced by 8.5°C due to the 0.7w difference between the dissipating heats from two compressor outlets. Thereafter, the new compressor prototype is manufactured via CNC and 3D-printing technologies. Consequently, an acceptable deviation (less than 5%) between CFD and test outcomes is identified on all cases considered in this work to validate the reliability of CFD approach. In summary, the accomplishment of this study not only attains a better compressor design, but also provides a systematic and reliable scheme to enhance performance for an oil-free scroll compressor.

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