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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/63499


    Title: 不同粒徑微多孔表面在狹小空間內之池沸騰熱傳性能研究
    Authors: 王政皓;Wang,Zheng-Hao
    Contributors: 能源工程研究所
    Keywords: 微多孔表面;粒徑大小;狹小空間;池沸騰;Micro porous surface;Particle size;Confined space;Pool boiling
    Date: 2014-01-27
    Issue Date: 2014-04-02 15:41:00 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 本研究使用兩種不同粒徑大小(3.6 μm and 20 μm)的鋁粉分別製作厚度(80、105和150 μm)的微多孔表面,以甲醇為工作流體在垂直加熱面上分別進行開放空間與狹小空間(1mm)的池沸騰熱傳性能實驗。不同粒徑大小其堆疊孔洞大小也不同,活化所需過熱度與生成汽泡大小也會跟著受到影響。研究結果發現在低熱通量時,小粒徑微多孔表面因所需活化過熱度高因此熱傳性能比大粒徑微多孔表面差。隨著熱通量增加,小粒徑微多孔表面活化孔洞的數量增加,其熱傳性能會逐漸接近大粒徑微多孔表面,在高熱通量時甚至會比大粒徑微多孔表面還要好。
    在狹小空間內時,聚合汽泡會佔據狹小空間,液體較難補充至加熱表面造成熱傳性能提升效果減弱。而小粒徑微多孔表面生成的氣泡大小比大粒徑微多孔表面生成的氣泡小,因此汽泡聚合的大小也小,在相同狹小空間下,液體補充所受影響也較小。小粒徑微多孔表面其毛細吸力比大粒徑微多孔表面強,而研究結果發現厚度較大的微多孔表面在狹小空間高熱通量時,小粒徑微多孔表面其熱傳性能會比開放空間時還要好,而大粒徑微多孔表面生成汽泡受到空間限制,其熱傳性能反而比開放空間時差。; This study used two aluminum particle sizes (3.6 μm and 20 μm) to production the same thickness(80,105 and 150 μm) micro porous surface , with methanol as the working fluid, the pool boiling heat transfer experiments is heated in a vertical surface. Respectively, open space and a small space (1mm) at 1 atm. Different particle sizes change the cavities sizes, the superheat required for the activation of the bubble size and generation will follow affected. The results showed that in the low heat flux, the small particle size of the micro porous surfaces required high superheating for activation the cavities. Therefore, its heat transfer performance is poor than large particle size micro porous surface. With heat flux increases, the number of active cavities increases, the heat transfer performance will be close to the large particle size micro porous surface gradually, even better at high heat flux.
    In confined space, when coalesced bubbles occupy the small space long, liquid supplement hard to the heating surface. It caused the heat transfer performance reduced. And the small particle size micro porous surface generate the small size of bubbles, so the coalesced bubble size is small, in the same confined space, refilling the impact is small. Will lead to a liquid supplement to a small space, the capillary suction of small particle size micro porous surface is stronger than the large particle size micro porous surface. While the study found that the small particle size micro porous surface heat flux in the narrow space, the heat transfer performance is better than the open space.
    Appears in Collections:[能源工程研究所 ] 博碩士論文

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