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標題: | 利用池沸騰所改質表面的沸騰熱傳特性之研究 Investigation of Boiling Heat Transfer Properties On a Nano-coating Surface Modified by Pool Boiling |
作者: | Hung-Hsia Chen 陳虹遐 |
指導教授: | 陳炳煇(Ping-Hei Chen) |
關鍵字: | 奈米修飾銅表面,粒徑大小,臨界熱通量,沸騰熱傳係數, Nano-coated surface,Particle size,Critical heat fluxes,Boiling heat transfer coefficient, |
出版年 : | 2014 |
學位: | 博士 |
摘要: | 本文主要探討各種濃度、粒徑之二氧化矽奈米流體,於池沸騰實驗前後的水平純銅加熱表面熱傳性質。文中將工作流體與加熱面的組合分為「1-純水-純銅」、「2-奈米流體-純銅」以及「3-純水-奈米修飾銅」三種組合。
工作流體是以二階混合法製作三種不同粒徑(10nm、25nm、50nm)、五種不同濃度(0.005~0.1wt%)的二氧化矽奈米顆粒和純水製作奈米流體,在一大氣壓與水平純銅加熱面進行過冷態池沸騰實驗。 由於各種粒徑大小、濃度變化在銅加熱表面堆疊的孔洞、厚度、粗糙度也會不同,因此熱傳特性會受到影響。研究結果發現加熱表面的平均粗糙度、粒徑交互作用下,「2-奈米流體-純銅」的臨界熱通量會比「1-純水-純銅」還高103%,而「3-純水-奈米修飾銅」的臨界熱通量則是比「1-純水-純銅」還高88%。但是「2-奈米流體-純銅」、「3-純水-奈米修飾銅」兩種表面的平均熱傳係數有部分呈現大幅增加而部分卻變得比純水差。 Critical heat fluxes (CHF) and boiling heat transfer coefficient (BHT) are the primary concerned properties in the design of electrical component cooling or nuclear reactor. Various concentrations and particle sizes of suspension SiO2 nanoparticles in pure water, called nanofluids, were manipulated in subcooled pool boiling experiment in this study. After nanofluids boiling experiment, the porous nano-coated surfaces were boiling again with pure water in pool. During boiling, nanoparticles in the nanofluids deposit on the bare copper heater surface continuously, which is porous and hydrophilic, leading to a higher CHF compared to pure water. The results showed that all the CHF of plain surfaces with nanofluids and nano-coated surface with pure water experiments were enhanced significantly compared with pure water. It also showed that part of the BHT of bare surface and nanocoated surface were improved but also some of them were deteriorated compared with pure water. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/55519 |
全文授權: | 有償授權 |
顯示於系所單位: | 機械工程學系 |
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