應用二氧化矽奈米顆粒沉積於蒸發器之沸騰熱傳實驗研究

機構典藏 > College of Engineering > Graduate Institute & Department of Mechanical and Electro-Mechanical Engineering > Thesis > Item 987654321/102626

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Title:	應用二氧化矽奈米顆粒沉積於蒸發器之沸騰熱傳實驗研究
Other Titles:	Experimental investigations of boiling heat transfer in an evaporator using silica nanoparticle coatings
Authors:	黃俊賢;Huang, Chun-Hsien
Contributors:	淡江大學機械與機電工程學系博士班康尚文
Keywords:	二氧化矽奈米顆粒;沸騰熱傳;蒸發器;熱性能;沉積結構;Silica nanoparticle;Boiling heat transfer;Evaporator;Thermal performance;Coating structures
Date:	2014
Issue Date:	2015-05-04 10:00:25 (UTC+8)
Abstract:	本文以將二氧化矽奈米顆粒製作沉積層進行沸騰熱傳研究，以分析沸騰過程中奈米顆粒結構對熱傳性能及汽泡生成與成長的影響。文中將二氧化矽顆粒以物理溶膠沉積於蒸發底板上方，二氧化矽顆粒分別為多孔性奈米顆粒(MCM-41)、無孔奈米顆粒(SiO2-S)及微米顆粒(SiO2-L)。MCM-41及SiO2-S結構具有良好的親水性，其接觸角皆為10°以內且液滴迅速擴散，並比較TEOS溶膠結構、平板結構及二氧化矽顆粒的熱傳性能，分別以水位調節虹吸熱管與迴路式虹吸熱管蒸發器於一大氣壓與負壓情況下進行實驗研究，工作流體為純水，分別探討其沸騰熱傳由自然對流熱傳、核沸騰、薄膜蒸發到燒乾及池沸騰狀態的熱傳性能與汽泡生成情形。實驗結果顯示，二氧化矽奈米顆粒結構具有較大的熱通量，其因具有良好的表面親水濕潤性，在一大氣壓及過熱度為20 oC時，SiO2-S結構的最大熱通量為677 kW/cm2，是平板結構的2.4倍。在負壓及過熱度為30 oC時，SiO2-S結構熱通量為2391 kW/cm2是平板結構的4倍。最大熱通量及最小蒸發熱阻依序為SiO2-S、SiO2-L、MCM-41、TEOS及平板結構。因此奈米顆粒沉積層結構具有良好的熱傳性能，但MCM-41顆粒的熱性能較差於SiO2-S及SiO2-L顆粒，是因為顆粒本身較難以沉積於加熱表面上方所導致。 This study investigated the effects of silica nanoparticle structures on boiling heat transfer at evaporator. The experiment reveals the effect of thermal performance and bubble growth by nanoparticle structures. The nanoparticle coated structures were used in heating surface of evaporator, and the particles are mesoporous silica nanoparticle (MSM-41), silica nanoparticle (SiO2-S) and silica mircoparticle (SiO2-L), respectively. Comparison of TEOS sol and plat structures are thermal performance with silica particles. The MCM-41 and SiO2-S coated structures contact angle were less than 10 and droplets expanding very fast. The experimental method of using level adjustable thermosyphon (LAT) and two phase loop thermosyphon (TPLT) are researched of boiling heat transfer in atmospheric pressure and sub-atmospheric pressure, respectively. The working fluid is DI water. During a cycle of experiment, the primary heat transfer mechanisms of LAT is sequentially from natural convection, nucleate boiling, thin-ﬁlm evaporation and dryout in atmospheric pressure, as LAT and TPLT were experimental investigated in pool boiling. The experimental results show that silica nanoparticle structures have a higher heat flux, because they have better surface wettability of hydrophilic. In the atmospheric pressure and surface superheat is 20 oC, the SiO2-S structure heat flux is 677 kW/cm2. SiO2-S structure heat flux is 2.4 times of plat structure. In the sub-atmospheric pressure and surface superheat is 30oC, the SiO2-S structure heat flux is 2391 kW/cm2. SiO2-S structure heat flux is four times of plat structure. The maximum heat flux and minimum thermal resistance in turn were SiO2-S, SiO2-L, MCM-41, TEOS and plat structures. Therefore, nanoparticles coated structures has better thermal performance. The thermal performance of MCM-41 is poor than SiO2-S and SiO2-L, because it is difficult to coated on the heating surface.
Appears in Collections:	[Graduate Institute & Department of Mechanical and Electro-Mechanical Engineering] Thesis

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