銀奈米流體可視化池沸騰之研究

Visualization of Pool Boiling Experiments with Silver-Nanofluids

黃俊顏(Chun-Yen Huang)

指導教授 ： 康尚文

淡江大學/工學院/機械與機電工程學系碩士班/碩士(2009年)

https://doi.org/10.6846/TKU.2009.00304

摘要

本研究為探討奈米流體對於池沸騰熱傳的影響。本實驗於一大氣壓下，使用外徑0.2mm、長度56mm的鎳鉻電熱絲作為加熱器；純水與五種濃度的銀奈米流體(10ppm~50ppm)作為工作流體。銀奈米流體使用平均粒徑30nm的銀奈米顆粒並以超音波震盪的方式分散於純水之中。
本實驗以臨界熱通量(CHF)為探討指標，並繪製沸騰曲線比較銀奈米流體與純水的沸騰熱傳特性。實驗結果顯示銀奈米流體的臨界熱通量(CHF)平均為純水的2.2倍(約95%~159%的提升)。實驗過程使用高速攝影的方式拍攝，證實銀奈米流體具有較佳的表面沾溼性且銀奈米顆粒沉積之孔隙層(porous layer)亦有助表面沾濕性的改善。實驗後使用掃描式電子顯微鏡(SEM)觀察電熱絲表面，發現有奈米顆粒沉積的情形；並使用能量散佈光譜儀(EDS)確認沉積顆粒的成分為銀。本文最後分析銀奈米顆粒沉積於加熱表面之成因與影響；並分析奈米流體提升熱管效能的主要機制為表面沾濕性變佳。

關鍵字

沸騰 ； 池沸騰 ； 奈米流體

並列摘要

An experiment was performed at atmospheric pressure to investigate the critical heat flux (CHF) characteristic of 10ppm, 20ppm, 30ppm, 40ppm and 50ppm water-based silver nanofluids. The NiCr wire heater used in this study has an outer diameter of 0.2 mm with a length of 56 mm, and the mean diameter of silver nanoparticles is 30nm.
The experiment was performed to measure the heat flux and the difference between the wire temperature and the saturation temperature, then plot the boiling curves. The results show that the CHFs of silver nanofluids are enhanced over that of pure water by 95% ~159%. SEM and EDS analysis of the wire surface reveal that a porous layer of nanoparticles are built up on the wire surface during boiling. This layer significantly improves the surface wettability on the nanofluid-boiled wire compared with the pure-water-boiled surfaces.

並列關鍵字

Boiling ； Pool boiling ； Nanofluid

參考文獻

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