- 學位論文
奈米流體製備參數對流體內粒子懸浮性之研究
Research on the influence of preparation parameters on the suspension of particles in nanofluids
摘要
本論文完成奈米流體內粒子懸浮性之分析。主要目的在探討不同重力場作用下，製備參數對流體內粒子懸浮能力之影響。首先，我們藉由化學共沉法以製備磁鐵礦奈米粒子。接著，我們藉由溶膠凝膠法以包覆穩定劑層於奈米粒子，再透過改變不同烘乾去水條件以製備煤油基奈米流體之成品。進一步，透過X光繞射儀以鑑定奈米材料成份及推估材料晶粒尺寸。最後，透過透光分析儀以分析奈米流體內粒子懸浮性。 研究結果發現，共沉時之pH值和攪拌速度對材料晶粒尺寸影響甚大，晶粒尺寸越小，奈米流體內粒子可獲得較好之懸浮性。包覆時之pH值越高，奈米流體內粒子懸浮能力越好；而溫度越高，懸浮能力一開始越好，隨後則越差。烘乾時之溫度較低和壓力較低，奈米流體內粒子懸浮能力可獲得較好之表現。
並列摘要
This paper presents a study on the analysis of particle suspension of nanofluids. The main purpose is to study the influence of preparation parameters on suspension ability of particles in fluids under various gravitational fields. First, we prepare magnetite nanoparticles by the co-precipitation method. Then, we coat a stabilizer layer on each nanoparticle by the sol-gel method, and further change different drying conditions to prepare kerosene-based nanofluids. Also, through the X-ray diffractometer to identify the nanomaterial composition and estimation the material crystallite size. Finally, through the light transmission meter to analyze the suspension of particles in nanofluids. Results reveal that when the pH value and stirring speed in the co-precipitation procedure have significant effects on the material crystallite size. As the crystallite size decreases, nanoparticles can achieve better suspension in nanofluids. As for the sol-gel procedure, when the pH value increases, the suspension ability of particles in nanofluids rises; when the temperature increase, the ability is first enhanced and then reduced. For the drying procedure it is found that a nanofiuid can have a better suspension at a lower temperature and a higher pressure.