- 學位論文
化學共沉技術製備不同粒徑於奈米流體黏滯係數之研究
Study on the viscosity of nanofluids with different particle sizes prepared by chemical co-precipitation technique
摘要
本論文完成化學共沉法製備參數於Fe3O4奈米流體粒徑之影響，並針對含有不同粒徑之奈米流體進行其黏滯係數分析。由過往文獻可發現酸鹼度、溫度、酸性溶液濃度皆會對化學共沉法所產生之粒徑造成影響，故本研究調控化學共沉時進行之環境酸鹼度、酸性溶液濃度及環境溫度，以取得不同粒徑之奈米流體。進一步，於不同溫度下對製成之奈米流體進行黏滯係數測試，觀察奈米流體之粒徑對黏滯係數之影響。 研究結果發現，當共沉環境酸鹼度提高，將使得化學共沉法所製成之奈米粒徑降低，使用較低濃度的酸性溶液進行滴定所得的奈米粒徑較使用較高濃度的酸性溶液進行滴定所得的粒徑低。隨著環境溫度的升高，粒徑則有逐步上升的趨勢。在黏滯係數分析的方面，考慮相同粒子濃度，當奈米流體中所含粒徑較小，其黏滯係數將高於所含粒徑較大之奈米流體，然而此粒徑效應所受溫度之影響並不明顯。
並列摘要
This study conducts experiments to explore the influences of chemical co-precipitation technique preparation parameters on Fe3O4 nanoparticle size and the analysis of viscosity of nanofluids for different particle sizes. According to the literature, we can found that, in the co-precipitation experimental operation, the pH value, temperature and concentration of acidic solution will affect the particle size. This study, therefore, controls the environmental pH value, temperature and concentration of acidic solution to the prepare nanofluids with different particle sizes. Further, the viscosity of nanofluids with different particle sizes is measured at various temperatures. It is found that when the pH value of the co-precipitation environment increases, the particle size decreases. The size of nanoparticles obtained at a lower concentration of acidic solution is lower than that obtained at a higher concentration. In addition, as the ambient temperature increases, the nanoparticle size could increase. As for the analysis of fluid viscosity, results reveal that, for a fixed particle concentration, the viscosity of nanofluids of greater nanoparticle size will be lower than that of smaller nanparticle size. However, such an particle size effect is not obviously affected by temperature.