Numerous methods, such as sintered or machined surface, have been proposed to enhance the boiling performance. On the other hand, nanofluids are also reported to increase the convective heat transfer and become attractive in many engineering applications. In this study, anodizing was tried to produce porous structure on the heater surface to enhance the boiling performance. Two electrolyes, phosphoric acid and oxalic acid, were used. It was found the anodized pores prepared by oxalic acid were smaller. However, the phosphoric acid anodized surface exhibited a CHF increment by 40% with almost no superheat increment. A nanofluid pre-boiling process was also proposed. An aluminum wire was used as the heater to boil nanofluid for a certain time at a certain heat flux. 0.1 wt% TiO2 nanofluid was used as the working fluid during the pre-boiling process. The wire then went on being the heater for pure water. It is found that aluminum wires exhibit boiling enhancement after preboiling in nanofluid. The most effective process heat flux and duration were found experimentally. The experimental results showed an 11° decrease of the surface superheat. According to SEM photos, two layers were deposited on the aluminum surface. The top layer is more like clusters of deposited nanoparticles, and the layer could be dissolved into water when perform subsequent pure water boiling. The other layer located beneath is more condensed and reliable. It is believed that the second layer could be the main mechanism to exhibit the boiling enhancement.
- Heat Transfer Division
Boiling Enhancements by Anodizing and Pre-Boiling in Nanofluid
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Huang, C, & Lee, C. "Boiling Enhancements by Anodizing and Pre-Boiling in Nanofluid." Proceedings of the ASME 2009 Heat Transfer Summer Conference collocated with the InterPACK09 and 3rd Energy Sustainability Conferences. Volume 3: Combustion, Fire and Reacting Flow; Heat Transfer in Multiphase Systems; Heat Transfer in Transport Phenomena in Manufacturing and Materials Processing; Heat and Mass Transfer in Biotechnology; Low Temperature Heat Transfer; Environmental Heat Transfer; Heat Transfer Education; Visualization of Heat Transfer. San Francisco, California, USA. July 19–23, 2009. pp. 511-516. ASME. https://doi.org/10.1115/HT2009-88552
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