【摘要】 对纳米流体池内核态沸腾进行了研究.沸腾传热面为水平加热面,基液使用蒸馏水和乙醇,纳米颗粒使用CuO和SiO2,扩散剂使用十二烷基苯磺酸钠(SDBS).实验发现:对于添加了扩散剂的水基纳米流体,在壁温超过大约112℃后,传热面上出现烧结层,沸腾实验无法继续进行;没有添加扩散剂时,传热面上有极薄的颗粒吸附层形成,表面粗糙度和固液接触角都减小,可以获得完整的核态沸腾曲线,换热特性比纯水有所降低,临界热流密度有较大增加;对于乙醇纳米流体,无论是否添加扩散剂,传热面上都没有出现烧结层.实验以扩散剂对池内核态沸腾换热表面特性的影响为研究重点,证明了壁温和扩散剂是产生传热面烧结现象的主要因素.更多还原

【Abstract】 The pool nucleate boiling heat transfer experiments of water based and alcohol based nano-fluids on the plain heated copper surface were carried out.The study was focused on the sorption and agglutination phenomenon of nano-fluids on a heated surface.The nano-fluids consist of both liquids of water and alcohol and both nano particles of CuO and SiO₂.The surfactant is sodium dodecyl benzene sulphate（（SDBS）.） The experimental results show that for the water based nano-fluids consisted of water,nano-particles and SDBS,the agglutination phenomenon occurs on the heated surface when the wall temperature（overruns） 112℃ and the steady nucleated boiling can not carry out.However,for the suspensions consisted of water and nano-particles without SDBS,no agglutination phenomenon occurs on the heated surface and the steady boiling can carry out in the whole nucleate region.For the alcohol based nano-liquids either with SDBS or without SDBS,no agglutination phenomenon occurs on the heated surface.The boiling heat transfer of the nano-fluids is somewhat worse than that of the pure fluids while the critical heat fluxes（CHF） for the nano-fluids increase significantly.更多还原