Abstract: In order to examine the combined effects of surface roughness and concentration on pool boiling of nanoparticle suspensions, an experimental study of quenching processes of aqueous suspensions with carbon nanotubes (0.1 and 0.5%) was conducted using nickel-plated copper spheres with surface roughnesses of Ra0.5 and Ra12.5. Quenching curves were acquired directly, whereas boiling curves during the quenching processes were calculated based on a lumped capacitance model. It was shown that increase in both concentration of the suspensions and surface roughness causes expedited quenching speeds and enhanced critical heat fluxes. Increase in surface roughness decreases the time duration of nucleate boiling, whereas the shortened film boiling time is primarily due to increased concentration. Due to the combined effects of surface roughness and concentration, it may be suggested to utilize quenching objects with rough surfaces in nanoparitcle suspensions of relatively high concentration so as to significantly shorten quenching times for engineering applications.

Key words: carbon nanotube suspensions, pool boiling, quenching, critical heat flux, surface roughness

摘要： 为了研究表面粗糙度及浓度对纳米悬浮液大容器沸腾特性的耦合影响，对粗糙度为Ra0.5和Ra12.5的镀镍铜球在体积分数为0.1和0.5%的水基碳纳米管悬浮液中的淬火过程进行了实验研究，得到了不同条件下的淬火曲线并通过集总参数模型得到了淬火过程的沸腾曲线。结果表明，悬浮液浓度与表面粗糙度的增加都能加快淬火速率并提高临界热流密度。表面粗糙度的增加缩短了核态沸腾阶段的时间，而悬浮液浓度的增加则主要体现了对膜态沸腾阶段的加速作用。在二者的共同影响下，采用表面较为粗糙的淬火物体在浓度较高的纳米悬浮液中进行淬火可以显著地缩短淬火冷却时间，对工程应用具有指导意义。

关键词: 碳纳米管悬浮液, 大容器沸腾, 淬火, 临界热流密度, 表面粗糙度