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首页> 外文会议>4th International Conference on Nanochannels, Microchannels and Minichannels 2006(ICNMM2006) pt.A >HEAT TRANSFER BEHAVIOR OF OXIDE NANOPARTICLES IN POOL BOILING EXPERIMENT
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HEAT TRANSFER BEHAVIOR OF OXIDE NANOPARTICLES IN POOL BOILING EXPERIMENT

机译：池沸腾过程中氧化物纳米颗粒的传热行为

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摘要

The heat transfer characteristics of silica (SiO_2), ceria (CeO_2), and alumina (Al_2O_3) nanofluids at 0.5% concentration and particle size of 10nm and 20 nm in pool boiling have been analyzed. The influence of acidity on heat transfer has been studied. The pH value of the nanosuspensions is important from the point of view that it determines the stability of the particles, their mutual interactions towards the wire. When there is no particle deposition on the wire, the nanofluid with any oxide suspension increases CHF by about 50% within uncertainty limits regardless of the type of the oxide particle and its size. The extent of oxidation on the wire impacts CHF, and is influenced by the chemical composition of nanofluids in buffer solutions. Amorphous oxides (SiO_2) are generally more disordered and less closely packed compared to the crystalline oxides such as CeO_2 and Al_2O_3. The arrangement of the atoms within the unit cell and the layer of water molecules at the surface possibly influence the natural convection as well as the CHF. The boiling regime is further extended to higher heat flux when there is agglomeration on the wire. This agglomeration allows high heat transfer through interagglomerate pores, resulting in a nearly 3-fold increase in CHF. This deposition occurs for the charged 10 nm silica particle, and was not seen for other oxide particles. The chemical composition, oxidation and packing of the particles within the deposition on the wire are shown to be the reasons for the extension of the boiling regime and the net enhancement of the Critical Heat Flux.
机译：分析了池沸腾中浓度为0.5％的二氧化硅（SiO_2），二氧化铈（CeO_2）和氧化铝（Al_2O_3）纳米流体的粒径和10nm和20nm的传热特性。研究了酸度对热传递的影响。从纳米悬浮液的pH值确定颗粒的稳定性，它们与金属丝的相互相互作用的角度来看很重要。当导线上没有颗粒沉积时，具有氧化物悬浮液的纳米流体在不确定性范围内会将CHF增加约50％，而与氧化物颗粒的类型和大小无关。导线上的氧化程度会影响CHF，并受缓冲溶液中纳米流体的化学组成影响。与诸如CeO_2和Al_2O_3的结晶氧化物相比，非晶氧化物（SiO_2）通常更无序且堆积更紧密。晶胞内原子的排列以及表面的水分子层可能会影响自然对流以及CHF。当金属丝上发生团聚时，沸腾状态进一步扩展到更高的热通量。这种团聚允许通过团聚孔的高热量传递，导致CHF升高近3倍。对于带电的10 nm二氧化硅颗粒，会发生这种沉积，而对于其他氧化物颗粒，则看不到这种沉积。线上沉积物中颗粒的化学组成，氧化和堆积被证明是延长沸腾范围和提高临界热通量的原因。

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