The Impact of TiO2 Nanoparticle Concentration Levels on Impulse Breakdown Performance of Mineral Oil-Based Nanofluids
The Impact of TiO2 Nanoparticle Concentration Levels on Impulse Breakdown Performance of Mineral Oil-Based Nanofluids
复制标题
TiO2 纳米颗粒浓度水平对矿物油基纳米流体脉冲击穿性能的影响
DOI：
10.3390/nano9040627
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发表时间：
2019-04-01
期刊：
影响因子：
5.3
通讯作者：
Chen, Weijie
中科院分区：
文献类型：
--
作者：
Wang, Ziyi;Zhou, You;Chen, Weijie
矿物油基纳米流体的绝缘性被发现随纳米颗粒的不同浓度水平而变化。然而，这一研究发现背后的机制还没有得到很好的研究。在本文中，矿物油基纳米流体的制备通过悬浮纳米二氧化钛的重量百分比为0.0057%至0.0681%。在标准雷电脉冲波形下，观察了纳米流体的击穿电压和斩波时间。实验结果表明，纳米TiO 2的存在提高了矿物油在正极性下的击穿电压。当纳米粒子的浓度超过0.0227wt%时，击穿强度的提高趋于饱和。纳米粒子界面区域形成的电子陷阱，可以捕获油中的快电子，降低预击穿流光前的空间电荷净密度，是提高击穿强度的主要原因。当颗粒浓度水平较高时，Gouy-Chapman扩散层的重叠导致纳米流体中陷阱密度的饱和。因此，纳米流体的击穿强度饱和。在负极性下，电子很可能在朝向阳极的途中被纳米颗粒散射，导致流光尖端附近的电场增强和击穿电压降低。
The insulation of mineral oil-based nanofluids was found to vary with different concentration level of nanoparticles. However, the mechanisms behind this research finding are not well studied. In this paper, mineral oil-based nanofluids were prepared by suspending TiO2 nanoparticles with weight percentages ranging from 0.0057% to 0.0681%. The breakdown voltage and chop time of nanofluids were observed under standard lightning impulse waveform. The experimental results show that the presence of TiO2 nanoparticles increases the breakdown voltage of mineral oil under positive polarity. The enhancement of breakdown strength tends to saturate when the concentration of nanoparticle exceeds 0.0227 wt%. Electronic traps formed at the interfacial region of nanoparticles, which could capture fast electrons in bulk oil and reduce the net density of space charge in front of prebreakdown streamers, are responsible for the breakdown strength enhancement. When the particle concentration level is higher, the overlap of Gouy–Chapman diffusion layers results in the saturation of trap density in nanofluids. Consequently, the breakdown strength of nanofluids is saturated. Under negative polarity, the electrons are likely to be scattered by the nanoparticles on the way towards the anode, resulting in enhanced electric fields near the streamer tip and the decrement of breakdown voltage.