Liquid dielectrics filled with nanoparticles have drawn huge attentions due to enhanced dielectric and thermal properties. Despite of great achievements have been made, the charging mechanisms of nanoparticles suspended in liquid dielectrics are still open questions. It is previously argued that field charging with Maxwell–Wagner relaxation fails to explain the enhanced breakdown strength when nanoparticles have longer relaxation time constant than the timescale of streamer development in liquid dielectrics. However, it is proven in this article when the condition that the charging time constant τpc≪\tau _{\mathrm {pc}} \ll the charging time tpct_{\mathrm {pc}} is fulfilled, nanoparticles can acquire significant number of charges even if tpc≪t_{\mathrm {pc}} \ll relaxation time constant τMW\tau _{\mathrm {MW}} . It is also showed that the field charging models for nanoparticles suspended in gases and liquids share the same formulation and thus can be unified. In addition, diffusion charging is proposed to be one of the charging mechanisms for nanoparticles in liquid dielectrics, and Fuchs’s model is extended from aerosol science to liquid dielectrics. It is demonstrated the diffusion charging could be far more important than field charging in liquid dielectrics. This work may bridge the gaps of charging mechanisms and models between gaseous and liquid dielectrics.

中文翻译：

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悬浮在液体电介质中的纳米颗粒的充电机制和模型


由于增强的介电和热性能，填充纳米粒子的液体电介质引起了巨大的关注。尽管已经取得了巨大的成就，悬浮在液体电介质中的纳米颗粒的充电机制仍然是一个悬而未决的问题。先前有人认为，当纳米颗粒的弛豫时间常数比液体电介质中流注发展的时间尺度更长时，麦克斯韦-瓦格纳弛豫场充电无法解释击穿强度的增强。然而，本文证明，当满足充电时间常数 τpc≪\tau _{\mathrm {pc}} \ll 充电时间 tpct_{\mathrm {pc}} 的条件时，纳米颗粒可以获得大量的即使 tpc≪t_{\mathrm {pc}} \ll 弛豫时间常数 τMW\tau _{\mathrm {MW}} 也会充电。还表明，悬浮在气体和液体中的纳米颗粒的场充电模型具有相同的公式，因此可以统一。此外，扩散充电被提出作为纳米颗粒在液体电介质中的充电机制之一，并且Fuchs的模型从气溶胶科学扩展到液体电介质。事实证明，在液体电介质中，扩散充电可能比场充电重要得多。这项工作可以弥补气态和液态电介质之间充电机制和模型的差距。