纳米SiO2掺杂对石蜡基绝缘油散热性能改进的分子模拟研究

Study on the improvement of heat dissipation of paraffin-based insulating oil doped by nano-SiO

利用分子模拟方法,建立纯石蜡基油模型和不同纳米SiO2掺杂浓度的石蜡基油模型,通过分子动力学计算得到各个模型的热导率、热扩散系数和介电常数等参数.在此基础上分析不同质量浓度SiO2掺杂下,石蜡基油的散热性能、流动性能和介电性能的变化规律.研究表明,随着掺杂SiO2质量浓度的提高,石蜡基油的黏度也随之提高,但仍与纯油黏温曲线一致;当掺杂质量浓度大于4 g·L^(-1)时,介电常数和介质损耗明显增大,不利于变压器油绝缘性能的保持,掺杂浓度在2 g·L^(-1)左右时,石蜡基绝缘油的散热性能最好.

Paraffin-based oil is the main raw material for the production of various high-voltage insulating oils,but the complexity of the flow and heat transfer of paraffinbased oils results in poor heat dissipation of the insulating oils.Improving the heat dissipation performance of paraffin-based oils is of great significance for improving the heat-resistant grade and insulation life of paraffin-based oils.In this paper,a molecular dynamics simulation method is used to construct a paraffin-based oil model doped with SiO2,and simulate calculation and analysis of paraffin-based oil doped with different concentrations.It is concluded that the viscosity of the doped paraffinic base oil has increased,but it is still consistent with the viscosity-temperature characteristic curve of the pure oil,and both show a downward trend with the increase of temperature,and is compared with the pure oil at a temperature of 70℃~90℃.It is close and will not affect the overall fluidity of the paraffin base oil.When the doping mass concentration is about 2 g·L^(-1),the thermal conductivity and thermal diffusivity of the paraffin-based oil reach the maximum,and the heat dissipation performance of the doped paraffin-based insulating oil is the best.The dielectric properties of paraffinbased oils change with the doping of nano-SiO2.When the doping mass concentration is greater than 4 g·L^(-1),the dielectric constant and dielectric loss increase significantly,which is not conducive to the maintenance of paraffin-based oils.This is because although there are significant effect SiO2 paraffinic base oils to improve thermal conductivity,with the increase of doping concentration,the viscosity of the oil body gradually increases,which slows down the transfer of heat in the oil body from the diffusion and flow properties,manifesting as a decrease in the thermal diffusivity.In summary,SiO2 doping with a mass concentration of 1~2 g·L^(-1) can improve the heat dissipation performance of paraffin-based oil and enhance the heat resistance level of paraffin-based insulating oil.In addition,in accordance with the "6℃ rule" for transformer insulation aging,SiO2 doped paraffin base oil can significantly increase the electrical insulation life of transformers and other power equipment by improving heat dissipation performance.