油浸式变压器内部绕组的匝间纸绝缘受温度的影响会析出气泡,进而引发局部放电导致绝缘劣化。该文通过研究油纸界面的微观结构和气泡产生的物理过程,建立气泡演化的数值模型,结合气泡生长过程中的受力分析,得到了气泡在不同条件下的生长...油浸式变压器内部绕组的匝间纸绝缘受温度的影响会析出气泡,进而引发局部放电导致绝缘劣化。该文通过研究油纸界面的微观结构和气泡产生的物理过程,建立气泡演化的数值模型,结合气泡生长过程中的受力分析,得到了气泡在不同条件下的生长规律。首先,基于Rayleigh-Plesset方程建立油纸界面处由气泡内压强主导的气泡生长过程。其次,根据理想气体体积定律与Hertz-Knudsen界面蒸发冷凝方程量化界面处水蒸气进入气泡的质量通量,并在此基础上建立气泡内压的控制方程。最后,求解获得了升温时油纸系统中气泡的生长曲线,并根据气泡生长时的受力分析得到了气泡脱离半径进而计算出气泡初始逸出温度(initial temperature of bubble escape,ITBE)。计算的气泡脱离半径与实验结果具有较好的一致性,此外预测的ITBE与实验结果的最小平均相对误差为1.11%。模型结果表明,纸中水分质量分数越高,气泡生长速度越快。而绝缘纸微观结构的变化主要通过影响气泡初始半径和气泡在界面处所受表面张力的大小,从而影响气泡的形成过程。展开更多
The bubble behavior is one of the key factors for the design and the process of aluminum reduction cell using inert anode.A see-through cell is constructed to investigate the bubble flow behavior and the electrolyte f...The bubble behavior is one of the key factors for the design and the process of aluminum reduction cell using inert anode.A see-through cell is constructed to investigate the bubble flow behavior and the electrolyte flow pattern induced by bubbles.The test results show that the electrolyte is driven by the bubble to move around the cathode,and also some vortices occur in local areas.The bubble generated at the anode bottom undergoes the processes of formation,growth,sliding,detachment and coalescence.However,the bubble generated at the middle of anode detaches rapidly from the anode surface and moves upward and collides with other bubbles,which results in coalescence or break-up.Most bubbles are released into the atmosphere at the liquid surface,while some other bubbles taken by the electrolyte flush to the height higher than the mean horizontal level of the liquid and then drop down and move horizontally and they are released finally.Some bubbles are kept unbroken and are sliding on the electrolyte surface.The diameter of bubble generated at inert anode is smaller than that of bubble generated at graphite anode.Moreover,the bubbles on inert anode are spherical,which was different from those in tubular or disk form on graphite anode.展开更多
文摘油浸式变压器内部绕组的匝间纸绝缘受温度的影响会析出气泡,进而引发局部放电导致绝缘劣化。该文通过研究油纸界面的微观结构和气泡产生的物理过程,建立气泡演化的数值模型,结合气泡生长过程中的受力分析,得到了气泡在不同条件下的生长规律。首先,基于Rayleigh-Plesset方程建立油纸界面处由气泡内压强主导的气泡生长过程。其次,根据理想气体体积定律与Hertz-Knudsen界面蒸发冷凝方程量化界面处水蒸气进入气泡的质量通量,并在此基础上建立气泡内压的控制方程。最后,求解获得了升温时油纸系统中气泡的生长曲线,并根据气泡生长时的受力分析得到了气泡脱离半径进而计算出气泡初始逸出温度(initial temperature of bubble escape,ITBE)。计算的气泡脱离半径与实验结果具有较好的一致性,此外预测的ITBE与实验结果的最小平均相对误差为1.11%。模型结果表明,纸中水分质量分数越高,气泡生长速度越快。而绝缘纸微观结构的变化主要通过影响气泡初始半径和气泡在界面处所受表面张力的大小,从而影响气泡的形成过程。
基金Projects(51304216,51371161)supported by the National Natural Science Foundation of China
文摘The bubble behavior is one of the key factors for the design and the process of aluminum reduction cell using inert anode.A see-through cell is constructed to investigate the bubble flow behavior and the electrolyte flow pattern induced by bubbles.The test results show that the electrolyte is driven by the bubble to move around the cathode,and also some vortices occur in local areas.The bubble generated at the anode bottom undergoes the processes of formation,growth,sliding,detachment and coalescence.However,the bubble generated at the middle of anode detaches rapidly from the anode surface and moves upward and collides with other bubbles,which results in coalescence or break-up.Most bubbles are released into the atmosphere at the liquid surface,while some other bubbles taken by the electrolyte flush to the height higher than the mean horizontal level of the liquid and then drop down and move horizontally and they are released finally.Some bubbles are kept unbroken and are sliding on the electrolyte surface.The diameter of bubble generated at inert anode is smaller than that of bubble generated at graphite anode.Moreover,the bubbles on inert anode are spherical,which was different from those in tubular or disk form on graphite anode.
