An electrical impedance tomography (EIT) system design is proposed for imaging of phase distribution in gas-water two-phase flow from boundary measurement of electrical potentials in response to direct current (DC) injection. DC injection simplifies substantially the system design, but introduces problems due to polarization of injection electrodes. Electrode polarization means charge accumulation on the electrode-water interface causing a drift in the interfacial potential difference. The polarization problems are coped with by using dedicated electrodes for injection and potential measurement, and using a current source unaffected by the polarization of current-carrying electrodes (CCEs). Furthermore, the polarization of CCEs is controlled, to lessen the possible influence on the sensing electrodes (SEs), by using a short (milliseconds in width) pulse for injection with a charge balanced injection strategy. The impact of electrode polarization and the effectiveness of countermeasures introduced in the present design are discussed through comparisons of measured boundary potentials and of images reconstructed for a simple object simulating large bubbles in water.

提出了一种电阻抗断层扫描 (EIT) 系统设计，用于根据响应直流 (DC) 注入的电位边界测量对气水两相流中的相分布进行成像。直流注入大大简化了系统设计，但由于注入电极的极化而引入了问题。电极极化是指电极-水界面上的电荷积累导致界面电位差漂移。通过使用专用电极进行注入和电位测量，并使用不受载流电极 (CCE) 极化影响的电流源来解决极化问题。此外，控制 CCE 的极化，以减少对感应电极 (SE) 的可能影响，通过使用具有电荷平衡注入策略的短（宽度为毫秒）脉冲进行注入。通过比较测量的边界电位和为模拟水中大气泡的简单物体重建的图像，讨论了电极极化的影响和本设计中引入的对策的有效性。