The gas–liquid microreactors can be widely used in gas–liquid absorption, gas–liquid two-phase or gas–liquid-solid three-phase reaction process in the chemical industry. It is necessary to study the gas–liquid two-phase flow and bubble behavior in microchannels. The flow characteristics and the visualization images of gas–liquid two-phase flow in a vertical circular microchannel are studied using ERT and high-speed camera techniques. The effects of superficial velocity (U_L = 0.263–1.491 m/s, U_G = 0.088–1.666 m/s) on flow pattern, gas hold up and frictional pressure drop are presented with tap water as liquid phase and air as the gas phase. Five flow patterns of bubble flow, bubbly-cap flow, slug flow, elongated slug flow and unstable slug flow are observed. The accuracy rate of identification of the flow pattern data is 90.8% by the eigenvalue extraction method from ERT. And the bubble generation mechanism under different flow patterns is proposed. In addition, the ERT technique can also reproduce the 3D flow of the gas–liquid two-phase flow in the microchannel and present the gas holdup of the system through analysis. Its value is well consistent with the calculated value of the Mishima and Hibiki’s correlation, but it is slightly lower than that of the high-speed camera technology’s results with the average error 8.5%. The friction pressure’s result is in good agreement with the predictive result of the literature. But it is observed that the flow pattern changes have no obvious effect on the friction pressure drop of the system. It has proved that ERT technique is a reliable method to study the characteristics of gas–liquid two-phase flow in microchannels.

气液微反应器可广泛应用于化工行业的气液吸收、气液两相或气液固三相反应过程。有必要研究微通道中的气液两相流动和气泡行为。使用ERT和高速相机技术研究了垂直圆形微通道中气液两相流的流动特性和可视化图像。表观速度的影响 (U _L  = 0.263–1.491 m/s, U _G = 0.088–1.666 m/s) 在流动模式上，气体滞留率和摩擦压降以自来水为液相和空气为气相呈现。观察到气泡流、气泡帽流、段塞流、拉长段塞流和不稳定段塞流五种流动模式。ERT特征值提取方法对流型数据的识别准确率为90.8%。并提出了不同流型下的气泡产生机理。此外，ERT技术还可以再现微通道中气液两相流的3D流动，并通过分析呈现系统的持气量。其值与Mishima 和Hibiki 相关性的计算值非常一致，但略低于高速相机技术的结果，平均误差为8.5%。摩擦压力的结果与文献的预测结果非常吻合。但观察到流型变化对系统的摩擦压降没有明显影响。证明ERT技术是研究微通道气液两相流动特性的可靠方法。