CFD Analysis on Gas-Liquid Mixing in a Stirred Tank through Electrical Capacitance Tomography Measurements

Abstract

Electrical Capacitance Tomography (ECT) serves as a non-invasive imaging method employing electrical measurements to reconstruct and assess flow regimes and entrainment levels within a stirred tank, without disrupting the flow system. However, the development of an ECT experimental setup is associated with considerable cost and time investment for optimizing parameters. Thus, the study addresses this challenge by focusing on the creation of an ECT model. A stirred tank, measuring 0.64 m in height and 0.5 m in diameter, equipped with an impeller and surrounded by electrodes, was developed using COMSOL Multiphysics software. Various parameters such as air velocity, impeller velocity, voltage energy, and types of inlet gases (oxygen, nitrogen, and hydrogen) were examined to observe their influence on gas-liquid mixing conditions within the ECT vessel. Simulation results revealed that fluid flow distribution increased with higher gas velocities, and gas retention also escalated with increased gas density. Notably, hydrogen gas demonstrated the lowest gas retention compared to other gases. The velocity of gas-liquid mixing increased with the impeller's rotational speed. Interestingly, the voltage applied to ECT electrode showed minimal variation. This developed ECT model holds promise for enhancing local economies by advocating optimal mixing techniques in stirred tank operations.