| Electrical capacitance volume tomography (ECVT) is a novel non-invasive process tomography technique which can provide phase distribution information inside the imaging domain. Compared with other radiation based or magnetic resonance based process techniques, the cost of ECVT is very low, and it has high imaging speed. Compared with conventional electrical capacitance tomography, ECVT can deliver 3-D images and can accommodate to the imaging domains with irregular geometries. In the current study, ECVT is applied to various multiphase flow systems; the feasibilities of ECVT are demonstrated, and the limitations are discussed.;The major limitation of capacitance based tomography techniques is the low spatial resolution. One possible improvement approach is to increase the number of capacitance plates. In the current study, after introducing the basic principle of ECVT, a 24 channels ECVT sensor is compared with a 12 channels sensor. Different static solid objects are imaged by both sensors, and the results indicate that the image quality from 24 channels sensor is much better than the 12 channels system.;Trickle beds are widely used in industrial processes. A trickle bed is a column with gas and liquid concurrently flow downward through a packed bed. Although the structure is simple, the hydrodynamics is complex in a trickle bed, and there are several flow regimes exist. In this study, of particular interest are the trickling regime and pulsating regime. By applying ECVT to an air-water trickle bed, the liquid maldistribution in the trickling regime is observed. The pulse properties in pulsating regime are quantified. A mathematical model is derived to estimate the actual liquid velocity inside the pulsating trickle bed, and it is found that the pulsation is wave propagation.;In gas-liquid separation, sometimes a passive cyclonic gas-liquid separator is favored because of its simple structure, high efficiency and low energy consumption. In this study, ECVT is applied to a passive cyclonic gas-liquid separator, and the liquid distribution and the gas core behavior are investigated. A hydrodynamic model is mathematically derived to explain the gas core behavior, and the calculated results match the ECVT images well.;Bubble motion inside bubble columns is a very important topic. In this study, ECVT is applied to bubble columns with various distributors operating in different flow regimes. The spiral motion of the bubble plume is imaged, and the results match the data from optical fiber probe. Some other phenomena, such as flow regime transition, and the bubble acceleration inside a tapered conical shape column are also investigated. The last portion of this work considers ECVT applications in gas-solids systems. The gas jet in a fluidized bed is imaged by ECVT and MRI, and the results are compared quantitatively. As for irregular shape imaging domain, a bend shape ECVT is employed to investigate the solids distribution inside the riser exit region in a circulating fluidized bed.;By conducting this study, feasibilities of ECVT applications on multiphase flow systems are demonstrated. In the last chapter of this dissertation, future works are recommended. |
