Electrical Enhancement Technique for CO2 Absorption by Water Flowing on a Plate Electrode

An electrohydrodynamic enhancement technique for CO2 absorption by a water film was studied experimentally. In the experiment, water flows across a plate electrode while above the gas phase flows in the opposite direction to the primary direction of the water flow. Placed above the water film flow are wire electrodes, set parallel to the plate electrode and normal to the primary directions of the water/gas flows, with small needles attached to their sidewalls pointed toward the plate electrode. When the plate electrode is set nearly horizontally and the water film flowing on the plate electrode is relatively thick, CO2 absorption is enhanced. This enhancement is due to secondary spiral flows in the water film, which were observed independently in a separate experiment to be likely caused by hydrodynamic shear force acting on the interface from the ionic wind induced by the needles on the wire electrodes. When the plate electrode is set vertically, and the water film flowing down the plate is thin, the enhancement is modest as there is insufficient space to allow this spiral flow.