Three-Dimensional Electrohydrodynamic Enhanced Water Evaporation Using Needle-Arrayed Electrodes

A study was made of the electrohydrodynamic (EHD) effect on the water evaporation rate of a channel flow with a needle-arrayed electrode system using both numerical and experimental methods. The local charged density, flow, and concentration distributions and their growth along the flow stream of a rectangular channel were described in detail. The results showed that the EHD effect on the evaporation rate increased with increases in applied voltage and electrode pitch and decreased in electrode height. For example, at an applied voltage of 16 kV, the mass transfer enhancement was 1.5 times than that of the electrode pitch from 50 to 100 mm at an electrode height of 20 mm. The mass transfer enhancement was twice as great for electrode height from 20 to 15 mm at an applied voltage of 12 kV and pitch of 100 mm. The present needle-arrayed electrode system results were compared with a five-wire electrode system based on the same geometric model and boundary conditions. It was concluded that the needle electrode cases achieved better mass transfer gains than the wire electrode cases for the present evaluated cases. Finally, the numerical results obtained satisfactory consistency with experimental data with a maximum error of 25%.