EHD-enhanced drying with multiple needle electrode

The enhancement of drying rate by corona discharge from a multiple-needle electrode has been experimentally evaluated in this study. Corona wind produced by an assembly of three needle electrodes impinges and removes moisture from the surface of uniform glass beads (with a diameter of 3 mm or 6 mm) completely wetted with water. Corona discharges with positive and negative polarities have been considered. Two sets of experiments have been conducted (one with the cross-flow of air and the other without), at 1 kV increments from the corona threshold voltage to a maximum voltage of 25 kV. To evaluate the drying enhancement, a companion experiment was carried out simultaneously for each case under the same ambient conditions but without the application of the electric field. Each experiment lasted for at least 5 h. The weight loss of water as well as the ambient temperature and humidity were measured. The results are compared with those obtained using a single needle electrode to evaluate the effectiveness of a multiple-electrode system.