EHD-enhanced drying with multiple needle electrode

Abstract 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.

[1]  A. Wolny.  Intensification of the evaporation process by electric field , 1992 .

[2]  J. Kirschvink,et al.  Electrostatic enhancement of industrial drying processes , 1986 .

[3]  F. Kulacki,et al.  A preliminary study of electrohydrodynamic augmented baking , 1978 .

[4]  N. N. Barthakur,et al.  ELECTROHYDRODYNAMIC (EHD) DRYING OF APPLE SLICES , 1999 .

[5]  T. Yamamoto,et al.  Electrohydrodynamics in an electrostatic precipitator , 1981, Journal of Fluid Mechanics.

[6]  T. R. Bajgai,et al.  HIGH ELECTRIC FIELD DRYING OF JAPANESE RADISH , 2001 .

[7]  R. Fax,et al.  The Influence of Electric Fields on Convective Heat and Mass Transfer from a Horizontal Surface under Forced Convection , 1972 .

[8]  R. E. Bolz,et al.  CRC Handbook of tables for Applied Engineering Science , 1970 .

[9]  Y. H. Chen,et al.  Potato slab dehydration by air ions from corona discharge , 1991 .

[10]  H. R. Carlon,et al.  Enhanced drying rates of wetted materials in electric fields , 1992 .

[11]  F. C. Lai,et al.  EHD-Enhanced Drying with Needle Electrode , 2003 .

[12]  T. R. Bajgai,et al.  DRYING OF SPINACH WITH A HIGH ELECTRIC FIELD , 2001 .

[13]  Jane H. Davidson,et al.  Turbulence generation by electric body forces , 1986 .

[14]  Oscillatory Electrohydrodynamic Gas Flows , 1995 .

[15]  A. Wolny,et al.  The Effect of Electric Field on Heat and Mass Transfer , 1996 .

[16]  G. Woolsey,et al.  Characterization and use of an optical fiber interferometer for measurement of the electric wind. , 1995, Applied optics.

[17]  S. Edward Law,et al.  Electroosmotically enhanced drying of biomass , 1997 .

[18]  Roger B. Keey,et al.  Drying principles and practice , 1972 .