Electrohydrodynamic Drying Characteristics of Agar Gel

Heat-based drying methods often produce undesirable changes in the physical and chemical properties of materials. This paper describes the non-thermal drying capability of a relatively new technique using electrohydrodynamic (EHD) principles. The EHD system consisted of a DC power supply with a single overhead point electrode and an aluminum dish filled with 1% agar gel which acted as the grounded plate electrode. The EHD drying kinetics was highly linear (R2=0.999) and showed about three times faster drying rate than the ambient air-drying control. The relationship between the water vapor flux and the electric field strength was governed by a power law (R2=0.90), whereas the former varied logarithmically with the variation of the electrode gap (R2=0.91). The EHD-induced electric wind was considered to be the principal driving force which accelerated the drying rate through turbulence and vortex motions. Enhanced EHD sublimation occurred from the frozen gel at −14°C.