Electrohydrodynamic drying of apple slices: Energy and quality aspects

In this study, EHD was applied for apple slices drying through a multiple needle-to-plate electrode with a fixed 25 mm gap, using different combinations of voltage and air velocity at room temperature. Effects of EHD on drying kinetics, color degradation, and energy consumption were studied. High voltage significantly increased drying rate by 1.5-4 times at high (5 m/s) and low (1 m/s) air velocity, respectively. Combined EHD-convective drying was more efficient for moisture removal than sole EHD drying. The most significant effect of EHD on drying rate was observed at the highest voltage and low air velocity. Effect of EHD on color was insignificant at voltages below 10 kV, but higher voltage intensified progressively color degradation. Energy, used in EHD drying, was negligibly small (1-2%) as compared to the total energy consumption of AC/DC converter.