Electrohydrodynamic drying of sand

Abstract

This study analyzes the electrohydrodynamic (EHD) drying characteristics of sand.Effect of process parameters (independent variables) including air speed, electrode gap and applied voltage on drying kinetics and dependent variables including percentage water removed (%), Sherwood number, EHD number and specific energy consumed (kJ·kg -1 ) were also investigated using a central composite design and response surface methodology. Maximum drying was obtained for process parameter combination of air speed (2 m·s -1 ), electrode gap (1.5 cm) and applied voltage (15 kV). Air speed and electric field intensity (ratio of applied voltage to electrode gap) were found to have significant effect on percentage water removed (%) and Sherwood number. In case of EHD number and specific energy consumed during the EHD drying process, all process Downloaded by [University of Nebraska, Lincoln] at 16:37 06 June 20162 parameters had significant effect on them. The specific energy consumed increased with an increase in applied voltage but reduced with an increase in air speed at any given applied voltage suggesting that the EHD drying process, in combination with cross-flow, will lead to higher drying rate and low energy consumption under ambient conditions. Regression models were also developed describing the relation between independent and dependent variables.

Electrically enhanced drying of white champignons

“…In contrast, 2×2 electrode initiated exponential drying kinetics (falling drying rate), which indicates diffusion-limited drying. Both cases have been reported in literature, [5,10] however the reason for the difference in drying behaviour has not been discussed.…”

Electrohydrodynamic drying of food: New insights from conjugate modeling

“…The ion current is small, in the order of a few milliamps per meter of wire. Previous experimental studies (Martynenko and Zheng, 2016;Singh et al, 2017) reported slightly lower currents (below 1 mA), which are most likely related to shorter wires or needle electrodes that were used. A quadratic relation between ion current and emitter voltage is found, in correspondence with previous studies (Dalvi-Isfahan et al, 2016;Martynenko and Kudra, 2016).…”

Future perspectives for electrohydrodynamic drying of biomaterials

“…Typically only crossflow air speeds, generated mechanically with a fan, are reported in the case of hybrid fan-assisted EHD drying. Instead, analytical predictions are used to estimate the corona wind speed, based on the bulk electric field strength E b [30,44,53]:…”

“…Although the voltage is in the kV range, the corona ion current is often very low, in the mA range [44,52,53]. Thereby, the power required for the corona discharge P EHD is quite low, typically 1-10 W (Figure 2), which is in the same range as a computer fan.…”