The influence of voltage and air flow velocity of combined convective-electrohydrodynamic drying system on the kinetics and energy consumption of mushroom slices

Abstract

Electrohydrodynamic (EHD) is a promising process for reducing the energy consumption of convective drying processes. In this study, a combined convective-EHD drying system was designed, constructed, and examined as an economical drying system for drying mushroom slices. The effects of two levels of velocities (0.4 and 2.2 m/s) and four levels of voltages (0, 20, 25, and 30 kV) on drying kinetics, drying rate, final moisture content, and specific energy consumption of EHD system (SECEHD), convective system (SECtunnel), and combined convective-EHD system (SECtotal) were studied. The results confirmed that by applying electric field at 0.4 m/s air velocity, the enhancement in the drying rate increased with the applied voltage. The combination of 30 kV voltage with the air velocity of 0.4 m/s could significantly increase the drying rate and simultaneously reduce the specific energy consumption of the combined convective-EHD system. However, a cross-flow with the high velocity of 2.2 m/s diminished corona wind effect. Results showed that increasing velocity alongside decreasing voltage reduced the SECEHD, but SECtunnel and SECtotal declined as velocity diminished. In fact, 30kV-0.4 m/s treatment resulted in statistically similar averaged drying rate and final moisture content to 0kV-2.2 m/s, 20kV-2.2 m/s, 25kV-2.2 m/s, and 30kV-2.2 m/s treatments, but it represented considerably less SECtotal value in comparison to them. As such, the appropriate combination of electric field intensity with air velocity such as 30kV-0.4 m/s treatment is a promising solution for reducing the substantial energy consumption of industries using convective drying technique.