Abstract

Drying of moist porous media, such as paper and pulp, is an extremely energy-consuming process. Traditional drying techniques are primarily associated with convection, conduction, and thermal radiation. It is desirable to develop innovations in non-thermal and high-efficiency drying techniques. In the previous study, a novel drying technology, making use of the Dielectrophoresis (DEP) mechanism, has been experimentally proved to be an energy-efficient method to enhance the drying rate of moist porous media. DEP is a translational motion of neutral matter caused by the polarization effects in a diverging electric field. During the drying process, in the presence of the DEP force, the vapor phase is extracted away from the porous medium, which results in an increase of the evaporation rate and a decrease of the sample surface temperature. This paper extends previous experimental studies by including analysis of the heat-transfer characteristics. Specifically, the heat flux rate underneath the moist paper is monitored during the drying process. The sample surface temperature is monitored through an Infrared (IR) camera. Moreover, the convection heat transfer coefficients are estimated, and the sample’s initial moisture content is studied as a function of drying time. The experimental results show an up to 132% increase of the heat flux rate and a 242% increase of the convection coefficient due to the application of an electric field, as compared to conventional drying process. The experimental results also illustrate that the DEP effects diminish at low moisture levels. The detailed heat transfer analysis provides a foundation for the enhancement of moist porous media using the DEP mechanism for drying fragile products.

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