Supawan Tirawanichakul, Jutharat Tasara, and Yuthana Tirawanicahkul

pp. 325 - 333

Abstract

Thermo-physical properties and high voltage electrical field (HVEF) effecting to drying rate of paddy was presented in this research. Thermo-physical properties in terms of apparent-density, specific heat capacity, void fraction and equilibrium moisture content were studied. The results show that apparent density and void fraction are linearly related to initial moisture contents of paddy, whilst the specific heat capacity is a polynomial function of initial moisture content. Determining the equilibrium moisture content using static method showed that the calculated value by Henderson's model was the best fitting with the
experimental results.
         For studying effect of high voltage electric field on drying rate of paddy, paddy with initial moisture contents of 25-35% dry-basis was placed between electrode gaps of 2 and 3 cm and treated by electrostatic discharge time of 20, 30, 40 min. Drying conditions was set at 50°C and air speed of 1.9 m/s. The desired final moisture content was about 14-16% dry-basis. The results concluded that drying rate of the treated paddy by higher voltage electric field was faster than treating with a lower voltage electric field. In addition, drying
rate of paddy was linearly dependent to high voltage electric field add discharge time and inversely related
to electrode gap.