Effects of Air Drying and Mechanical Drying on Thermal Properties of corn

Abstract

In order to grasp heat and mass transfer properties during the process of conditioning, drying and cooling , this paper described the measurement of thermal properties, namely specific heat, thermal conductivity and thermal diffusivity of corn under air drying and mechanical drying. The apparent specific heat at different moisture content were determined in the temperature ranging from 50-80°C using a KD2 Thermal Properties Analyzer and a continuous Differential Scanning Calorimeter (DSC) method, respectively. And thus thermal diffusivity was calculated. The results showed that the specific heat increased from 1839 to2976 J/kg K with an increase in temperature from 50°C to 80°C and moisture content from 8% to12%. The thermal conductivity increased from 0.126 to 0.204 W/m K with an increase in temperature from 50°C to 80°C and moisture content from 8% to 20%. The heat conductivity and apparent specific heat of corn under air drying and mechanical drying increased while temperature rising, however, air drying corn had lower values. The specific heat of corn under high air drying was inclined to increase, with increasing drying temperature and moisture content. The specific heat, thermal conductivity and thermal diffusivity displayed second order polynomial relationships with temperature and moisture content. The models were established in this study could provide references for similar models of food and feedstuffs.