Computational modeling of spatial variation in moisture content and temperature distribution in corn at different superheated steam temperatures

Abstract

The Superheated steam has been shown to be more effective than hot air for drying corn. Modeling studies have been carried out in fluidized bed dryers to determine the moisture and heat transfer characteristics of corn, but there are no modeling studies for a single corn kernel. Knowledge of heat and mass transfer characteristics in a single kernel would produce a better understanding of steam characteristics needed for specific drying rates. The study sought to determine the influence of steam temperature and velocity on the drying rate of a corn kernel. It used computational fluid dynamics (CFD) to model the transfer of heat and moisture between the corn kernel and superheated steam. The simulation used cone geometry to represent the corn kernel. The kernel had characteristic dimensions and 20% initial moisture content. The condition of the steam, which was typical of that found in industry, had temperatures of 120–200°C and velocities of 0.5–1.5 m/s. There was a decrease in the duration of the initial condensation phase as the temperature of superheated steam increased from 120°C to 200°C. The highest steam temperature and velocity resulted in the shortest duration for steam condensation. Contrary to what has been reported, there was no moisture loss from the corn kernel when exposed to superheated steam at 120°C, which may be due to how heat was retained in the drying chamber. Thus, the processes of tapping steam and retaining heat are important elements in the operation of industrial steam driers.