Finite Element Simulation of Drying of Rough Rice (original) (raw)

A liquid diffusion model for thin-layer drying of rough rice

European Food Research and Technology, 2008

In this study, the drying behavior of single-layer rough rice with a moisture content of between 22 and 24% on the dry basis was simulated by means of a liquid diffusion model, based on a prolate spheroid geometry. For this purpose, the solution of liquid diffusion equation was fitted to the experimental moisture ratios for drying air temperatures between 40 and 60 °C and velocity 1.5 m s−1. In order to make a comparison, the predictions of liquid diffusion equations for a spherical and finite cylindrical geometry were also fitted to the experimental results. Modeling was performed by selecting the diffusion coefficients in diffusion equations in such a manner as to minimize the sum of the squared differences between the experimental results and the theoretical predictions. It was found that the liquid diffusion model, based on a prolate spheroid geometry, explains single-layer drying behavior of rough rice well. It was also found that the model, based on a prolate spheroid geometry, has better agreement with the experimental results than the other geometries.

Drying kinetics of rough rice grain

International Journal of Food Science and Technology, 1982

It is shown that thin layer drying of rewetted rough rice grain in air flow may be interpreted in terms of Fick's law solution for diffusion from a sphere. Diffusion coefficients were calculated by non-linear regression analysis comparing actual and predicted values of grain moisture content. The activation energy of rough rice was calculated assuming an Arrhenius type equation for moisture diffusivity dependence on the inverse of the absolute temperature.

A diffusion based model for intermittent drying of rough rice

Heat and Mass Transfer, 2008

In this study, intermittent drying behavior of single layer rough rice with a moisture content of between 22 and 24% on the dry basis was simulated by means of a liquid diffusion model based on a prolate spheroid geometry. For this purpose, solution of the liquid diffusion equation was fitted to the experimental data for the drying air temperature 40°C, drying velocity 1.5 ms−1 and tempering periods ranging from 0 to 1 h. In order to make a comparison, solution of the liquid diffusion equation for a finite cylindrical geometry was also fitted to the experimental data. The results show that the liquid diffusion model based on a prolate spheroid geometry explains the drying behavior of rough rice more accurately. The results also show that greater variations occur in diffusion coefficient with increasing tempering time for prolate spheroid geometry which is more realistic geometry for a rough rice grain.

Experimental study of deep-bed drying kinetics of rough rice

A non-equilibrium model for the numerical simulation of rough rice drying in a deep-bed dryer was evaluated for predicting the variation of average grain moisture content with time. For this purpose, a laboratory scale deep-bed dryer was designed and built, and the average moisture content of the bed was experimentally determined during the drying process. The effects of temperature, velocity, and relative humidity of the drying air on the average grain moisture content were similarly investigated. Relative error and mean relative error were calculated for the simulation results, and found to be in acceptable range (10%-15%, and <10%, respectively). Results revealed that the temperature of drying air was the most influential parameter on the drying time. Finally, the model proved to be able to predict the variation of the average moisture content with respect to the time with a good accuracy. Citation: Torki Harchegani M., A. Moheb, M. Sadeghi, M. Tohidi, and Z. Naghavi. 2012. Ex...