Heat and Mass Transfer Modeling of Rough Rice under Convective and Infrared Drying

摘要

Infrared drying of rice can reduce drying time, perform disinfestations and reduce rice fissuring compared to traditional hot air drying method. Fissures in the rice kernels are caused by high moisture content gradients within the kernels. To understand the moisture distributions within a rice kernel under different drying methods, we have developed a coupled heat and mass transfer processes based model. In this model, the rough rice kernel is considered to be three- dimensional ellipsoid composed ofthree components: hull, bran and endosperm. The model is solved by finite element method using COMSOL Multiphysics simulation tool. The model is validated by experiments conducted using laboratory scale infrared dryer and convective air column dryer. For these experiments, Californian medium grain ice variety, M206, with three different initial moisture contents, were used. Model predictions show good agreement with the experimental results. Using this model, a multi-pass drying process can be designedto minimize the moisture gradients, reduce the fissures and thus improve the crop market value.