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This chapter is devoted to study heat and mass transfer and dimension variations of arbitrary-shaped porous materials. The focus is on the drying process of clay ceramic materials. Here, different topics related to history, manufacturing, drying process, phenomenological lumped modeling, and parameters estimation are present and discussed. Emphasis is given to industrial clay bricks, with theoretical and experimental approaches.

Rice (Oryza sativa L.) is a greatly important socio-economic crop. Immediate threshing and drying of wet harvested grains, to reach 18–19% (w.b) moisture content, is a practical method used by individual farmers to slow deterioration and increase selling prices. However, rough rice grain is different from other grains because it has an outer cover shell (palea and lemma) and a bran layer. Thus, the heat and mass transfer processes that take place during grain drying are different from those of other cereal grains, so understanding the effect of different treatments, drying temperature, moisture content and the gradients in rice grains is essential to optimize the drying conditions. In this sense, the current study aims to analyze the moisture removal and its effects on the stress cracking and the number of brown rice grains (BRSMG CONAI variety) at the temperatures of 60 and 80°C.

This work aims to study convective drying of ellipsoidal solids. Aplication has been done to drying of wheat Kernel. Diffusion equation in cylindrical coordinates has been solved via Galerkin-based integral method considering convective boundary conditions and constant thermo-physical properties. Results of the temperature and moisture content are presented and compared with wheat experimental drying data at relative humidity 33.8 % and temperature 47.0°C. It was verified that heat transfer in the drying process occurs much faster than the mass transfer, thus providing a rapid heating of the product, which reduces grain quality.

Transport phenomena in porous media represent an important research area related to heat and mass transfer, and fluid flow fields. This chapter presents information about anomalous behaviour of moisture transient diffusion in vegetable fiber-reinforced composites materials. Composites reinforced with natural fibers are sensitive to influences from environmental agents such as moisture and temperature. Herein, topics related to theory, experiments, mathematical modeling and solution procedures, and technological applications are presented and discussed in detail. An advanced model that (Langmuir-type model) to describe water absorption in polymer composites and the analytical (Laplace transform technique) and numerical (finite-volume method) solutions of the governing equation has been obtained, considering constant thermo-physical properties. In the Langmuir model, moisture sorption can be explained by assuming that water exists in the free and bound phases inside the material. Application has been done to water uptake in Caroa fiber-reinforced polymer composites. Results of the absorption kinetics and concentration distribution of water (free and trapped water molecules) within the material along the process are presented and analyzed. Predicted results compared to experimental data of average moisture content have shown that the model was effective for description of the phenomenon, allowing a better understanding about the effects of moisture migration mechanisms.

The objective of this study was to investigate numerically heat and mass transport during drying of grains with particular reference to bean and rough rice. The proposed mathematical models based on the Fick’s and Fourier’s Laws consider constant physical properties and convective boundary condition at the surface of the solid. The solutions of the governing equations were performed using ANSYS CFX®software. The grains were regarded as an ellipsoid of revolution. Results of the drying and heating kinetics and moisture content and temperature distributions in the grains along the drying process are presented and analyzed.

Drying can be defined as a simultaneous heat and mass transfer process between product and air drying. These phenomena have occurred due to thermal and moisture gradients and they are affected by different parameters. The inadequate management of this process can cause severe damage to the product such as cracking, loss of nutritional properties and even loss of the product quality. Thus, this paper proposes a numerical study of heat and mass transfer that occurs during the rough rice drying process, using the commercial software ANSYS CFX®. Herein the grain was considered as ellipsoid of revolution.