Zagorka Radojević

Methods of Determination for Effective Diffusion Coefficient During Convective Drying of Clay Products

© 2012 Vasic et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Methods of Determination for Effective Diffusion Coefficient During Convective Drying of Clay Products

Mathematical Modeling of Isothermal Drying and its Potential Application in the Design of the Industrial Drying Regimes of Clay Products

The processes of simultaneous moisture and heat transfer, which are often nonstation‐ ary, and the distinct nature and properties of the material to be dried complicate the description of the drying process. The theory of moisture migration and modeling of drying process has been the subject of many studies. Three theories, the diffusion, the capillary flow, and the evaporation‐condensation, have won general recognition for the explanation of moisture transfer in porous media. This study has several objectives. The first one was to present a new method for calculation of the variable effective diffusivity as well as to identify different drying mechanisms and its exact transitions during isothermal drying of clay tiles. The second and main objectives were to analyze all obtained isothermal data, to create a link with the comprehensive theory of moisture migration during drying, and to set up the non‐isothermal drying process. The procedure was based on the principle of controlling the mass transport during the drying process. Proposed regimes were consisted from several isothermal segments. Isothermal segments were selected and specificated in accordance with the clay raw material nature and the moisture migration theory.

The Effects of Chemical Composition and Firing Temperature in Heavy Clay Brick Production — Chemometric Approach

Factors influencing final clay brick properties are numerous, since the raw materials are highly heterogeneous. The chemometric approach is rarely used in analysis in this field, although it could significantly improve understanding of the overall system behavior and the quality of products. Principal component analysis (PCA) was used on a group of 139 samples collected in Serbia to discriminate groups of samples according to similarity of chemical composition and fired laboratory products properties. The focus of this study was to determine the importance of parameters that describe clay brick production and quality, depending on final usage of raw material in the clay brick industry. A fuzzy synthetic evaluation, using a membership trapezoidal function with defined optimal interval values for different types of heavy clay products, is chosen for the study. The optimal sample’s chemical composition and firing temperature were chosen by the fuzzy synthetic evaluation, regarding the kind of the heavy clay product.