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
COMPARISON OF TWO METHODS OF POULTRY MANURE DRYING
The high content of water in poultry manure creates problems for its collection, transport and storage on the large scale farms with breeding laying hens. The aim of this paper is to inform about the experimental and theoretical investigations and comparisons of moisture content reduction from poultry manure by two different methods of forced convection. The experimental data created the background for calculation and modelling, which resulted in definition of the theoretical drying coefficient, useful for description and modelling of the drying process. The theoretical model has been verified and compared with the experimental results obtained from the measurement. Manure drying is compared with the air flow on the top of manure, with the air flow passing from the bottom through supporting trays with different diameter holes and therefore through manure up. Using the experimental data with different convective air speed and hole size in the laboratory conditions there was the drying coefficient calculated depending on the drying time and air speed at constant temperature. The experimental data show that the air flow will significantly increase the amount of moisture carried away from the material. The hole size does not significantly affect the water runoff by convection without additional air flow.
Thermodynamics of water sorption in clay
Experimental data on desorption isotherms of three types of clay at different temperatures (40, 50 and 60°C) were determined using a static method. The results were fitted by the famous Guggenheim-Anderson-deBoer (GAB) model. The thermodynamic functions, differential heat of sorption, net integral enthalpy and entropy, were evaluated at several moisture contents. Heat of sorption decreased with the moisture content and the trend became asymptotic as the moisture content of 0.01 (d.b.) was approached.