اثر متغيرهاي عملياتي بر سينتيك خشك شدن قطعه هاي سراميكي قالب ريزي شده به روش ژل

The Effects of Operating Parameters on Drying Kinetics of Ceramic Moulded Parts by the Gel Method

There are two stages for drying of the pieces made by the gel casting method. The first stage is more important because of its effect on the shape of final segment. It is usual to dry segments by hot air under controlled humidity and temperature conditions but it has negative effect on final segment quality, so it is suggested to use liquid desiccant instead of air. The aim of this work is to investigate the effects of main parameters on drying of ceramic specimens. In the drying process of ceramic specimens using liquid desiccant, temperature, concentration, desiccant type and ceramic packing are the main parameters among other effective factors. The first experiments were done on cylindrical specimens with 7 , 9 mm diameter and length grater than 4mm, and the experimental data were analyzed with Qualitek-4 software. The results show that concentration and temperature of desiccant has the strongest effect on the drying process. A mathematical model for drying with non-constant diffusion coefficient is proposed and solved Diffusion coefficients at different temperature and concentration of liquid desiccant were calculated and compared. The result also shows that the increasing in temperature and concentration increases the diffusion coefficient. In addition, the experimental data is used to obtain a correlation for the mass transfer diffusion coefficient.