Determination of effective moisture diffusivity and thermodynamic properties variation of regional wastes under different atmospheres

Abstract

During the thermal process to transform lignocellulosic wastes in energy, the drying process is an important stage because it requires energy and decreases overall process yield. Considering this process, moisture diffusivity is an important factor that is considered essential to understand for design, analysis, and its optimization. In this work, this parameter was analyzed at non-isothermal condition and considering the process under inert and oxidative atmospheres. Lower diffusivities were obtained under low heating rates, due to the disfavoring the moisture diffusion in the particles. Higher effective diffusivity (Deff) values were obtained when the drying is carried out under the atmosphere oxidative. Moreover, the thermodynamic parameters and DTA curves were determined. ΔH values are positive in all cases, showing that the drying process is endothermic. ΔG are positive and ΔS negative, indicating that the process is non-spontaneous. DTA curves show that the drying process is endothermic, according with the calculated ΔH.