Study of water diffusion through raffia Vinifera fibres of the stem from bandjoun-cameroon: Case of drying kinetics

Abstract

The objective of this study is to determine some physic-chemical properties of raffia Vinifera fibres resulting from the stem. The moisture content rate of these fibres was evaluated along the stem and varies in the intervals [12-6] % and [19-107] % for dry and fresh fibres respectively. Thermo gravimetric method using the temperatures 60, 70 and 80°C respectively, enables us, through Fick's 2nd law, to find other parameters. Owing to the data on the moisture content, the different curves were plotted. Fourteen models were tested to predict the drying kinetics of fibres with cylindrical form. It comes out that the models "Diffusion approach" and "Verma et al. (1985)" models fitted well with the phenomenon. The effective diffusion coefficient of the initial phase varies in the intervals [6.32×10-11-3.00×10-10] m2/s and [1.76×10-10-4.47×10-10] m2/s for dry and fresh fibres respectively. We notice that the moisture content and the effective diffusion coefficient grow from the periphery towards the centre in each cross-section. Owing to the relation of Arrhenius, the activation energy was evaluated only in the initial phase and oscillates respectively in [4.72 - 22.86] KJ/mol.K and [4.65 - 12.13] KJ/mol.K for dry and fresh fibres.