Simulation of Drying Behavior of Cotton Bobbins by a Simultaneous Heat and Mass Transfer Model

In this study, the drying process of cotton bobbins for different drying air temperatures has been simulated by a simultaneous heat and mass transfer model. In the model, the mass transfer is assumed to be controlled by diffusion. In order to make the simulation, firstly, drying behavior of cotton bobbins for different drying air temperatures has been determined on an experimental bobbin dryer setup which was designed and manufactured based on hot-air bobbin dryers used in textile industry. In the experimental setup, temperatures of different points in cotton bobbins were measured by thermocouples placed inside the bobbins, and weights of the bobbins during the drying period were determined by means of a load cell. Then, moisture ratio and temperature values of the model have been fitted to the experimental ones. The fit was performed by selecting the values for the diffusion coefficient and the thermal diffusivity in the model in such a way that these values make the sum of the squared differences between the experimental and the model results for moisture ratio and temperature minimum. Results show that there is a good agreement between the model results and the experimental measurements. The results also show that temperature has a significant effect on mass transfer and the temperature dependence of the diffusion coefficient may be expressed by an Arrhenius type relation.