The present work is focused on mass transfer characterization of hygroscopic materials used for insulation, such as Low Density Fibreboards. Due to their particular morphology, these panels present a very high mass diffusivity in the connected gaseous phase and a very low thermal conductivity. This combination of properties exacerbates the coupling between heat and mass transfer in transient state. Based on experimental data obtained with an original set-up and relevant simulations performed using a comprehensive physical formulation, a throughout vision of this question is proposed in the present study. In particular, we emphasize on: - The impressive change in core temperature in terms of magnitude and duration, - The great impact of the internal temperature gradient, which slows down mass diffusion, - The dramatic error on mass diffusivity value if the coupling is ignored. Keywords: experiment; identification; modelling; RH at back-face; transient state
Freeze-drying in protective bags: Characterization of heat and mass transfer