Physical modeling of heat and moisture transfer in wet bio-sourced insulating materials

Simultaneous heat and moisture transfers in bio-sourced insulating materials are significant phenomena in thermal metrology. The present study focuses on these phenomena by experimental and numerical approaches based on the asymmetric hot-plate method. In this paper, a bio-sourced insulating material based on flax fibers is developed. The thermal and hygric properties of the sample are then investigated in the humid atmosphere. The temperature is maintained at 30 degrees C, and the relative humidity varies between 30% and 90% RH. A physics-based model of simultaneous heat and moisture transfer is developed for thermal conductivity estimation. This model is discretized with finite difference methods and implanted in MATLAB (R). With the Levenberg-Marquardt algorithm, the thermal conductivity of the sample in different hygrothermal conditions is estimated and confirmed by experimental results. The reduced sensitivity of the model to estimated parameters is studied. The results confirm and validate the theoretical and the experimental results. Published by AIP Publishing.