Effect of the water content measurements on the estimation and identifiability of water diffusion and convection mass transfer coefficients

The aim of this work was to determine the impact of water content measurements on the structural and practical identifiability of the diffusion and the convection mass transfer coefficients. Global or internal water content were generated from the diffusion model with the addition of Gaussian noise. The diffusion and convection mass transfer coefficients were estimated from the water content by least-squares minimization and their confidence interval was calculated using the profile likelihood and the asymptotic methods. A unique combination of mass transfer coefficients reproduced exactly water content values without noise, indicating their structural identifiability. The coefficients were practically identifiable from the internal water content or the global water content if the noise intensity was less than 2% and 5%, respectively. The confidence intervals of the coefficients were asymmetric and were not accurately described by the asymptotic method.