A novel identification method for the non-equilibrium heat transfer problem in porous material

In this study, a novel method is proposed to effectively identify the thermal properties of porous composite materials, which are challenging to determine directly through experiments due to non-equilibrium heat transfer between the porous matrix and fluids. To solve the non-equilibrium heat transfer in saturated porous media and calculate temperature sensitivities to unknown properties, a complex-variables-based spectral element collocation method is developed. The proposed collocation method achieves high accuracy and employs an explicit time-marching approach to avoid repetitively solving of large-scale linear systems. Additionally, a normalization conjugate gradient method is introduced to overcome the slow convergence issue of the original conjugate gradient method caused by stiffness problems. Numerical cases demonstrate that this proposed method significantly improves efficiency in solving inverse non-equilibrium heat conservation problems, making it valuable for identifying complex systems with numerous unknown parameters.