The internal heat exchange between each phase and the Local Thermal
Equilibrium (LTE) scenarios in multi-phase fibrous materials are considered
in this paper. Based on the two-phase heat transfer model, a criterion is
proposed to evaluate the LTE condition, using derived characteristic
parameters. Furthermore, the LTE situations in isothermal/adiabatic boundary
cases with two different heat sources (constant heat flux and constant
temperature) are assessed as special transient cases to test the proposed
criterion system, and the influence of such different cases on their LTE
status are elucidated. In addition, it is demonstrated that even the
convective boundary problems can be generally estimated using this approach.
Finally, effects on LTE of the material properties (thermal conductivity,
volumetric heat capacity of each phase, sample porosity and pore hydraulic
radius) are investigated, illustrated and discussed in our study.