Three-dimensional numerical modeling and simulation of the thermal properties of foamed concrete

In this paper, a three-dimensional method was developed for modeling the heat transfer of foamed concretes with a large range of densities (300-1700 kg/m). A random generation method was extended from two dimensions (2D) to three dimensions (3D) for reproducing the microstructure of foamed concrete. A finite volume method (FVM) was then used to solve the energy transport equations for two phase coupled heat transfer through the porous structure. The effective thermal conductivities (ETCs) of foamed concretes were thus numerically calculated and the 3D predictions were compared with the existing experimental data and other analytical models. The numerical results show that the predicted effective thermal conductivity varies with the lattice number in the third dimension following an exponential relationship, and it needs at least 20 lattices along the third dimension to stabilize the simulation results. In addition, the 3D numerical predictions agree more with the experimental results, since the heat conduction in the third direction is omitted in 2D simulation, leading to the underestimation of effective thermal conductivities prediction in the same boundary conditions. Finally, a correlation was then derived between the results computed with 3D and 2D numerical models.