Journal of Porous Media

GRAIN SIZE EFFECTS ON EFFECTIVE THERMAL CONDUCTIVITY OF POROUS MATERIALS WITH INTERNAL THERMAL CONTACT RESISTANCE

SINOPSIS

We study the effective thermal conductivity of granular porous materials with or without consideration of the thermal contact resistance. A negligible thermal contact resistance means the particles connect well with each other. Otherwise we assume thermal contact resistance layers between the particles forming a network frame in the system We calculate the effective thermal conductivity by a high-efficiency lattice Boltzmann method and examine its dependence on the grain size of porous materials. The results show that the effective thermal conductivity decreases slightly with the averaged grain size for negligible thermal contact resistance, consistent with existing observations in engineering materials studies. When the thermal contact resistance is significant, the effective thermal conductivity decreases sharply as the grain size gets smaller, which agrees with the experimental measurements on nanoporous materials where the particles are not able to contact well with each other and the resistance dominates the thermal transport.