Stochastic microstructure modeling and thermal conductivity of coal-based carbon foam

Abstract

The mechanical, thermal and electrical properties and applications of coal-based carbon foam (CCF) are based on its porous structure. In the present study, a 3-D stochastic numerical program was used to model the microstructure of CCF considering its non-uniformly distributed elliptical pores (i.e., pore dispersity). The heuristic program derived from the foaming process reflected the heterogeneity of foam. Stochastic seeding was used to regulate the pore location dispersity caused by material unevenness and impurities, while the pore size dispersity was revealed by assigning dissolved gas to adjacent pores during pore growth. The structural similarity was confirmed by comparison between the established model and the actual foam in geometrical features, including ligament edge/wall thickness, pore size and ligament cross-section shape etc. The effective thermal conductivity (ETC) of the stochastic model is more sensitive to changes in porosity, compared to that of uniform model of previous literatures. The reason was suspected to be the longer heat transfer path and less cross-section variation of the ligaments of heterogeneous foam. Pore location and size dispersities were regulated in a stable range by program parameters, which indicated that the stochastic model accurately simulated the microstructural complexity of CCF.