The effective thermal conductivity of coated/uncoated fiber-reinforced composites with different fiber arrangements

Fiber-reinforced composites are attractive for many applications in energy fields, such as thermal energy storage and building energy-saving. In these applications, their effective thermal conductivity is extremely important; however, research addressing the effect of various parameters on effective thermal conductivity is scarce. In this paper, the influences of different parameters, including volume fraction, aspect ratio, and orientation of fibers, and the thickness of coating layers on the effective thermal conductivity of fiber-reinforced composites, are numerically investigated by the Lattice Boltzmann method. Based on numerous numerical results, a correlation of the effective thermal conductivity is proposed for the composites with fibers randomly distributed in space. It is found that the thermal conductivity of fiber and coating layers are the two most dominant factors which influence the effective thermal conductivity of fiber-reinforced composites. The thickness of the coating layer affects the effective thermal conductivity of composites with fibers randomly distributed in space remarkably, while its effect on the effective thermal conductivity of composites with fibers arranged perpendicular to the heat transfer is negligible. The results of this work could provide important references for the process design and improvement of thermal performance of fiber-reinforced composites.