Numerical study on effective thermal conductivity of transparent electrospun polymer composite

Abstract

With the increased power of optoelectronic devices, enhancing thermal conductivities of transparent materials is key to thermal dissipation. Recently, our group has experimentally demonstrated a novel composite material with both high thermal conductivity and transparency by electrospinning. In this study, a numerical model was built to explore the effective thermal conductivity of the composite with non-overlapping electrospun polymer fibers and solved by the finite element method. Effects of the side length of a representative volume element and thermal conductivity along different directions of the composite were investigated by the model by adjusting the size and angle of the representative volume element. In the meanwhile, the effects of fiber volume and fiber orientation on the effective thermal conductivity were analyzed which is realized by controlling the fiber orientation with normal distribution. The generated models consisted of randomly distributed long fibers. Moreover, the overlapping methods of fiber films were studied to optimize the thermal dissipation. The electrospun composite was applied on a light emitting diode (LED) modules in a simulation way. In those modules, simulated effective thermal conductivity of the electrospun composite was applied and the temperature reduction on phosphor of the modules have been studied. This study provides a deeper understanding of effective thermal conductivity of composite that is reinforced by continuous long fibers and a useful tool to simulate the effective thermal conductivity with desired fiber volume fraction and fiber orientation.