Finite Element Analysis of Fillers and Bubbles on the Thermal Conductivity of Paraffin-based Composite Phase Change Materials

Thermal conductivity is a critical parameter in designing composite phase change materials (PCMs). This study employs the finite element method to analyze the effects of fillers and bubbles on thermal conductivity of paraffin-based PCMs. The results reveal that CNTs significantly enhance thermal conductivity, with improvements scaling with their volume fraction, smaller diameters, and longer lengths. Alignment in a layered structure along the loading direction further maximizes thermal performance. Conversely, bubbles disrupt heat transfer, with thermal conductivity decreasing as bubble volume fraction increases. Bubble diameter exhibits an initial positive impact on thermal conductivity, followed by a decline as insulating zones form. Bubbles near CNTs slightly mitigate their disruptive effect by redirecting heat flow through the fillers. These findings enrich the understanding of material microstructure-thermal conductivity relationships in the PCM field.