Convection Enhanced Phase Change Composite Fibers for Advanced Thermal Management

Abstract Thermal management in modern electronic devices is increasingly challenging, as phase change materials (PCMs) can store large amounts of heat but suffer from inherently low thermal conductivity. We present a strategy to overcome this limitation by harnessing convective flow in molten PCMs to enhance heat transfer in phase change composites (PCCs). Unlike conventional PCCs that rely solely on conductive fillers, our approach exploits active heat transport via PCM fluid motion. We engineered core/shell fibers with macro-channels (>90% porosity) to enable convective flow, surrounded by a dense outer shell for structural integrity and conductive support. Using non-solvent-induced phase separation (NIPS), we tuned the internal channel architecture and examined its influence on thermal performance. Both experiments and simulations reveal that specific channel structures significantly enhance convective heat transfer, surpassing the contribution from the material’s intrinsic conductivity. The optimized PCC fiber achieves an apparent thermal conductivity of 1.05 W·m⁻¹·K⁻¹ with only 4 wt% conductive additives, which outperforms higher-conductivity composites lacking convective enhancement. We further demonstrate improved thermal buffering in electronic devices using these fibers. This work underscores the importance of thermal convection in PCCs and introduces a new design strategy that integrates internal channels to maximize heat transfer efficiency in thermal energy storage systems.