515 / 2019-01-03 04:16:43

Constructing and Performance Strengthening of Graphite-based Composite Phase Change Materials for Thermal Energy Storage

Thermal energy storage technology; Phase change material; Graphite; Thermal storage characteristics; Performance strengthening

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Based on strengthening of hermal energy storage capability and thermal conductivity of graphite-based composite phase change materials (PCM), the thermal storage characteristics of graphite in aspects of surface, interlayer, and interface were explored to obtain supporting materials with evident characteristics. Then, the PCM was absorbed into supports to prepare graphite-based PCM composites for thermal energy storage. Natural flake graphite (FG) was modified by microwave-H2O2 treatment and then absorbed stearic acid (SA) to prepare composites. It proposed a new method of surface modification of graphite for enhancing thermal energy storage performances, through investigating the influences of surface properties and structure characterizations on the thermal storage properties. Flake graphite was stripped through a coupled ultrasonication-milling process followed by a shear-assisted supercritical CO2 stripping, to obtain untrathin graphite sheets (UGS) with different layer thickness and then the graphite sheets were used as support to prepare composites. It revealed the mechanism of interlayer stripping of flake graphite for enhancing thermal energy storage performances through studying the relationships between stripping degree and thermal storage properties. Carbon nanofibers (CNF) was grew on the surface of flake graphite and then were coupled to bentonite (Bm) through ‘chemical bonding' to build supporting material (FG-CNF-Bm) with ternary structure for preparing composites. It illuminated the synergetic effect of interfacial coupling based on graphite for enhancing thermal energy storage performances via exploring the mechanism of coupling behavior on thermal storage properties. It can achieve the controlling and strengthening of thermal storage performances of composites through building connections between structure and performances, and can provide new method for the preparation and application of form stable phase change material with high performances.