Fig. 1. Dispersion stability of composite phase change material (GNP 0.5 wt.%) without addition of dispersant and with adding different kinds of dispersants: (a) Initial state; (b) let the mixture stand for 15 min; (c) let the mixture stand for 30 min; (c) solidification state.未添加分散剂与添加不同种类分散剂的复合相变材料(GNP 0.5 wt.%)分散稳定性　(a)初始状态; (b)静置15 min; (c)静置30 min; (d)凝固状态

Fig. 2. Statuses of composite phase change material (GNP 0.5 wt.%) after different melting-solidification cycles: (a) After 5 cycles; (b) after 10 cycles.复合相变材料(GNP 0.5 wt.%)经历不同次数熔化-凝固循环后的状态　(a) 5次; (b) 10次

Fig. 3. Composite phase change materials with different mass fractions of graphene nanoplatelets.含有不同纳米石墨烯片质量分数的复合相变材料

Fig. 4. The microstructure and morphology of (a) graphene nanoplatelets (× 5000); (b) graphene nanoplatelets (× 25000); (c) composite phase change materials (× 5000); (d) composite phase change materials (× 20000).微观形貌结构　(a)纳米石墨烯片(× 5000); (b)纳米石墨烯片(× 25000); (c)复合相变材料(× 5000); (d)复合相变材料(× 20000)

Fig. 5. FTIR spectra of n-octadecane and 2.0 wt.% graphene nanoplatelets composite phase change materials.正十八烷与2.0 wt.%纳米石墨烯片复合相变材料的FTIR光谱

Fig. 6. The DSC curves of n-octadecane and composite phase change materials.正十八烷及其复合相变材料的DSC曲线

Fig. 7. Temperature dependence of specific heat capacity of composite phase change materials.复合相变材料比热容随温度变化关系

Fig. 8. Average specific heat capacity before and after phase transition.相变前后的平均比热容

Fig. 9. Thermal diffusion coefficient and thermal conductivity of graphene nanoplatelets composite phase change materials with different mass fractions at 20 ℃.不同质量分数的纳米石墨烯片复合相变材料在20 ℃时的热扩散系数及导热系数