改性碳气凝胶/石蜡复合相变储热材料的研究

Research on modified carbon aerogel/paraffin composite phase change thermal storage materials

将石蜡与墙体材料复合能降低建筑人居能耗,但其易泄漏的问题严重影响了复合相变储热材料的广泛应用,采用吸附能力强的碳气凝胶为吸附载体,有望解决复合相变材料容易泄漏的弊端。为进一步提高碳气凝胶吸附石蜡的性能,采用不同质量分数的三甲基氯硅烷对碳气凝胶表面进行改性,通过XRD、SEM与FT-IR等表征手段探究了碳气凝胶表面结构的变化规律。结果表明:改性过程中三甲基氯硅烷的—Cl—Si(CH_(3))_(3)基团能与碳气凝胶表面的—OH发生枝接反应,该变化丰富了试样表面—CH_(3)数量,改善了制品的憎水性与孔结构,提高了其吸附非极性石蜡的能力;当三甲基氯硅烷的质量分数为30%时,改性碳气凝胶具有最佳的吸附性能,充分浸渍后能吸附85.87%的石蜡。经200次熔融-冷凝循环试验后,复合样品不仅未发生明显的泄漏现象,而且相变温度和相变焓均未发生显著变化。该研究制备的复合相变储热材料具有优异的稳定性与良好的隔热保温性能,为开发新型墙体隔热保温材料提供了新的思路。

The building energy consumption can be reduced with the utilization of paraffin for walls,but an easy leakage of this material seriously affects the extensive application of composite phase change heat storage materials,which is expected to be solved by using carbon aerogel with large adsorption capacity as adsorption carrier.In order to further improve the par-affin adsorption performance,the surface of carbon aerogel was modified with trimethylsilyl chloride in different concentra-tions and the surface microstructure evolution of carbon aerogel was investigated by XRD,SEM and FT-IR.The experiment manifested that the—Cl—Si(CH_(3))_(3) group of trimethylchlorosilane could branch with—OH on the surface of carbon aero-gel in the process of modification,which enriched the amount of—CH_(3) on the surface of the sample,improved the hydro-phobicity and pore structure of the product,and improved its ability to adsorb non-polar paraffin.When the mass concentra-tion of trimethylsilyl chloride reached 30%,the carbon aerogel showed the best adsorption performance,and could absorb 85.87%of paraffin after full immersion.After 200 melting-condensation cycles,no obvious leakage was found and signifi-cant change was not obvious in phase change temperature and enthalpy.The composite phase change material had excellent structural stability and thermal insulation performance,which provided new ideas for the development of new wall insula-tion materials.