石墨烯增强相变材料导热性能的研究
发布时间：2018-11-11 20:13
【摘要】：相变储能材料的研究近年来引起了广泛的关注,它可以应用于太阳能储存、节能建筑材料和余热的回收利用等诸多领域。有机相变材料具有理想的相变潜热、无毒无腐蚀、化学性质稳定等优点,但具有导热系数低、相变时易泄露等缺点。为了克服有机类相变材料的缺陷,必须提高相变材料的导热性能。石墨烯具有诸多特殊的物理性能,如超高的导热系数,对于提高相变材料热导率具有广泛的前景。本论文通过三种不同的方法制备石墨烯,提高有机相变材料导热性能,并采用多种测试方式对制备的复合相变材料的性能进行深入研究。研究的主要内容如下：(1)通过改进Hummers法制备氧化石墨烯,再用水合肼还原制备了石墨烯纳米片(GNs)。将GNs与相变材料(PCM)复合制备GNs/PCM复合相变材料。通过SEM、 TEM、FT-IR、XRD、DSC和热常数分析仪等测试对石墨烯和复合前后的相变材料进行测试。结果表明：随着GNs添加量的增大,复合相变材料的热导率逐渐增大,当GNs含量为2 wt%时,热导率为1.8428 W/(m·K),是纯PCM热导率的10.1倍。200次冷热循环后GNs/PCM复合相变材料的热导率降低。GNs/PCM复合相变材料热焓值△Hm和△Hc分别为208.2J/g和195.4 J/g,GNs的添加对相变材料的相变温度和相变焓影响很小。FT-IR和XRD分析得出GNs和PCM没有发生化学反应,并且晶体结构没有发生变化。(2)采用160℃水热还原不同浓度的氧化石墨烯溶液制备石墨烯自组装气凝胶(SGA),分别采用自然吸附法和真空浸渍法制备SGA/PCM复合相变材料,并通过SEM、 FT-IR、XRD、DSC和热常数分析仪等测试对复合前后的相变材料进行测试。测试结果表明：当GO浓度为2 mg/mL时,自然吸附法和真空浸渍法制备的SGA2/PCM复合相变材料热导率分别为1.7123 W/(m·K)和2.7324 W/(m-K),明显高于纯PCM的热导率；热焓值△Hm和△Hc分别为203.4 J/g和194.5J/g、209.1J/g和197.6J/g。真空浸渍法制备的SGA2/PCM复合相变材料比自然吸附法稳定。SGA对PCM的晶体结构基本没有影响,没有发生化学反应导致新的物质生成。(3)采用环境友好型还原剂维生素C还原氧化石墨烯的方法制备三维多孔石墨烯气凝胶(VC-GA)。并通过SEM证实所制备的VC-GA结构表面光滑而内部三维多孔结构。VC-GA可显著提高相变材料PCM的热导率,特别当起始氧化石墨烯的浓度为3mg/mL时,VC-GA3/PCM复合相变材料的热导率为1.7324 W/(m·K),是纯PCM热导率的9.5倍,热焓值△Hm和△Hc分别为213.5J/g和199.8 J/g。 VC-GA对PCM的热稳定性有明显提高作用。VC-GA对PCM的晶体结构基本没有影响,没有发生化学反应导致新的物质生成。
[Abstract]:The research of phase change energy storage materials has attracted extensive attention in recent years. It can be used in many fields such as solar energy storage energy saving building materials and waste heat recovery and so on. Organic phase change materials have the advantages of ideal latent heat of phase change, non-toxic and non-corrosive, stable chemical properties, but have the disadvantages of low thermal conductivity and easy leakage during phase transition. In order to overcome the defects of organic phase change materials, the thermal conductivity of phase change materials must be improved. Graphene has many special physical properties, such as ultra-high thermal conductivity, which has a broad prospect for improving the thermal conductivity of phase change materials. In this paper, graphene was prepared by three different methods to improve the thermal conductivity of organic phase change materials. The main contents are as follows: (1) graphene oxide was prepared by modified Hummers method and then (GNs). Was prepared by hydrazine hydrate reduction. GNs/PCM composite phase change materials were prepared by combining GNs with phase change material (PCM). Graphene and phase change materials before and after composite were tested by SEM, TEM,FT-IR,XRD,DSC and thermal constant analyzer. The results show that the thermal conductivity of the composite phase change material increases with the increase of GNs content. When the GNs content is 2 wt%, the thermal conductivity is 1.8428 W / (m K),. The thermal conductivity of GNs/PCM composite phase change material decreased after 200 cycles. The enthalpy values of Hm and Hc of GNs/PCM composite phase change material were 208.2J/g and 195.4 J / g, respectively. The addition of GNs has little effect on the phase transition temperature and enthalpy of phase change. FT-IR and XRD analysis show that there is no chemical reaction between GNs and PCM. The crystal structure did not change. (2) graphene self-assembled aerogel (SGA), was prepared by hydrothermal reduction of graphene oxide solution of different concentrations at 160 鈩，
本文编号：2326012
[Abstract]:The research of phase change energy storage materials has attracted extensive attention in recent years. It can be used in many fields such as solar energy storage energy saving building materials and waste heat recovery and so on. Organic phase change materials have the advantages of ideal latent heat of phase change, non-toxic and non-corrosive, stable chemical properties, but have the disadvantages of low thermal conductivity and easy leakage during phase transition. In order to overcome the defects of organic phase change materials, the thermal conductivity of phase change materials must be improved. Graphene has many special physical properties, such as ultra-high thermal conductivity, which has a broad prospect for improving the thermal conductivity of phase change materials. In this paper, graphene was prepared by three different methods to improve the thermal conductivity of organic phase change materials. The main contents are as follows: (1) graphene oxide was prepared by modified Hummers method and then (GNs). Was prepared by hydrazine hydrate reduction. GNs/PCM composite phase change materials were prepared by combining GNs with phase change material (PCM). Graphene and phase change materials before and after composite were tested by SEM, TEM,FT-IR,XRD,DSC and thermal constant analyzer. The results show that the thermal conductivity of the composite phase change material increases with the increase of GNs content. When the GNs content is 2 wt%, the thermal conductivity is 1.8428 W / (m K),. The thermal conductivity of GNs/PCM composite phase change material decreased after 200 cycles. The enthalpy values of Hm and Hc of GNs/PCM composite phase change material were 208.2J/g and 195.4 J / g, respectively. The addition of GNs has little effect on the phase transition temperature and enthalpy of phase change. FT-IR and XRD analysis show that there is no chemical reaction between GNs and PCM. The crystal structure did not change. (2) graphene self-assembled aerogel (SGA), was prepared by hydrothermal reduction of graphene oxide solution of different concentrations at 160 鈩，
本文编号：2326012
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