纳米复合材料的制备及相变特性研究
|
摘要
以4种不同类型的纳米碳材料(纳米石墨烯GNP-B、纳米石墨烯GNP-C、多壁碳纳米管MWCNTs和石墨化多壁碳纳米管G-MWCNTs)为填料,采用两步法制备了不同质量分数(0.2%～3.0%)的纳米复合相变材料。扫描电镜分析表明纳米碳材料较好地被石蜡包覆,由于纳米碳材料具有不同的管状和层状结构,纳米复合材料表现出不同的比表面积。红外光谱分析(FT-IR)表明纳米碳材料与石蜡之间未发生化学反应,仅以物理方式彼此结合。差示扫描量热分析(DSC)表明,纳米碳材料的种类和浓度对纳米复合材料相变温度的影响很小,熔化和凝固过程中最大的相变温度差分别为0.74℃和1.11℃。但随碳纳米颗粒质量分数的增加,复合相变材料的相变潜热值逐渐减小。对于4种纳米复合材料,当质量分数为3%时,4种纳米复合材料(MWCNTs、G-MWCNTs、GNP-C和GNP-B)熔化过程的相变潜热相比纯石蜡分别降低了7.3%、13%、12%和12.8%,凝固过程的相变潜热相比纯石蜡分别降低了11.2%、19.9%、17.8%和11.4%。
Four types of nanocomposite PCMs were prepared by mixing paraffin with multi-wall carbon nanotubes(MWCNTs),graphitized MWCNTs and nanographenes with different layer numbers(GNP-B,GNP-C).The SEM images analysis showed that the carbon nanofillers were well coated with multiple layers of paraffin.Moreover,the surface of the composites showed different images due to the difference of tubular and flaky structures of the carbon nanofillers.The FT-IR spectrum proved that it was a physical interaction between paraffin and the carbon nanofillers and there was no chemical reaction in the infiltrating process.There was no clear relationship between the phase change temperature and the type and loading of the carbon nanofillers.It showed that phase change enthalpy of nanocomposite PCM decreased gradually with the increasing of the loading of carbon nanofillers.Among the four kinds of carbon nanofillers,at the highest loading of 3 mass% for MWCNTs,G-MWCNTs,GNP-C and GNPB,the melting enthalpies were lowered by 7.3%,13%,12% and 12.8% compared with pure paraffin for 196.2 J/g,respectively.Similarly,the freezing enthalpies were lowered by 11.2%,19.9%,17.8% and 11.4%.
Four types of nanocomposite PCMs were prepared by mixing paraffin with multi-wall carbon nanotubes(MWCNTs),graphitized MWCNTs and nanographenes with different layer numbers(GNP-B,GNP-C).The SEM images analysis showed that the carbon nanofillers were well coated with multiple layers of paraffin.Moreover,the surface of the composites showed different images due to the difference of tubular and flaky structures of the carbon nanofillers.The FT-IR spectrum proved that it was a physical interaction between paraffin and the carbon nanofillers and there was no chemical reaction in the infiltrating process.There was no clear relationship between the phase change temperature and the type and loading of the carbon nanofillers.It showed that phase change enthalpy of nanocomposite PCM decreased gradually with the increasing of the loading of carbon nanofillers.Among the four kinds of carbon nanofillers,at the highest loading of 3 mass% for MWCNTs,G-MWCNTs,GNP-C and GNPB,the melting enthalpies were lowered by 7.3%,13%,12% and 12.8% compared with pure paraffin for 196.2 J/g,respectively.Similarly,the freezing enthalpies were lowered by 11.2%,19.9%,17.8% and 11.4%.
引文
[1] Sharma A,Tyagi V,Chen C,et al.Review on thermal energy storage with phase change materials and applications[J].Renewable Sustainable Energy Rev,2009,13(2):318-345.
[2] Nomura T,Tsubota M,Oya T,et al.Heat storage in directcontact heat exchanger with phase change material[J].Applied Thermal Engineering,2013,50(1):26-34.
[3] Pintaldi S,Perfumo C,Sethuvenkatraman S,et al.A review of thermal energy storage technologies and control approaches for solar cooling[J].Renew Sustain Energy Rev,2015,41:975-995.
[4] Kaygusuz K,Sari A.High density polyethylene/paraffin composites as form-stable phase change material for thermal energy storage[J].Energy Sources Part A,2007,29:261-270.
[5] Alkan C.Enthalpy of melting and solidification of sulfonated paraffins as phase change materials for thermal energy storage[J].Thermochimica Acta,2006,451(1-2):126-130.
[6] Wu S,Zhu D,Zhang X,et al.Preparation and melting/freezing characteristics of Cu/paraffin nanofluid as phase-change material(PCM)[J].Energy Fuels,2010,24(3):1894-1898.
[7] Wu S Y,Wang H,Xiao S,et al.An investigation of melting/freezing characteristics of nanoparticle-enhanced phase change materials[J].J Therm Anal Calorim,2012,110(3):1127-1131.
[8] Kumaresan V,Velraj R,Das S K.The effect of carbon nanotubes in enhancing the thermal transport properties of PCM during solidification[J].Heat and Mass Transfer,2012,48(8):1345-1355.
[9] Harish S,Orejon D,Takata Y,et al.Thermal conductivity enhancement of lauric acid phase change nanocomposite with graphene nanoplatelets[J].Applied Thermal Engineering,2015,80:205-211.
[10] Fan L W,Fang X,Wang X,et al.Effects of various carbon nanofillers on the thermal conductivity and energy storage properties of paraffin-based nanocomposite phase change materials[J].Appl Energy,2013,110:163-172.
[11] Warzoha R J,Weigand R M,Fleischer A S.Temperature-dependent thermal properties of a paraffin phase change material embedded with herringbone style graphite nanofibers[J].Appl Energy,2015,137:716-725.
[12] Li J F,Lu W,Zeng Y B,et al.Simultaneous enhancement of latent heat and thermal conductivity of docosane-based phase change material in the presence of spongy grapheme[J].Sol Energy Mater Sol Cells,2014,128:48-51.
[13] Li M,Wu Z.Thermal properties of the graphite/n-docosane composite PCM[J].J Therm Anal Calorim,2013,111(1):77-83.
[14] Gao J W,Zheng R T,Ohtani H,et al.Experimental investigation of heat conduction mechanisms in nanofluids clue on clustering[J].Nano Lett,2009,9(12):4128-4132.
[15] Fang X,Fan L W,Ding Q,et al.Increased thermal conductivity of eicosane-based composite phase change materials in the presence of graphene nanoplatelets[J].Energy Fuels,2013,27:4041-4047.
[2] Nomura T,Tsubota M,Oya T,et al.Heat storage in directcontact heat exchanger with phase change material[J].Applied Thermal Engineering,2013,50(1):26-34.
[3] Pintaldi S,Perfumo C,Sethuvenkatraman S,et al.A review of thermal energy storage technologies and control approaches for solar cooling[J].Renew Sustain Energy Rev,2015,41:975-995.
[4] Kaygusuz K,Sari A.High density polyethylene/paraffin composites as form-stable phase change material for thermal energy storage[J].Energy Sources Part A,2007,29:261-270.
[5] Alkan C.Enthalpy of melting and solidification of sulfonated paraffins as phase change materials for thermal energy storage[J].Thermochimica Acta,2006,451(1-2):126-130.
[6] Wu S,Zhu D,Zhang X,et al.Preparation and melting/freezing characteristics of Cu/paraffin nanofluid as phase-change material(PCM)[J].Energy Fuels,2010,24(3):1894-1898.
[7] Wu S Y,Wang H,Xiao S,et al.An investigation of melting/freezing characteristics of nanoparticle-enhanced phase change materials[J].J Therm Anal Calorim,2012,110(3):1127-1131.
[8] Kumaresan V,Velraj R,Das S K.The effect of carbon nanotubes in enhancing the thermal transport properties of PCM during solidification[J].Heat and Mass Transfer,2012,48(8):1345-1355.
[9] Harish S,Orejon D,Takata Y,et al.Thermal conductivity enhancement of lauric acid phase change nanocomposite with graphene nanoplatelets[J].Applied Thermal Engineering,2015,80:205-211.
[10] Fan L W,Fang X,Wang X,et al.Effects of various carbon nanofillers on the thermal conductivity and energy storage properties of paraffin-based nanocomposite phase change materials[J].Appl Energy,2013,110:163-172.
[11] Warzoha R J,Weigand R M,Fleischer A S.Temperature-dependent thermal properties of a paraffin phase change material embedded with herringbone style graphite nanofibers[J].Appl Energy,2015,137:716-725.
[12] Li J F,Lu W,Zeng Y B,et al.Simultaneous enhancement of latent heat and thermal conductivity of docosane-based phase change material in the presence of spongy grapheme[J].Sol Energy Mater Sol Cells,2014,128:48-51.
[13] Li M,Wu Z.Thermal properties of the graphite/n-docosane composite PCM[J].J Therm Anal Calorim,2013,111(1):77-83.
[14] Gao J W,Zheng R T,Ohtani H,et al.Experimental investigation of heat conduction mechanisms in nanofluids clue on clustering[J].Nano Lett,2009,9(12):4128-4132.
[15] Fang X,Fan L W,Ding Q,et al.Increased thermal conductivity of eicosane-based composite phase change materials in the presence of graphene nanoplatelets[J].Energy Fuels,2013,27:4041-4047.
© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址：北京市海淀区学院路29号 邮编：100083 电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700 |