【作者】 邱美鸽；

【导师】 唐炳涛；

【作者基本信息】 大连理工大学 ， 精细化工， 2012， 硕士

【摘要】 本文设计合成了导热增强型相变储能材料,即以聚乙二醇(PEG)为有机相变组分来实现储能和释能,以SiO2为无机支撑骨架来实现定形,通过原位掺杂导热增强剂(如Al2O3、Cu和MCNT)得到相变焓值较高、导热性能好的复合定形相变储能材料。借助超声辅助溶胶-凝胶过程原位掺杂Al2O3制备PEG/SiO2-Al2O3复合定形相变储能材料。研究了制备方法和相变组分对材料定形效果、相变性能的影响。采用有机异丙醇铝和无机硝酸铝制备了不同A12O3含量的复合材料。通过宏观状态、红外、x射线衍射、差热分析、热重分析、导热系数测试和降温曲线,对材料进行结构与性能表征。结果表明：PEG与SiO2-Al2O3是物理嵌合的关系,PEG的结晶受到无机网络结构的限制,焓值略有下降。有机铝制备的材料Ai2O3含量为3.3%时,相变焓值为102.3J/g,导热系数达0.414W/(m·K),与PEG/SiO2相比,导热增强率为15%；硝酸铝制备的材料Al2O3含量为3.3%时,相变焓值达126.2J/g,导热系数达0.398W/(m·K),导热增强率为10.6%,降温曲线的测试结果与导热系数测试相符。复合材料在290℃以下均具有良好的热稳定性。借助超声辅助溶胶-凝胶过程原位还原Cu2+实现原位掺杂Cu单质制备PEG/Cu/SiO2复合定形相变储能材料。采用碘量法和XPS分析确定复合定形相变材料中Cu单质的含量。材料中铜主要以Cu单质的形式存在,材料表面形貌平整,SiO2的孔状结构被PEG和Cu完全填充。结构上三者是物理复合的。当复合相变材料中Cu单质含量为2.1%时,相变焓值为114.6J/g,导热系数达0.41W/(m·K),导热增强率为13.9%。当达到同一温度48℃时,Cu含量为2.1%的材料的降温时间与纯PEG相比,缩短了69.9%,具有较好的储能效果和导热性能。复合材料在260℃以下具有良好的热稳定性。借助超声辅助溶胶-凝胶过程原位掺杂多壁碳纳米管(MCNT)制备PEG/MCNT/SiO2复合定形相变储能材料。由于MCNT在紫外-可见区有全波段吸收,故可以作为光收集器掺杂到相变储能材料中进行太阳能的光热转换实现对能量的转换与存储。MCNT和PEG将作为无机骨架的SiO2的孔状结构完全填充,说明SiO2对它们起到包裹作用。当加热到相变组分的熔点以上时无液体渗出,具有良好的定形效果。红外分析证明PEG、 SiO2和MCNT之间无化学键生成。当MCNT含量为1%时,复合材料相变焓值为116J/g,导热系数达0.421W/(m·K),导热增强率为16.9%；复合材料在300℃以下具有良好的热稳定性,其光热转换效率达0.918.更多还原

【Abstract】 The form-stable phase change materials (PCMs) with enhanced thermal conductivity were synthesized in this thesis. Polyethyleneglycol (PEG) was acted as oganic phase change component to realize the storage and release of energy, SiO2was used as inorganic supporting material to realize form-stable effect. The form-stable PCMs with high latent enthalpy and good thermal conductivity were prepared through in-stu thermal conductivity enhanced agents (such as Al2O3, Cu and MCNT) doping.PEG/SiO2-Al2O3form-stable composite PCMs were prepared through ultrasound assisted sol-gel method. The influence of preparation method and phase change component to the form-stable effect and phase change properties of the PCMs were researched. Aluminium isopropoxide and aluminium nitrate were used to prepare the form-stable composite PCMs with different content of Al2O3. The structure and properties of the PCMs were studied by FTIR, XRD, DSC, TGA and the thermal conductivity instrument. The results showed that PEG and SiO2-Al2O3combined physically, the latent heats were a little decrease because the crystallization of PEG were limited by the inorganic network. When the PCM prepared by aluminium isopropoxide included3.3%of Al2O3, the latent heat was102.3J/g, the thermal conductivity was0.414W/(m·K), the thermal conductivity enhancement was15%. While the PCM prepared by aluminium nitrat included3.3%of Al2O3, the latent heat was126.2J/g, the thermal conductivity was0.398W/(m·K), the thermal conductivity enhancement was10.6%. The results of cooling curves were corresponded with the thermal conductivities. The composite PCMs were stable below290℃.A novel type of PEG/Cu/SiO2hybrid form-stable PCM with high thermal conductivity was obtained by in situ reduction of CUSO4solution through ultrasound-assisted sol-gel method. The XPS result of this material showed that the valence state of copper was mainly zero. The FTIR demonstrated that there was no new chemical bond between Cu, PEG6000and SiO2. The SEM images showed that SiO2network in the composites was filled with PEG and Cu additives. The phase change enthalpy of Cu/PEG/SiO2PCM reached up to114.6J/g, and the thermal conductivity was0.414W/(m·K) for2.1wt%Cu in PEG/SiO2, which was enhanced by13.9%compared with PEG/SiO2. The PEG/Cu/SiO2hybrid material had excellent thermal stability below260℃. To achieve the same temperature of48℃, the freezing time of the form-stable PEG/Cu/SiO2(2.1wt%) composite PCM was reduced by699%compared with that of pure PEG.PEG/MCNT/SiO2composite forma-stable PCMs were synthesized through in-situ doping multi-walled carbon nanotube (MCNT) by ultrasound assisted sol-gel method. We introduced MCNT, which has broad absorbance of UV-Vis light and good light-thermal conversion capability, into PCMs system to store solar thermal energy. The results showed the SiO2network in the composites were filled with additives, which confirm the quasi-uniform distribution of the additives in the shape-stabilized PCMs. When the PCMs were heated over the melting point of the phase change component, there was no liquid leakeage. The FTIR ananlysis proved that there was no chemical bond between MCNT, SiO2net and PEG. When the mass fraction of MCNT was1%in the PCM, the phase change enthalpy was116J/g, the thermal conductivity was0.421W/(m·K), the thermal conductivity enhancement was16.9%. The composite PCM had a good stability below340℃, the light-thermal efficiency reached0.918.更多还原