中低温有机固—固相变材料的制备及其热性能研究

发布时间：2018-03-20 23:30

本文选题：硬脂酸　切入点：石蜡　出处：《陕西理工学院》2015年硕士论文　论文类型：学位论文

【摘要】：热能储存,可将暂时不用或多余的能量通过一定介质储存起来,用于解决能量供需在时间、空间上不匹配的问题。相变材料利用相转变过程进行能量的储存与释放,是一种理想化的储能介质。中低温有机相变材料,相变温度适中,相变潜热大,是近年来国内外研究的热点。本文选择具有吸附作用和良好导热性能的活性炭和膨胀石墨作为骨架支撑材料,PEG、硬脂酸和石蜡为相变主材料。应用物理吸附原理,通过共混法制备了系列复合相变材料。运用老化试验箱测试了复合材料在相变过程中的宏观状态,采用DSC、导热系数测试仪、同步热分析仪等对复合相变材料的相变温度、相变焓、热导率和TG等基础数据进行测定并进行了初步分析。结果表明:膨胀石墨或活性炭对有机小分子材料(硬脂酸和石蜡)定型效果较差,相变过程中液体渗出、渗漏及变形严重,对有机高分子材料(PEG)定型效果较好,当复合材料中活性炭和膨胀石墨含量大于等于16%时,PEG基相变材料在相变过程中宏观表现为固态;随着支撑材料含量增大,材料相变过程中的宏观定型效果越来越好,且活性炭对材料的吸附定型作用强于膨胀石墨。随着活性炭或膨胀石墨含量的增加,复合材料的实际相变焓值低于理论计算值(除石蜡/膨胀石墨,小分子蜡进入膨胀石墨层结构重排),但仍在可利用范围内,相变温度基本保持不变;支撑材料含量相同时,PEG/膨胀石墨复合相变材料的相变焓值高于PEG/活性炭的相变焓值。活性炭和膨胀石墨均可有效提高有机相变材料的导热性能,提高程度随其含量的增多而增大;无论相变主材料为PEG、石蜡还是硬脂酸,支撑材料含量相同时,膨胀石墨对有机相变材料导热性能的改善效果优于活性炭。多孔结构的活性炭和膨胀石墨对有机相变材料及其分解气相产物具有的吸附作用,可抑制有机相变材料的热分解,提高材料的耐热性能。
[Abstract]:Thermal energy storage, which can be used to solve the problem of time and space mismatch between energy supply and demand, can be stored through a certain medium. Phase change materials use the phase transition process to store and release energy. It is an idealized energy storage medium. The medium and low temperature organic phase change materials have moderate phase transition temperature and large latent heat. In this paper, activated carbon and expanded graphite with good adsorption and thermal conductivity are selected as skeleton support materials, stearic acid and paraffin are used as phase change materials, and physical adsorption principle is applied. A series of composite phase change materials were prepared by blending method. The macroscopic state of composite materials during phase transition was tested by aging test box. The phase transition temperature of composite phase change materials was measured by DSC-Tester, thermal conductivity tester, synchronous thermal analyzer, etc. The basic data of phase change enthalpy, thermal conductivity and TG were measured and analyzed. The results show that the effect of expanded graphite or activated carbon on the setting of organic small molecular materials (stearic acid and paraffin) is poor, and the liquid exudates during the phase transformation. When the content of activated carbon and expanded graphite in the composite is greater than or equal to 16, the PEG-based phase change material appears to be solid macroscopically in the process of phase transformation, and with the increase of the content of the supporting material, The macroscopical setting effect in the process of material transformation is getting better and better, and the adsorption effect of activated carbon on the material is stronger than that of expanded graphite, and with the increase of the content of activated carbon or expanded graphite, The actual enthalpy of phase transition of the composite is lower than that of the theoretical calculation (except paraffin / expanded graphite, the small molecular wax enters the rearrangement of the expandable graphite layer structure, but it is still within the available range, and the phase transition temperature remains basically unchanged; The enthalpy of phase transition of PEG / expanded graphite composite phase change material is higher than that of PEG/ activated carbon when the content of supporting material is the same. The thermal conductivity of organic phase change material can be improved effectively by activated carbon and expanded graphite. The degree of improvement increases with the increase of its content; whether the main phase change material is PEG, paraffin or stearic acid, when the content of the supporting material is the same, The effect of expanded graphite on the thermal conductivity of organic phase change materials is better than that of activated carbon. The adsorption of porous activated carbon and expanded graphite on organic phase change materials and their decomposition gas phase products can inhibit the thermal decomposition of organic phase change materials. Improve the heat resistance of the material.
【学位授予单位】：陕西理工学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB34

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