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测量材料热物性的准稳态方法与参数估计张欣欣,殷晓静(北京科技大学热能工程系北京100083)关键词热物性,参数估计,准稳态测量方法1前言材料的导热系数人建立了热流密度与温度梯度的关系,表征物质的导热能力;体积热容量pC则表征单位体积物质的蓄热能力;对... 相似文献
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本文首先制备并表征了介孔二氧化硅SBA-15、 填充导电聚合物的复合材料PANI/SBA-15和复合材料PPy/SBA-15, 并建立双流计实验台开展了材料压片情况下的热导率研究. 在测量得到复合材料热导率的基础上, 引入当量孔径, 结合测量孔径对 PANI/SBA-15和PPy/SBA-15复合材料热导率随填充量的变化进行了定性分析. 分析表明: PANI/SBA-15和PPy/SBA-15复合材料的热导率比基材SBA-15的热导率大得多; 在相同的测量孔径和当量孔径情况下, PANI/SBA-15复合材料的热导率比PPy/SBA-15复合材料的热导率大; 导电聚合物填充到复合材料孔道内和孔道外都有助于热导率的提高, 填充到孔道内比填充到孔道外对热导率提高的贡献更大. 相似文献
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细菌纤维素基柔性锌离子电池正极的构筑及性能研究 总被引:1,自引:0,他引:1
柔性锌离子电池(ZIBs)具有高安全性、低成本和高能量密度等优势, 但是现有的ZIBs柔性电极难以兼具高电化学性能和力学稳定性. 其中, 缺少适合的基底材料是限制柔性电极发展的关键. 本工作中, 以细菌纤维素(BC)为基底材料, 结合原位聚合及真空过滤方法, 制备了具有3D多孔结构的BC/聚苯胺/碳纳米管(BC/PANI/CNTs)柔性电极. BC固有的高抗拉伸强度和超细纳米纤维网络结构等特点, 在赋予柔性电极高弯曲特性的同时, 还有利于活性物质的负载及电解液离子的快速扩散. 结果表明, BC/PANI/CNTs具有高柔韧性、7.3 mg/cm2的负载量和157 mAh/g的比容量. 以BC/PANI/CNTs电极构建的准固态ZIBs展现了109 mAh/g的比容量, 且200次充放电循环后容量保持率大于90%. 相似文献
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Anti-perovskite solid-state electrolyte Li2 OHCl usually exhibits orthorhombic phase and low ionic conductivity at room temperature. However, its ionic conductivity increases greatly when the temperature is up to 40℃, while it goes through an orthorhombic-to-cubic phase transition. The cubic Li2 OHCl with high ionic conductivity is stabilized at room temperature and even lower temperature about 10℃ by a simple synthesis method of wet mechanical milling. The cubic Li2 相似文献
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Mesoporous silica SBA-15 consists of uniform hexagonal, unconnected cylindrical channels with diameters that can be tuned within a range of 1.5 nm-30 nm, and is thought to have a special thermal conductivity. The theoretical investigation of the shell thermal conductivity of the mesoporous silica is performed in the relaxation time approximation in this paper and an available one-dimensional heat transfer model is used to predict the effective thermal conductivity (ETC) of the mesoporous silica. The experimental result of the ETC is also presented for comparison. The shell thermal conductivity of the mesoporous silica decreases with mesochannel radius increasing or wall thickness decreasing, but does not strictly decrease with porosity increasing. The thermal radiation possibly plays a primary role in heat transfer at the large porosity scale. The predicted ETC of SBA-15 with only conduction considered is quite low at the large porosity, even lower than the thermal conductivity of the silica aerogels. To realize it, doping carbon or other matters which can strongly absorb infrared light into SBA-15 is a possible way. 相似文献
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以相变芯材为核心的复合相变材料的潜热储存技术,对解决可再生能源间歇性问题有着关键作用.本研究以天然竹木为原材料,使用高温碳化方法得到碳化竹木,并使其分别吸附氧化石墨烯和还原氧化石墨烯,最终与聚乙二醇(PEG2000)复合形成稳定的复合相变材料.实验结果表明,还原氧化石墨烯可以达到很好的包封率、热导率和光热转换效率提升效果.碳化竹木/还原氧化石墨烯/聚乙二醇三元复合相变材料包封率高达81.11%,熔化潜热为115.62 J/g,凝固潜热为104.39 J/g,热导率大幅提升至1.09 W/(m·K)(纯PEG2000的3.7倍),光热转换效率大幅提高至88.35%(纯PEG2000的3.1倍). 相似文献