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无机盐/陶瓷基复合储能材料制备、性能及其熔化传热过程的研究
Study on Fabrication Technology, Performances and Melting Heat Transfer Process of Salt/Ceramic Composite Energy Storage Material
【作者】 李爱菊；
【导师】 张仁元；
【作者基本信息】 广东工业大学 ， 材料学， 2005， 博士
【摘要】 热能储存技术可以解决能源供给与需求失配的矛盾,达到提高能源利用率和保护环境的目的。但是目前储能技术中应用较多的两大类储能材料——相变材料和显热材料,均存在一些缺点。如:相变材料存在释热时液.固两相界面处热阻大导致传热效果很差、化学稳定性不好、对容器腐蚀严重等缺点,显热材料存在蓄热密度小、蓄（释）热过程难控制、选材有限等缺点。因此,研制能够结合相变材料和显热材料二者优点,克服二者缺点的新型复合储能材料已经成为人们研究的热点和难点。 本文提出了将无机盐和陶瓷材料进行复合的创新方法,采用混合-烧结法成功地制备出了新型无机盐/陶瓷基复合储能材料,克服现有无机盐相变材料和显热材料存在的缺点。在储能过程中,这种材料可与相容性流体直接接触换热,大大提高了换热效率。 本文通过实验和理论分析选择相变潜热和比热大、高温蒸汽压小的Na2SO4作为相变材料;选择与Na2SO4具有良好化学相容性,且热震稳定性好和导热系数大的二氧化硅（SiO2）作为载体基质。系统地研究了Na2SO4/SiO2复合储能材料的制备工艺,讨论了原料配比、成型压力、烧结温度、保温时间和粘结剂用量等工艺参数对材料结构和力学性能及其显微组织的影响,从而获得Na2SO4/SiO2复合储能材料的最佳制备工艺条件。在此基础上,通过XRD、SEM、偏光显微镜详细地研究了Na2SO4/SiO2复合储能材料的物相组成和显微结构。XRD结果表明,Na2SO4和SiO2之间没有新物质生成,二者仅仅是机械嵌合作用;SEM和偏光显微镜分析表明,Na2SO4和SiO2之间结合良好,不存在相分离,而且SiO2的显微粗糙表面有利于把持Na2SO4提高复合材料的强度,同时SiO2微孔结构对Na2SO4的包覆作用提高了复合材料长期反复循环中的性能稳定性。 本文通过差示扫描量热仪、激光热常数仪、Instron 8032材料试验机和自制温度采集系统等对制备出的Na2SO4/SiO2复合储能材料热物理性能和热循环稳定性进行了详细的研究。其结果表明,Na2SO4/SiO2复合储能材料具有较高的储能密度、良好的导热性和一定的高温强度,经过长期反复循环使用后性能稳定,能够经得
【Abstract】 Heat energy storage technique can solve the inconsistency of energy supply and demand, improve utilization efficiency of energy and conserve environment. Phase change materials （PCMs） and sensible heat materials applied in the heat energy storage technique have some fatal disadvantages. The heat transfer effect of PCMs is very bad on the interface of solid and liquid, the chemical stability is very low, and it will erode the container. The heat storage density of sensible heat materials is very low, the process of energy storaging or releasing is very difficult to be controlled, and type of sensible heat materials is very limited to be selected. So it is the focus and difficulty to develop a new type of composite energy storage material what can integrate advantages of PCMs and sensible heat material and get rid of their disadvantages.An innovating technology is put forward in this paper and the new type salt /ceramic composite energy storage material （CESM） is fabricated successfully by mixing and sintering method. The CESM can solve problems of existing PCMs and sensible heat materials, and exchange heat in direct contact with compatible fluid in the process of energy storage, so the efficiency of exchanging heat is improved greatly.Sodium sulfate has bigger latent heat and specific heat, and lower vapor tension. Silicon dioxide has better thermal stability feature and high heat conductivity coefficient. And the chemical compatibility of them is very good. So sodium sulfate is selected as PCM and silicon dioxide as carrier material. The fabrication technology of salt/ceramic CESM is researched and the effect of the technology parameters including raw material percentage, forming pressure, sintering temperature, heat preservation time and binder percentage to structure and mechanical performances and microstructure is discussed. And the optimum technology conditions of fabricating Na2SO4/SiO2 CESM are obtained. The components and microstructure of Na2SO4/SiO2 CESM are researched in detail by XRD, SEM and POL.. The XRD results show no new substance appears other than sodium sulfate and silicon dioxide. The SEM and