导热增强型复合相变材料的影响因素及传热机理研究

Paraffin/polymer phase change materials have been applied in temperature controlling system. Because of their low thermal conductivity, they have low thermal utilization rate and poor temperature controlling effect. In this project, two-dimensional expanded graphite nano-sheets and one-dimensional carbon nano-fibers will be used as thermally conductive fillers, because both of them have low density, large surface area and high thermal conductivity. The continuous and synergetic thermally conductive network system will be constructed by adding the two-dimensional expanded graphite nano-sheets and the one-dimensional carbon nano-fibers into the paraffin/polymer phase change materials. Phase change temperature, phase change enthalpy, leakage rate, mechanical strength and molding process of phase change materials with high thermal conductivity will be designed. Then, phase change materials which have high phase change enthalpy, low leakage rate, high thermal conductivity, excellent mechanical strength and molding property will be prepared. Design technique and preparation technology of phase change materials with high thermal conductivity will be mastered. The effect of selection, modification and dispersion state of thermally conductive fillers on thermal conductivity and thermal utilization rate of phase change materials will be studied. Phase change process and heat transferring process of phase change materials will be studied by step-cooling curve and temperature distributive curve. Thermally conductive model and heat transferring mechanism of phase change materials will be constructed. Lastly, the performance of phase change materials with high thermal conductivity will be predicted and designed. The project will provide theoretical guidance and experimental basis for phase change materials with enhanced thermal conductivity, and it has important theoretical significance and application value.

石蜡/聚合物型复合相变材料已用作某系统的控温材料，但导热率小，热利用率低，控温效果较差。项目选取密度低、表面积大、导热率高且形状互补的二维膨胀石墨纳米片与一维碳纳米纤维互配为导热填料，通过协同导热网络体系设计，加入石蜡/聚合物中制备导热率高、相变焓大、渗漏率低、力学强度及成型性能优良的导热增强型复合相变材料。通过对导热复合相变材料的相变温度、相变焓、渗漏率、力学强度、成型工艺系统优化设计，掌握导热增强型复合相变材料的设计和制备技术。研究导热填料的选择、改性及其分散状态对复合相变材料导热率、热利用率的影响；采用步冷曲线和温度场分布，分析导热复合相变材料的相变过程和热传导历程；结合实验结果建立复合相变材料的导热模型，研究其传热机理，反馈优化导热复合相变材料的设计方法，实现其性能的可预测和可设计性。项目将为导热增强型复合相变材料的设计和制备提供理论指导和实验依据，具有重要的意义和价值。

项目针对石蜡/聚合物型复合相变材料导热率小、热利用率低、控温效果较差等问题，选取密度低、表面积大、导热率高的膨胀石墨（EG）为导热填料，采用熔融共混法将EG加入石蜡/高密度聚乙烯（HDPE）定形复合相变材料中制备了导热率高、相变焓大且渗漏率低的石蜡/HDPE/EG导热增强型复合相变材料，研究了EG含量对石蜡/HDPE/EG热导率的影响，探索了石蜡/HDPE/EG的导热机理。采用形状互补的二维膨胀石墨纳米片与一维碳纳米纤维（CF）互配为导热填料，通过协同导热网络体系设计，制备了石蜡/EVA/EG-CF导热定形复合相变材料，研究了不同形貌填料EG和CF之间的协同导热效应。同时，以自组装制备的石墨烯气凝胶（GA）为导热骨架，与石蜡进行复合，得到新型石蜡/GA导热复合相变材料，研究了GA结构对石蜡/GA热导率的影响。通过对几类导热复合相变材料的相变温度、相变焓、渗漏率、制备工艺的系统优化设计，掌握了导热增强型复合相变材料的制备和性能表征技术，研究了导热填料的选择及其分散状态对复合相变材料热导率的影响，分析了导热复合相变材料的相变过程和传热行为，建立了复合相变材料的导热模型，探索了其传热机理。项目研究结果为导热增强型复合相变材料的设计和制备提供了理论指导和实验依据，具有重要的意义和价值。