相变纳米胶囊储能ECC微观结构调控及热-力特性强化机制研究

In recent years, phase change energy storage cement-based materials used for building energy conservation and thermal comfort have become a hot topic in the interdisciplinary field of civil engineering and material science. This project takes phase change energy storage ECC as the research carrier. In order to solve the problems of the low strength and the difficulties in using as structural materials, the phase change material nanocapsules are incorporated into cement matrix and the microstructure regulations of phase change energy storage ECC are carried out based on particle close packing theory. Firstly, the controlled emulsification method is proposed to continuously regulate the particle sizes of phase change material nanocapsules, and the response surface regression model is established to predict the particles sizes of nanocapsules; Secondly, the three-dimensional discrete element modelings are performed to analyse the random close packing of phase change material nanocapsules within the pore structures stacked by cement particles, to determine the particle size distribution and reasonable admixture volume of phase change material nanocapsules, thus the microstructure regulation based on random close packing is achieved. Thirdly, the thermal-mechanical transfer simulations based on the microstructures of the thermal energy storage hardened cement paste incorporated with phase change material nanocapsules are established to analyse the damage failure mechanism of the cement matrix of the phase change energy storage ECC in thermo-mechanical coupling case; Lastly, the development laws of thermal and mechanical properties of the phase change energy storage ECC are clarified, so as to reveal that the internal relationship of the macroscopic mechanical properties and the microstructure development. The research achievements of this project can be expanded to various cement-based materials, laying a theoretical basis for structure-function integration design of phase change energy storage cement-based materials.

面向建筑节能和热舒适应用的相变储能水泥基材料是近些年来土木工程和材料科学领域交叉研究的热点。本项目以相变储能ECC为研究对象，根据颗粒紧密堆积理论，拟将相变纳米胶囊填充到水泥石，对相变储能ECC进行微观结构调控，解决其强度严重不足、难以作为结构材料使用的领域难题。首先，提出相变纳米胶囊颗粒尺寸连续可调节的乳化控制方法及颗粒尺寸预测的响应面回归模型；其次，基于三维离散元法分析相变纳米胶囊在水泥中的随机紧密填充过程，确定相变纳米胶囊的颗粒尺寸分布及掺量范围取值，实现颗粒紧密填充的微观调控；再次，通过相变纳米胶囊储能水泥石热-力传递模拟，阐明热-力耦合作用下相变储能ECC的水泥基体损伤失效机制；最后，从宏观角度厘清相变储能ECC的热力性能演变规律与因应性机制，揭示其微结构演化与宏观力学性能的内在关系。本项目研究成果可以拓展到各种水泥基材料，为相变储能水泥基材料的结构-功能一体化设计提供理论依据。

随着我国经济和社会的快速发展，诸多产业都迈向高质量发展道路。其中，建筑业是资源消耗最大的产业，面临着重大的转型升级。这对于提升室内热舒适、节约建筑能耗、降低建筑排放等都提出了更高的要求。面向建筑节能减排和热舒适应用的相变储能水泥基材料的研究近年来备受关注。掺加相变微胶囊的水泥基材料虽然获得了热存储功能，但也存在强度损失严重、难以作为结构材料使用的领域难题。本项目依托此研究背景，针对建筑材料用高强、高表面活性相变微胶囊的开发与制备，相变微胶囊对水泥基材料微观结构、宏观力学强度与热工性能的影响机制，以及相变储能水泥基材料宏观力学性能与微观结构演化的数学关系等进行了深入的研究分析与科学总结，形成了一系列研究成果。.1.提出了基于粉煤灰漂珠腐蚀打孔技术的相变微胶囊制备方法，确立了粉煤灰漂珠定型载体最优制备工艺，制备的粉煤灰漂珠定型载体形貌完整，力学强度高；2.基于溶胶-凝胶技术对相变微胶囊进行纳米二氧化硅表面改性，实现了相变微胶囊的二次包覆与表面纳米二氧化硅均匀密实生长，经过纳米二氧化硅接枝修饰的相变微胶囊无泄漏且热性能良好。3.基于合成的相变微胶囊，制备了力学性能提升的相变储能水泥基材料，探明了相变储能水泥基材料的控温作用。4.基于相变储能水泥基材料微观结构、水化产物演化规律，分析得出了纳米增强相变储能水泥基材料力学性能提升的微观机制。5.建立了相变储能水泥基材料细观随机骨料投放模型，揭示了相变储能水泥基材料细观结构与应力分布的演变关系，验证了微观结构形貌改善、功能组分与基体兼容性增强对相变储能水泥基材料力学性能提升的有效性。6.基于基于粉煤灰漂珠相变微胶囊，制备了相变储能ECC材料，通过微观力学分析模型，揭示了高强相变微胶囊与相变储能ECC材料力学性能之间的数学关系，为相变储能ECC材料结构-功能一体化设计提供了理论参考。