氢氧化钙/氧化钙热化学储能系统循环稳定性多尺度研究

Thermochemical heat storage is an effective way to efficiently utilize the waste heat and solar energy across time and space, which is a promising process. The Insufficient cycling stability is the key bottlenecks in the development and application of the thermochemical energy storage systems. In this work, the experimental and theoretical simulation study on the degradation mechanism and improvement method of the cycling stability of the Ca(OH)2/CaO thermochemical energy storage will be performed through the study of molecular scale reaction-transfer mechanism and flow/heat transfer characteristics in the micro-porous system. The molecular scale reaction-transfer mechanism of calcium hydroxide dehydration / calcium oxide hydration will be firstly revealed. And then based on the reliable experimental study and quantitative detection, The characteristic of crystal structure deformation, microtopography varying and agglomerate of the particles related to thermochemical reaction and their influencing factor will be also clarified. The relationship of cycling stability and the intrinsic characteristics of reactive materials will be analyzed, and the reactive materials with better performances will be prepared. And then, The flow and heat transfer characteristics in the complex inhomogeneous micro-porous system will be revealed, and their correlations will be obtained.the connections between agglomeration and flow/heat transfer characteristics will be revealed by building the unsteady modeling of the thermochemical reactor. Finally, The efficient principle will be built to guide the preparation of the reactive materials based on the reliable experimental verification. The aims are to obtain the effective measures and methods to enhance cycling performance of the thermochemical heat storage system. This project will provide important theory basis and key technique support for the relevant studies and applications of the thermochemical utilization process of energy.

热化学储能是实现工业余热及太阳能跨时空利用的有效途径，应用前景广阔。目前循环稳定性不足是制约热化学储能系统发展和应用的主要瓶颈。本项目采用理论与实验相结合方法，从分子尺度反应传递机理和孔隙体系微尺度流动传热特性入手，对氢氧化钙/氧化钙热化学储能系统的循环稳定性下降机制和改进方法进行系统研究。首先通过深入揭示氢氧化钙脱水/氧化钙水合分子尺度反应传递机理，并在可靠实验观测的基础上，阐明由反应诱导的晶体结构变形和颗粒微观形貌变化规律及影响因素，明晰循环性能下降与反应材料本征特性之间的内在关联，制备出循环性能优异的反应材料；其次，揭示复杂非均匀微细孔隙内流动传热机理，获得可靠关联式。建立反应器尺度非定态反应传递耦合数理模型，揭示颗粒团聚与流动传热及反应之间的关联耦合机制；最终，获得提高氢氧化钙/氧化钙热化学储能系统循环稳定性的有效措施，为热化学储能系统研究及应用提供重要理论依据与关键技术支撑。

本项目针对氢氧化钙/氧化钙热化学储能系统的循环稳定性不足的问题，用实验与理论相结合的方法，对分子尺度反应传递机理和孔隙体系微尺度流动传热特性进行系统深入研究。通过反应分子动力学模拟，阐明了由反应诱导的晶体结构变形和颗粒微观形貌变化规律及影响因素，明晰了循环性能下降与反应材料本征特性之间的内在关联。在此基础上，制备出了多种循环性能优异的钙基热化学储能材料，发展了多种绿色低成本材料制备方法。建立了基于热化学储能的太阳能跨季节供暖系统模型，通过与水箱蓄热相比较分析了热化学储能在太阳能长周期存储中应用的可行性。最终在以上研究的基础上建成了谷电化学蓄热供暖系统样机，经试验测试和经济性分析发现其具有技术和经济上的可行性，为热化学储能系统的工业应用奠定了基础，也为其他体系热化学利用过程提供了可借鉴的研究方法。