基于水合盐的低温热化学储能研究进展

Research progress of hydrate salt-based thermochemical energy storage at low temperature

水合盐低温热化学储能具有储能密度高和长期存储热损失小等优点,在可再生能源利用、低品位余热回收和设备热管理等领域具有广阔的应用前景。本文从系统级和材料级2个方面对基于水合盐的热化学储能研究进行了综述。在系统级方面,对比了开放式和封闭式反应系统的特点,分类讨论了常见反应器的优缺点和优化设计,探讨了不同反应堆布置形式对储热过程的影响;在材料级方面,评估了单一水合盐、混合水合盐和多孔载体复合水合盐等材料的热化学性能,介绍了水合盐热化学研究中的宏观反应动力学和微观分子动力学模型。研究结果表明:在开放系统中,传质是限制反应的主要因素,床层渗透率加倍可以减少50%左右反应时间;封闭系统中反应的主要限制则为传热,导热率加倍可以减少14%左右反应时间;设计分离式/多模块反应器和移动床反应器,采用不同热化学材料串级布置、热化学材料与相变材料串级布置、材料仿生排布等反应堆布置形式,可以有效改善填充床反应器不均匀反应等问题;混合水合盐和多孔载体复合水合盐能够解决单一水合盐循环稳定性差等问题。未来动力学模型和微观分子动力学研究是了解水合盐气/固反应机理的重要研究方向。

The hydrated salt-based low temperature thermochemical energy storage has the advantages of high energy storage density and low heat loss in long-term storage. It has good application prospects in the fields of renewable energy utilization, low-grade waste heat recovery and equipment thermal management. In this paper,the research on hydrated salt-based thermochemical energy storage was reviewed from two aspects, including system level and material level. At the system level, the characteristics of open and closed reaction systems were compared. The advantages and disadvantages of common reactors and the optimization design were classified and discussed. The effects of material pile arrangement types on the heat storage process were discussed. In terms of material level, the thermochemical properties of materials such as single hydrated salts, mixed hydrated salts and porous support complex hydrated salts were evaluated. The macroscopic reaction kinetics and microscopic molecular dynamics models in the study of the thermochemical behavior of hydrated salts was introduced. The results show that mass transfer is the main factor limiting the reaction in an open system, and doubling the bed permeability can reduce the reaction time by about 50%. In a closed system, the main limitation of reaction is heat transfer, and doubling the thermal conductivity can reduce the reaction time by about 14%. Designing separated/multi-module reactors, moving bed reactors and adopting the cascade layout of different thermochemical materials, the cascade layout of thermochemical materials and phase change materials, and the material bionic arrangement can effectively improve the uneven reaction of packed bed reactor. The mixed hydrated salts and porous support complex hydrated salts can solve the poor circulation stability of single hydrated salts. In the future, the study of reaction kinetic model and micro molecular dynamics are important research directions to understand the gas-solid reaction mechanism of hydrate salt.