液态空气储能系统蓄冷工质筛选及其热物性研究

Large scale energy storage technology can smooth the volatility of renewable energy sources such as wind power and adjust the power grid peak valley, thus, is crucial for the sustainable development of energy industry. Liquid air energy storage (LAES) technology has the advantages of long service life, environmental friendliness, high energy storage density and low storage pressure. Therefore, the LAES has much potential in the application of large energy storage technology. The efficiency of cool storage system has significant influence on the LAES. However, the research on liquid cool storage cycle, cool storage working fluid selection method and the corresponding thermophysical properties is still insufficient, which make it more difficult to optimize the cool storage system. In this project, the research on the cool storage cycle of liquid air energy storage system will be carried out to obtain the optimal cool storage cycle. Then, an active cool storage working fluid selection method will be set up from the atomic (group) level, based on the demand of the working fluid thermophysical properties from the optimal cool storage cycle. Finally, the thermophysical property research on the possible cool storage working fluids will be improved, laying a foundation for the precise design of the high efficiency cool storage system.

大型储能技术可抚平风能等可再生能源的波动性、调节电网峰谷差，对能源行业的可持续发展至关重要。液态空气储能技术具有长寿命、环保无污染、高储能密度和低储存压力等优点，极具应用潜力，其核心在于蓄冷系统的高效性。但目前液相蓄冷循环、蓄冷工质的筛选和相应的热物理性质研究仍有不足之处，对蓄冷系统的最优化设计产生了一定的制约。本项目将针对液态空气储能系统蓄冷循环与空气的压缩和膨胀过程匹配特性，开展理论分析和实验测试，获得最优蓄冷循环的构建原则；基于蓄冷循环对工质热物理性质的需求，建立从原子(基团)层面出发的蓄冷工质主动筛选体系；完善备选工质的热物理性质研究，为高效蓄冷系统的精确设计奠定基础。

液态空气储能技术是一种很有前景的大规模储能技术，但其关键物理过程——蓄冷过程的基础研究尚不充分。因此，本项目基于液态空气储能系统的主要热力过程，开展了不同压缩和膨胀压力等条件下，空气侧从超临界状态到压缩液态之间的物性变化规律，进行了蓄冷级数分析工作，获得了系统整体效能随蓄冷级数的变化规律；以100 kW级液相空气储能平台为对象，开展实际系统蓄冷级数的划分以及每一级的温位确定工作，初步筛选了响应的蓄冷工质并进行系统蓄冷效率实验；提出基于固液相变蓄冷的液态空气储能流程，通过热力学模拟计算系统研究了储能压力、释能压力和最小相变传热温差等关键参数对系统储能效率和蓄冷级数的影响规律；开展了主动式蓄冷工质筛选研究，探索了基于分子基团贡献的最优工质筛选方法；测量了新型环保流体工质基础热物性参数；开展了液态空气储能的低温节流过程机理研究，结合本课题组廊坊 100 kW 液态空气储能平台研究了低温液态增压过程对系统整体性能的影响；总结液化天然气 (LNG) 冷能的利用现状，探索了基于液态空气储能系统蓄冷循环高效利用LNG冷能的方法，进一步建立了综合利用LNG冷能与化学能的多元化联合循环，开展了该循环的性能分析；针对液态空气储能系统间歇运行的特性，分析非稳态过程的影响，提出了抑制非稳态影响的方法；研究液态空气储能系统空气复温膨胀的补热过程，探索了基于太阳能热利用的补热流程，太阳能传热储热过程以及高效太阳能利用方法, 为液态空气储能技术的应用打下基础。