压缩空气储能系统的有限时间热力学优化设计方法研究

Compressed air energy storage (CAES) technology is regarded as one of the most potential large scale energy storage technologies. However, currently there is no comprehensive optimal design method for CAES systems, leading to the insufficient exploitation of the potential regarding system efficiency and energy density. Based on the correspondence characteristics of CAES systems, the concept of ‘corresponding-point methodology’ was proposed in this project. By adopting finite-time thermodynamics and considering system off-design performance, this project aims to establish a general methodology for optimizing and designing CAES system, on the basis of corresponding-point methodology. The general methodology established here enables more practical working conditions, optimal performance, and speed in the system design process. The mechanisms of energy loss and coupling mechanisms of parameters in corresponding-point methodology were revealed. Optimization and calculation methods of inverse problems were also studied. Relevant experimental data and component performance were obtained through a MW-scale experimental CAES platform at our lab. The key processes and the entire CAES system were modeled and analyzed by means of finite-time thermodynamics. Then the effect of finite time/size on system performance was revealed. Off-design performance of the CAES system was obtained by combining experimental data fitting and numerical calculations, while the off-design performance was analyzed for analytic solutions. Then the effect of off-design operation on system performance was revealed. On the basis of the above studies, through analyzing the general characteristics of the CAES system, new parameters and evaluation indices were derived and a general methodology for optimal design was established.

压缩空气储能是目前最具发展潜力的大规模储能技术之一，而目前对压缩空气储能系统尚无完善的优化设计方法，致使其系统效率和能量密度的潜力未得到充分挖掘。本项目基于压缩空气储能系统的对应性，提出了“对应点分析方法”，基于该方法，采用有限时间热力学手段，综合考虑系统变工况特性，建立压缩空气储能系统通用优化设计方法，使系统优化设计达到贴近实际工况、性能最优及快捷的目的。揭示对应点分析方法中能量损失机理和参数耦合机理，并研究系统反问题优化求解方法；通过MW级压缩空气储能系统实验平台获取相关实验数据及设备性能；对系统的关键过程和系统整体进行有限时间热力学建模与分析；揭示有限时间/有限尺寸对系统性能的影响规律；通过实验数据和数值计算结合的方式，获取系统变工况特性，并进行解析，揭示变工况运行对系统性能的影响规律。在以上研究基础上，通过对系统进行共性分析，建立新的分析参数和评价指标，最终建立通用优化设计方法。

压缩空气储能是目前最具发展潜力的大规模储能技术之一，而目前对压缩空气储能系统尚无完善的设计方法，致使其存在系统效率和能量密度低等问题。本项目基于压缩空气储能系统的对应性，提出了“对应点分析方法”，基于该方法，采用有限时间热力学手段，综合考虑系统变工况特性，建立压缩空气储能系统通用优化设计方法，使系统优化设计达到贴近实际工况、性能最优及快捷的目的。项目主要研究内容包括以下4个方面，1）对应点分析方法中的能量损失机理及参数匹配优化研究；2）关键对应过程及系统整体的有限时间热力学建模及分析研究；3）压缩空气储能系统变工况特性的计算分析及解析；4）压缩空气储能系统优化设计方法研究。经过本项目研究，建立了基于对应性的压缩空气储能系统的㶲传递和㶲损失模型，发现除了级数，一个参数仅影响一到两个㶲传递系数，且影响热㶲传递系数的参数最多；提出了用于分析温度和压力匹配程度的热功协调率概念及C-P分析图，发现热功协调率的改变通常伴随着热功转换或冷/热效应；揭示了压缩空气储能系统的有限时间热力学特性，得到了系统的有限时间热力学边界，约低于传统热力学1-2个百分点，获得了运行时间与换热器尺寸的最佳匹配关系；深入揭示了不同设计点下压缩空气储能系统的变工况特性和动态特性，发现非稳态效应可使系统效率下降0.5个百分点左右；经过变工况解析和不同时刻的对应性处理，将变工况特性应用于对应点分析方法中，同时通过将有限时间和有限尺寸引入对应点分析中，发现通过对应商的约束，可有效、快速得到系统的最优解。最后提出了针对压缩空气储能系统的“三层此”理论设计体系。本项目具有的重要科学意义包括：1）发展了对应点分析方法，将其从稳态工况分析拓展至变工况分析；2）首次建立了压缩空气储能系统的反问题求解方法；3）提出了完整的压缩空气储能系统热力学理论设计体系。