混合工质有机朗肯循环实时浓度调控及运行机理研究

Performance weakening caused by the fluctuation of heat/cooling sources is a key problem in the research of the organic Rankine cycle (ORC). This project proposed a new scientific conception of adjusting the composition of the zeotropic mixture used in the ORC to improve the adaptability of the ORC system to the fluctuation of heat/cooling sources. Consequently, the performance could be increased. Thermodynamic analysis will be carried out and focus on the working fluid selection, the cycle design and the economic evaluation. The characteristics of fluid flow, heat transfer and composition shift of the zeotropic mixture will be tested and provide basic data and correlations to the simulation of the system. The test and static simulation of the ORC system will be performed to study the adaptability of the ORC system with composition regulation to the fluctuation of heat/cooling sources. The distribution and transfer of the irreversible destruction in the ORC will be revealed. The test and dynamic modeling of the ORC system will also be carried out to investigate the transient behaviors during system start up, shut down and changing operation parameters. The match mechanism between the composition regulation and the operation parameter, the corresponding principle of the ORC to the disturbance and active adjustment will be investigated. The system design will be optimized and the control strategy will be suggested. The investigation of this project will reveal the match and relation between the ORC system and the heat/cooling sources, the system and the components, the design and the operation of the system. The results of this project can be basic data and theoretical supports to the ORC design for the fluctuating heat/cooling sources.

针对ORC研究中冷热源波动使系统偏离设计工况运行，降低系统性能这一难题，本项目提出“非共沸混合工质ORC实时浓度调控”的科学构想，通过调节混合工质浓度，增强系统对冷热源波动的适应性，减少不可逆损失，提高系统性能。开展系统热力学分析，建立非共沸混合工质筛选准则与系统综合评价指标；测试备选混合工质的流动、换热和浓度迁移特性，为系统分析与建模提供基础数据；基于实验与稳态仿真，研究变浓度混合工质ORC对冷热源波动的适应性，揭示能质传递/转换过程中的不可逆损失分布与迁移规律，优化系统设计；通过实验与动态仿真，分析系统启停和变工况特性，获得浓度调控与运行参数调整的匹配机制，揭示系统对外部扰动和主动调控的响应规律，建议合理的控制策略。通过本项目的研究，挖掘ORC与冷热源、系统与部件、设计与运行等不同层面之间的匹配机理，为波动冷热源使用场景中的ORC设计提供基础数据和理论支撑。

有机朗肯循环（ORC）系统是利用中低温热源实现热功转换最有潜力的技术之一，其应用场景受冷热源波动影响较大，本项目基于“非共沸混合工质ORC实时浓度调控” 的科学构想研究ORC系统偏离设计工况运行特性，通过调节混合工质浓度，增强系统对冷热源波动的适应性，减少不可逆损失，提高系统性能。项目开展了混合工质ORC系统热力学分析与工质筛选准则的研究，建立了混合工质 ORC 热力学理论分析模型和热经济性分析模型，基于ORC系统与冷热源耦合机理的分析，形成了开口热源和闭口热源下亚临界混合工质ORC以及开口热源下超临界混合工质ORC系统工质筛选准则，可通过简单的工质物性查询筛选适宜的混合工质对及其浓度，避免了盲目和繁琐的热力学计算；建设了基于精馏单元的浓度可调混合工质ORC试验台，进行了工质充装量、回热器对系统运行特性影响的测试，并开展了机组稳态和动态性能测试，获得了变浓度混合工质 ORC多工况和变工况条件下的混合工质换热与循环特性；基于混合工质换热实验数据建立了适用于板式换热器的非共沸混合工质换热关联式，并应用于稳态仿真模型中；开发了混合工质 ORC 系统稳态和动态仿真模型，并将两种仿真模型集成于便于工程化推广的APP界面，开展了混合工质 ORC系统稳态和动态仿真，研究了系统稳态多工况和瞬态变工况运行性能，形成了系统浓度调控和运行策略；通本项目的研究，梳理了ORC与冷热源、系统与部件、设计与运行等不同层面之间的匹配机理，为波动冷热源使用场景中的ORC设计提供基础数据和理论支撑。