利用外部温度匹配与内部能量回收的近洛伦兹循环构建与优化

Organic Rankine cycle（ORC）is one of the effective technical means that transform thermal energy into electricity. So far, the present situation of the imperfect temperature matching between evaporation & condensing process and heat source & heat sink still exists. Based on the characteristic of temperature glide for zeotropic mixture, utilizing external temperature matching and internal energy recovery to approach to the Lorenz cycle, the concept of the regenerative organic Rankine cycle by ternary mixtures with large temperature glide is put forward. Taken the incomplete property prediction model for ternary mixtures and the obvious composition shift for large temperature glide mixtures into consideration, the following research contents are to be carried out in this project:.(1) The accurate model of predicting the temperature-enthalpy relationship and vapor liquid equilibrium behavior for ternary zeotropic mixture by the Gibbs ensemble Monte Carlo simulation;.(2) The functional mechanism of key thermodynamic parameters (dryness, composition ratio etc.) and flowing characteristic parameters (Reynolds number, flow pattern etc.) on the composition shift of ternary zeotropic mixture during the phase change are exploring theoretically and experimentally, and the semi theoretical and semi empirical correlation of composition shift influenced by the thermodynamic parameters and flowing characteristic parameters is built;.(3) The global synergy optimization of the temperature matching for external heat source and sink and internal working fluid is carried out by the heat exchange network technology，and the construction of the regenerative organic Rankine cycle by ternary mixtures with large temperature glide is realized. .This study will enrich thermodynamic cycle, and has important scientific significance and application value.

有机朗肯循环是将中低温热源转化为电能的有效手段之一，目前仍然存在蒸发冷凝过程与冷热源温度匹配不完善的现状。基于非共沸工质相变时温度滑移的特性，通过利用外部温度匹配和内部能量回收以接近洛伦兹循环，提出了大温度滑移三元混合工质回热有机朗肯循环的概念。考虑到三元混合工质物性预测模型不完善、大温度滑移混合工质存在显著的组分迁移等问题，本课题将展开以下研究（1）通过Gibbs系综蒙特卡罗方法预测三元混合工质温焓特性及汽液相平衡行为；（2）理论和实验探索关键热力学参数（干度、组分比等）和流动特性参数（雷诺数、流型等）对三元混合工质相变过程组分迁移特性的作用机制，建立关键热力学参数和流动特性参数对组分迁移影响的半理论半经验关联式；（3）利用换热网络技术对外部冷热源和内部工质间的温度匹配进行全局优化，完成大温度滑移三元混合工质回热有机朗肯循环的构建。该研究将丰富热力循环，具有重要的科学意义和应用价值。

有机朗肯循环是将中低温热能有效转化为电能的有效手段。然而由于循环结构和循环工质的内在制约，现有的有机朗肯循环的热力学完善的仍然不高，存在较大的提升空间。本课题从外部温度匹配和内部能量回收的角度出发，从高效的热力循环、快捷的设计方法和准确的物性预测模型等方面做了些工作。具体包括：提出了针对液化天然气冷能回收的高效两级冷凝朗肯循环，对关键系统参数进行了分析与优化；探究了冷凝级数对多级冷凝朗肯循环的影响规律；发现了膨胀压缩布局的拓展性，并通过建立超结构热力循环对循环拓扑结构进行优化设计。提出了混合工质的组元组分的同步优化方法，构建了“系统结构-系统工质-系统参数”的协同优化框架；采用机器学习的方法，对混合工质的物性进行了有效的预测工作；建立了三元混合工质组份迁移的预测模型，并对当地组份进行了预测。通过本项目的研究，可为有机朗肯循环的实际应用提供理论依据和技术支持。