耦合传递与转换过程模型的有机朗肯循环热力学研究

The Organic Rankine Cycle is one of the key technologies to fulfill the efficient utilization of low/medium heat sources. The research progress indicates that the coupling mechanism of ORC with heat/cool sources needs to be well investigated; theoretical optimization model mainly focuses on the system level, requiring the coupling of transfer/conversion process models; parameter optimization mainly aims at the single case, lacking the multi-case optimization. Based on the analysis above, the main research contents we will carry out are as follows. (1)develop a theoretical model of the ORC coupled with submodels of 3 key transfer/conversion processes, including the heat exchanger, the expader and the fluid bumping unit. This model can keep a good balance between the system level optimization and the prcess level calculation. The coupling mechanism of ORC system with the heat/cool sources will be investigated. (2) The coupling calculation between system design and performance prediction will be well organized to implement the multi-case optimization of the ORC. System parameters will be optimized under constraints of the heat/cool sources. The performance variation and process interaction rules will be well researched as the ORC's working conditions deviate from the optimum ones. (3) Tests of system performance and key process parameters will be carried out with one or two kinds of pure working fluids under subcritical cycle mode. The theoretical results will be validated by the experimental ones. Based on the studies above, we can obtain the suitable working fluids, system design as well as the optimum operation parameters, matching well with the properties of heat/cool sources.The present study can serve as the basic scientific reference for the efficient utilization of low/medium heat sources by ORC.

有机朗肯循环（ORC）是实现中低温热源有效利用的关键技术之一。针对现有ORC研究中系统与冷热源耦合机理有待深入挖掘；理论模型以系统层面的热力学分析为主，急需加强对传递/转换过程层面的有效耦合；系统分析与优化大多针对单一工况，急需解决多个工况下的综合优化等问题，本项目提出，(1)建立耦合换热器、膨胀机和流体输送三个关键传递/转换过程子模型的ORC热力学分析模型，进行系统层面与过程层面的协同计算，探索ORC系统与冷热源耦合机理。（2）以冷热源属性为约束条件，集成ORC设计优化和性能预测两个阶段的计算，进行多个工况的综合优化与评价，揭示系统偏离设计工况时的运行规律和系统与过程的匹配机理。（3）利用团队现有ORC实验台，开展1-2种纯工质的亚临界循环性能测试，验证热力学分析结果。根据以上研究，得到与典型冷热源属性相匹配的循环工质、循环模式及运行参数，为中低温热源有效利用提供数据支撑。

针对有机朗肯循环系统与冷热源匹配机理、部件/过程之间的匹配与反馈机制、系统偏离设计工况运行的多工况综合优化的复杂性，本项目从试验和模拟两方面展开研究，具体工作介绍如下：（1）对ORC回路的冷热源自动调节、数采和控制系统进行升级完善，采用改造的涡旋膨胀机为做功部件。（2）测试了ORC系统在140-160℃温度范围内使用纯工质R123循环的动态和稳态性能，揭示了恒流量和恒转速两种运行模式下系统的动态运行特性。另，发现通过焓值计算的系统性能与实测值偏差很大，因此依赖焓值计算会误导机组设计，需要建立更为贴近实际情况的仿真模型分析设备间的具体匹配与反馈机制。（3）建立了耦合传递与转换过程子模型的ORC仿真程序，模拟结果与实验结果吻合良好。（4）通过该模型研究了ORC系统与冷热源的耦合机理，一二次侧流体温度的匹配是减少换热过程不可逆损失的关键，导热油温度和流量对机组运行影响明显，而冷却水在极小流量时会提高背压，在其他流量下对机组性能影响不大。（5）通过对背压、非凝性气体、膨胀机内容积比和蒸发器面积的优化获得最佳机组设计，可以提高输出功率和系统热效率一倍以上。该机组设计对环境温湿度变化敏感，温湿度的增加会严重削弱机组做功能力，且湿度的影响随温度升高更为显著。（6）依托项目计划内容的成果，设计开发了第二代移动式集成发电机组，采用单螺杆膨胀机，优化了机组设备的匹配并实现了自动变工况控制系统，可并网发电或孤岛运行。.项目执行期间，发表学术论文6篇，其中SCI检索论文3篇；申请发明专利1项；培养和协助培养研究生6人，毕业博士生2人，硕士生2人，其中2人获批中央高校基本业务费学生项目支持；项目负责人及2名参与人许佳和陈宏霞顺利从讲师晋升为副教授职称；项目负责人及参与人陈宏霞依托该项目成果申请到国家留学基金委公派访学资格。