不同冷源温度下有机朗肯循环热力性能的实验和理论研究

Organic Rankine cycle (ORC) favorably operates at low-medium temperature. The ORC has the ability to output both power and heat, and is suitable for rural cogeneration. The combined heat and power(CHP)generation improves the economic performance of the ORC, and thus offers easier access to the marketplace. Therefore，it is necessary to get a scientific view of the CHP operation with ORC.Thermodynamics of the ORC under different cold reservior temperatures is the key scientific issue that is fundamental to the CHP performance evaluation and optimization. The ORC cold reservior temperature varies with environment temperature and the demand for power and heat. The cold reservior temperature influences the ORC power conversion efficiency, available energy of the output heat, expansion ratio of the organic fluid at the expander inlet and outlet, net positive suction head (NPSH) in the pumping process, heat transfer temperature difference in the exchangers, and so on. It is difficult to predict the cycle performance due to the variable operating conditions. At present, research on this topic is rare. This project focuses on experimental investigation and thermodynamic analysis of the ORC under different cold reservior temperatures. The specific scientific issues of the project are: 1) Clarifying the key factors that affect the ORC power output and establishing a rigorous thermodynamic relationship for power generation. 2) Revealing and analyzing the thermodynamic irreversibility in the ORC. 3)Working fluid selection. 4)Investigating and estimating the cogeneration performance. The proposed project aims to present a thorough and comprehensive view of the ORC thermdynamics under different cold reservior temperatures. It will provide essential experimental and theoretical support for evaluation and optimization of ORC cogeneration and annual power generation.

有机朗肯循环(ORC)具有良好的中低温运行性能。利用工质冷凝余热实现热电联供是推动ORC在太阳能、生物质能等领域低成本规模化开发利用的重要方式。ORC的冷源温度是其热电联供的关键参量。ORC冷源温度因不同时间段的用电用热需求及环境温度而调整。冷源温度影响ORC热功转化效率、输出热能的品位、膨胀机压比、泵气蚀余量、换热器温差等，使得ORC关键单元及整体的热力性能具有很强的不确定性。而目前缺乏冷源温度对ORC热力性能影响的深入研究。本项目拟基于实验开展不同冷源温度下ORC热力性能研究。侧重点为不同冷源温度下ORC热功转化影响因素研究及热力学关系式建立，组成单元及整体热力学不可逆损失研究与优化，有机工质筛选，热电联供综合效率研究。以期阐明不同冷源温度下ORC热力学不可逆损失机制，明确热电联供模式与单一发电模式ORC能源利用效率的差异，为评估和优化ORC热电联供性能、全年发电性能提供科学依据。

在有机朗肯循环(ORC)结构优化方面，提出了新型重力增压ORC循环，有效避免了低功率泵存在的技术难度大、效率低、易气蚀等问题，具有效率和经济性两方面优点；提出了太阳能和液化天然气(LNG)复合发电系统，建立了等效发电效率模型,基于该模型评价了复合系统的性能，弥补了已有的热效率和可用能效率等模型的不足；提出了基于蒸汽螺杆膨胀机的直膨式太阳能复叠朗肯循环系统；与常规的基于透平的槽式抛物面集热器—蒸汽朗肯循环系统相比有显著优点。.分别测试了基于1kW涡旋膨胀机和3.5kW涡轮膨胀机的ORC系统。通过对不同冷源温度下ORC的热力性能进行了实验研究，阐明了不同冷源温度下ORC关键单元及整体热力学不可逆损失机制；揭示了ORC热力学不可逆损失的主要因素；明确了热电联供模式与单一发电模式太阳能ORC热发电系统能源利用效率的差异。. 项目开展以来，负责人作为第一或通讯作者，已出版英文专著1本，由国际知名出版商Springer出版；在Applied Energy、Energy、Solar Energy、Energy Conversion &Management、Applied Thermal Engineering等权威期刊发表SCI论文6篇，国际会议论文2篇，申请专利2项。同时另有2篇论文处于审稿状态。项目按计划完成了研究任务。