CO2-丙烷二元混合工质拟临界区传热恶化机理研究

Mixing the second component in CO2 is an important technical to adjust the operating parameters and improve the cycle efficiency of the system. The heat transfer deterioration phenomenon of CO2 binary mixed in the pseudo-critical region is directly related to the safe and efficient operation of heat exchange equipment and systems, which is an important scientific problem that needs to be solved in the development of advanced circulation systems. However, the thermal mass transfer effect between mixed components are increased the complexity of heat transfer deterioration problem, which is still lacks theoretical understanding of its mechanism so far. In this project, the supercritical CO2-propane binary mixed fluid is taken as the research object, and the mechanism of heat transfer deterioration in the pseudo-critical region will be studied from three aspects, including apparent phenomena, macroscopic characteristics and local physical field structure. The phenomenological characteristic when heat transfer deterioration occurs will be observed. We will develop advanced multi-physics test technology, and find out the temporal and spatial distribution and evolution characteristics of local physics parameters before and after heat transfer deterioration. The effect of thermal mass transfer, buoyancy force, flow acceleration and the variation of thermo-physical properties to the heat transfer deterioration will be revealed. The research of this project will enrich the basic theory of multiphase flow thermo-physics, and provide theoretical support for the improvement of air conditioning, heat pump, refrigeration systems and the new power generation technologies.

在超临界CO2中混入适当的第二组分工质是调节系统运行参数、提高效率的重要手段。其中，CO2二元混合工质在拟临界区的传热恶化现象直接关系到换热设备和系统的安全高效运行，是发展先进循环系统需要解决的重要科学基础问题，但二元混合工质组分间的热质迁移效应增加了拟临界区传热恶化问题的复杂性，目前对其发生机制仍缺乏理论认识。本项目拟以超临界CO2-丙烷二元混合工质为研究对象，从表观现象、宏观特性及局部物理场结构三个层面对拟临界区传热恶化机制开展研究。发展先进多物理场测试方法，总结传热恶化发生时的现象学规律，获得传热恶化发生前后局部物理场参数的时空分布特性和演变规律，揭示热质迁移效应、浮升力和流动加速效应、物性参数变化对传热恶化现象的影响机制。本项目研究将丰富多相流热物理学科基础理论，同时为空调、热泵、制冷系统安全经济性的提高以及新型动力及发电技术的发展提供理论支撑。

在超临界CO2中混入适当的第二组分工质是调节系统运行参数、提高系统循环效率的重要手段。其中，CO2二元混合工质在拟临界区的传热恶化现象直接关系到换热设备和系统的安全高效运行，是发展先进循环系统需要解决的重要科学基础问题。本项目以超临界CO2-丙烷二元混合工质为研究对象，采用机理实验和理论分析相结合的研究方法，从表观现象、宏观特性及局部流场结构三个层面对CO2-丙烷二元混合工质拟临界区的传热恶化特性及机制开展系统研究。构建了超临界CO2二元混合工质流动传热实验研究平台，发展了PIV-BOS速度场-密度场同步测量方法，获得了传热恶化发生前后局部物理场参数的时空分布特性和演变规律，分析了关键因素对传热恶化特性的影响规律，揭示了浮升力和流动加速效应、物性参数变化对传热恶化现象的影响机制，此外本项目还对超临界CO2混合工质布雷顿循环系统的在太阳能发电及中低温余热废热中的应用进行了性能评价分析。本项目研究将丰富多相流热物理学科基础理论，同时为空调、热泵、制冷系统安全经济性的提高以及新型动力及发电技术的发展提供理论支撑。相关研究成果发表SCI论文6篇，EI论文3篇；登记软件著作权1项；申请发明专利2项；培养硕士研究生5名。参加国内工程热物理多相流年会7人次；获得工程热物理多相流年会优秀科普作品奖1项；项目负责人担任工程热物理多相流年会分会场主席1次。