紧凑式超临界二氧化碳吸热器的高效吸热机理及光热协同调控机制

The mini-channel based compact solar receiver is one of the most promising receivers for application in the direct supercritical CO2 (S-CO2) solar thermal power generation systems. However, high-density, non-uniform, and alternating solar flux can address great challenges including hot spot and stress failure for its efficiency and safety. This project aims at revealing the mechanisms of the high-efficiency photo-thermal conversion and synergistic regulation for compact S-CO2 solar receivers to solve the above problems and the following studies are carried out. Firstly, the numerical and experimental studies are carried out for the flow and heat transfer characteristics in complex mini-channels under non-uniform and alternating heat flux, and the effects of channel scale and boundary conditions are discussed with emphasis. Secondly, the mechanism of the convective heat transfer enhancement in S-CO2 mini-channels is investigated, and the optimization of the S-CO2 channel structure with excellent thermo-hydraulic performance is carried out for avoiding the hot spot. Finally, the characteristics of the thermal stress in the compact S-CO2 solar receiver are analyzed based on a photo-thermal-stress coupled model, and the photo-thermal synergistic regulation approaches are proposed through the collaborative optimizations for tackling the non-uniform and alternating solar flux. This project can provide key theoretical foundation for the design of S-CO2 solar receiver with high-efficiency and safety, facilitating the development of S-CO2 solar thermal power generation technology.

基于细通道传热的紧凑式吸热器是应用在直接式超临界CO2（S-CO2）太阳能热发电系统中最具发展潜力的吸热器形式之一，但面临由高密度、非均匀、周期交变的太阳辐射能流引起的局部过热与应力失效的安全隐患。本项目旨在通过阐明紧凑式S-CO2吸热器的高效吸热机理及光热协同调控机制解决上述难题，具体研究工作为：针对非均匀交变能流边界下细通道复杂结构内S-CO2的流动换热开展数值模拟与实验研究，揭示尺度效应、边界条件等关键因素对S-CO2压降及传热特性的影响规律；阐明吸热通道内S-CO2高效低阻的强化传热机理，完成吸热通道的创新构型，实现对高密度太阳能流的有效消纳；基于光热力耦合模型，探讨紧凑式S-CO2吸热器应力失效的发生机制，构建聚光吸热过程的协同优化模型，提出应对非均匀交变能流的光热协同调控方法。本项目可为安全高效的S-CO2吸热器的设计奠定理论基础，推动S-CO2太阳能热发电技术的发展。

安全高效的超临界CO2（S-CO2）吸热器的设计研发是限制直接式S-CO2太阳能热发电技术发展的关键瓶颈之一。基于细通道传热的紧凑式吸热器是应用在直接式S-CO2太阳能热发电系统中最具发展潜力的吸热器形式之一，但面临由高密度、非均匀、周期交变的太阳辐射能流引起的局部过热与应力失效的安全隐患。本项目首先开展了非均匀能流边界下细通道内S-CO2流动换热特性研究，获得了单侧受热条件下细通道内浮升力效应与热加速效应的影响规律，并总结了浮升力与热加速效应修正的对流换热经验关联式；然后探讨了吸热通道内近壁面区域温度场、物性场与湍动能的分布特征，揭示了S-CO2对流传热强化与恶化发生机制，提出了吸热通道内高效低阻的三维翅片扰流结构；最后发展了紧凑式S-CO2吸热器光-流-热-力多场耦合模型，揭示了多物理场耦合作用下S-CO2吸热器局部过热与应力集中发生机制，提出了应对非均匀交变能流的光热协同调控方法。本项目研究成果可为安全高效的S-CO2吸热器的设计奠定理论基础，有助于推动S-CO2太阳能热发电技术的发展。基于本项目的研究工作，共发表学术论文8篇，其中5篇SCI论文（1篇入选ESI高被引论文），3篇会议论文；申请发明专利3项，授权实用新型专利1项。项目执行期间，项目负责人晋升河北工业大学准聘教授、入选天津市青年人才托举工程、河北省“三三三人才工程”第三层次。