高增益太阳能非成像聚光器聚能及光热转换机理研究

Nonimaging concentrating solar system plays an important role in photothermal utilization. The project will be studied that refers to the mathematical model and energy transferring mechanism of solar concentrator with synchronous improvement in both acceptance half-angle and concentration ratio(named high gain nonimaging concentrator in back writing). The aim of the research is to obtain a novel high gain nonimaging concentrator with circular absorber. First of all, the mathematical model of geometric surface shape on high gain compound parabolic concentrator (CPC) with circular absorber are obtained based on the generalized edge ray principle. Moreover, the characteristics of high gain CPC on concentrating solar radiation will also be researched. And then, the effective approach to obtain compound plane concentrator (CPC-A) from CPC with circular absorber will be studied via the theory of equal acceptance half-angle and equal escape half-angle. At last, we will build the experimental system to investigate the photothermal conversion performance of CPC and CPC-A which is influenced by the distribution characteristics of energy flux density on absorbent surface, physical property and flowing characteristics of working medium, the change of season and longitude-latitude, and so on. To acquire a novel integrated utilization mode of solar nonimaging concentration with high efficiency in concentrating solar radiant and photothermal conversion, the key scientific issues of the concentrating principle and the integrating thermal characteristics about high gain solar concentrator will be resolved in this project, which owns particular value on scientific research.

太阳能非成像聚光系统是一种重要的光热利用方式，本项目针对接收半角和聚光比同步提高（高增益）的聚光器结构及能量传输特性进行研究，旨在获得一种基于圆形吸收体的高增益太阳能非成像聚光器。首先，基于广义边缘光线原理，构建圆形吸收体高增益太阳能复合抛物聚光器（CPC）的几何面形数学模型，并研究所构建的高增益CPC的聚能特性。其次，基于非成像聚光器等接收半角和等逃逸半角理论，探索由高增益CPC获得高增益太阳能复合平面聚光器（CPC-A）的有效方法。最后，建立实验系统以研究圆形吸收体高增益CPC和CPC-A吸收体表面能流密度分布特征、工质物性和流动特性、季节变化和经纬度改变等对其光热转换性能的影响规律。项目通过对高增益太阳能非成像聚光器聚光原理和集热特性的关键科学问题进行研究，以期获得集高效光能收集和光热转换为一体化的太阳能非成像聚光利用模式，具有一定的科学研究价值。

太阳能作为一种丰富、广泛、清洁的可再生能源已获得广泛利用，将太阳能转化为热能直接应用可有效缓解人们对能源增长的需求。太阳能非成像聚光器以其具有不需跟踪静态聚光、直散辐射同步收集、结构简单易于构建的优势，已在工业供热、谷物干燥、中央空调等领域中获得应用，并受到越来越广泛的关注。. 本项目基于太阳能真空管吸收体的高增益非成像聚光器结构及能量传输特性进行了研究。首先，基于广义边缘光线原理和微分几何曲线理论，构建了非成像太阳能复合抛物聚光器面形结构一般性数学模型，并获得了高增益非成像聚光器几何面形数学计算式。其次，基于数值计算、光学仿真及实验验证的方法，对高增益非成像聚光器的聚光性能进行了分析，研究表明高增益非成像聚光器的可接收角为74.39˚时平均光学效率为86.77%，且高增益非成像聚光器吸收体表面能流分布较常规非成像聚光器更均匀。再次，采用粒子群智能搜索算法，优化设计了太阳能复合平面聚光器，研究发现优化构建的复合平面聚光器会聚太阳能直辐射的有效工作时间提高了1.82%，反映了复合平面聚光器在应对天气变化时具有更好的适应性。最后，构建了优化设计的非成像聚光太阳能系统，并采用理论模型和实验测试两个维度验证了集成系统能量收集和光热转换的稳定性、可靠性及适用性，研究结果显示非成像聚光集成系统的平均集热效率为61%。. 通过本项目的研究，揭示了高增益太阳能非成像聚光器聚能及光热转换内在机理，获得了一种集高效会聚太阳辐射能与光热转换为一体化的非成像太阳能技术途径，具有潜在的工程应用前景。