体积吸收式复合太阳能分频液冷高倍光电光热接收器工作机理研究及优化

In conventional concentrated photovoltaic/thermal (CPV/T) hybrid system, an important issue is that obtaining a higher heat transfer fluid outlet temperature comes at the expense of electrical efficiency. Further, the efficiency of the CPV/T system with spectral splitting filter is still low. Therefore, volumetric absorption combined spectral splitter together with direct liquid immersion cooling are proposed for high CPV/T system. And a high CPV/T solar receiver coupled with volumetric absorption combined spectral splitter and liquid immersion cooling is suggested in this project. Firstly, the entire solar radiation transfer process in the receiver integrated with the concentrator will be simulated based on Monte Carlo ray tracing method, and the variation of the energy flux distribution with space and time will be revealed accurately. Then, the coupled electrical/thermal models will be constructed for energy transfer process description of the novel receiver. Based on the models, the coupled relationship and interaction mechanism between photovoltaic conversion, photothermal conversion and volumetric absorption combined spectral splitter, liquid immersion cooling will be explored. Combined with the receiver outdoor experiment, the prediction model of the novel receiver performance related to operating conditions, solar cell characteristics and combined spectral splitter properties will be developed. Thus, the synergy mechanisms of all kinds of energy flow in the novel receiver will be discussed to achieve an optimal comprehensive solar energy utilization. This research is an interdisciplinary project in optics, electricity, heat transfer and fluid mechanics and of great academic importance for the extending of engineering thermophysics. In addition, it is also very helpful to master the key techniques of the CPV/T systems, to develop solar photovoltaic/thermal hybrid receiver with high electrical efficiency and high thermal efficiency and of great practical significance to realize engineering application of CPV/T systems.

基于聚光太阳能光电光热（CPV/T）综合利用思路，针对传统CPV/T中光伏、光热单元间热耦合及光谱分频型CPV/T效率低的问题，创新性地将体积吸收式复合太阳能分频与液浸冷却有机结合应用于高倍CPV/T系统，提出一种体积吸收式复合太阳能分频液冷高倍光电光热接收器。采用光迹追踪法研究集聚光器一体的接收器内太阳辐射能流分布的准确描述及其变化规律；构建描述接收器能量传递过程的电热耦合模型，探索光电转换、光热转换与吸收式复合分频、液浸冷却间的耦合关系及影响机制，结合户外试验，建立基于工作条件、电池特性、复合分频器性能多因素复杂耦合的接收器性能预测模型，揭示多股能流间协同配合机制，实现太阳能综合利用效率最大化。研究涉及光学、电学、传热学及流体力学等学科交叉，对本学科拓展具有重要学术意义；同时对于掌握CPV/T关键核心技术，研发具有高光电、光热转换效率接收器，实现CPV/T实际工程应用具有重要现实意义。

基于聚光太阳能光电光热（CPV/T）综合利用思路，针对传统CPV/T中光伏、光热单元间热耦合及光谱分频型CPV/T效率低的问题，本项目将体吸收太阳能分频技术和聚光电池冷却技术有机结合应用于CPV/T系统。采用理论分析、数值模拟和实验相结合的手段，对体吸收式太阳能分频光伏光热接收器相关过程的基础问题展开了系统深入的研究。取得的代表性成果如下：（1）研究了体吸收式太阳能分频器的分频性能及对聚光太阳能电池输出的影响规律。结果表明，液+固复合分频器和纳米流体分频器的分频性能要优于普通液体的分频性能，加入固体吸收式滤光片或纳米流体虽降低了电池的电输出，但可明显提升接收器的输出温度，接收器综合性能有所提升。（2）设计了液+固复合分频接收器和相应的聚光器，研究了聚光条件下复合分频接收器电、热性能。结果表明，所设计的条形平面镜聚光器在接收面处可获得97.88%的光照均匀度；所设计的接收器可使光伏电池组件的光电转化效率最高提升至26.45%。采用丙三醇+水1:3溶液+HB650滤光片复合分频器时接收器可获得最高49.53%的综合效率。（3）建立了纳米流体分频型热管冷却CPV/T系统的模型，研究了不同环境温度、风速、储水箱水量、集热器水量、聚光比以及分频液质量流量对该系统全天性能的影响。结果表明，该系统在5倍聚光下，全天的平均热效率、电效率、总效率分别为46.02%、7.64%和53.67%。当聚光比小于7时，分频型热管冷却CPV/T系统的综合性能优于热管冷却CPV/T系统和分频型CPV/T系统。（4）结合室内模拟光实验，采用蒙特卡罗光线追迹法+有限体积法耦合模拟的方法研究了采用线性菲涅耳反射聚光器和复合分频接收器的复合分频聚光光伏光热系统的综合性能。光学模拟结果表明该系统具有较高的光学效率且接收器中电池表面的光照均匀性较高。CFD模拟结果表明，高进口温度和低流速下，系统可以取得最大的㶲效率。（5）此外，申请人还在纳米流体分频液的制备和稳定性考察等方面开展了研究，取得了相应成果。以上成果可为实现CPV/T系统工程应用提供关键的理论指导。