线性菲涅尔式太阳能聚光系统二次聚光器研究进展

Research progress on secondary concentrator for linear Fresnel reflector

二次聚光器配合固定安装的高温真空集热管(由吸热管和玻璃管组成)可以解决旋转接头高温动密封的技术难题,运行更高温的传热介质,使线性菲涅尔式太阳能聚光系统在提高发电效率和降低成本方面更具潜力.本文综述了传统复合抛物面二次聚光器(CPC)和新型二次聚光器的研究进展,重点论述了CPC间隙确定方法和接收半角的选择对其光学性能的影响,分析了新型二次聚光器的优缺点,探讨了二次聚光器的实际应用问题,展望了二次聚光器未来的研究重点.分析结果表明:对于CPC间隙确定方法,渐开线起始点前移的间隙损失较小且易于后期加工;接收半角的选择应综合考虑CPC光学性能和开口宽度.基于自适应方法的新型二次聚光器光学效率与CPC相当;当要求吸热管表面达到更高的能流密度或吸热管周向能流分布更均匀时,CPC为最佳选择.

As the most abundant renew energy resource,solar energy has aroused the interest of scientists all over the world.In order to increase its efficient use,collectors maximizing sun power density are developed.According to concentration type,the solar collector system consists mainly of the linear Fresnel reflector(LFR),the parabolic trough collector(PTC),the solar power tower and the parabolic dish collector.LFR has attracted much attention because of its simple construction,low wind loads and optimal utilization of land area.The molten salt can be used as the heat transfer fluid when the fixed secondary concentrator is combined with the high temperature evacuated tube,which makes the system has great potential in reducing the cost of power generation.In this paper,the development of traditional compound parabolic concentrator(CPC)and new secondary concentrator is reviewed.Approaches of leaving a gap between secondary concentrator and receiver and the choice of the half-acceptance angle of the CPC are analyzed.The advantages and disadvantages of new secondary concentrators are summarized.The practical application of secondary concentrator is discussed,and the future research directions of secondary concentrator are prospected.The analysis result shows that for the approaches of leaving the gap,the gap loss of involute starting point moving forward is small and easy to process.Geometric optical efficiency and aperture width of the CPC should be considered for the choice of the half-acceptance angle.The efficiency of the new secondary concentrator based on the adaptive method is close to that of the CPC.When a higher flux intensity or a medium to high circumferential flux intensity homogeneity is required,the CPC is the best choice.