【作者】 韩延民；

【导师】 王如竹； 代彦军；

【作者基本信息】 上海交通大学 ， 制冷与低温工程， 2007， 博士

【摘要】 作为新能源,太阳能具有绿色环保可持续利用等优点,在解决传统能源危机中,太阳能利用是各国竞相开发和研究的热点。同时,由于太阳能的能量密度小,光照过程不连续,使得太阳能在收集、传输以及转化过程产生高耗性投资。非聚光及低倍太阳能聚光不利于能源品味的进一步提高,限制了太阳能的应用范围,因而太阳能只是作为传统能源的辅助性能源。从提高能源利用效率和能源梯级利用的角度,必须研究开发太阳能模块化聚光技术和中高温能源的储存利用技术。本文为太阳能利用在强度和时间上的内在制约提供了新型的解决方案,研究成果对高倍聚光太阳能系统在特殊场合的实用性,常规条件下的商业规模化都具有重要的意义。研究的具体内容包括:(1)通过应用热力学第一定律和第二定律过对太阳能聚光能量传输和利用系统进行热力学分析,发现理想系统对外输出功率最大时的集热温度为2464K,几何聚光比为2617,太阳能的转换效率极限值可达84.9%。这表明在太阳能高倍聚光条件下,对太阳能综合利用效率具有较大的提升潜力。(2)基于几何光学的知识,对全光谱的太阳光进行光线追踪,优化高倍聚光太阳能的实现方案。通过对三种两级高倍聚光方法的理论分析和相关实验研究,分析了太阳辐射特征与聚光光斑尺寸,入射偏角与热流密度的关系,也对光学效率的进行了测试和分析,获得聚光器形面的设计方法以及提高光学效率的能量传输方式,并提出了以两级菲涅尔透镜系统为模块化的太阳能高倍聚光方案。(3)根据所提出的两级菲涅尔透镜聚光方案,建立了菲涅尔透镜几何光学分析模型,通过仿真计算,获得了不同偏角下的静态聚光光斑的位置,能量密度,光强分布特性。基于太阳辐射的变工况条件,研究聚焦光斑在接收面上的偏移,光斑处的温度变化特性,太阳辐射以及热流密度的关系,得到的结果对模块化时的接收面研制的合理性和有效性有指导意义。(4)通过实验对所提出的菲涅尔两级聚光太阳能系统进行整体性能评估,同时,对仿真模型的有效性进行了验证。利用所建立的两级多维调试测量平台,研究了聚光太阳能系统的能量效率,包括传光及传能特性。结果表明,聚光比大于1000倍条件下,聚光系统的全光谱平均能量效率大于50%,在可见光的范围内,4合1耦合光纤的传光效率大于50%,光导管中的近红外光的能量传输效率大于70%;研究表明两级系统的追踪角误差可以控制在1°范围内,从而证明了所研制的菲涅尔两级聚光系统可以在较大的追踪允许误差范围内工作,可以降低追踪系统的投资费用。(5)探讨了高倍聚光太阳能转换装置在一种电热联用系统中的应用。以一种电热联用的模块化应用为例,对系统光热和光电转换特性进行了分析和评估。光电转换过程的分析结果认为,聚光条件下的热电联用具有提升利用效率的潜力。把热分区技术应用于能量储存,可以在规模化应用的大型太阳能系统中获得更多的可用能储存。通过研究,总体效率可以达到70%以上。更多还原

【Abstract】 With the renewable characteristic, solar energy has the advantages of environmental friendly and sustainable for uitilization. During the process of solving the traditional energy crisis, many countries focus their eyes on exploitation and research of solar energy. However, with the low power density, discontinuous radiation, solar energy generates high investments on collection, transfer and conversion, non-concentration and lower concentration solar energy block the universal application and make it to be as the auxiliary in comparision with the traditional energy.Based on the viewpoint of high efficiency and grad utilization of solar energy, modularized transmission and utilization system of high concentration solar energy, as well as energy storage at high temperature, are in consideration, which brings out a new solution to relieve the restriction of strength and time. Research results have proved the significance and the feasibility of high concentrated solar energy used under special conditions and also its market potentials. The specific contents include the following work:(1) The first law and the second law of thermodynamics are used to analyze the energy conversion of a solar concentrator with high concentration ratio, it is founded that the optimal collector temperature is 2464K and concentration ratio is 2617 suns, under which the conversion limit is 84.9%. It is of great potential in improving the energy conversion efficiency comprehensively with the high concentration of solar radiation(2) Based on geometrical optics, solar ray trace is done for the full spectrum, and high concentration schemes are optimized. By comparison of three different means based on theoretical analysis and experimental validation, the radiation characteristic is investigated including diameter of solar facular spot, relations of deviation angle and energy density, thermal efficiency, measurement on optical efficiency and analysis. Design on concentrator profile and transfer means of concentrated energy are obtained. Based on this analysis, a set of highly concentrated solar energy system with the two-stage Fresnel lens is proposed.(3) With the designed two stages Fresnel lens system, optical model of Fresnel lens is presented and simulated. The position of focus spot at different deviation angle, energy density and radiation distribution are achieved. Under the variable conditions of solar radiation, the deviation of focus spot at receiver, temperature features of focus spot, relations of solar radiation and heat flux are studied. Those conclusions have significant effect on receiver modular design for the rationality and the validity.(4) Experimental validation is done based on the design of the two stage Fresnel lens system, and the simulation model is also validated. Optical efficiency measurements have been carried out on the practical Fresnel lens group, including heat and light transfer performance. According to this study, 50~60% of the collected solar radiation can transmit through the Fresnel lens group under condition of over 1000 suns, light transfer efficiency is near 50% in the four in one light path. Infrared ray can transmit more than 70% through light tube. The track angle error of two stage system can be limited within 1°, which shows that the designed device has the higher precision on solar tracking and lower investment.(5) To exploit the application of highly concentrated solar energy, a combination system of photovoltaic and thermal system is introduced and investigated, and thermal and power characteristics of this coupled system are analyzed. The results of photovoltaic process show that the combination system has the potential ability on efficiency improving, and more exergy can be obtained in large scale solar energy storage by using thermal partition technology. It is found that the whole efficiency can be expected more than 70%.更多还原