【作者】 翟辉；

【导师】 吴静怡； 代彦军；

【作者基本信息】 上海交通大学 ， 制冷及低温工程， 2009， 博士

【摘要】 线聚焦太阳能集热器是规模化太阳能中高温利用特别是中温利用的主要技术和手段,在需要热源温度在100℃—300℃之间的中高温利用领域,线聚焦太阳能集热器能够保持较高的光热转换效率,同时在规模化应用中具有很好的经济优势。目前线聚焦太阳能集热器中的吸收器多采用直通式金属—玻璃真空集热管,虽然高真空夹层大大减少了热损失,但是同时存在着金属与玻璃的封接出长期工作后漏气的问题,而采用以黑腔原理为基础的腔体吸收器可以有效的避免上述问题,提高系统运行的可靠性,降低研究和生产的难度和成本。因此本文开展了基于抛物面槽式反射镜/线聚焦平板菲涅尔透镜和腔体吸收器的中高温太阳能集热器及其应用的理论及实验研究,主要研究工作包括:(1)利用几何光学理论建立了截面为圆锥曲线的槽式反射镜和线聚焦平板型菲涅尔透镜的三维聚光模型,利用该模型计算并分析了入射角度、焦距误差、追踪误差和加工误差对聚光比和平板吸收器上光带的能量分布的影响;设计并加工了抛物面槽式反射镜和平板菲涅尔两种聚光器,对其聚光性能和接收角进行了实验研究。理论和实验研究结果表明:吸收器开口宽度为5cm,接收角控制在±0.4°内时可以获得较高的光学效率。(2)自行设计和加工半圆形、圆弧形、三角形和正方形四种不同几何形状的腔体吸收器,从实验和理论两方面入手分析了腔体吸收器的光学性能和热力学性能,分析结果表明,三角形的腔体吸收器具有更好的光学效率和较小的热损失。最终选择了三角形腔体和两侧反射的矩形腔体吸收器并对其结构进行优化,证明在采用抛物面槽式反射镜作为聚光器时三角形腔体吸收器的开口深度为4cm时最好,正方形腔体吸收器的开口深度为2cm时最好。根据最终的优化结果加工成了长度为1m的两种吸收器。(3)自行设计了采用腔体吸收器的0.64m2平板菲涅尔透镜太阳能集热器和8m2抛物面槽式集热器的支撑结构和驱动装置,开发了能够准确有效的实现单轴追踪的微型控制器。其中以抛物面槽式反射镜+三角形腔体吸收器太阳能集热器的性能最优,晴好天气时集热器在半小时之内从环境温度升至366℃,根据实验测得的集热器效率曲线,在介质温度150℃,直射辐射600W/m2条件下,集热器效率达46%。在集总参数法的基础上建立了建立了抛物面槽式+腔体吸收器太阳能集热器的瞬态传热模型,利用该模型分析了结构参数和材料特性对抛物面槽式反射镜+腔体吸收器集热器热效率的影响,结果表明,当聚光器的开口宽度大于2m,保温材料的导热系数小于0.0035W/mK,腔体吸收器内表面发射率小于0.1时,抛物面槽式反射镜+腔体吸收器集热器的性能可以接近采用直通式真空管的太阳能集热器。(4)建立了固定、单轴追踪和双轴追踪的集热器阵列排布方式的几何模型,根据该模型可以指导工程实际中阵列的排布,计算了各种阵列的最优间距并将结果拟合成公式作为设计时的参考。(5)构建了两种采用抛物面槽式聚光镜+三角形腔体吸收器太阳能集热器的太阳能系统——地热与太阳能联合的发电系统以及基于双螺杆动力机的太阳能冷热电联供系统,并对其在西藏地区的应用进行了可行性分析,结果显示对于第一种类型的系统,在一年之内,最高时可以将不采用太阳能辅助过热的发电系统的发电功率提高38.6%;对以第二种类型的系统,从能量平衡的角度来看,系统的全年热效率达到了40.2%,这要远高于普通槽式热发电系统的热效率;而从可用能的角度分析,系统的?效率有13.1%,略高于普通槽式热发电系统的?效率。更多还原

【Abstract】 Linear concentrating solar collector is a main technique in the area of middle and high temperat. solar thermal utilization. When the heat source temperat. range is between 100?C and 300?C, linear solar collector can keep high thermal efficiency and advantage of cost. At present, the most popular absorbed used in linear solar collector is the metal-glass evacuated tube. Although the evacuated layer between metal tube and glass annular largely reduces the heat loss, it is inevitable that there is vacuum leakage after long time working. But the reliability can be increased effectively and research and producing cost will also be down if the cavity absorbed is chosen. So this thesis is devoted to research on the middle-high temperat. parabolic trough/Fresnel lens solar collector with cavity absorber and its application. The main works are summarized as following:(1)Three dimensions concentrating mathematical models for linear flat Fresnel lens and trough reflector which cutting surface is conic curve are developed. The influences of incidence angle, focus error, tracking error and surface error on concentration ratio and energy distribution in the concentrated light trap have been investigated. Based on the theoretical analysis results, one kind of parabolic trough reflector and one kind of flat plate Fresnel lens are designed and made. Moreover, experimental investigation of concentrating performance and accept angle have been done. The experimental results show that good optical efficiency can be gotten when the apert. width of absorber is 5cm and the accept angle is controlled between -0.4°and +0.4°(2)Four shapes of cavity absorbed which are semi-circular, arc, triangle and square shape are designed and made. Their optical and thermal performances are investigated under both experiment and theory. According to the results, the triangle shape cavity absorbed has better optical performance and the minimum heat loss. Furthermore, triangle cavity and squared cavity with two reflectors are chose and their construction is optimized. The conclusion is that the optimized depth of the former is 4cm and that of the later is 2cm. Based on these results, two kinds of 1m length cavity absorbed is produced.(3)The 0.64m2 flat plate Fresnel lens solar collector and 8m2 parabolic trough solar collector are designed and manufact.d. The developed micro controller for one-axis automatic sun-tracking can track the sunlight accurately. In four kinds of designed linear concentrating solar collectors, the parabolic trough solar collector with triangle cavity absorber appears the best performance. In fine day, the highest temperat. can reach 366°C. According to the thermal efficiency curve, the thermal efficiency of this solar collector is 46% when the flow media temperat. is 150°C and beam solar radiation is 600 W/m2. Moreover, heat transfer model is developed and the effect of struct. and material on thermal performance is analysis. The results show that the performance parabolic trough solar collector with cavity absorber is near that of parabolic trough solar collector with evacuated tube if the concentrator apert. is larger than 2m, the heat conductivity of insulation material is smaller than 0.0035 W/mK and the emissity of selective coating is smaller than 0.1.(4)The geometric models of the arrangement of non-tracking, one-axis tracking and two-axis tracking solar collector array have been developed. These models are useful for guiding how to arrange collector array in engineering practice. At the same time, the optimum distance of the array of three kinds collectors are calculated and fitted in equations, which can be used for reference.(5)Two kinds of systems in which linear concentrating solar collector can be used is supposed. One is the combined geothermal and solar power generation system, the other is combined CCHP system based on helical screw expander. Possibility analysis in Tibet is investigated. For the former system, the assisted heating of solar energy can enhance the power generation 38.6% (maximum). For the later one, both the yearly energy efficiency (40.2%) and exergy efficiency (13.1%) are higher than those of normal solar power generation system in which parabolic trough collector is used.更多还原