两级聚光光伏系统中砷化镓电池特性的实验研究

针对一般聚光系统中光斑不均匀而导致电池性能下降的问题,设计并搭建了具有二级聚光器的碟式聚光光伏发电系统,介绍了系统的结构及工作原理,进行了户外实验。在相同聚光比条件下(150X),与单级聚光系统相比,三结砷化镓光伏电池的平均峰值功率为1.515 W/cm2,平均效率为29.29%,平均峰值功率和平均效率分别提高了23.32%和9.12%。     

聚光型太阳能分频利用系统的光学性能分析

提出一种基于折平板聚光器的光电光热分频利用系统,利用蒙特卡洛法对比分析3种不同结构分频利用系统的光学性能,重点研究集热石英管的几何参数、表面反射率及真空层对透光效率、光斑均匀性的影响。结果表明:先分频后聚光系统与先聚光后分频系统相比,前者具有更高的光斑均匀度与透光效率,但无法获得高品位热能;先聚光后分频系统中集热管形状分别为矩形与半圆形,矩形集热管系统的透光效率较半圆形集热管系统高,而光斑均匀度较半圆形集热管系统低;在石英管内外壁面间布置真空层,透光效率显著降低,能量损失主要由表面反射所引起。     

塔式太阳能热发电站圆月夜聚光实验研究

在塔式太阳能热发电系统中,吸热器采光面上的聚光能流密度分布的测量对优化整个系统的光热性能有着重要意义。本文提出一种基于月光聚光信息的塔式电站定日镜场聚光能流密度分布的间接测量方法。主要介绍2018年9月24日晚在延庆塔式电站开展的两种对月聚光实验：一种是通过塔上布置的照度计标定电荷耦合元件（Charge-coupled Device, CCD）相机拍摄的光斑图像,得到定日镜场聚光光斑的照度分布;另一种是使聚光光斑扫描过照度计,得到不同时刻的照度计数值,通过高斯拟合得到聚光光斑的照度分布。将聚光光斑的照度分布与月光测光站测得的月光法向直射照度对比,得到塔上聚光光斑的相对能流密度分布。实验结果表明,通过月光聚光实验,可以得到塔式电站的聚光光斑的相对能流密度分布（即聚光比分布）,为后续依据太阳和月亮之间的亮度分布关系,转换为日光聚光能流密度分布提供实验数据支持。     

旋转曲面式两级反射系统的太阳能聚集与传输特性分析

提出一种改进型卡塞格林反射太阳能聚集系统,将其二次镜面方位进行旋转变换,接收面可据此灵活布置,对聚集系统的结构优化具有重要应用价值。通过建立旋转曲面式两级反射系统的数理模型,根据几何光学原理推导二次镜最大可旋转角度,并用射线踪迹蒙特卡洛法(MCRTM)模拟接收面能流分布特性。结果表明,此系统下聚集光斑遵循高斯分布,虽然聚光比同单级碟式抛物面有所降低,但可在保持较高聚光比的同时灵活改变光路方向。     

槽式均匀聚光系统设计及分析

为提高槽式聚光系统的聚光均匀性,提出一种槽式均匀聚光系统,建立了该系统反射聚光器模型,并对其聚光效果进行了分析.对系统的几何参数分析表明,随着反射镜面数量的增加其宽度在逐渐减小而其倾角却在逐渐增加,系统最大几何聚光比随系统的几何高宽比δ增大而增加.利用蒙特卡罗光线追迹方法对该聚光器的聚光效果进行模拟,结果表明该系统的聚光均匀性明显优于传统的槽式聚光器聚光效果,能够满足设计需求.     

凹形球面石英窗对碟式系统腔体吸热器光学性能的影响

吸热器表面非均匀且高强能流载荷会降低其工作效率、安全性和服役寿命。提出一种凹形球面石英窗用于太阳能碟式聚光系统的腔体吸热器,可改善吸热器的能流均匀性、降低最大局部聚光比等光学性能指标。基于蒙特卡洛光线追迹法,考虑腔体吸热器由等开口、等面积和等高度三者共同约束,研究圆柱形、圆台形、圆柱-圆台形和球形4种腔体结构吸热器的光学性能。研究表明:采用平面石英窗时4种腔体结构吸热器的非均匀系数分别为0.60、0.86、0.70和0.74,最大局部聚光比分别为1050.0、1350.0、1190.0和1080.0;而采用凹形球面石英窗时4种腔体结构吸热器光学效率和采用平面石英窗时基本相同,但吸热器的非均匀系数分别下降到0.36、0.62、0.54和0.60,最大局部聚光比分别下降到743.7、922.2、916.5和1000.4,采用凹形球面石英窗比平面石英窗对各吸热器的光学性能均有明显提高,且其中圆柱形腔体吸热器比另外3种结构吸热器具有更好的光学性能。     

聚光装置的极限聚光比和极限温度

在抛物镜、透镜或定日镜群的聚焦面上可获得很高的温度。虽然决定温度高低的因素很多,但最重要的是聚光比。聚光比定义为抛物镜的开口面积或定目镜群的总面积与它们焦平面上光斑面积之比,它是设计聚光型太阳能利用装置最重要的参数之一。聚光比越大,光斑的温度就越高。那么聚光比有没有极限值呢?如果有,它是多大?我们在回答这个问题之前,首先作两个极端的假定: (1) 聚光装置位于地球的大气层外,因而可以不考虑对流和传导热损。 (2) 聚光装置是理想的,它的镜面反射系数为1(如是透镜,它的透过系数为1),它能将接受到的太     

新型多平面太阳能聚光器性能分析

提出一种新型多平面太阳能聚光器,该型聚光器由若干矩形小平面镜和抛物型结构的框架组合而成,适用于太阳能在中温领域的应用。利用几何学原理和Monte Carlo方法研究新型多平面太阳能聚光器的几何光学特征及焦平面能流密度分布,分析不同综合误差对几何聚光比及能流密度分布的影响。研究结果表明:相比传统碟式聚光器,新型多平面聚光器在焦平面的光斑面积增大且能流密度分布均匀;该型聚光器的几何聚光比随着镜面排数M的增加而增加,在镜面排数M分别为7、9、11时,相应几何聚光比可达69、125、210,满足中温领域的使用要求;在相同的外部条件下,其运行性能受综合误差的影响较传统碟式聚光器小。     

聚光型光伏系统光电耦合性能研究

针对复合抛物面聚光型光伏（PV-CPC）系统,建立光电耦合模型,模拟不同聚光比下光伏阵列表面太阳辐照度分布规律,并比较3种不同网格电路模型的适用性和准确性。结果表明：采用离散网格照度方法模拟精度最高,同时聚光型光伏系统在提升发电功率的同时也导致一定效率损失。当聚光比增大时,光伏阵列表面辐照度值及不均匀性增大,最佳聚光面处的照度分布均匀性优于CPC出口处;光伏阵列的发电功率和效率与太阳总辐照度呈正相关、散射比呈负相关关系。     

双面正交条纹透镜理论分析

双面正交条纹透镜的聚光倍数较高，光斑均匀，光线经它两次折射后能到达任意指定的方向。对该透镜进行了理论分析。     

Radiation performance of dish solar concentrator/cavity receiver systems

The Monte-Carlo ray-tracing method is applied and coupled with optical properties to predict radiation performance of dish solar concentrator/cavity receiver systems. The effects of sunshape and surface slope error have been studied and the corresponding probability models are introduced in this paper. Taking into account the above-mentioned factors, we show that the directional features of the focal flux affect the radiation flux distribution of cavity receiver, present criteria for the characterization of directional attributes, and describe a method for their calculation. Based on the concept of equivalent radiation flux, an upside-down pear cavity receiver is proposed in view of directional attributes of focal flux. Receiver design and modelling guidelines are presented. The uniformity performance of the wall flux is compared with five traditional geometries.     

一种新型极轴跟踪式定日镜的研究

提出一种新型采用轮胎面聚光镜极轴跟踪式定日镜。分析了极轴跟踪式定日镜的跟踪原理,设计了用于该定日镜的轮胎面并分析其聚光性能。结果表明:该定日镜聚光性能较高,能够满足生活热水、太阳炉等应用领域的要求。     

Mirror rearrangement optimization for uniform flux distribution on the cavity receiver of solar parabolic dish concentrator system

The nonuniform and high‐gradient solar radiation flux on the absorber surface of solar dish concentrator/cavity receiver (SDCR) system will affect its operational reliability and service lifetime. Therefore, homogenization of the flux distribution is critical and important. In this paper, 2 mirror rearrangement strategies and its optimization method by combining a novel ray tracing method and the genetic algorithm are proposed to optimize the parabolic dish concentrator (PDC) so as to realize the uniform flux distribution on the absorber surface inside the cavity receiver of SDCR system. The mirror rearrangement strategy includes a mirror rotation strategy and mirror translation strategy, which rotate and translate (along the focal axis) each mirror unit of the PDC to achieve multipoint aiming, respectively. Firstly, a correlation model between the focus spot radius and mirror rearrangement parameters is derived as constraint model to optimize the PDC. Secondly, a novel method named motion accumulation ray‐tracing method is proposed to reduce the optical simulation time. The optical model by motion accumulation ray‐tracing method and optimization model of SDCR system are established in detailed, and then, an optimization program by combining a ray‐tracing code and genetic algorithm code in C++ is developed and verified. Finally, 3 typical cavity receivers, namely, cylindrical, conical, and spherical, are taken as examples to fully verify the effectiveness of these proposed methods. The results show that the optimized PDC by mirror rearrangement strategies can not only greatly improve the flux uniformity (ie, reduce the nonuniformity factor) and reduce the peak local concentration ratio of the absorber surface but also obtain excellent optical efficiency and direct useful energy ratio. A better optimization results when the PDC is optimized by mirror rotation strategy at aperture radius of 7.0 m, focal length of 6.00 m, and ring number of 6; the nonuniform factor of the cylindrical, conical, and spherical cavity receivers is greatly reduced from 0.63, 0.67, and 0.45 to 0.18, 0.17, and 0.26, respectively; the peak local concentration ratio is reduced from 1140.00, 1399.00, and 633.30 to 709.10, 794.00, and 505.90, respectively; and the optical efficiency of SDCR system is as high as 92.01%, 92.13%, and 92.71%, respectively. These results also show that the dish concentrator with same focal length can match different cavity receivers by mirror rearrangement and it can obtain excellent flux uniformity.     

抛物柱面聚光器焦面能流分布特性研究

采用蒙特-卡罗法对抛物柱面聚光器聚焦光斑能流密度进行计算,分析聚光器的表面形状误差、跟踪误差、接收器位置误差、接收器的遮挡、太阳形状、漫反射和聚光器边缘角对焦面能流分布的直接影响,为该面型聚光器的系统设计、安装和能流密度测量提供依据.     

具有二次聚光器的新型大开口槽式太阳集热器设计与光学性能分析

针对大开口和更高运行温度的槽式太阳能热发电系统,提出一种可实现高聚光比、低辐射热损及能流密度均匀的新型槽式太阳集热器,即在集热管内放置外壁具有太阳选择吸收膜层和内壁具有反射膜层二次聚光器的大开口槽式太阳集热器。建立圆弧为微元段的自适应设计新方法,提出3种典型的二次聚光器面型,利用蒙特卡洛光线追迹方法仿真新型集热器的能流密度分布特性,验证该光学仿真方法,分析影响集热器光学性能的各种因素。结果表明,该集热器可显著提升集热效率。     

A solar dish concentrator based on ellipsoidal polyester membrane facets

The design of a solar parabolic dish concentrator is proposed based on an array of polyester mirror membrane facets that are clamped along their edges by elliptical rims and focused by applying a slight vacuum underneath the membranes, creating an ellipsoidal shape. The axes ratio of the elliptical rims varies with the position on the dish to approach the paraboloidal shape. The elastic mirror membrane deformation under uniform pressure load is simulated by finite element structural analysis and the resulting radiative flux distribution at the focal plane of the dish is determined by the Monte Carlo ray-tracing technique. Optimization of the membrane deflection is accomplished for maximum solar flux concentration at the focal plane. Two dish geometries are examined: (i) a 1.5-m radius 3-m focal length small dish, comprising 19 facets of 0.275-m radius with four different curvatures, yielding a peak solar concentration ratio of 5515 suns and a mean solar concentration ratio of 1435 suns with an intercept factor of 90% over a 3-cm radius disk target and (ii) a 10.9-m radius 11-m focal length large dish, comprising 121 facets of 0.9-m radius with 15 different curvatures, yielding a peak solar concentration ratio of 23,546 suns and mean solar concentration ratio of 8199 suns with an intercept factor of 90% over a 10.4-cm radius disk target. The performance of the second geometry is compared to that of the more conventional design of a multi-facet dish concentrator consisting of identical circular facets and shown to reach – on the same target area – a 12% higher mean solar concentration ratio as well as a 6.6% higher intercept factor. The simulated membrane shape is experimentally verified with photogrammetrical measurements carried out on a prototype facet of the small dish.     

三角元薄膜拼合太阳能聚光器汇聚性能研究

针对一种轻质量的张拉薄膜太阳能汇聚系统,以三角元薄膜拼合反射面为研究对象,同时考虑模型原理误差、太阳光不平行度、接收器遮挡影响,跟踪误差等因素,采用蒙特卡罗法数值对比2种不同三角元拼合膜面在接收面的汇聚辐射能流密度分布情况,分析不同拼合形式、分环数、焦径比、跟踪误差对接收面辐射能流密度分布的影响,为三角元薄膜拼合太阳能聚光器参数选择和聚焦性能分析提供依据。     

Optical design of a flat-facet solar concentrator

We present a procedure to design a facet concentrator for laboratory-scale research on medium-temperature thermal processes. The facet concentrator approximates a parabolic surface with a number of flat square facets supported by a parabolic frame and having two edges perpendicular to the concentrator axis. The optimum size and position of each facet are found by employing Monte Carlo ray tracing analysis to achieve desired flux characteristics in the focal plane. A 164-facet concentrator with realistic specularly-reflecting surface and facet positioning accuracy will deliver up to 8.15 kW of radiative power over a 15 cm radius disk located in the focal plane, with average concentration ratio exceeding 100.     

A comparison of power density for axial flux machines based ongeneral purpose sizing equations

Based on the concept of the converter fed machine (CFM), an optimal machine design can be considered as the best match of the machine topology, the power electronic converter and the performance specification. To compare power production potential of axial flux machines with various topologies, different waveforms of back EMF and current, general purpose sizing and power density equations for such machines are needed. In this paper, a general approach is presented to develop and to interpret these equations. Sample applications of the sizing and power density equations are the axial flux toroidal permanent magnet utilized to compare the axial flux toroidal permanent magnet (AFTPM) machine and the axial flux two-stator permanent magnet (AF2SPM) machine     

环形加热炉内管坯辐射热流均匀性的分析

管坯在环形加热炉内加热时,其表面辐射热流的分布是很不均匀的,靠近炉底的管坯表面的辐射热流比上部的小得多,因而造成管坯表面自下向上温度分布不均匀。适当增加管坯间距与其半径比(一般在3～4较为适宜),以及提高炉底反射率,可提高管坯表面热流分布的均匀性,改善加热质量。