Collection times for trough-type concentrators having arbitrary orientation

A mathematical condition is derived which determines the times at which acceptance of the sun's beam radiation begins and ceases for a trough-type concentrator having arbitrary orientation. The concentrator considered is a two-dimensional ideal concentrator which has a definite range of acceptance angles. Sample calculations are performed which investigate the period of acceptance of a 1.8X concentrator. For year-round optimal collection a south-facing 1.8X concentrator should be oriented with axis horizontal and with slope equal to the latitude. If the concentrator faces slightly away from south, however, a horizontal axis and a slope equal to latitude will result in severely reduced collection times near a solstice.     

Concentration distributions in cylindrical receiver/paraboloidal dish concentrator systems

Concentration distributions on a cylindrical receiver in a paraboloidal dish concentrator are computed for space applications (no atmosphere). A geometric optics method is applied which integrates over the solar disk and the concentrator projected surface, and maps analytically, in implicit closed form, through the concentrator and onto the receiver. Finite sunshape, concentrator surface errors, and pointing system zero-mean and constant offset errors are considered. Results define the section of the receiver surface which receives the majority of the concentrated flux, where the receiver's aperture might be located. Results are given in terms of concentrator geometry, concentrator total system error tolerance, receiver geometry, and pointing offset error. In cases with pointing offset error (nonzero mean pointing error), circumferentially varying concentration distributions are shown.     

Stretched tape design of fixed mirror solar concentrator with curved mirror elements

The optical design of a fixed mirror line-focus solar concentrator, using curved mirror elements whose radius of curvature is matched to the radius of the reference cylinder of the concentrator, is presented. It is shown that this design leads to a considerable decrease in the transverse width of the focal intensity profile as compared with a fixed mirror solar concentrator of similar design made of flat mirror elements, and thus enables reduction in the cost of the heat receiver assembly. The development of a stretched tape construction of a 12 m × 3 m fixed mirror solar concentrator, conforming to the above design by using cold rolled steel tapes with constant levels of curvature across their width as substrates for the curved mirror elements, is briefly reported. Results from optical tests on the concentrator, which confirm the predictions from the theoretical model of the optics of the concentrator, are presented.     

Static solar concentrator with vertical flat plate photovoltaic cells and switchable white/transparent bottom plate

A new type of static solar concentrator is proposed to match the aesthetic features of towns. The concentrator consists of vertical plate solar cells and white/transparent switchable bottom plate, which is operated with external power. The bottom is switched to be a diffuse reflection white surface when the cell generates electric power, and switched to be a light transmissible transparent surface when the cell does not deliver power. The light collection of this concentrator was analyzed by using multiple total internal reflection model and ray tracing simulation. For the same ratio of the area of the solar cells to that of the collector surface, the collection efficiency for the proposed concentrator is about half of that of the conventional concentrator for flat plate cell, and nearly equal to that of the concentrator for the embedded spherical silicon solar cells.     

一种多级惯性煤粉浓缩器的结构优化

采用正交试验的原理和数值模拟方法对一种多级惯性煤粉浓缩器进行了试验和模拟,研究了煤粉浓缩器结构参数对煤粉浓淡比的影响,由正交设计获得了多级惯性煤粉浓缩器的最优组合结构．结果表明：与由经验设计得到的结构相比,优化结构煤粉浓缩器的浓淡分离效果有所提高,为采用试验方法对惯性煤粉浓缩器结构进行深入研究奠定了基础．     

A new trough solar concentrator and its performance analysis

The operation principle and design method of a new trough solar concentrator is presented in this paper. Some important design parameters about the concentrator are analyzed and optimized. Their magnitude ranges are given. Some characteristic parameters about the concentrator are compared with that of the conventional parabolic trough solar concentrator. The factors having influence on the performance of the unit are discussed. It is indicated through the analysis that the new trough solar concentrator can actualize reflection focusing for the sun light using multiple curved surface compound method. It also has the advantages of improving the work performance and environment of high-temperature solar absorber and enhancing the configuration intensity of the reflection surface.     

Solar distillation of water using a V-trough solar concentrator with a wick-type solar still

A V-trough solar concentrator has been combined with an inclined flat-plate wick-type solar still. Outdoor testing was carried out with and without the solar concentrator on clear days in summer and winter. The equipment was used to investigate the enhancement of the outdoor performance of the wick-type solar still by the solar concentrator.It has been concluded that use of the solar concentrator with the inclined wick-type solar still can lead to a greater fractional increase in still efficiency and productivity on clear days in winter than on clear days in summer.     

A novel multiple curved surfaces compound concentrator

A novel multiple curved surfaces compound concentrator is developed in this paper. It is composed of a parabolic and a flat contour. This new concentrator has a focus at the backside which is extremely useful and convenient for some applications. The reflected rays here are transmitted forward instead of backward as in the conventional parabolic concentrators. The design method of the concentrator is introduced. Some of important parameters are discussed and the value rang of them is determined. Simple comparisons between proposed concentrators and traditional paraboloid and CPC are made. Light rays tracing are carried out in the concentrator.     

Concentration characteristics of a two stage solar concentrator: Effect of primary mirror surface errors

The concentration characteristics of a two-stage linear solar concentrator employing a perfectly tracked parabolic trough as the primary and a seasonally adjusted compound parabolic concentrator as the secondary stage with a flat horizontal absorber are studied. The Monte Carlo ray trace technique is used for this purpose. The effect of randomly distributed primary mirror surface errors on the concentration characteristics of the two stage concentrator is also investigated.     

Concentrating performances of an ellipsoid-cone system for optical furnaces

A way to increase the concentration in an URAN optical furnace by means of a secondary concentrator (C) is examined. The opening angle of the concentrator is optimized. It is revealed that by using the concentrator, it is possible to increase the mean irradiance to a spot of 10 mm in diameter by almost a factor of 2.     

弯头和百叶窗浓缩器联合作用时浓淡风比试验

进行了单独使用浓缩器、弯头及弯头和浓缩器联合作用时浓淡风比的试验研究。单独使用浓缩器时，随着叶片级数增加，浓淡风比值(RQ)增加；当叶片级数相同时，叶片布置形式对RQ的影响较小。单独使用弯头时，RQ随气流转弯角度增加而增大；随弯头后续管段长度增加而减小。弯头和浓缩器联合作用时的RQ与弯头方向有关，当弯头和浓缩器对煤粉气流的分离作用一致时，RQ小于弯头单独作用和浓缩器单独作用时的浓淡风比值之和；当两者对煤粉气流的分离作用相反时，RQ大于弯头单独作用和浓缩器单独作用时的浓淡风比值之差；此时，叶片布置形式对RQ影响较大。图5表3参5     

Performance improvement of a static concentrator module with an asymmetric v-groove backsheet structure

A light-trapping type concentrator module with a new asymmetric V-groove structure at the rear surface is proposed to improve the performance of static concentrator module. Fundamental optical properties of various asymmetric V-grooves are calculated using a ray-tracing method. Based on these results, yearly integrated irradiance ratios of the concentrator module to a conventional flat-plate module are calculated using meteorological data. By the use of Ag as a reflection material, yearly integrated irradiance ratio of concentrator module with an asymmetric V-groove is 1.34, and the occupation area of Si cells in a module can be reduced to 74% compared with a conventional flat-plate module.     

太阳能会聚器的优化设计

讨论了用光学设计软件CODE V对太阳能会聚器进行优化设计的问题。在描述了太阳能会聚器的主要设计参数后，我们分析了抛物型会聚器的特性。利用光学设计软件，设计出一类新的高次非球面会聚器。实验结果表明，此类会聚器可实行间断跟踪太阳，且接收面光能量分布均匀，提高了系统转换效率，还具有节约能量、降低成本等优点。     

An optical analysis of a static 3-D solar concentrator

Concentrating technology is long established in the field of solar thermal applications. However, there is still scope for improvement due to innovation in design, materials and manufacturing methods. The optical efficiency of a solar concentrator depends largely on the geometry of the concentrator profile. This paper evaluates the optical performance of a static 3-D Elliptical Hyperboloid Concentrator (EHC) using ray tracing software. Ray tracing has been used extensively to calculate the optical efficiency of the static 3-D EHC. Performance parameters such as effective concentration ratio, optical efficiency and geometric concentration ratio are also evaluated for different aspect ratios of the elliptical profile. Optimization of the concentrator profile and geometry is also carried out to improve the overall performance; this parametric study includes the concentrator height, solar incidence angle and aspect ratio of the ellipse. The overall performance of the concentrator was assessed based on the acceptance angle, effective concentration ratio and optical efficiency. Finally, the flux distribution on the receiver area for different concentrator heights is also presented.     

Review on Development of Small Point-Focusing Solar Concentrators

The technology of small point-focusing concentrator of solar energy has been developing rapidly in recent years owing to its compact structure and high collecting efficiency. This report presents important developments of small point-focusing concentrator in the past decade. This kind of solar concentrator refers to the parabolic dish concentrator, the point-focusing Fresnel lens, and the Scheffler reflector. Technological advances of these concentrators and the related performances have been presented. There are three main mirror fabrication technologies for dish concentrator, which are high polishing metal, silver-glass mirror and vacuum-membrane. Polymethyl methacrylate is widely used as material in Fresnel lens. Many scholars have proposed new lens shape to improve the uniformity of focusing. The Scheffler reflector has a characteristic of fixed focus, but its design parameters are not perfect so current research focuses on the theoretical calculation of the mirror. In addition, typical applications of the small point-focusing concentrator in photovoltaic system, solar thermal system, solar chemical system, and day-lighting system are summarized. Upon listing the important publications in open literature, a category of main applications of such kind of solar collector is provided based on the working characteristics of the system.     

Modeling and Calculation of Optical-Geometric Characteristics of a Solar Concentrator with Flat Fresnel Mirrors

The basic characteristics of a concentrator, such as the number of reflectors, their coordinates and orientation, the degree of concentration, and others are determined with the use of the optical-geometric approach depending on the configuration parameters of the concentrator. Based on the presented formulas and numerical results, it is possible to determine the parameters of an arbitrary configuration of a linear-focus concentrator with flat Fresnel reflectors located on a parabolic base. The specific features of the distribution of the energy density over the receiver are determined. The paths of solar beams in the system and formation features of the transverse focal lines of the concentrated optical radiation are graphically analyzed for the case of the exact orientation of the concentrator on the Sun.     

Effect of finite angular width of the sun on design and concentration characteristics of a fresnel-winston tandem concentrator system

The effect of the finite angular width of the sun on the design and concentration characteristics of a Fresnel reflector concentrator and a compound parabolic concentrator in tandem is investigated.     

Optimized variable-focus-parabolic-trough reflector for solar thermal concentrator system

A solar thermal concentrator system is proposed comprising a cylindrical heat-pipe receiver and a variable-focus-parabolic-trough (VFPT) reflector in which the focal length varies as a function of the vertical displacement of the incidence point relative to the horizontal centerline of the receiver. The light ray paths within the concentrator system are analyzed using a skew-ray tracing approach. A method is then proposed for optimizing the geometry of the concentrator system in such a way as to optimize the uniformity of the irradiance distribution on the heat-pipe surface. The validity of the proposed optimization method is demonstrated by means of ZEMAX/SolidWorks-Flow simulations. It is shown that the optimized VFPT concentrator yields a significant improvement in both the irradiance uniformity and the heating efficiency compared to conventional cylindrical-trough and parabolic-trough concentrators.     

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.     

百叶窗浓缩器内气固两相流动PDPA试验研究

采用二维相多普勒粒子分析仪（PDPA）对典型结构的百叶窗浓缩器内气两相流劝进行了定量测量,得到了百叶窗深缩器内气固两相流场特点,探讨了百叶窗深缩器气固分离机理,即浓度机理,定量解释了对浓缩器性影响的气固两相流动的本质所在。