共查询到20条相似文献,搜索用时 15 毫秒
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Fritz Zaversky Javier García-Barberena Marcelino Sánchez David Astrain 《Solar Energy》2012,86(7):2128-2139
In this work, an uncertainty and sensitivity analysis for the annual performance of a parabolic trough collector plant based on a probabilistic modeling approach of the solar-to-thermal energy conversion process has been accomplished. Realistic probability functions have been assigned to the most relevant solar field performance parameters. The Latin Hypercube sampling method has been used to create equal probable parameter combinations. The so obtained sample matrix has been used to run multiple annual electricity yield simulations in SimulCET, a validated parabolic trough collector plant simulation software, developed by the National Renewable Energy Center (CENER) in Spain García-Barberena et al., 2012. This procedure has led to a representative distribution for the annual plant performance, given the uncertainty in the input data. For this study the parabolic trough power plant model has been run in solar driven operation mode, without the use of thermal storage or fossil fuel back up. While being aware of the great influence of the solar irradiation on the power plant performance, only one single reference meteorological year has been used as solar input data. This has been done in order to emphasize the influence of technical design- as well as solar field maintenance parameters, factors that can be controlled or affected by mankind. In order to assess and rank the impact of each varied model parameter a multiple linear regression has been performed. The standardized regression coefficients, the Pearson correlation coefficients as well as the coefficient of multiple determination R2 are discussed. Varied parameters are the collector mirror reflectance, the collector mirror cleanliness factor, the collector glass tube transmittance, the collector receiver tube absorptance, and the collector receiver tube heat loss characteristic. Based on existing and published bibliography, a set of parameter distributions and ranges have been chosen for this work and the simulation results show that the cleanliness factor has the strongest influence on the model output. The cleanliness is followed (in this sequence) by the mirror reflectance, the glass tube transmittance, the receiver tube absorptance and, finally, by the receiver tube heat loss characteristic. 相似文献
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A 50-m2 experimental prototype of a solar parabolic trough plant has been realized and is at present functioning to produce industrial process heat in an Italian brewery. The prototype, which is of the long focus with a black body receiver, is used to carry out both static and dynamic experimental analyses of the cavity receiver itself and to determine a series of experimental parameters to be used in setting up mathematical models. These models simulate the plant performances under any working conditions with particular attention to the fluid-dynamic, hydraulic and heat transfer aspects. In the present paper the experimental results are presented and the theoretical results forecast by the computer model are outlined.The experimental performances of the cavity receiver, although working in not-optimum conditions, appear very promising being comparable to those obtainable from more expensive receivers. The elaboration of the experimental results suggests the way for technological improvements in the receiver construction. For example an annulus inside the blackbody receiver appears useful. Finally the computer outputs constitute useful design tools both to foresee the net power furnished by the plant and to optimize its physical parameters, for example the mass flow rate of the thermal vector fluid. 相似文献
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Control scheme for direct steam generation in parabolic troughs under recirculation operation mode 总被引:1,自引:0,他引:1
Electricity production using solar thermal energy is one of the main research areas at present in the field of renewable energies, these systems being characterised by the need of reliable control systems aimed at maintaining desired operating conditions in the face of changes in solar radiation, which is the main source of energy. A new prototype of solar system with parabolic trough collectors was implemented at the Plataforma Solar de Almería (PSA, South-East Spain) to investigate the direct steam generation process under real solar conditions in the parabolic solar collector field of a thermal power plant prototype. This paper presents details and some results of the application of a control scheme designed and tested for the recirculation operation mode, for which the main objective is to obtain steam at constant temperature and pressure at the outlet of the solar field, so that changes produced in the inlet water conditions and/or solar radiation will only affect the amount of steam produced by the solar field. The steam quality and consequently the nominal efficiency of the plant are thus maintained. 相似文献
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In order to reduce the cost and improve the efficiency of daylighting, an innovative parabolic trough solar lighting and thermal (PTL/T) system is designed and analyzed in this paper. Parabolic trough solar lighting and thermal system uses parabolic trough collector (PTC) controlled by two‐axis solar tracking system as solar collector. The collected sunlight is split by a cold mirror into visible light and infrared. The visible light is reflected by cold mirror, re‐concentrated by a second‐stage Fresnel lens, and then delivered by plastic optical fiber to the buildings for daylighting. The infrared goes through cold mirror, reaches thermal system, and is used for heating generation. The basic structure of PTL/T was outlined and described. The dimension of fiber bundle and parabolic trough was chosen after an optimal analysis. The cost of illuminating unit area was expressed as a function of illumination space dimensions and critical components efficiency. A case study was conducted to get a specific optimized illumination area and PTC area for the first time. The optimized result is to use 8‐m2 PTC as collector to illuminate 500‐m2 office space. The total solar energy utilization efficiency is 39.4%, with the lighting efficiency of 16.3% and thermal efficiency of 23.1%. The maximum energy savings and simple payback period were calculated for 10 typical cities when applied in residential, commercial, and industrial sectors. The amounts of greenhouse gas‐emission reductions were also calculated. The payback period in Sunbelt region is as low as less than 10 years like in Los Angeles. The results show the proposed PTL/T system is competitive compared with traditional solar energy systems. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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Evacuated CPC (compound parabolic concentrator) collectors with non-tracking reflectors are compared with two novel tracking collectors: a parabolic trough and an evacuated tube collector with integrated tracking reflector. Non-tracking low concentrating CPC collectors are mostly mounted in east–west direction with a latitude dependent slope angle. They are suitable at most for working temperatures up to 200–250 °C. We present a tracking evacuated tube-collector with a trough-like concentrating mirror. Single-axis tracking of the mirror is realized with a magnetic mechanism. The mirror is mounted inside the evacuated tube and hence protected from environmental influences. One axis tracking in combination with a small acceptance angle allows for higher concentration as compared to non-tracking concentrating collectors. Ray-tracing analysis shows a half acceptance angle of about 5.7° at geometrical concentration ratio of 3.2. Losses of well constructed evacuated tube collectors (heat conductivity through the manifolds inside the thermally insulated terminating housing are low) are dominated by radiation losses of the absorber. Hence, reducing the absorber size can lead to higher efficiencies at high operating temperature levels. With the presented collector we aim for operating temperatures up to 350 °C. At temperatures of 300 °C we expect with anti-reflective coating of the glass tube and a selective absorber coating efficiencies of 0.65. This allows for application in industrial process heat generation, high efficient solar cooling and power generation. A first prototype, equipped with a standard glass tube and a black paint absorber coating, was tested at ZAE Bayern. The optical efficiency was measured to be 0.71. This tube-collector is compared by ray-tracing with non-tracking market available tube-collectors with geometrical concentration ratios up to 1.1 and with a low cost parabolic trough collector of Industrial Solar Technology (IST) with an acceptance half angle about 1.5°, a geometrical concentration ratio of 14.4 and a measured optical efficiency of 0.69. 相似文献
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Y. T. Chen K. K. Chong C. S. Lim B. H. Lim K. K. Tan Omar Aliman T. P. Bligh B. K. Tan Ghazally Ismail 《Solar Energy》2002,72(6):531-544
Following the publication on the principle and theory of a newly proposed non-imaging focusing heliostat, this paper presents a report on the design, optical alignment and application of the first prototype heliostat. In the architecture of the first prototype, 25 mirrors, each with a dimension of 40×40 cm, are arranged into five rows and five columns to form a total reflective area of 4 m2. The design of the essential part of the first prototype heliostat will be discussed in this paper, which consists of two primary elements; a rotation–elevation system for tracking a mirror support frame which carries 25 mirror facets, and a separate two-axis tracking system for compensating (each second) off-axis aberrations of 24 slave facets relative to the central mirror, which is fixed in the mirror frame. The rotation–elevation system consists of a pedestal supporting a rotational tracking mechanism carrying a U-shaped arm and a second tracking system for tracking a moving frame in elevation. The moving frame carries a central stationary (relative to the frame) mirror, called a master mirror. Slave mirrors are arrayed in five rows and five columns, and eight stepper motors drive the outer four rows and columns relative to the master mirror via a computer programme implementing newly proposed formulas to eliminate the first-order aberration. With a second stage concentrator comprising a small aperture size parabolic mirror (diameter of 60 cm), a cost-effective high temperature solar furnace was constructed. In our experiment, the highest furnace temperature of 3400°C has been recorded through the melting of pure tungsten wires. 相似文献
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Steven C. Rogers Connor Barickman Greg Chavoor Matt Kinni Nik Glazar Peter V. Schwartz 《Solar Energy》2012,86(1):132-138
Using a combination of custom computer code and commercially available ray-tracing software, we explore variations of concentrator geometries where sunlight is first incident onto a stationary primary mirror of circular cross section. The reflected radiation is incident onto a smaller, secondary moveable mirror, which focuses the radiation onto a stationary target. Simulations for this trough geometry show peak concentrations of 38 solar equivalents. 相似文献
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The geometrical optical performance characteristics of a composite parabolic trough (CPT) with a fin receiver have been studied. The variation of geometrical concentration ratio with mirror element size and the rim angle of the parent parabola has been studied and the results are presented graphically. The distribution of local concentration ratio over the receiver plane has also been determined for some typical concentrator designs. 相似文献
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An algorithm for calculating the solar radiation flux on the receiving surface of a nontracking parabolic trough concentrator with a louvered heliostat is presented. Cylindrical geometry of the concentrator and shape and arrangement of mirror lamellae of the heliostat make it possible to consider sunlight passage across the mirror system of the module as a whole band, which significantly increases the computational efficiency of the algorithm proposed. 相似文献
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Alan Gallagher 《Solar Energy》2011,85(3):496-505
The design and operation of a large-area frying pan heated by solar radiation is described. A mirror below the pan directs the radiation to the pan bottom, which is coated with a low-emissivity black absorber. The mirror uses flat, hexagonal panels of aluminized-Mylar to provide uniform illumination across most of the pan bottom. The mirror mount allows 8 h/day operation with a single mirror-angle adjustment, plus a seasonal mounting adjustment for full-year use. A 0.46 m (18″) diameter pan and ∼1.2 m (48″) diameter mirror are used in the prototype, which is designed for cooking 0.42 m diameter slices of injera bread in East Africa. The prototype provides ∼640 W of heating power (60% efficiency compared to the full mirror area), and loses ∼100 W while cooking the bread. This allows for cooking ∼4 kg of bread per hour. The pan preheats to the 180 °C cooking temperature in 15-20 min. Materials and design are chosen for low-cost, and the prototype US-retail materials cost is ∼100 US$. The design is scalable to any desired pan size, with cost proportional to pan area. Most of the construction requires only hand tools, encouraging production in the country of use. 相似文献
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通过风洞实验对平屋顶槽式聚光器的镜面风压进行测量,通过高阶矩与风压时程曲线和概率密度直方图对镜面风压分布的概率特性进行了分析;得到镜面风压分布的高斯判别标准,并给出典型工况下的镜面高斯区域划分。然后通过Sadek-Simiu(SAD)法计算出聚光器的极值风压系数,给出典型工况下的极值风压系数等值线图,并对极值风压系数分布规律和特征进行分析,镜面风压极值最大值出现的主要区域为镜面边缘角落区域,极值风压系数最大值出现的工况为仰角30°风向角45°,其值为6.136。 相似文献
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In this work a feasibility study is carried out in order to investigate whether the installation of a parabolic trough solar thermal technology for power generation in the Mediterranean region is economically feasible. The case study takes into account the available solar potential for Cyprus, as well as all available data concerning current renewable energy sources policy of the Cyprus Government, including the relevant feed-in tariff. In order to identify the least cost feasible option for the installation of the parabolic trough solar thermal plant a parametric cost–benefit analysis is carried out by varying parameters, such as, parabolic trough solar thermal plant capacity, parabolic trough solar thermal capital investment, operating hours, carbon dioxide emission trading system price, etc. For all above cases the electricity unit cost or benefit before tax, as well as after tax cash flow, net present value, internal rate of return and payback period are calculated. The results indicate that under certain conditions such projects can be profitable. 相似文献
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依据槽形抛物镜-管簇结构腔体式吸收器太阳能集热器的热阻网络和建立的集热器效率优化模型,在单一改变太阳直射辐照度及同时改变腔体窗光学性能情况下,分别计算了工作介质温度Tfm,m的最优运行取值。 相似文献
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A solar concentrator with one-axis tracking is being developed at our institute. This concentrator system achieves a high geometrical concentration ratio of 300 using a parabolic trough mirror and a three-dimensional second stage consisting of compound parabolic concentrators. The design of the system as well as the characterisation of the second stage is described in this paper. 相似文献
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This paper presents an analytical study of a stationary plane mirror solar concentrator. It is composed of an array of East-West oriented trapezoidal channels with two sided reflecting walls and a tubular absorber as a receiver at the base. We have analysed and identified the most practical design parameters for a trough like concentrator. The one- and two-faceted plane side wall configurations with tubular receiver at the base of the trough have been studied in detail. It has been concluded that large savings in reflecting surfaces are possible while sacrificing some reduction in concentration. A theoretical prediction for the dependance of absorber efficiency on temperature has been obtained. 相似文献