A New Design of a (3D) Fresnel Collector With Fixed Mirrors and Tracking Absorber

2000 ◽  
Vol 122 (2) ◽  
pp. 63-68 ◽  
Author(s):  
A. B. Larbi
Keyword(s):  
Concentration Ratio ◽  
Focal Length ◽  
Computer Code ◽  
Design Parameters ◽  
Medium Temperature ◽  
Maintenance Costs ◽  
Energy Delivery ◽  
Half Angle ◽  
Optical Behavior ◽  
Fixed Mirrors

In this paper we developed model of a (3D) Fresnel collector with fixed mirrors and tracking absorber which approximates the optical behavior of a fixed spherical collector (hemispherical bowl). The aim of the study is to investigate the possibility of using this type of installation for applications in medium temperature processes (200—300°C). Via a computer simulation which includes ray-tracing, we evaluate the sensitivity of the geometric concentration ratio to: concentrator design parameters and the option of using curved versus flat elementary mirrors. The developed computer code permits the optimization of the concentrator reflecting area, the focal length (or rim half-angle), and the dimensions and number of reflecting elementary mirrors. The (3D) Fresnel collectors can be a practical alternative to spherical collectors (hemispherical bowl). Capital and maintenance costs can be significantly lower than for spherical collectors, but with reduced energy delivery. [S0199-6231(00)00302-6]

scholarly journals A New Approach for Design Optimization and Parametric Analysis of Symmetric Compound Parabolic Concentrator for Photovoltaic Applications

2021 ◽  
Vol 13 (9) ◽  
pp. 4606
Author(s):  
Faisal Masood ◽  
Perumal Nallagownden ◽  
Irraivan Elamvazuthi ◽  
Javed Akhter ◽  
Mohammad Azad Alam
Keyword(s):  
Parametric Analysis ◽  
Concentration Ratio ◽  
Synergistic Effects ◽  
Geometric Optimization ◽  
Design Parameters ◽  
Imaging Device ◽  
Compound Parabolic Concentrator ◽  
Photovoltaic Applications ◽  
Half Angle ◽  
The Impact

A compound parabolic concentrator (CPC) is a non-imaging device generally used in PV, thermal, or PV/thermal hybrid systems for the concentration of solar radiation on the target surface. This paper presents the geometric design, statistical modeling, parametric analysis, and geometric optimization of a two-dimensional low concentration symmetric compound parabolic concentrator for potential use in building-integrated and rooftop photovoltaic applications. The CPC was initially designed for a concentration ratio of “2×” and an acceptance half-angle of 30°. A MATLAB code was developed in house to provoke the CPC reflector’s profile. The height, aperture width, and concentration ratios were computed for different acceptance half-angles and receiver widths. The interdependence of optical concentration ratio and acceptance half-angle was demonstrated for a wide span of acceptance half-angles. The impact of the truncation ratio on the geometric parameters was investigated to identify the optimum truncation position. The profile of truncated CPC for different truncation positions was compared with full CPC. A detailed statistical analysis was performed to analyze the synergistic effects of independent design parameters on the responses using the response surface modeling approach. A set of optimized design parameters was obtained by establishing specified optimization criteria. A 50% truncated CPC with an acceptance half-angle of 21.58° and receiver width of 193.98 mm resulted in optimum geometric dimensions.

Parametric Analysis of the Fixed Mirror Solar Concentrator for Medium Temperature Applications

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Ramon Pujol-Nadal ◽  
Víctor Martínez-Moll ◽  
Andreu Moià-Pol
Keyword(s):  
Ray Tracing ◽  
Focal Length ◽  
Design Parameters ◽  
Solar Concentrator ◽  
Medium Temperature ◽  
Thermal Output ◽  
Optimal Values ◽  
Palma De Mallorca ◽  
Trans Asme ◽  
Optical Ray Tracing

The fixed mirror solar concentrator (FMSC) possesses a geometry that can produce thermal energy in medium temperature range. Due to its static reflector, the FMSC has several advantages when compared to other designs, such as being one of the best adapted for integration onto building roofs. An optical ray-tracing analysis of its geometry was presented in a previous paper (Pujol Nadal and Martínez Moll, 2012, “Optical Analysis of the Fixed Mirror Solar Concentrator by Forward Ray-Tracing Procedure,” Trans ASME J. Solar Energy Eng., 134(3), pp. 031009-1-14). The optical results were obtained in function of three design parameters: the number of mirrors N, the ratio of focal length and reflector width F/W, and the intercept factor γ (in order to represent different receiver widths). In this communication, the integrated thermal output of the same parameter combinations has been determined in order to find optimal values of the design parameters at a working temperature of 200 °C. The results were obtained for three different climates and two orientations (North-South and East-West). The results show that FMSC can produce heat at 200 °C with an annual thermal efficiency of 39, 44, and 48%, dependent of the location considered (Munich, Palma de Mallorca, and Cairo). The best FMSC geometries in function of the design parameters are exhibited for medium range applications.

Resolution Attainable With the Present Day STEM

1973 ◽  
Vol 31 ◽  
pp. 230-231 ◽  
Author(s):  
J. S. Wall ◽  
J. P. Langmore ◽  
H. Isaacson ◽  
A. V. Crewe
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Incident Beam ◽  
Scanning Transmission Electron Microscope ◽  
Aperture Size ◽  
Magnetic Lens ◽  
Peak Intensity ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Half Angle

The scanning transmission electron microscope (STEM) constructed by the authors employs a field emission gun and a 1.15 mm focal length magnetic lens to produce a probe on the specimen. The aperture size is chosen to allow one wavelength of spherical aberration at the edge of the objective aperture. Under these conditions the profile of the focused spot is expected to be similar to an Airy intensity distribution with the first zero at the same point but with a peak intensity 80 per cent of that which would be obtained If the lens had no aberration. This condition is attained when the half angle that the incident beam subtends at the specimen, 𝛂 = (4𝛌/Cs)¼

scholarly journals Monte Carlo Ray-Tracing Simulation of a Cassegrain Solar Concentrator Module for CPV

2021 ◽  
Vol 9 ◽  
Author(s):  
Seung Jin Oh ◽  
Hyungchan Kim ◽  
Youngsun Hong
Keyword(s):  
Monte Carlo ◽  
Ray Tracing ◽  
Concentration Ratio ◽  
Collection Efficiency ◽  
Focal Length ◽  
Tracking Error ◽  
Target Area ◽  
Solar Concentrator ◽  
Acceptance Angle ◽  
Energy Applications

The concentration ratio is one of the most important characteristics in designing a Cassegrain solar concentrator since it directly affects the performance of high-density solar energy applications such as concentrated photovoltaics (CPVs). In this study, solar concentrator modules that have different configurations were proposed and their performances were compared by means of a Monte Carlo ray-tracing algorithm to identify the optimal configurations. The first solar concentrator design includes a primary parabolic concentrator, a parabolic secondary reflector, and a homogenizer. The second design, on the other hand, includes a parabolic primary concentrator, a secondary hyperbolic concentrator, and a homogenizer. Two different reflectance were applied to find the ideal concentration ratio and the actual concentration ratio. In addition, uniform rays and solar rays also were compared to estimate their efficiency. Results revealed that both modules show identical concentration ratios of 610 when the tracking error is not considered. However, the concentration ratio of the first design rapidly drops when the sun tracking error overshoots even 0.1°, whereas the concentration ratio of the second design remained constant within the range of the 0.8° tracking error. It was concluded that a paraboloidal reflector is not appropriate for the second mirror in a Cassegrain concentrator due to its low acceptance angle. The maximum collection efficiency was achieved when the f-number is smaller and the rim angle is bigger and when the secondary reflector is in a hyperboloid shape. The target area has to be rather bigger with a shorter focal length for the secondary reflector to obtain a wider acceptance angle.

Plasma channel formation in the knife-like focus of laser beam

2020 ◽  
Vol 86 (3) ◽  
Author(s):  
O. G. Olkhovskaya ◽  
G. A. Bagdasarov ◽  
N. A. Bobrova ◽  
V. A. Gasilov ◽  
L. V. N. Goncalves ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Laser Beam ◽  
Plasma Channel ◽  
Focal Length ◽  
Computer Code ◽  
Nanosecond Laser Pulse ◽  
Nanosecond Laser ◽  
Channel Formation ◽  
Azimuthal Symmetry ◽  
Sufficient Degree

The plasma channel formation in the focus of a knife-like nanosecond laser pulse irradiating a gas target is studied theoretically, and in gas-dynamics computer simulations. The distribution of the electromagnetic field in the focus region, obtained analytically, is used to calculate the energy deposition in the plasma, which then is implemented in the magnetohydrodynamic computer code. The modelling of the channel evolution shows that the plasma profile, which can guide the laser pulse, is formed by the tightly focused short knife-like lasers. The results of the simulations show that a proper choice of the convergence angle of a knife-like laser beam (determined by the focal length of the last cylindrical lens), and laser pulse duration may provide a sufficient degree of azimuthal symmetry of the formed plasma channel.

scholarly journals Optical modeling of a solar dish thermal concentrator based on square flat facets

2014 ◽  
Vol 18 (3) ◽  
pp. 989-998 ◽  
Author(s):  
Sasa Pavlovic ◽  
Velimir Stefanovic ◽  
Suad Suljkovic
Keyword(s):  
Ray Tracing ◽  
Focal Length ◽  
Performance Model ◽  
Thermal Processes ◽  
Medium Temperature ◽  
Optical Modeling ◽  
Radiative Power ◽  
Temperature Levels ◽  
Reflecting Surface ◽  
Optical Ray Tracing

Solar energy may be practically utilized directly through transformation into heat, electrical or chemical energy. We present a procedure to design a square facet concentrator for laboratory-scale research on medium-temperature thermal processes. The efficient conversion of solar radiation into heat at these temperature levels requires the use of concentrating solar collectors. Large concentrating dishes generally have a reflecting surface made up of a number of individual mirror panels (facets). Optical ray tracing is used to generate a system performance model. A square facet parabolic solar concentrator with realistic specularly surface and facet positioning accuracy will deliver up to 13.604 kW of radiative power over a 250 mm radius disk (receiver diameter) located in the focal plane on the focal length of 1500mmwith average concentrating ratio exceeding 1200. The Monte Carlo ray tracing method is used for analysis of the optical performance of the concentrator and to identify the set of geometric concentrator parameters that allow for flux characteristics suitable for medium and high-temperature applications.

Study on Load-Bearing Mechanism of Stabilizing Pile-Groups by FEM and its Application

2014 ◽  
Vol 638-640 ◽  
pp. 656-670
Author(s):  
Huan Feng Qiu ◽  
Shao Jun Fu
Keyword(s):  
Computer Code ◽  
Soil Mass ◽  
Design Parameters ◽  
Pile Groups ◽  
Soil Pressure ◽  
Soil Arching ◽  
Fine Grained ◽  
Arching Effect ◽  
Soil Arching Effect ◽  
Pile Diameter

The behaviour of pile-groups subjected to lateral soil pressure is a key consideration in establishing the design parameters of pile-groups. In this paper, one representative section of the Chongqing Jiangdong slope is taken as an example. The existence of an arching zone around pile groups for granular and fine-grained soils is first examined using the finite element computer code CORE-3D. Pile load-displacement curves and the arching effect are considered together to explain how the stresses are transferred from the soil to the piles. The key parameters controlling the soil arching effect are centre-to-centre pile spacing (S), thickness of stable soil mass (H), depth (L) of pile embedment, pile diameter (D) and these were studied extensively. An empirical equation summarising the results is presented and the results have been adopted by the designer in practice.

Analytical Methods to Evaluate Flux Distributions From Point-Focus Collectors for Solar Furnace and Dish Engine Applications

2010 ◽  
Author(s):  
Clifford K. Ho ◽  
Siri S. Khalsa ◽  
Nathan P. Siegel
Keyword(s):  
Analytical Methods ◽  
Maximum Concentration ◽  
Concentration Ratio ◽  
Flux Distribution ◽  
Focal Length ◽  
Solar Furnace ◽  
Analytical Function

This paper introduces a new analytical “stretch” function that accurately predicts the flux distribution from on-axis point-focus collectors. Different dish sizes and slope errors can be assessed using this analytical function with a ratio of the focal length to collector diameter fixed at 0.6 to yield the maximum concentration ratio. Results are compared to data, and the stretch function is shown to provide more accurate flux distributions than other analytical methods employing cone optics.

Nonlinear Frequency Responses of Functionally Graded Carbon Nanotube-Reinforced Sandwich Curved Panel Under Uniform Temperature Field

2018 ◽  
Vol 10 (03) ◽  
pp. 1850028 ◽  
Author(s):  
Kulmani Mehar ◽  
Subrata Kumar Panda ◽  
Trupti Ranjan Mahapatra
Keyword(s):  
Finite Element ◽  
Carbon Nanotube ◽  
Sandwich Panel ◽  
Weak Form ◽  
Computer Code ◽  
Functionally Graded ◽  
Design Parameters ◽  
Nonlinear Frequency ◽  
Uniform Temperature ◽  
Benchmark Solutions

The higher-order kinematic theory in conjunction with Green–Lagrange strain field has been incorporated to compute the nonlinear frequency parameter of the curved (single/doubly) graded (functionally) sandwich panel structure numerically via finite element technique. The current sandwich panel model is derived assuming the functionally graded carbon nanotube face sheets and isotropic (epoxy) core. The current mathematical model is generic in nature, i.e., the grading configurations of the face sheets and sandwich construction including the different geometrical shapes can be achieved easily. The governing equation of the sandwich structure is obtained and the subsequent weak form derived with the help of the isoparametric finite element method. The nonlinear solutions are computed via an original computer code using a robust numerical method (direct iterative method). The consistency and the accuracy of the current finite element solutions are established by executing different types of numerical examples. Also, the concurrence of current numerical solution is established by comparing the results with the available benchmark solutions. Finally, the effect of various design parameters on the nonlinear natural frequency values have been computed under the uniform temperature environment and the inferences provided in detail.

Design of Fresnel Lens With Constant Height Spherical Facets

2020 ◽  
Author(s):  
Kuldeep Awasthi ◽  
Desireddy Shashidhar Reddy ◽  
Mohd. Kaleem Khan
Keyword(s):  
Ray Tracing ◽  
Concentration Ratio ◽  
Focal Length ◽  
Constant Width ◽  
Fresnel Lens ◽  
Aperture Diameter ◽  
Constant Height ◽  
Proposed Model ◽  
Fresnel Lenses ◽  
Ray Tracing Model

Abstract In the present work, a ray tracing model based on Snell’s law of refraction is developed using MATLAB for the design of Fresnel lens with spherical facets of equal height. In practice, the facet curvature is approximated by straight line, which causes an increase in spherical aberrations and reduction in concentration ratio. The proposed model takes facet curvature into consideration, which will result in effective utilization of incident solar radiations. Fresnel lenses are available with facets having constant width and facets with constant height. A comparison of spherical aberrations in the two cases has also been presented using different f - numbers (ratio of focal length to aperture diameter). Effect of different parameters like number of facets and refractive index of lens material on concentration ratio is also presented in present study. The proposed ray tracing model is validated with the model developed in SolTrace, an open access software. The predictions from the proposed model are in good agreement with the results of SolTrace model with an average deviations of 6.8% for concentration ratio and 2.2% for focal length.

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