Design of Fresnel Lens With Constant Height Spherical Facets

ASME 2020 14th International Conference on Energy Sustainability ◽

10.1115/es2020-1652 ◽

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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A Novel High Concentration Fresnel Lens as a Solar Concentrator

Journal of Solar Energy Engineering ◽

10.1115/1.4051975 ◽

2021 ◽

pp. 1-29

Author(s):

Kuldeep Awasthi ◽

Desireddy Shashidhar Reddy ◽

Mohd. Kaleem Khan

Keyword(s):

Optical Axis ◽

Spherical Aberration ◽

Spherical Surface ◽

Fresnel Lens ◽

High Concentration ◽

Aperture Diameter ◽

Convex Lens ◽

Flat Base ◽

Fresnel Lenses ◽

Outer Vertex

Abstract This paper describes the design methodology for a novel Fresnel lens. The original Fresnel lens is obtained from a plano-convex lens, whose spherical surface is split into a number of divisions (called facets), collapsed onto the flat base. Thus, all the facets of the original Fresnel lens have the same radius as that of the plano-convex lens. The proposed design aims to achieve better ray concentration and reduced spherical aberration than the original Fresnel lens by constructing spherical facets with unequal radii. The centers and radii of facets are constrained so that the ray refracted from the bottom vertex of each facet on one side of the optical axis and the ray refracted from the outer vertex of the corresponding facet on the other side of the optical axis must intersect at the focal plane. The proposed lens design has resulted in a 275% gain in the concentration ratio and a 72.5% reduction in the spherical aberration compared to the original lens of the same aperture diameter and number of facets. The performance of both novel and original Fresnel lenses when used as solar concentrators with a conical coil receiver is evaluated. The novel Fresnel lens led to increased heat gain and resulted in a compact solar collector design.

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

Frontiers in Energy Research ◽

10.3389/fenrg.2021.722842 ◽

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.

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A Hybrid Deterministic-Stochastic Propagation Model for Short-Range MIMO-UWB Communication Systems

Frequenz ◽

10.1515/freq-2012-0039 ◽

2012 ◽

Vol 66 (7-8) ◽

Author(s):

Malgorzata Janson ◽

Juan Pontes ◽

Thomas Fügen ◽

Thomas Zwick

Keyword(s):

Ray Tracing ◽

Communication Systems ◽

Short Range ◽

Direction Selectivity ◽

Propagation Model ◽

Ultra Wideband ◽

Frequency Range ◽

Channel Characteristics ◽

Proposed Model ◽

Ray Tracing Model

AbstractThis paper presents a computationally effective approach for including dense multipath components in ray tracing simulations of ultra wideband (UWB) channels. Through a combination of a standard ray tracing model with a simple geometric-stochastic model realistic scenario-specific simulations are possible. The frequency and direction selectivity of the channel are reproduced accurately by the model. The structure and parameters of the stochastic part of the model are derived from measurements in the FCC-UWB frequency range. Compared to conventional ray tracing simulations the proposed model reduces considerably the differences between simulated and measured channel characteristics.

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Two Types of Calorimeters for Assessing Fresnel Lens Performance in Concentrating Solar Systems

ASME 2011 5th International Conference on Energy Sustainability, Parts A, B, and C ◽

10.1115/es2011-54166 ◽

2011 ◽

Cited By ~ 1

Author(s):

Aaron Sahm ◽

Robert Boehm ◽

Kwame Agyenim-Boateng ◽

Ken Hynes ◽

Kim Hammer ◽

...

Keyword(s):

Steady State ◽

Temperature Rise ◽

Focal Point ◽

Focal Length ◽

Fresnel Lens ◽

Lumped Mass ◽

Optical Efficiency ◽

Concentration Process ◽

Mass Approximation ◽

Fresnel Lenses

Concentrating solar energy systems can use either refractive or reflective approaches to achieve the desired concentration ratio. However this is done, there is always a question about what the flux might actually be incident on the target of interest after the concentration process. Assessing the losses due to the concentration process is quite important in understanding the overall performance of the solar concentrating system. An issue that impacts this measurement is the type of system being evaluated, as the total flux at the focal point could be quite large. We have been working with concentrating PV units that utilize acrylic Fresnel lenses to achieve the necessary concentration on a single multi-junction cell. The magnitude of the losses associated with these types of lenses was desired. We developed two calorimeters for the purpose of evaluating the optical efficiency of Fresnel lenses utilized in various point focus concentrating systems. The first calorimeter developed utilizes a transient technique whereby a time-measured pulse of the beam is directed to a mass of material in a cavity form. The material has a high conductivity, so the lumped mass approximation can be used for the analysis of the energy absorbed if the temperature rise of the material is measured. The other calorimeter developed was a steady-state type that employs a technique commonly known as flow calorimetry. In this approach, the concentrated flux is beamed into the core of the calorimeter which is cooled to some steady-state value of temperature with a liquid (water near the ambient temperature was used in our tests). Knowing the liquid flow rate and temperature rise of the fluid allows the total heat input to be assessed. This paper discusses the development, testing, and comparison of the two calorimeters. Results are given for the evaluation of several types of commercial acrylic Fresnel lenses having different characteristics such as groove density and focal length.

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К 125-летию со дня рождения лауреата Нобелевской премии академика Николая Николаевича Семенова Высокоэффективные фотоэлектрические модули с концентраторами солнечного излучения

Журнал технической физики ◽

10.21883/jtf.2021.06.50859.314-20 ◽

2021 ◽

Vol 91 (6) ◽

pp. 913

Author(s):

А.В. Чекалин ◽

А.В. Андреева ◽

Н.Ю. Давидюк ◽

Н.С. Потапович ◽

Н.А. Садчиков ◽

...

Keyword(s):

Solar Cells ◽

Research And Development ◽

Thermal Regime ◽

Solar Irradiance ◽

Concentration Ratio ◽

Fresnel Lens ◽

Photovoltaic Modules ◽

Module Design ◽

Multijunction Solar Cells ◽

Fresnel Lenses

The paper outlines the results of research and development of solar concentrated photovoltaic modules with an aperture area of 0.5 m^2. Module design was based on Fresnel lenses with inverted pyramids as secondary concentrators of solar irradiance, and multijunction solar cells located in the focus of Fresnel lens. The developed modules are characterized with up to 700X solar concentration ratio and optimal operational thermal regime for solar cells. The efficiency of developed photovoltaic modules exceeds 32% which makes them on par with modules of the similar design developed and manufactured globally.

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