scholarly journals Study on the Optical Properties of the Point-Focus Fresnel System

2021 ◽  
Vol 13 (18) ◽  
pp. 10367
Author(s):  
Fei Shen ◽  
Weidong Huang
Keyword(s):  
Density Distribution ◽  
Flux Density ◽  
Optical System ◽  
Focal Length ◽  
Optical Design ◽  
Solar Flux ◽  
Characteristic Analysis ◽  
Design And Optimization ◽  
Receiver Plane ◽  
Flux Density Distribution

The characteristic analysis of the flux formed by the heliostat in the optical system is the basis in design and optimization of the whole system. In this paper, our research subject is a pilot installation of the point-focus Fresnel system, which is a new optical design between the tower system and the dish system. For the optical system, it is very important to accurately calculate the solar flux density distribution on the receiver plane. Aiming at the case that the focal length of the heliostat is not equal to the distance from the center of the heliostat to the center of the receiver plane, based on the projection, an approximate calculation method is proposed. Using the method to calculate the solar flux density distribution of the point-focus Fresnel system, and the results are compared with that calculated by SolTrace code, it is found that the solar flux density distribution of both is relatively consistent in shape and numerical value, which verifies the accuracy of the method and it can be used for design and optimization of the point-focus Fresnel system.

Flux Density Distribution in the Focal Region of a Solar Concentrator System

1991 ◽  
Vol 113 (2) ◽  
pp. 112-116 ◽  
Author(s):  
M. Schubnell ◽  
J. Keller ◽  
A. Imhof
Keyword(s):  
Density Distribution ◽  
Flux Density ◽  
Ray Tracing ◽  
Radiation Flux ◽  
Focal Length ◽  
Solar Furnace ◽  
Focal Region ◽  
The Sun ◽  
Parabolic Dish ◽  
Flux Density Distribution

In high temperature solar energy applications highly concentrating optical systems, such as, e.g., parabolic dishes, achieve typical radiation flux densities >2 MW/m2. In order to investigate thermo and photochemical reactions at temperatures >1500 K and radiation flux densities >2 MW/m2 a solar furnace was built at Paul Scherrer Institute (PSI). This furnace is a two-stage concentrator. The first stage is a prefocusing glass heliostat with a focal length of 100 m. The second stage is a highly concentrating parabolic dish with a focal length of 1.93 m. To design experiments to be carried out in the focal region of the parabolic dish, the radiation flux as well as its density distribution have to be known. This distribution is usually measured by radiometric methods. However, these methods are generally rather troublesome because of the high temperatures involved. In this paper we present a simple method to estimate the characteristic features of the radiation flux density distribution in the focal region of a concentrator system. It is well known from solar eclipses that the mean angular diameter of the moon is almost equal to that of the sun (9.1 mrad versus 9.3 mrad). Hence, the lunar disk is well suited to be used as a light source to investigate the flux distribution in a solar furnace. Compared to the sun the flux density is reduced by 4·105 and the flux density distribution can be inspected on a sheet of paper located in the plane of interest, e.g., the focal plane. This distribution was photographed and analyzed by means of an image processing system. The density distribution was also simulated using a Monte Carlo ray tracing program. Based on this comparison, and on further ray tracing computations, we show that the peak flux density decreases from 8.9 MW/m2 in December to values below 4 MW/m2 in June and the net radiation flux from 25 kW to 15 kW, respectively.

Solar Flux-Density Distribution due to Partially Shaded/Blocked Mirrors Using the Separation of Variables/Superposition Technique With Polynomial and Gaussian Sunshapes

1996 ◽  
Vol 118 (2) ◽  
pp. 107-114 ◽  
Author(s):  
M. Elsayed ◽  
K. A. Fathalah
Keyword(s):  
Density Distribution ◽  
Flux Density ◽  
Numerical Technique ◽  
Separation Of Variables ◽  
Numerical Procedure ◽  
Solar Flux ◽  
Partial Shading ◽  
Basic Flux ◽  
Superposition Technique ◽  
Flux Density Distribution

In a previous work (El Sayed et al., 1994), the separation of a variable/superposition technique was used to predict the flux density distribution on the receiver surfaces of solar central receiver plants. In this paper further developments of the technique are given. A numerical technique is derived to carry out the convolution of the sunshape and error density functions. Also, a simplified numerical procedure is presented to determine the basic flux density function on which the technique depends. The technique is used to predict the receiver solar flux distribution using two sunshapes, polynomial and Gaussian distributions. The results predicted with the technique are validated by comparison with experimental results from mirrors both with and without partial shading/blocking of their surfaces.

Measurements of solar flux density distribution on a plane receiver due to a flat heliostat

Solar Energy ◽  
1995 ◽  
Vol 54 (6) ◽  
pp. 403-411 ◽  
Author(s):  
Moustafa M. Elsayed ◽  
Kadry A. Fathalah ◽  
Omar M. Al-Rabghi
Keyword(s):  
Density Distribution ◽  
Flux Density ◽  
Solar Flux ◽  
Flux Density Distribution
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