<title>Linear Echelon Refractor/Reflector Solar Concentrators</title>

Abstract

This paper describes some new configurations for linear incremental or Fresnel refractors and reflectors for solar energy concentration. The first system, a reflex type lens, uses crossed linear echelon elements and has convergence power in two dimensions. This refractor /reflector concentrates solar radiation to a spot focus. Large area solar concentrators can be sectionally constructed to provide high power solar flux concentration. The second type of echelon reflector forms a linear focus of incident solar radiation. The reflector is selectively tilted with respect to incoming solar radiation, such that the design eliminates all riser step blockage of radiation at the reflecting echelons. This results in a higher efficiency concentrator than is achievable with a normally oriented linear focus concentrator. Design parameters and a ray trace analysis are presented for both concentrator systems. SOLAR RAY SPOT FOCUS SPIE Vol. 161 Optics Applied to Solar Energy IV (1.978) / 23Abstract This paper describes some new configurations for linear incremental or Fresnel refractors and reflectors for solar energy concentration. The first system, a reflex type lens, uses crossed linear echelon elements and has convergence power in two dimensions. This refractor/reflector concentrates solar radiation to a spot focus. Large area solar concentrators can be sectionally constructed to provide high power solar flux concentration. The second type of echelon reflector forms a linear focus of incident solar radiation. The reflector is selectively tilted with respect to incoming solar radiation, such that the design eliminates all riser step blockage of radiation at the reflecting echelons. This results in a higher efficiency concentrator than is achievable with a normally oriented linear focus concentrator. Design parameters and a ray trace analysis are presented for both concentrator systems.

Design and fabrication of aspheric Fresnel-type lenses for solar energy by using a 3D printer

“…In particular, the nonimaging Fresnel lenses are designed with the objective of concentrating light rather than forming an image, in addition to maximize the amount (energy) and quality (flux uniformity) of solar radiation, see for example the references. [1][2][3][4][5][6][7][8][9][10] An Aspheric Fresnel-type lens (for short AFL) consists of a series of adjacent microprisms designed to vary the angle of refraction by programming the angles of the flat surfaces of each of the prisms, either to collimate or focus incident light. 11,12 AFL have important properties since they reduce the thickness of the lens and less material is used in its construction producing lighter designs.…”

Design and fabrication of an off-axis Fresnel-type reflector by using 3D printing

“…[4][5][6][7] In fashionable design, the most common Fresnel-type surfaces are flat optical devices that can be calculated by implementing geometrical optics and adding the principles of nonimaging design. [8][9][10][11][12] In view of the above, we propose in this work a procedure to divide an off-axis conic surface, analogous to those we have proposed for other types of surfaces, [13][14][15][16] in order to analytically obtain the parametric equation, which will describe an off-axis Fresnel-type reflector with finite groove width and constant groove depth, 17 in such a way that this representation allows us to implement an exact ray trace considering a plane wavefront incident. In other words, we provide an analytical function to represent the grooves of the Fresnel's surface, to reflect an incoming beam of rays from each echelon, which can be propagated towards a predetermined area of the light collector.…”

Design and fabrication of a linear Fresnel-type reflector for solar concentration based on caustic surfaces by reflection

“…In this work we will implement this knowledge for the design of the classical type of LFR which considers exclusively a single linear absorber. [5][6][7][8][9] Traditionally, the nature of the mathematics used in the design of Fresnel systems sometimes does not allow to provide an analytical formulation to describe the reflecting surface. Therefore, numerical solutions may be called for.…”