Fiber Optic Daylighting System using Parabolic Trough

Objective

The main purpose of this research is to achieve uniform light into the optical fibers and to deliver it to large-scale building interiors. Consequently, a novel approach is proposed for the parabolic trough. Sunlight is concentrated and focused toward the parabolic reflector, and then collimated light is transmitted toward the trough compound parabolic concentrator (CPC). Previously, it was not possible to achieve high concentration through the parabolic trough for the optical fibers. We introduce the trough CPC to solve the issue of high concentration for the optical fibers. After the trough CPC, a linear array of optical fibers is positioned. To make the system cost effective, POFs were used for most of the transmission. They are very sensitive to heat. Therefore, we used silica optical fibers (SOFs) before the POFs to reduce the heat problem. The proposed system is advantageous because it is expandable, whilst only requiring one tracking module. It can be expanded by increasing the rectangular aperture height and width of the parabolic trough. If the rectangular aperture height is increased, optical fiber arrays will be increased. In the same way, more fibers can be added in the single array by increasing the rectangular aperture width. Therefore, the required design can be easily created to satisfy the necessary illumination for a specific area.

Parabolic trough based solar lighting system

Method

A parabolic trough captured sunlight and directed the light toward a parabolic reflector, which illuminated the optical fibers with collimated illumination. Here, the main issue was to achieve a very high concentration, which was very difficult. In this approach, sunlight must be focused from a large concentrator onto a small parabolic reflector. To demonstrate the system, perfect alignment, and a high concentration was necessary. Thus, there is a need to solve the high-concentration issue to use the concentrator for the optical fibers.

Previously, the parabolic trough was not introduced in daylighting systems due to the issues described above. To solve the issue of high concentration, the trough CPC, which is a well-known, non-imaging optical element, was introduced upstream of the optical fibers. The trough CPC captured collimated light and then maximum sunlight was diverted into the optical fibers. For the parabolic trough, collimated light entered into the trough CPC through the parabolic trough and then light entered into the optical fibers, as shown in the following Figures. Perfect alignment of the components was achieved to produce better results for both approaches.

Daylighting system using parabolic trough without trough CPC Daylighting system using parabolic trough with trough CPC

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