A Study of Transmission and Illumination of Light through Rectangular Light Pipes with Bends

Author(s): Supachart, W., Taengchum, T., Chirarattananon, S., Rakwamsuk, P. & Chaiwiwatworakul, P.

Publication date: 19th-21st November 2014

Publication type: Conference Proceedings

Journal: 5th International Conference on Sustainable Energy and Environment

Abstract:  Light pipes can bring daylight from the sky into deep interior spaces of a building. A pipe is often connected with a bend so as to orient the entry port in the direction that optimizes light reception and transmission. Another bend is connected before the exit port to optimize delivery of light into a room. This paper presents results of modeling, experiments, and simulation of transmission of beam and diffuse daylight through rectangular light pipes. Analytic method is used for tracing light rays from the source into the bend through to the straight section and through to the bend and then the exit port into the room, or forward raytracing method. The curve surface of the bend is modeled as a pie bend section. The interior surface of each section is specular but may have different reflectances. The algorithms of calculation are coded in MATLAB scripts and functions. The interior surfaces of the rectangular light pipe and bends are lined with a film of reflectance of 99%. A set of experiments was conducted indoor using an LED lamp as a point source. Results of calculation using the method match closely with those from experiments.

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