Experimental Research Of Transparent Solid Daylighting System With Total Reflection

With the development of solar daylighting technology, its application prospect is broader and broader. A lighting system that is low cost, easy operation, high efficiency has become a focus of concern for domestic and overseas researchers. In order to fit rapid development of social economy, it is significant to develop a daylighting system with independent intellectual property rights which is suitable for the situation of our country.This article summarizes research achievement of light pipe and optical fiber at home and abroad. At the enlightenment of comparing advantages and disadvantages of two types of traditional lighting technologies, a daylighting system with total reflection is designed. And its design principle, parameter, characteristics, and the structure are introduced. The concentrator transmits light by virtue of total reflection of light. According to design parameter, a computer model of the concentrator is built and then optically simulated in optical software TracePro. The feasibility of concentrator has initially been confirmed. After necessary correction of its parameters on the basis of simulating result, a transparent solid concentrator is manufactured. With the concentrator as the core parts a daylighting system is formed and tested under two working conditions. The first condition is tracking. The test device is consist of a concentrator with area of 3.38×10-3m2, a plastic optical fiber with its length of 2.5m, and its diameter is 1.2×10-2m, and a integrating sphere whose diameter is 0.3 m. When the solar irradiance is 930 W /m2, the maximum illuminance inside the integrating sphere is 476 lx. The second condition is non-tracking. The elevation of the concentrator is 42° and its azimuth is directly south. The test device includes two concentrators. Their corresponding fiber’s final ends are inserted side by side into a darkroom whose size is 1.2×1.2×1.8m3. The detector of the illuminance meter is located at a distance 0.4m from the ends of the fibers. The illuminance meter shows that the maximum illuminance is 561.8 lx while the solar irradiance is 747.3W/m2. When the distance is 0.6 m, the illuminance is 1661x with the irradiance of 703.4 W/m2. In the distance of 1m the illuminance reaches 63.641x with a irradiance of 716.3W/m2.The illuminance is still 52.9 percent of the most value while the sun light deviate from the normal of concentrator by ±3°. Experimental investigations show that the new day lighting system is characterized by high brightness, large degree of tolerance in tracking, simple construction. It is hopeful to become a kind of fixed lighting system with optical fiber.