A study on use of three-dimensional miniature dielectric compound parabolic concentrator (3D dCPC) for daylighting control application

Low-concentration solid dielectric parabolic concentrator (dCPC) is regarded as a high-potential design in daylighting control and energy saving in lighting system. The incident light could penetrate the lateral surfaces of dCPC as its incident angle is beyond the acceptance angle of dCPC, by which dCPC will control the amount of daylighting coming into the room according to the sun position. The light within the incident angle will be concentrate to the bottom of dCPC. This study is a further research based on the evaluation of two-dimensional (2D) dCPC, which aims to investigate the advantages of three-dimensional (3D) miniature solid dCPC comparing with 2D dCPC based on their daylight transmittance values under sunny sky. An optical analysis software Photopia is used to simulate the daylighting control performance of different types of concentrators. The performances of concentrators in Nottingham, UK (53° N, 1.2° W) are put forward as a case study. It is demonstrated that 3D dCPC has great advantages than 2D dCPC in control daylight, which performs higher transmittance in the morning and afternoon and lower transmittance at noon. Then, two types of 3D dCPC are compared for its tolerance on horizontal rotation angle. One has polygonal apertures with 4 sides (3D s-dCPC), and the other is revolved 3D dCPC (3D r-dCPC). Each dCPC has two different structures, which are with non-reflective material affixing on base and without base coating. Results show that the 3D non-coated r-dCPC may be the best choice in application with the advantages of installation, more stable illuminance level it provides and lower cost in manufacture.