Mean wavelength-based Fresnel lens solar collector for eliminating the hotpot problem in daylighting systems

In this paper, the mean-wavelength-based Fresnel lens was designed by merging the modified edge ray principle and idea of superposition. The bottom-to-top approach optimizes the design of individual prisms according to the predetermined plastic optical fiber (POF) bundle size. The simulated optical efficiency of the collector for the sun's visible spectrum (380-740 nm) light is 82.93% with a uniformity ratio of 0.434. Based on the designed collector, the daylighting system can deliver 199.38 lumens via a 10 m long POF bundle with an efficiency of 23.78%. The thermal analysis revealed that the maximum temperature on the focus plane was 49.7°C.