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Illumination of dense urban areas by light redirecting panels

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With the high population growth rate, especially in developing countries, and the scarcity of land resources, buildings are becoming so close to each other, depriving the lower floors and the alleys from sunlight and consequently causing health problems. Therefore, there is an urgent need for cost-effective efficient light redirecting panels that guide sun rays into those dim places. In this paper, we address this problem. A novel sine wave based panel is presented to redirect/diverge light downward and enhance the illumination level in those dark places. Simulation results show that the proposed panel improves the illuminance values by more than 200% and 400% in autumn and winter respectively, operates over wide solar altitude ranges, and redirects light efficiently. Experimental and simulation results are in good agreement.

© 2014 Optical Society of America

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Figures (21)

Fig. 1
Fig. 1 Dim light wells and streets in dense urban areas (a) real case in Egypt (b) model to be simulated.
Fig. 2
Fig. 2 Proposed structure.
Fig. 3
Fig. 3 (a) Slope variation across period. (b) Amplitude variation. (c) Period variation.
Fig. 4
Fig. 4 Results from GeoGebra for 72° solar altitude. Refractive index n = 1.49.
Fig. 5
Fig. 5 Ray path when subjected to tilted panel.
Fig. 6
Fig. 6 The blockage effect for solar altitude 42° that is not considered in GeoGebra model.
Fig. 7
Fig. 7 Simulation methodology.
Fig. 8
Fig. 8 Ray tracing simulations showing the effect of: (a) total internal reflections (b) blockage of neighboring sine periods.
Fig. 9
Fig. 9 Simulation results for 1:4 amplitude to period ratio at 0° tilt for incident angles ranging from 10° to 90°.
Fig. 10
Fig. 10 Transmitted power percentage, maximum and minimum emergence angles versus incident angles for different design ratios (a) 2:1, (b) 1:1, (c) 1:2, (d) 1:4, (e) 1:8, and (f) isosceles (80°, 80°, 20°).
Fig. 11
Fig. 11 Panel performance after considering the tilt angle, design ratio is 1:4. (a) 10° tilt angle (b) 20° tilt angle.
Fig. 12
Fig. 12 Integrated transmitted power percentage for different designs.
Fig. 13
Fig. 13 Normalized power density versus displacement for different design ratios.
Fig. 14
Fig. 14 Integrated transmitted power percentage for different designs after considering the uniformity condition.
Fig. 15
Fig. 15 Illuminance with and without the proposed panel at two timings: (a) Autumn, (b) Winter.
Fig. 16
Fig. 16 Isolux at the ground with and without the proposed panel at two timings: (a) Autumn, b) Winter.
Fig. 17
Fig. 17 The die used in manufacturing. Mould material is chromated tool steel. Dimensions are in (mm).
Fig. 18
Fig. 18 Picture of the fabricated sample.
Fig. 19
Fig. 19 (a) Experimental test setup. (b) Output light from the 1:4 sample with 0° tilt and 90° incident angle.
Fig. 20
Fig. 20 Comparison between simulated and measured emerging angles.
Fig. 21
Fig. 21 Well prototype with and without panel, dimensions are 40cm × 40 cm × 120 cm. a) Without panel, b) with panel θtilt = 10°, c) maximum illumination can be achieved inside the well.

Tables (2)

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Table 1 Transmitted Power Percentage Integrated over Solar Altitude Range 10° to 80° for Different Designing Ratios and Different Tilt Angles

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Table 2 Average Illuminance Enhancement at the Ground before and after Using the Panel

Equations (4)

Equations on this page are rendered with MathJax. Learn more.

n 1 sin θ 1 = n 2 sin θ 2
θ max θ tilt + 90
θ min θ tilt
θ in =SA+ θ tilt


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