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Journal ArticleDOI

Illuminance Degradation of LED Streetlighting Luminaires in a Hot Environment

16 Sep 2013-Leukos (Taylor & Francis)-Vol. 9, Iss: 3, pp 201-216
TL;DR: In this article, two LED streetlighting luminaires were installed in the city of Al-Ain, United Arab Emirates, one of the hottest regions in the world, and the street was closed to traffic and illuminance measurements were taken daily every 10 minutes for 300 days including the summer of 2010.
Abstract: Two LED streetlighting luminaires were installed in the city of Al-Ain, United Arab Emirates, one of the hottest regions in the world. The street was closed to traffic and illuminance measurements were taken daily every 10 minutes for 300 days including the summer of 2010. Temperature and relative humidity values were acquired inside the driver compartment of the luminaires and outside of the luminaires. This paper reports the illuminance levels, temperature, and relative humidity data. Illuminance did not change by more than 12 percent throughout the test period. The drop in illuminance was 4.5 percent per 10 degree C for the ambient temperature range of 20–40 degrees C.
Citations
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01 Jan 2004
TL;DR: In this paper, the effect of chip packages on junction to board thermal resistance was compared for both SiC and Sapphire chips, and a conceptual LED illumination system was chosen and CFD models were created to determine the availability and limitations of passive air-cooling.
Abstract: Light emitting diodes, LEDs, historically have been used for indicators and produced low amounts of heat. The introduction of high brightness LEDs with white light and monochromatic colors have led to a movement towards general illumination. The increased electrical currents used to drive the LEDs have focused more attention on the thermal paths in the developments of LED power packaging. The luminous efficiency of LEDs is soon expected to reach over 80 lumens/W, this is approximately 6 times the efficiency of a conventional incandescent tungsten bulb. Thermal management for the solid-state lighting applications is a key design parameter for both package and system level. Package and system level thermal management is discussed in separate sections. Effect of chip packages on junction to board thermal resistance was compared for both SiC and Sapphire chips. The higher thermal conductivity of the SiC chip provided about 2 times better thermal performance than the latter, while the under-filled Sapphire chip package can only catch the SiC chip performance. Later, system level thermal management was studied based on established numerical models for a conceptual solid-state lighting system. A conceptual LED illumination system was chosen and CFD models were created to determine the availability and limitations of passive air-cooling.

242 citations

Journal ArticleDOI
17 Feb 2017-Leukos
TL;DR: In this paper, the authors discuss various aspects of outdoor lighting energy efficiency by means of new light sources and smart lighting systems and discuss visibility, traffic flow, safety, and environmental and economic aspects.
Abstract: This article discusses various aspects of outdoor lighting energy efficiency by means of new light sources and smart lighting systems. We will also discuss visibility, traffic flow, safety, and environmental and economic aspects. The use of an optimum level of road lighting maximizes the contrast between the background and the object to be seen. This suggests that the combined effect of road lighting and car headlights should be taken into account. Solutions for future measurement need to include 3D modeling of the lighting environment and mesopic photometry. The life cycle environmental impacts of high-pressure sodium (HPS) and light emitting diode (LED) luminaires were found to be on a similar level, but it is expected that LED luminaires will surpass HPS luminaires in environmental friendliness across the whole life cycle in the future. The energy-saving potential is based on new energy-efficient technology, reduced burning hours with smart control, and new lighting dimensioning. The energy sav...

29 citations

References
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Journal ArticleDOI
TL;DR: In this article, the exponential decay of light output as a function of time provided a convenient method to rapidly estimate life by data extrapolation and showed that the life of these LEDs decreases in an exponential manner with increasing temperature.
Abstract: Even though light-emitting diodes (LEDs) may have a very long life, poorly designed LED lighting systems can experience a short life. Because heat at the p-n-junction is one of the main factors that affect the life of the LED, by knowing the relationship between life and heat, LED system manufacturers can design and build long-lasting systems. In this study, several white LEDs from the same manufacturer were subjected to life tests at different ambient temperatures. The exponential decay of light output as a function of time provided a convenient method to rapidly estimate life by data extrapolation. The life of these LEDs decreases in an exponential manner with increasing temperature. In a second experiment, several high-power white LEDs from different manufacturers were life-tested under similar conditions. Results show that the different products have significantly different life values.

671 citations

Journal ArticleDOI
TL;DR: In this paper, the degradation rate of white LEDs was investigated and it was shown that the degradation process depends on both the junction temperature and the amplitude of short-wavelength radiation.

595 citations

Proceedings ArticleDOI
26 Jan 2004
TL;DR: In this paper, the effect of chip packages on junction to board thermal resistance was compared for both SiC and Sapphire chips, and a conceptual LED illumination system was chosen and CFD models were created to determine the availability and limitations of passive air-cooling.
Abstract: Light emitting diodes, LEDs, historically have been used for indicators and produced low amounts of heat. The introduction of high brightness LEDs with white light and monochromatic colors have led to a movement towards general illumination. The increased electrical currents used to drive the LEDs have focused more attention on the thermal paths in the developments of LED power packaging. The luminous efficiency of LEDs is soon expected to reach over 80 lumens/W, this is approximately 6 times the efficiency of a conventional incandescent tungsten bulb. Thermal management for the solid-state lighting applications is a key design parameter for both package and system level. Package and system level thermal management is discussed in separate sections. Effect of chip packages on junction to board thermal resistance was compared for both SiC and Sapphire chips. The higher thermal conductivity of the SiC chip provided about 2 times better thermal performance than the latter, while the under-filled Sapphire chip package can only catch the SiC chip performance. Later, system level thermal management was studied based on established numerical models for a conceptual solid-state lighting system. A conceptual LED illumination system was chosen and CFD models were created to determine the availability and limitations of passive air-cooling.

247 citations

01 Jan 2004
TL;DR: In this paper, the effect of chip packages on junction to board thermal resistance was compared for both SiC and Sapphire chips, and a conceptual LED illumination system was chosen and CFD models were created to determine the availability and limitations of passive air-cooling.
Abstract: Light emitting diodes, LEDs, historically have been used for indicators and produced low amounts of heat. The introduction of high brightness LEDs with white light and monochromatic colors have led to a movement towards general illumination. The increased electrical currents used to drive the LEDs have focused more attention on the thermal paths in the developments of LED power packaging. The luminous efficiency of LEDs is soon expected to reach over 80 lumens/W, this is approximately 6 times the efficiency of a conventional incandescent tungsten bulb. Thermal management for the solid-state lighting applications is a key design parameter for both package and system level. Package and system level thermal management is discussed in separate sections. Effect of chip packages on junction to board thermal resistance was compared for both SiC and Sapphire chips. The higher thermal conductivity of the SiC chip provided about 2 times better thermal performance than the latter, while the under-filled Sapphire chip package can only catch the SiC chip performance. Later, system level thermal management was studied based on established numerical models for a conceptual solid-state lighting system. A conceptual LED illumination system was chosen and CFD models were created to determine the availability and limitations of passive air-cooling.

242 citations

Journal ArticleDOI
TL;DR: In this article, the junction temperatures of high power LED arrays with and without heat pipe at the same air velocity of 7 m/s were reported to be 87.6 °C and 63.3 °C, respectively.

157 citations