This work focuses on the efficiency of the LED acting as the heat sink containing Phase Change Material(PCM). Three different heat sink configurations(H-1, H-2, and H-3) are used in this study. Input power and the num...This work focuses on the efficiency of the LED acting as the heat sink containing Phase Change Material(PCM). Three different heat sink configurations(H-1, H-2, and H-3) are used in this study. Input power and the number of fins are altered to find their effect on junction temperatures, luminous flux, and thermal resistance. The junction temperature of heat sink H-3 with PCM decreased by 3.1 % when compared with heat sink devoid of PCM at 10 W. The thermal resistance of the heat sink H-3 is reduced by 18.2 % when compared to its counterpart devoid of PCM at 10 W. The luminous flux of the PCM filled heat sink H-3 is found to increase by 12.15 % against the PCM not filled heat sink H-1 at 10 W. The H-3 heat sink with PCM showed superior performance because of the enhanced natural convection and conduction in bulk PCM with fins, and with added high latent heat capacity of PCM.展开更多
In the present work, recalibration of the National Institute for Standards （NIS, Egypt） working standard lamps from Osram Inc. and their associated expanded uncertainty budget were done. A set-up composed of ...In the present work, recalibration of the National Institute for Standards （NIS, Egypt） working standard lamps from Osram Inc. and their associated expanded uncertainty budget were done. A set-up composed of an integrating sphere, a standard photometer and a group of five luminous flux standard lamps ranged from 25 to 200 W calibrated and traceable to the National Physical Laboratory （NPL, UK） is used to measure and recalibrate the total luminous flux for these five working standard lamps. After recalibration, NIS （Egypt） maintains the national scales for luminous flux in lumen.展开更多
文摘This work focuses on the efficiency of the LED acting as the heat sink containing Phase Change Material(PCM). Three different heat sink configurations(H-1, H-2, and H-3) are used in this study. Input power and the number of fins are altered to find their effect on junction temperatures, luminous flux, and thermal resistance. The junction temperature of heat sink H-3 with PCM decreased by 3.1 % when compared with heat sink devoid of PCM at 10 W. The thermal resistance of the heat sink H-3 is reduced by 18.2 % when compared to its counterpart devoid of PCM at 10 W. The luminous flux of the PCM filled heat sink H-3 is found to increase by 12.15 % against the PCM not filled heat sink H-1 at 10 W. The H-3 heat sink with PCM showed superior performance because of the enhanced natural convection and conduction in bulk PCM with fins, and with added high latent heat capacity of PCM.
文摘In the present work, recalibration of the National Institute for Standards （NIS, Egypt） working standard lamps from Osram Inc. and their associated expanded uncertainty budget were done. A set-up composed of an integrating sphere, a standard photometer and a group of five luminous flux standard lamps ranged from 25 to 200 W calibrated and traceable to the National Physical Laboratory （NPL, UK） is used to measure and recalibrate the total luminous flux for these five working standard lamps. After recalibration, NIS （Egypt） maintains the national scales for luminous flux in lumen.
