Research on optimization of cooling structure of LED element (The 2nd report)

• Main Authors: Kobayashi, T, Sakate, Y, Hashimoto, R, Takashina, T, Kanematsu, H, Utsumi, Y
• Format: Conference Proceeding
• Language: English
• Subjects: ALUMINIUM; Aluminum; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CONVECTION; EFFICIENCY; EMISSIVITY; ENGINEERING; HEAT; HEAT SINKS; HEAT SOURCES; Heat transfer; Light emitting diodes; Luminaires; Mathematical models; Temperature; THERMAL ANALYSIS; Thermal energy; Thermal radiation; THERMOCOUPLES; THICKNESS
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/1.4866630

This report shows a design guideline on the parts dimension of LED light bulb for heat transfer. LED light bulb is popular owing to the high efficiency and long life. However, LED element is a point heat source. Therefore, LED light bulb has some problems about heat transfer when it is used for lighting. It sometimes causes deterioration by the raise of local temperature, resulting in lowering of efficiency and shorter life. Thus the thermal analysis focused on the number of element, all parts thickness, length, and radiant heat was studied, as systematic report on the points has not been found. In this report, heat radiation was taken into account in the thermal analysis in addition to natural heat convection. Furthermore the temperature of a heat sink model for LED light bulb was measured with thermocouples and thermo-viewer to verify the calculation. The emissivity of aluminum used for the calculation was 0.4. As the result of analysis, it was found that the maximum temperature was mainly influenced by ring length, ring diameter and disk thickness as a design guideline. Concretely, longer length, larger diameter and thicker disk gave lower temperature of LED element. The temperatures of the best and worst model were around 70 °C and 120 °C respectively in the above condition. The temperatures calculated were consistent with those in experiment.