Experimental Investigation of Heat Dissipation Factors for High-Power LEDs

• Main Authors: Zheng-Hong Huang, 黃正宏
• Other Authors: Rong-Yuan Jou Ph.D.
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/685bde

碩士 === 國立虎尾科技大學 === 機械設計工程研究所 === 101 === Heat generations were inevitable transport phenomenon of high-power LED lighting. While high-power LEDs in operation can produce high luminance, but they also generate significant heat at the same time. The optical output of the LED is sharply degraded with the increase in junction temperature because the high temperature significantly influences the reliability and durability of the LED. The heat dissipation factor, Kh, for a lighting device is defined as heat dissipation from the lighting to total electrical input power of the lighting. It will be beneficial and critical to modeling and simulate thermal designs of lighting if the Kh factor of the specific LEDs is precisely obtained. In this study, a methodology is proposed and experiments are conducted to find the LEDs heat dissipation factors. Experiment procedures are changing the input powers to LEDs, and then gathering information by related instruments for the whole transient to steady states. Experimental results showed that, for two different brands of LEDs under test, different values of heat dissipation factor were found, and the optical outputs of luminous flux were affected by the value of heat dissipation factor. By using the simple method to measure the heat dissipation factor, the theoretice luminous flux can be evaluated; and comparing it to the luminous flux evaluated by the method of using a forward current model and a junction temperature model, the absolute error between these two results is less than 10%. It is expectable that the measured Kh factor will be helpful to thermal designs and characterizations of optical-thermal interdependence of LED lightings.