Increase heat dissipation efficiency of Al plate according to surface roughness treatment by sandpaper or sandblast

사포, 샌드블라스트로 표면 거칠기 처리에 따른 알루미늄 판의 방열 효율 증대

Abstract

Recently, as the interest in energy savings has increased, there has been increasing use of LED lighting, which is an eco-friendly device that replaces high energy consuming fluorescent lamps and incandescent lamps. In the case of a high output LED, however, the life time is shortened due to deterioration caused by heat generation. As a solution to this problem, this paper evaluated the LED life extension effect by increasing the convective heat transfer coefficient of the heat sink surface for LED packaging. A roughing process was carried out using sandpaper and sand blasting. The changes in surface roughness and surface area after each surface treatment process were evaluated quantitatively and the convective heat transfer coefficient was measured. When sandblasting and sandpaper were used to roughen the aluminum surface, a higher convection heat transfer coefficient was obtained compared to the untreated case, and a high heat dissipation efficiency of 82.76% was obtained in the sandblast treatment. Therefore, it is expected that the application of heat dissipation to the heat sink will extend the lifetime of the LED significantly and economically by increasing the heat efficiency.

최근 에너지 절감에 대한 관심도가 높아짐에 따라 에너지 소비가 높은 형광등과 백열등을 대체하는 친환경소재인 LED의 조명을 활용하는 움직임이 활발하다. 그러나, 고출력 LED의 경우 발열에 의한 열화현상 때문에 수명이 단축되는 현상이 발생하게 된다. 이에 대한, 해결방안으로 본 논문은 LED Packing중 방열판표면의 거칠기 처리를 통하여 열전달 계수를 증대시킴으로서 LED 수명연장 효과를 평가하였다. 거칠기 공정은 사포 및 샌드블라스트를 이용하여 진행하였다. 각 표면처리 공정에 따른 거칠기 및 표면적 변화를 정량적으로 평가하였으며, 열전달 계수를 측정하였다. 샌드블라스트, 사포를 이용하여 알루미늄 표면에 거칠기처리를 진행했을 경우 미 처리 시 보다 높은 대류 열전달 계수를 얻을 수 있었고, 샌드블라스트 처리 시 약 82.76%의 높은 방열 효율 향상을 얻을 수 있어, 이를 방열판에 적용할 시 큰 경제적 부담 없이 기존대비 더 높은 방열효율 증대를 통해 LED 수명을 대폭 연장 시킬 것으로 기대된다.

Fig. 1. Cell models for convective heat transfer coefficient measurement

Fig. 2. Convective heat transfer coefficient with roughness values obtained by sandblast and sandpaper treatment

Fig. 3. Convective heat transfer coefficient according to the number of sandpaper

Fig. 4. Convective heat transfer coefficient according to sandblast pressure

Fig. 5. Surface morphology of #50 specimen obtained by OLS5000

Fig. 6. Surface morphology of #220 specimen obtained by OLS5000

Fig. 7. Surface morphology of sandblast pressure 2 specimen obtained by OLS5000

Fig. 8. Surface morphology of sandblast pressure 6 specimen obtained by OLS5000

Table 1. Average roughness value of Al plate according to the number of sand paper

Table 2. Average roughness value of Al plate according to sandblast pressure with 3 sec. of operation

Table 3. Relative surface area measured by a confocal laser(sandpaper)

Table 4. Relative surface area measured by a confocal laser(sandblast)