EXPERIMENTAL STUDY ON NATURAL CONVECTION COOLING OF LED USING A FLAT-PLATE PULSATING HEAT PIPE

Heat dissipation structure is important for high-power LED chips because of a high heat flux. The experimental study of cooling high-power LED (up to 100 W) based on the combination of flat-plate pulsating heat pipe (PHP) and natural convection fins was conducted. The effects of heating power, working fluids, filling ratio (rate of liquid-filled volume to the total volume of channels), configuration parameters, and fin area on the start-up time and the thermal characteristics of the plate PHP were investigated experimentally. The experimental results indicated that cooling by a flat-plate PHP with natural convection fins was effective in lowering the temperature of high-power LED. However, the thermal characteristics of a flat-plate PHP with natural convection cooling possessed large disparity compared to that of forced convection cooling. The optimal filling ratio range was 30% to 50% in this research and the thermal performance of a flat-plate PHP with acetone as a working fluid was better than that with ethanol. Moreover, a flat-plate PHP with a trianglular cross-section channel led to a lower thermal resistance than that with a square cross-section channel. The study of thermal resistance based on channel cross-sectional area was suggested.