Analysis of thermal flow around heat sink with ionic wind for high-power LED

Abstract

This paper presents a new method of active cooling for a Light Emitting Diode (LED) application using the ionic wind which is a flow induced by a corona discharge at a tip of a curved electrode. Thermal flow around a heat sink for a high-power LED was analyzed and the ionic wind was investigated for the heat sink application in this study. Details of a numerical investigation of natural convection around the heat sink for the 200 W-LED were studied. The reliability of the computational fluid dynamics (CFD) was verified by experimental data of temperatures. A particle image velocimetry (PIV) test was performed to analyze the behavior of the ionic wind around the heat sink. The thermal flow around the heat sink fins was analyzed and it was concluded that the center pole of the cylindrical heat sink was unnecessary for the cooling performance. And, the ionic wind from a wire to cylinder electrode was applied to the heat sink to enhance the cooling performance. As a result, the optimum radius of the wire curvature and input voltage for the ionic wind were found to be 110 mm and 7.5 kV, respectively. The heat transfer coefficient of the heat sink increased by 37% from 96.7 to 133 W/m2 K by the ionic wind, which was confirmed experimentally. And, the cooling performance of the heat sink was enhanced by 148% in maximum by the ionic wind compared with that of the original heat sink for 0.6 W of the applied power. The result of this study can be used for the wide variety of the ionic wind application as a promising technology for the LED cooler.