Numerical investigation on heat sink with fluid pockets for high power LEDs

Abstract

The present numerical study explores the use of fluid pockets in the heat sink to enhance heat transfer in high power LEDs. A robust heat sink model has been presented and evaluated the heat transfer characterization in terms of reduced LED junction temperature via natural convection and studied the effect of fluid flow in the pockets of heat sink. The junction temperature of the LED has been measured, for enhanced heat transfer and the results have been compared with conventional heat sink. The cooling fluid inside the fluid pockets absorbs heat generated by LEDs resulting in exchange of heat from heat sink surface to the liquid medium in the fluid pockets. The heat gain causes the fluid to flow against gravity due to density variation, raises the mixture of liquid inside the fluid pockets and flow back by gravity effect when it is condensed by the extended fin surface. The performance of the heat sink with fluid pockets has been found to be better than normal heat sink of same geometry due to its ability to conduct heat by the presence of liquid. Fluid pockets filled with
de-ionized water in the heat sink have a noticeable effect on heat removal rate. A series of case studies have been done for accurate and efficient heat transfer output; these results then have been used as the benchmark to validate the experimental results. The numerical results have been found to be in good agreement with experimental results.