Enhancing thermal efficiency of aluminum heat sink by reduced graphene oxide-layer coating approach

Abstract

Light emitting diode (LED) technology plays a significant role in the market of lighting technologies due to its high efficiency compared to conventional lighting solutions. Cooling of high-power LEDs, on the other hand, is a critical aspect in maximizing LED performance. Furthermore, due to the powder, rain, and muds, LED armatures including a finned heat sink may not be efficient according to its design and utilization areas especially for outdoor illumination. Eliminating these factors, un-finned heat sink LED armatures are also preferred, yet the temperature dissipation of the un-finned type is not homogeneous relatively according to finned type. In this study, a graphene coated un-finned heat sink was developed to obtain relatively homogeneous temperature distribution and increase heat transfer of aluminum plate. An un-finned heat sink comprising thin graphene film was designed by a computer-aided-design (CAD) program and the thermal analysis was conducted by a finite element analysis (FEA) program. The experimental measurements offered that the maximum and minimum junction temperatures for the bare, and reduced graphene oxide (rGO)-layers coated aluminum heat sinks were obtained as 90 - 70 degrees C, and 59-54 degrees C, respectively. The outstanding in-plane thermal conductivity of rGO-layers facilitated the homogenous heat distribution throughout the aluminum heat sink. Moreover, the design and thermal analysis of developed heat sinks were validated with experimental results with the 2.4% error with respect to maximum junction temperature. It can be concluded that rGO-layers coated aluminum heat sink enabled to facilitated the heat transfer more than bare aluminum due to its higher thermal conductivity. In brief, this work opens a new gate for designing the graphene based materials-integrated cooling solution for LED applications.