Enhancement of Heat Dissipation Efficiency in a Channel by Passive Fluttering Flag Induced Vortex Flow

Abstract

Improving the heat dissipation efficiency is a bottleneck problem in the development of microelectronic technology because of the ongoing trend of increasing the number of transistors in a densely integrated circuit which dramatically increases the chance of overheating. Most of the excess thermal energy from electronics are dissipated through the use of heat sinks, leading to the various heat transfer studies aiming to improve heat sink performance. Inserting a fluttering flag in a heat sink channel has been experimentally examined to enhance the heat transfer rate, but the inserted flag will inevitably induce pressure drop for the channel, which to a certain extent, decreases the overall performance of the heat sink. This work aims to improve the overall heat dissipation efficiency through equally splitting the inserted flag into smaller parts. By keeping the flag length constant, the heat transfer enhancement with a single uncut flag as well as flag cut into equal parts along the flow direction are studied. The heat loss enhancement reaches a peak, while the pressure drop reaches a minimum with increasing number of divided parts of the flag, showing that there exists an optimal splitting number to achieve the best heat dissipation performance. This work can shed light on the relation between fluttering motion and the heat dissipation performance and provide useful reference to effective heat sink design.