Thermohydraulic characteristics of a single-phase microchannel heat sink coated with copper nanowires

Abstract

This study experimentally investigates single phase heat transfer and pressure drop characteristics of a shallow rectangular microchannel heat sink whose surface is enhanced with copper nanowires (CuNWs). The hydraulic diameter of the channel is 672 μm and the bottom wall is coated with Cu nanowires (CuNWs) of 200 nm in diameter and 50 μm in length. CuNWs are grown on the Cu heat sink by electrochemical synthesis technique which is inexpensive and readily scalable. The heat transfer and pressure drop results of CuNWs enhanced heat sink are compared with that of bare copper surface heat sink using deionized (DI) water as the working fluid at Reynolds Number (Re) ranging from 106-636. The experimental results indicate an enhancement in Nusselt Number (Nu) at all Re with a maximum enhancement of 24% at Re = 106. An increase in pressure drop is also observed in all test cases due to enhanced roughness. The enhanced thermal performance is attributed to the enhanced wettability and the increased heat transfer surface area due to the addition of CuNWs arrays. The surface morphology of the heat sink has also been studied before and after heat transfer experiments through SEM to determine the effect of fluid flow on CuNWs arrays. The SEM results demonstrate no notable changes in surface morphology for the Re range in which experiments have been conducted and for single phase flow.