Impact of fin geometry and surface roughness on performance of an impingement two-phase cooling heat sink

Abstract

Jet impingement two-phase cooling is often used to handle the high heat fluxes of high-performance electronics. While much of the literature focuses on thermal–hydraulic performance, the effects of fin geometry on the two-phase heat transfer and pressure drop have not been thoroughly investigated. This study was undertaken to examine those factors more closely. The thermal–hydraulic performance of a two-phase cooling impingement heat sink was studied for three different fin configurations: microchannel, pin fin array, and bare copper surface. A copper block with a top surface area of 1"×1" was used to mimic computer chip. A dielectric coolant Novec/HFE 7000 was used to study flow boiling heat transfer. It was observed that when the original microchannel heat sink was cut into pin fin array heat sink, thermal performance was improved by 51% and pressure drop decreased by 18%. The pin fin array heat sink performs better than the microchannel heat sink and the bare copper surface heat sink. Effects of enhanced surface roughness was also studied with 9% of improvement in thermal performance of a bare copper surface. Comparison with existing literature correlations for pool boiling and flow boiling led to mean absolute error below 12.8%, so a new correlation was developed that has a mean absolute error of 2.4%.