Effects of the Gap on Microchannel Heat Sink Cooling Performance

Abstract

With the surge in electronic systems' performance, the demand for efficient electronic cooling to facilitate high heat dissipation is becoming more imminent. Hence liquid cooling with phase change becomes imperative as far as high-flux electronics systems are employed. Among the cooling devices, a microchannel is commonly adopted. This research evaluates plain microchannel cold plates with a gap above the microchannels. The present study examines the effect of the gap above straight fin microchannels in the cold plate using the dielectric Novec 7000 as the working fluid. Two cold plates are made with a transparency cover. One has a gap above the microchannels (GAM) 1/3 of fin height, and another one with no gap above the microchannels (NGAM); the mass flux ranges from 25 to 260 kg/m 2 s, while the heat flux spans from 50 to 150 W/cm 2 . The results show quite an improvement in performance with this space gap above the microchannels. The test results showed that the design of the GAM shows a superior heat transfer coefficient (HTC), which is enhanced by 90% compared to that of NCBM. Moreover, the GAM design has a much lower pressure drop by about 7~24% compared to the NGAM design at different mass flux and heat flux at the fully liquid inlet. The proposed space gap of 33% of fin height above the microchannels, thereby enabling the reduction of surface temperature by around 3~7 °C compared to no gap above the microchannels. This phenomenon becomes even more pronounced in high heat-flux regions.