Sintered porous heat sink for cooling of high-powered microprocessors for server applications

Abstract

This paper experimentally investigates the sintered porous heat sink for the cooling of the high-powered compact microprocessors for server applications. Heat sink cold plate consisted of rectangular channel with sintered porous copper insert of 40% porosity and 1.44 × 10−11 m2 permeability. Forced convection heat transfer and pressure drop through the porous structure were studied at Re ⩽ 408 with water as the coolant medium. In the study, heat fluxes of up to 2.9 MW/m2 were successfully removed at the source with the coolant pressure drop of 34 kPa across the porous sample while maintaining the heater junction temperature below the permissible limit of 100 ± 5 °C for chipsets. The minimum value of 0.48 °C/W for cold plate thermal resistance (Rcp) was achieved at maximum flow rate of 4.2 cm3/s in the experiment. For the designed heat sink, different components of the cold plate thermal resistance (Rcp) from the thermal footprint of source to the coolant were identified and it was found that contact resistance at the interface of source and cold plate makes up 44% of Rcp and proved to be the main component. Convection resistance from heated channel wall with porous insert to coolant accounts for 37% of the Rcp. With forced convection of water at Re = 408 through porous copper media, maximum values of 20 kW/m2 K for heat transfer coefficient and 126 for Nusselt number were recorded. The measured effective thermal conductivity of the water saturated porous copper was as high as 32 W/m K that supported the superior heat augmentation characteristics of the copper–water based sintered porous heat sink. The present investigation helps to classify the sintered porous heat sink as a potential thermal management device for high-end microprocessors.