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 m 2 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/m 2 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 ( R cp ) was achieved at maximum flow rate of 4.2 cm 3 /s in the experiment. For the designed heat sink, different components of the cold plate thermal resistance (R cp ) 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 R cp and proved to be the main component. Convection resistance from heated channel wall with porous insert to coolant accounts for 37% of the R cp . With forced convection of water at Re = 408 through porous copper media, maximum values of 20 kW/m 2 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.