Flow optimizer architecture designs in high powered computing coolant chambers

Abstract

With the ever increasing trend of cramming more transistors on the silicon and the consequential increase in the thermal design power, combined with stacked die and multiple die configurations inside the package footprint, optimized coolant chambers becomes an imperative design need to remove heat efficiently from the silicon. Liquid cooling is investigated to efficiently meet the challenges of high heat loads on several different fin geometries, lowering thermal resistance, and lower noise. Branching flow evenly inside the coolant chamber is vital for optimal performance of the chamber. In this paper, we present computational investigations for improving the thermal performance of a liquid-cooled chamber by optimizing the coolant flow inside the chamber with the aid of novel symmetric baffles strategically located at the inlet and outlet. Flow animation visualization from CFD simulations also show that the baffle introduces turbulence inside the liquid-cooled chamber eliminating stagnant zones especially in the corners. A numerical conjugate convection in the channel and conduction on the fin plate/substrate heat transfer model was developed and setup to run for seven different fin geometries using Ansys Icepak CFD solver. A k-ε model was used to predict the turbulent flow and heat transfer through all the different finned coolant chamber. A new type of miniaturized fin, based on the NACA-0020 airfoil is introduced as a staggered array of pin fin configuration inside liquid cooled chambers and computationally investigated at several inlet velocities ranging from 0.5 m/s to 3.0 m/s (2000 ≤ Re ≤ 12,000) characterizing the variation of surface Nusselt number with Reynolds number. Surface Nusselt number, a dimensionless heat transfer coefficient is investigated along the surfaces of all the fins to predict the convective cooling capability of the fins being considered. Simulation results reveal that NACA-0020 airfoil fin structure with a 0.23 airfoil thickness-to chord length ratio, has the best performance compared against all the other fins investigated in this study. The findings from this investigation can improve thermal performance of liquid cooled heat sinks across a wide range of package powers.