Cooling Capacity Increase of CPU Liquid Cooling Systems using hBN Nanofluids
Many nanofluids, the colloidal suspensions nanoparticles within a base fluid, exhibit increase in thermal conductivity with respect to base fluid beyond the predictions of effective medium theories. However, viscosity also increases significantly accompanying the increase in thermal properties that limits the benefit of using nanofluids as a coolant for thermal management applications. Many recent studies have shown that insignificant or no improvement in cooling performance was introduced by using nanofluids due to the reduction of flow rate related to the increasing viscosity. This study focuses on liquid cooling systems utilized for thermal management of central processing unit of computers. Recently introduced hexagonal boron nitride (hBN) nanofluids are considered as a coolant in this study as their viscosity increase is lower with respect to other nanofluids such as with alumina nanoparticles, while the increase in thermal conductivity is more. The study considers the performance on the component and system level, to identify the effect of increasing particle volume concentration on cooling capacity. The cold plate and heat exchanger performance is calculated numerically using finite volume method using single phase homogeneous model relying on measured properties of nanofluid. Different cold plate designs and pumps are considered to be able to evaluate different and limiting cases. The cooling capacity increase is then quantified based on complete system behavior.