Effect of Design Variables and System-Level Constraints on Heat Pipes Heatsink Performance: Part II - Heat Pipes Staggering and Non-Uniform In-Server Conditions

In order to investigate the limitations and the theoretical cooling limit of the heat pipe heatsink technology, a parametric study of high-performance heatsinks under different design and in-service constraints was conducted. Although the fluid dynamics and heat transfer of finned heatsinks are well-documented, both experimental and numerical investigations have focused on flowbench-type boundary conditions. Therefore, the impact of surrounding IT equipment, such as upstream electronics, CPU power map, etc., has not be considered for comprehensive design optimization. In this second paper a computational model was developed to investigate the effect of non-uniform features on the heatsink thermal behavior. Of particular interest to this study is to examine the advantages of different heat pipes arrangements while keeping the heat pipes number constant. Four different heat pipes patterns were compared with the original design thermal performance as the associated flow impedance is presented. The impact of non-uniform air flow induced by the upstream IT equipment on the heatsink thermal performance was investigated by dividing the air flow in different number of air streams for different inlet opening percentage. For all analyzed opening areas, the four air streams case presented the best heatsink thermal performance. In order to study the effect of non-uniform heat source over the heatsink thermal behavior, a parametric analysis focused on both power distribution and hotspot orientation with respect the airflow was carried out. Nine symmetrical and three asymmetric fictitious CPU power maps were analyzed. Better heatsink thermal performances were achieved as the heat sources were located away from the center.