Great thermal management challenges have to be considered that the thermal design power (TDP) of central processing unit (CPU) in the high-performance computer cluster has reached 400 W with package heat flux of 25 W/cm². In this study, the three-dimensional numerical model of I-type microchannel heat sink (MCHS) with uniform heat source (400W) applied to the fin area was established to explore its fluid flow and temperature distribution. Three dimensionless parameters, ϕC (0.111, 0.148, 0.167, 0.185, 0.222), ϕW (0, 0.5, 1) and ϕL (0, 0.5, 1) were employed to comprehensively analyze the effects of the header shapes on the flow distribution in MCHS based on the Mal-distribution Factor (MF).
The numerical results showed that the variation of flow rate in MCHS behaves an overall trend of gradually decreasing from the middle channels to the channels on both sides due to the I-type inlet/outlet arrangement. Besides, the difference of flow rate among the microchannels in MCHS becomes relatively gentle because of ϕC increasing. It is found that rectangular header (ϕW=1, ϕL=1) performs best in flow distribution but triangular header (ϕW=0, ϕL=0) performs worst. These results indicate that the strategy to improve the flow distribution in the microchannels is to increase the value of the three dimensionless parameters. Summarizing the results of fluid flow distribution, temperature maximum and pressure drop obtained from all simulation calculations, the optimal I-type MCHS header design is with ϕC=0.185, ϕW=1 and ϕL=1. This study could provide a specific instruction for the design of the practical I-type MCHS for high TDP CPUs liquid cooling.