Thermal performance of a pin-finned vapor chamber heat spreader for CPU cooling applications

This work presents the thermal performances of a vapor chamber heat spreader (VCHS) composed of a grooved capillary structure and rectangular pin fins for central processing unit (CPU) cooling applications. The overall VCHS dimensions are 105.7 mm in length, 46.6 mm in width, and 38.5 mm in height (8 mm in base height and 30.5 mm in fin height). The variations of the thermal resistance versus the heat input power exhibit a minimum corresponding to the capillary limit ranging between 30 and 40 W (heat fluxes ranging between 30 and 40 W/cm²) depending on the operating conditions (air velocity and orientation). For the air velocity range considered in this study, the VCHS allows for heat flux dissipation up to 50 W/cm² with maximum wall temperatures ranging between 74.2 and 77.5 °C for the horizontal position and between 73.8 and 78.3 °C for the vertical one. The thermal performances are better for the horizontal position than those obtained for the vertical one. The comparison between the thermal performances of the VCHS and those of an aluminum heat sink (ALHS) having the same dimensional characteristics shows that for heat input powers less than 40 W, the VCHS allows a reduction in the thermal resistance ranging from 30 to 35% and from 23 to 27% for the horizontal and vertical positions, respectively. Compared to the ALHS, for heat input powers, higher than 40 W, the performances deteriorate and the reductions in thermal resistances are around 17% for the horizontal position and do not exceed 10% for the vertical one. Computational fluid dynamic (CFD) simulations are carried out using commercial software (cosmosfloworks–solidworks). Numerical modeling is carried out to determine the performance of the ALHS and the VCHS under the same experimental operating conditions. The results show that the VCHS allows better heat diffusion at its base and a reduction of the temperature gradients between the hot source and the cold ends. Thus, the spreading thermal resistance is decreased considerably, and the efficiency of the fins is augmented. Likewise, the results obtained by the model approach corroborate the experimental ones and a good agreement is obtained.