A detailed numerical study has been prepared to analyze a new design of a multiple inlet/outlet micro pin fin heat sink (MPFHS) and to compare its effectiveness in heat spreading with a conventional design based on the single inlet and single outlet configuration. The new design contains 4 manifolds placed on the sides of the heat sink. Moreover, the inlet channels have been shifted to the corners of the manifolds to create a vortex inside the heat sink and to reduce the maximum temperature of

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... he heat sink's surface. The aim of the study is to find the best design of the multiple inlet/outlet MPFHS in terms of thermohydraulic performance and the most uniform temperature profile. Besides, the other 2 designs have been tested: multiple inlet and multiple outlet designs without vortex generator. During the study, water and copper have been assumed as fluid and solid domains respectively. The heat flux assumed to be dissipated by the heat sink was equal to 150 W/cm2. The maximum, average, and minimum temperatures of the fluid and solid domain have been compared for various cases as well as pressure drops, velocity profiles, and streamlines. Moreover, parameters that allow describing particular cases in terms of temperature uniformity and heat transfer performance, namely mean absolute temperature difference, thermal resistance, Nusselt number, and overall thermal performance factor have been calculated. To get the most reliable comparison between particular cases, the same amount of fluid flowing in the MPFHS for all cases has been assumed. The results show that the multiple inlet with vortex generator design is characterized by the best thermohydraulic performance. The maximum temperature, mean average temperature difference, and thermal resistance can be reduced by 21.1%, 61.3%, and 23.5% respectively.