Hydraulic and thermal performances of micro pin fin heat sink with increasing pin fin height

This study investigates numerically the impacts of pin fins (PF) with varying height on the pressure drop Delta P, the bottom average temperature Tbw, the Nusselt number Nu and the thermal performance factor eta of a micro pin fin heat sink (MPFHS). Three groups of PF structure characterized by a different height increase mode are introduced: Case 1: structure with constant height step, Case 2: structure with increasing height step, and Case 3: structure with decreasing height step. The findings in this work show that Delta P and Nu increase but Tbw decreases with the increasing height step for Case 1 and with the increasing increment of the height step for Case 2 and Case 3. When comparing their thermal and hydraulic performances, Case 2 demonstrates the best thermal performances, whereas Case 3 has the best hydraulic performance when the total height steps of PFs in all three kinds of heat sink are kept constant. Furthermore, this study finds that the PF with increasing height can always enhance eta of the MPFHS compared to PF with uniform height. This finding validates the performance advantage of the PF with increasing height and offers the potential technique for the optimization design of MPFHS.