Effect of circular pin-fins geometry and their arrangement on heat transfer performance for laminar flow in microchannel heat sink

A computational simulation of seventeen types of microchannel heat sink (MCHS) models with the channels equipped with circular pin fins having various diameters (0.25 and 0.5 mm), spacing (1.5, 3.0 and 6.0 mm) and height (0.1, 0.25, 0.4 and 0.5 mm) in order to compare their performance with the conventional MCHS was performed. Mesh independence validation and experiments on MCHS without any pin fins were used to assess the reliability of computer simulation results. The simulation was carried out for five different Reynolds numbers in the range from 100 to 1000. Hydraulic and thermal parameters including pressure drop, Nusselt number and thermal resistance were considered for performance evaluations. To evaluate comprehensive performance, the heat sink effectiveness factor which represents a combination of the hydraulic and thermal performance was defined and corresponding figures were provided to define an optimum geometry. It was observed that thermal resistance substantially depends on the height of the pins: the higher are the pins, the better is the heat flux. The optimal pin placement step sp was revealed as six diameters dp of the pin: sp = 6 dp for the height of the pins hp = 0.1-0.25 mm; for hp = 0.5 mm the effectiveness factor of MCHS has the maximum value at sp = 3 dp.