Experimental Study of Water Flow and Heat Transfer in Silicon Micro-Pin-Fin Heat Sinks

An experimental study is performed to investigate water flow and heat transfer characteristics in silicon micro-pin-fin heat sinks with various pin-fin configurations and a conventional microchannel, with a length of 25 mm, a width of 2.4 mm, and a height of 0.11 mm. The micro-pin-fin heat sinks have different fin arrangements, fin shapes, and fin pitches. The results show that the micro-pin-fin heat sinks have the better overall thermal-hydraulic performance including the heat transfer enhancement and the pressure drop penalty compared to the conventional microchannel. A parametric study is carried out to investigate the effects of various pin-fin configurations on the flow and heat transfer characteristics. The linear relationship between fRe and Re is found for the water flow through the micro-pin-fin heat sinks for the first time. A new friction factor correlation is further developed based on the linear relationship between fRe and Re. Taking the effects of the various pin-fin configurations on the Nusselt number into consideration, a new Nusselt number correlation is also developed. The new correlations of friction factor and Nusselt number predict the experimental data well. An infrared thermo-imaging system was used to measure the temperature field of water heat transfer in the micro-pin-fin heat sinks and the conventional microchannel. The infrared thermo-images show the more uniform temperature profile in the transverse direction for the micro-pin-fin heat sinks than that for the conventional microchannel, which indicates the better heat transfer performance of the former than the latter. The dominant mechanism of heat transfer enhancement caused by the micro-pin-fins is the hydrodynamic effects, including fluid disturbance as well as the breakage and re-initialization of the thermal boundary layer near the wall of the heat sinks.