Nusselt Number and Friction Factor of Staggered Arrays of Low Aspect Ratio Micro-Pin-Fins Under Cross Flow for Water as Fluid

Experimental results of the thermal and hydraulic performances of silicon-based, low aspect ratio micro-pin-fin cold plates under cross flow conditions are reported. The pins were both circular and square in shape with dimensions (diameter for circular and sides for square) ranging from 50 to 150 μm. The test chip contained 20 integral 75×75 μm temperature sensors which were used to determine the thermal resistance (K W-1 ) of the cold plates. The experiments were conducted using water, over a Reynolds number (Re) ranging from 40 to 1000. The data show that the average Nusselt number (Nu) based on the fin diameter varies as Re0.84 for Re < 100 and as Re0.73 for Re > 100, where Re is the Reynolds number based on maximum velocity and the fin diameter. Analysis of the Fanning friction factor (f) data shows that f varies as Re-1.35 for Re < 100 and as Re-0.1 for Re > 100.