Experimental Investigation of Embedded Micropin-Fins for Single-Phase Heat Transfer and Pressure Drop

Three-dimensional (3D) stacked integrated circuit (IC) chips offer significant performance improvement, but offer important challenges for thermal management including, for the case of microfluidic cooling, constraints on channel dimensions, and pressure drop. Here, we investigate heat transfer and pressure drop characteristics of a microfluidic cooling device with staggered pin-fin array arrangement with dimensions as follows: diameter D = 46.5 mu m; spacing, S similar to 100 lm; and height, H similar to 110 mu m. Deionized singlephase water with mass flow rates of m = 15.1-64.1 g/min was used as the working fluid, corresponding to values of Re (based on pin fin diameter) from 23 to 135, where heat fluxes up to 141 W/cm(2) are removed. The measurements yield local Nusselt numbers that vary little along the heated channel length and values for both the Nu and the friction factor do not agree well with most data for pin fin geometries in the literature. Two new correlations for the average Nusselt number (similar to Re-1.04) and Fanning friction factor (similar to Re-0.52) are proposed that capture the heat transfer and pressure drop behavior for the geometric and operating conditions tested in this study with mean absolute error (MAE) of 4.9% and 1.7%, respectively. The work shows that a more comprehensive investigation is required on thermofluidic characterization of pin fin arrays with channel heights H-f < 150 lm and fin spacing S = 50-500 lm, respectively, with the Reynolds number, Re < 300.