Single-Phase Thermal and Hydraulic Performance of Embedded Silicon Micro-Pin Fin Heat Sinks using R245fa

Kong, D., Jung, K.W., Jung, S., Jung, D., Schaadt, J., Iyengar, M., Malone, C., Kharangate, C.R., Asheghi, M., Goodson, K.E., and Lee, H., 2019, "Single-phase thermal and hydraulic performance of embedded silicon micro-pin fin heat sinks using R245fa," International Journal of Heat and Mass Transfer, Vol., 141, pp. 145-155.

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Aggressive thermal management strategies such as liquid cooling have become essential for high-performance three-dimensional (3D) integrated circuit (IC) chips. Micro-pin fin arrays integrated between stacks can provide superior thermal performance with relatively less pumping power compared to microchannel cooling. In this work, we experimentally studied the single-phase heat transfer and pressure drop characteristics of micro-pin fin arrays. Three different samples consisting of 31-131 rows of cylindrical micro-pin fins with pin diameters D-h = 45-100 mu m, center-to-center pin spacings S = 74-298 mu m, and pin height H-f similar to 200 mu m were tested. Dielectric fluid R245fa was used as the working fluid with mass flow rates (m) over dot = 14.7-181.6 g/min and corresponding Reynolds numbers Re = 35 481.3. The heat fluxes ranged from 2.5 W/cm(2) to 48.7 W/cm(2), and the inlet fluid temperature was maintained at ambient temperature in the range of 22.2-25.3 degrees C. The local heater temperature distributions, average heat transfer characteristics, and pressure drops for various geometries of the embedded microfluid pin-fin arrays were determined. The experimentally determined heat transfer coefficient varied with both the mass flow rate and pin spacing with an averaged heat transfer coefficient of up to 18.2 kW/(m(2).K). Full-scale conjugate simulations with a turbulence model were conducted using ANSYS Fluent to validate the experimental results for the three cases. A comparison with the numerical model showed mean absolute errors of 9.1% for the heat transfer and 14.3% for the pressure drop. 

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