Simulation of three-dimensional laminar flow and heat transfer in an array of parallel microchannels

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Title: Simulation of three-dimensional laminar flow and heat transfer in an array of parallel microchannels
Author: Mlcak, Justin Dale
Abstract: Heat transfer and fluid flow are studied numerically for a repeating microchannel array with water as the circulating fluid . Generalized transport equations are discretized and solved in three dimensions for velocities , pressure , and temperature . The SIMPLE algorithm is used to link pressure and velocity fields , and a thermally repeated boundary condition is applied along the repeating direction to model the repeating nature of the geometry . The computational domain includes solid silicon and fluid regions . The fluid region consists of a microchannel with a hydraulic diameter of 85 .58 ?m . Independent parameters that were varied in this study are channel aspect ratio and Reynolds number . The aspect ratios range from 0 .10 to 1 .0 and Reynolds number ranges from 50 to 400 . A constant heat flux of 90 W /cm2 is applied to the northern face of the computational domain , which simulates thermal energy generation from an integrated circuit . A simplified model is validated against analytical fully developed flow results and a grid independence study is performed for the complete model . The numerical results for apparent friction coefficient and convective thermal resistance at the channel inlet and exit for the 0 .317 aspect ratio are compared with the experimental data . The numerical results closely match the experimental data . This close matching lends credibility to this method for predicting flows and temperatures of water and the silicon substrate in microchannels . Apparent friction coefficients linearly increase with Reynolds number , which is explained by increased entry length for higher Reynolds number flows . The mean temperature of water in the microchannels also linearly increases with channel length after a short thermal entry region . Inlet and outlet thermal resistance values monotonically decrease with increasing Reynolds number and increase with increasing aspect ratio . Thermal and friction coefficient results for large aspect ratios (1 and 0 .75 ) do not differ significantly , but results for small aspect ratios (0 .1 and 0 .25 ) notably differ from results of other aspect ratios .
URI: http : / /hdl .handle .net /1969 .1 /ETD -TAMU -1671
Date: 2009-05-15

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Simulation of three-dimensional laminar flow and heat transfer in an array of parallel microchannels. Available electronically from http : / /hdl .handle .net /1969 .1 /ETD -TAMU -1671 .

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