Performance of Microchannel Heat Sinks with Newtonian and Non-Newtonian Fluids

Authors: A. AZIMIAN1; M. SEFID1

Source: Heat Transfer Engineering, Volume 25, Number 8, December 2004 , pp. 17-27(11)

Publisher: Taylor and Francis Ltd

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Abstract:

In this paper, the flow behavior and heat transfer performance of a microchannel heat sink is examined. Microchannel heat sink is a heat exchanger that is used to control the temperature of electronic devices with high heat flux capacity. A comprehensive thermal model for a microchannel should include a three-dimensional conduction analysis in the solid parts, followed by an extensive three-dimensional developing flow in the fluid region. The heat transfer analysis in the transition region of the fluid section is a crucial matter. Hydrodynamic and thermal entrance lengths are two important parameters, among others, which are studied in the solution. To examine the potential of using a non-Newtonian fluid, the power law model was used for both Newtonian and non-Newtonian fluids. The numerical solution of the problem was based on a finite difference approach using a control volume with staggered grid system. The SIMPLE algorithm was applied to the problem, and convection terms were estimated using QUICK method. A comparison of the Newtonian and non-Newtonian results showed that for shear thinning fluids, the pressure drop could reduce up to 45%, while for shear thickening fluids, it can increase up to 48%. The same comparison for the Nusselt number showed about a 160%increase with shear thinning fluids and a 43%decrease with shear thickening fluids. The thermal resistance at a Reynolds number of 50 will reduce approximately 25%with shear thinning fluids and will increase approximately 5%with shear thickening fluids. At higher values of the Reynolds number, the changes in the value of the thermal resistance are more pronounced.

Document Type: Research article

DOI: 10.1080/01457630490519844

Affiliations: 1: Mechanical Engineering Department, Isfahan University of Technology, Isfahan, Iran

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