Numerical study on hotspots adaptive cooling and thermal-hydraulic performance enhancement of fractal microchannel heat sink embedded with hydrogels

The present study focuses on the numerical study of thermal and flow characteristics in a microchannel heat sink with alternating trapezoidal cavities in sidewall (MTCS). The effects of flow rate and heat flux on friction factor and Nusselt are presented. The results showed considerable improvement heat transfer performance micro channel heat sink with alternating trapezoidal cavities in sidewall with an acceptable pressure drop. The heat transfer rate has improved in the cavity area due the greater fluid mixing in fluid vortices and thermal boundary layer disruption. The slipping over the reentrant cavities and pressure gain reduces pressure drop appears as the reason behind of only minor pressure drop due to the cavities.

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Numerical Study of Forced Convection of Nanofluids in a Microchannel Heat Sink

ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels ◽

10.1115/icnmm2008-62306 ◽

2008 ◽

Cited By ~ 1

Author(s):

Parisa Vaziee ◽

Omid Abouali

Keyword(s):

Heat Transfer ◽

Pressure Drop ◽

Heat Sink ◽

Volume Fraction ◽

Numerical Study ◽

Heat Removal ◽

Al2o3 Nanoparticles ◽

Microchannel Heat Sink ◽

Particle Volume ◽

Volume Fractions

Effectiveness of the microchannel heat sink cooled by nanofluids with various particle volume fractions is investigated numerically using the latest theoretical models for conductivity and viscosity of the nanofluids. Both laminar and turbulent flows are considered in this research. The model of conductivity used in this research accounts for the fundamental role of Brownian motion of the nanoparticles which is in good agreement with the experimental data. The changes in viscosity of the nanofluid due to temperature variation are considered also. Final results are compared with the experimental measurements for heat transfer coefficient and pressure drop in microchannel. Enhancement in heat transfer is achieved for laminar flow with increasing of volume fraction of Al2O3 nanoparticles. But for turbulent flow an enhancement of heat removal was not seen and using higher volume fractions of nanoparticles increases the maximum substrate temperature. Pressure drop is increased with using nanofluids because of the augmentation in the viscosity and this increase is more noticeable in higher Reynolds numbers.

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The effect of viscous dissipation on laminar nanofluid flow in a microchannel heat sink

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1243/09544062jmes1465 ◽

2009 ◽

Vol 223 (11) ◽

pp. 2697-2706 ◽

Cited By ~ 10

Author(s):

M Ghazvini ◽

M A Akhavan-Behabadi ◽

M Esmaeili

Keyword(s):

Heat Transfer ◽

Nusselt Number ◽

Viscous Dissipation ◽

Heat Sink ◽

Volume Fraction ◽

Numerical Study ◽

Microchannel Heat Sink ◽

Fluid Temperature ◽

Nanofluid Flow ◽

Aspect Ratios

The present article focuses on analytical and numerical study on the effect of viscous dissipation when nanofluid is used as the coolant in a microchannel heat sink (MCHS). The nanofluid is made from CuO nanoparticles and water. To analyse the MCHS, a modified Darcy equation for the fluid and two-equation model for heat transfer between fluid and solid sections are employed in porous media approach. In addition, to deal with nanofluid heat transfer, a model based on the Brownian motion of nanoparticles is used. The model evaluates the thermal conductivity of nanofluid considering the thermal boundary resistance, nanoparticle diameter, volume fraction, and the fluid temperature. At first, the effects of particle volume fraction on temperature distribution and overall heat transfer coefficient are investigated with and without considering viscous dissipation. After that, the influence of different channel aspect ratios and porosities is studied. The results show that for nanofluid flow in microchannels, the viscous dissipation can be neglected for low volume fractions and aspect ratios only. Finally, the effect of porosity and Brinkman number on the overall Nusselt number is studied, where asymptotic behaviour of the Nusselt number is observed and discussed from the energy balance point of view.

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