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1 Turbulence : international journal

1 2004

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Numerical modelling of fluid flow and heat transfer in microchannels

Favre-Marinet M., Gamrat G., Asendrych D.

Turbulence : international journal

2004

Vol. 10

75-75

The work concerns three-dimensional numerical modelling of fluid flow and heat transfer in large-span rectangular microchannel. Channel height being the key geometrical parameter, was varied hi the range from 0.3 to 1 mm. The width of channel was equal to 250 mm what allowed to treat microchannel as a two-dimensional. The computational domain followed the details of experimental facility used in preceding research step. The numerical model assumed the laminar flow of water (506 < Re < 2023) with temperature-independent properties. The results obtained in experimental trials exhibited strong reduction of Nusselt number in comparison to theoretical law. The motivation of current simulation was to identify the reasons of discrepancies between theoretical predictions and experimental results. Among the explanations the effect of axial conduction resulting from complex geometry was supposed to have the highest significance. Main goal of current work was numerical prediction of coupling conduction-convection effect and its influence on Nusselt number values. Additionally the influence of entrance effects on the deviation of beat transfer results from the macroscale laws was taken into consideration. Comparison between experimental and numerical results was an essential part of current work and allowed to point out the weakness of some simplifications being assumed during interpretation of experimental data (i.e. uniform distribution of heat flux along fluid/solid interface turned out to be the origin of significant errors). Furthermore numerical simulations exhibited that significant part of heat resulting from conduction and insufficient insulation was delivered to water in inlet container. It could lead to false estimation of bulk temperature at channel inlet and to reduction of heat transfer effectiveness at the beginning part of microchannel. Results of current work allowed not only for verification of experimental conclusions, but also pointed out the weakness of already utilised experimental setup and were helpful in a design of a new experimental installation.