Test facilities

Diagnostic techniques


Boiling flow in microchannels

micro nano engineering


The experiments encompass measurements of the pressure drop and the longitudinal temperature distribution in the fully developed single phase liquid flow in circular and square cross section channels made of very smooth borosilicate glass with hydraulic diameters from 50m up to 500m. The flow conditions consider the use of distilled water, methoxy-nonafluorobutane and methanol, to account for the effects of liquid properties. The Hagen-Poiseuille law is respected for the range of diameters > 100mm and Re from 2 up to around 2400.

Friction losses
Friction factor, f, versus experimental Reynolds number, Re, for distilled water in tubes with a) circular cross section and b) square cross section

mPIV flow velocity profiles
a) measured velocity profile for S_200 microchannel for Re=10 at the horizontal plane height y=155.6mm and axial distance z0=28.21mm and b) mean value and standard deviation of the velocity profiles in a). The line represents the CFD analytical solution

Heat losses
Variation of a) Nusselt number and b) fluid average bulk temperature with the Reynolds number for fully developed conditions, for qeff 5000Wm-2 in S_300 for water (), HFE7100 () and methanol ().

For heat transfer studies, the channels are heated with constant wall heat flux supplied by Joule effect by means of a thin InOx film. Deviations from classical theory are obtained for lower Reynolds numbers.