Effects of Heat Transfer on Frictional Characteristics of Pressure-Driven Liquid Microflows

ABSTRACT

The present paper elucidates the effects of heat transfer on fluid friction characteristics of microfabricated channels. Microchannels with dimensions 45 mm(L) × 200 μm(W)× 300 μm(2H) were fabricated by micromilling process on 2mm thick aluminium plate and experiments were conducted with deionised water as the working fluid. For a specified value of heat flux, supplied by means of 35W strip heaters attached at the bottom of the aluminium plate, the flow rate of deionised water was increased in steps, and for each step the pressure drop across the length of the channel, inlet and outlet liquid temperature and the channel bed temperature were recorded. The flow-rates were varied between 0.6ml/min and 3ml/min. From the acquired experimental data Darcy friction factor was calculated. The Poiseuille number, which is the product of friction factor and Reynolds number, was also calculated and compared with the classical values of the same for plane-Poiseuille flows. The experimental values were found to be significantly smaller than the predictions made using the classical theory, and the mean value of the Poiseuille number, for a specified wall heat flux, was also found to be decreasing with increasing value of the supplied heat flux. This is of significance from both scientific and industrial perspectives. The implications of the obtained experimental results have been discussed in details.

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