This paper investigates the significance of several micro-effects that have been proposed to influence pressure drop measurements in microchannels. Pressure drop measurements were made for liquid flow within tubular microchannels nominally ranging in diameters from 97 mm to 260 mm and Reynolds numbers from 30 to 3000. Fused silica tubes, polyetheretherketone tubes, and stainless steel tubes were examined. Distilled water, tap water, and deionized water were used to investigate the effect of the fluid's ionic composition on the pressure drop. The combination of differing tube surfaces and differing ionic composition was use to examine the influence of surface polarity. The effect of micro particles was investigated by testing filtered and unfiltered test fluids. Statistical examination of the measurements showed that most all of the friction factor measurements exhibited the same dependence on Reynolds number despite variation in tube length, tube material, tube diameter, fluid type, and filtering. In addition, the measurements agreed well with classical theory. This includes the fact that no early transition from laminar flow to turbulent flow was observed. Finally, it was shown that the present pressure drop measurements were not significantly affected by viscous dissipation.
Citation: International Journal of Transport Phenomena
Pub Type: Journals
micro, micro devices, microfluidics, microtechnology, pressure drop, single-phase