Department of Energy (DOE) Office of Basic Energy Sciences

Department of Energy (DOE) Office of Basic Energy Sciences — Pressure Drop Measurements in a Microchannel.

Recent developments in micro-energy and micro-chemical systems have produced a need for greater understanding of flow in small channels. Several recent studies of friction factors and transition Reynolds numbers in rectangular microchannels have produced results that differ from classical laminar flow theory. We determined friction factors and laminar flow friction constants for water flowing in high aspect ration channels with depths ranging from 128 to 521 microns. Reynolds numbers were between 60 and 3450. Pressure drops were measures within the channel itself to exclude entrance and exit loses. Transitions to turbulence were observed with flow visualization. Uncertainties in measured variables were quantified and propagated into the estimated friction constants. Friction factors were also determined in a 1050 micron-deep channel that served as a control. After considering experimental uncertainties and systematic errors, significant differences remained between the results and classical theory.