A suspended microchannel with integrated temperature sensors for high-pressure flow studies

Abstract

A freestanding microchannel, with integrated temperature sensors, has been developed for highpressure . flow studies.These microchannels are approximately 20pm x 2pm x 4400pm, and are suspended above 80 pm deep cavities, bulk micromachined using BrF3 dry etch. The calibration of the lightly boron-doped thermistor-type sensors shows that the resistance sensitivity of these integrated sensors is parabolic with respect to temperature and linear with respect to pressure. Volumetric flow rates of N2 in the microchannel were measured at inlet pressures up to 578psig. The discrepancy between the data and theory results from the flow acceleration in a channel, the nonparabolic velocity profile, and the bulging of the channel. Bulging effects were evaluated by using incompressible water flow measurements, which also measures 1.045~10-~N-s/m~ for the viscosity of DI water. The temperature data from sensors on the channel shows the heating of the channel due to the friction generated by the high-pressure flow inside.

Slip flow in elliptic microchannels

“…For example, experiments conducted by Arkilic et al [2,3], Liu et al [4], Pfalher et al [5,6], Harley et al [7], Choi et al [8], Wu et al [9], Araki et al [10] on the transport of gases in microchannels confirm that continuum analyses are unable to predict flow properties in micro-sized devices.…”

Flow sensor using micromachined pressure sensor

“…Figure 1 shows the schematic representation and working principle of the flow sensor. Equation 1 explains the differential pressure sensing mode which utilizes the pressure sensors placed in the sensor cavity [4]. Equation 2 explains the sensing mode which utilizes pressure sensors in the restriction channel [5].…”

Design, simulation, and testing of a novel micro-channel heat exchanger for natural gas cooling in automotive applications

“…Wu [17] applied pressures of more than 40 bar. The diffusion-bonding process typically used in the construction of microchannel heat exchangers allows operating pressures as high as 1000 bar [18].…”