Investigation of Fouling and Its Mitigation in Silicon Microchannels

Particulate fouling studies with 4.0-μm silica and 1.25-μm alumina dispersions in water were performed in rectangular, silicon microchannels having a hydraulic diameter of 225 μm with a Reynolds number of 17. Data show the absence of particle deposition within the microchannels. The primary reason for this is the relatively high wall shear stress at the microchannel walls of 2.3 Pa compared to conventional size passageways. In contrast, the headers for the microchannels are quite susceptible to particulate fouling under the same conditions. This is because the shear stress in the header region is lower. Moreover, there is a secondary effect in particulate fouling when fibrous elements exist within the particle dispersion. The fouling behavior due to fibrous material is quite different. In fact, the presence of fibers is extremely detrimental to pressure drops within a microchannel device.