Hot wire anemometry for experimental determination of flow distribution in multilayer microreactors

Thermal anemometry with constant wire temperature for characterization of the flow distribution was applied for multilayered microchannel reactors first. A reactor system made by stereolithography was used as a model. The hot wire 400 μm long was placed in front of the microchannel exits 800 μm wide. Using a micrometer table all single channel volume flows were measured in the model reactor in dependence of the overall flow through the reactor. A strongly pronounced core flow through the microchannel body was observed at flows where laminar flow was calculated in the reactor inlet tube. This was a result from the design, i.e. of ratio of inlet tube cross-section area to the sum of channel cross-section areas. Calculating pressure drop of channel and reactor inlet tube showed that pressure drop was approximately 10 times higher in the tube than in the channels. In this special case inlet turbulence helped to equalize the flow over the channels.