Laser Diagnostic Analysis Of Complex Flow Patterns: A Chemical Engineering Experiment Using Applied Optics

A simple, yet effective, undergraduate experiment has been developed in collaboration between the Chemical Engineering Department and the Optical Sciences and Engineering Program at NJIT. During step change tracer experiments, absorption of red laser light serves as the diagnostic to reveal complex flow patterns in short and long lengths of square cross section clear pipe. The transient absorbance curves constructed from the optical data reveal significant back-mixing in the short flow cell. The long flow cell shows behavior consistent with laminar flow with dispersion in a conduit. This analysis is performed without invoking the complications of the residence time distribution.