Narrow residence time distributions (RTDs) are desirable in many chemical engineering\nprocesses. However, when a system operates in the laminar flow regime, significant fluid\ndynamic dispersion takes place. This problem is often encountered in micro and millifluidic\ndevices. Exploiting the beneficial effects of secondary flow and chaotic advection, so-called\ncoiled flow inverters (CFIs) are a promising solution for the reduction of fluid dynamic dispersion.\nThese devices, however, have not been extensively used due to the lack of experimental\ndata and of correlations relating the design parameters and operating conditions to the\namount of axial dispersion. In this work, we investigated RTDs in micro and millifluidic\ndevices using step input injection and UVââ?¬â??vis inline spectroscopy for the detection of the\nconcentration of a tracer. Experiments were performed for different operating conditions\nand geometries. Helically coiled tubes (HCTs) were similarly characterized. Dispersion data\nwere expressed in terms of an axial dispersion coefficient and an empirical correlation was\nderived. The experimental results show that lower axial dispersion is achieved in CFIs as\ncompared to HCTs and straight tubes.
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