Before revision: This curve is normalized in such a way that the area under it is unity: (1) The mean age of the exit stream or mean residence time is: (2) When a tracer is injected into a reactor at a location more than two or three particle diameters downstream from the entrance and measured some distance upstream from the exit, the system is analogous to an open-open system .
After revision: This curve is normalized in such a way that the area under it is unity: (1) The mean age of the exit stream or mean residence time is: (2) When a tracer is injected into a reactor at a location more than two or three particle diameters downstream from the entrance and measured some distance upstream from the exit, the system can be described by the Dispersion model with combinations of open or close boundary conditions .