Flow patterns in a scaled-down disk-ring reactor have been quantified for the purpose of modelling such systems. The major area of interest for these reactors occurs for the production of condensation polymers, especially polyethylene terephthalate, in which a volatile by product must be removed to drive the reaction toward completion. Previous researchers have modelled such reactors using restrictive mixing assumptions, (e.g. the bulk liquid pool is well-mixed). However, the high viscosity (5,000 - 100,000 Poise) found in these operations greatly reduces convective mixing and diffusional mass transfer.
Quantification of the flow patterns has been accomplished through computer video analysis. A particle in the fluid has been tracked by a video system connected to a computer with video analysis hardware and software. The motion of the particle is then discretized by calculating the position of the particle at discrete time intervals. After a set of data is collected from the videotapes, it is transformed by a calibration formula to a 3-dimensional coordinate system relative to the mixer. Each data record in the set is now composed of three spatial coordinates and time. A cubic spline is then fit to the data in order to regenerate an approximation to the flow patterns inside the mixer as a function of time.