Macroscopic convection in the thin-film processor

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Virginia Tech


The thesis explores the proposal that macroscopic fluid convection in thin-film processors may be adequately represented by simple linear deterministic models. In addition, it examines the suggestion that the models themselves provide a useful tool in the search for a generalizable 'intrinsic' process heat transfer film coefficient, i.e., one that includes the effects of axial dispersion of the process fluid. Such a parameter would be helpful in the design and scale up of thin-film equipment.

The following approach was used to investigate this proposal: first, experimental fluid residence time distributions were obtained t over a range of operating conditions, using an industrial pilot plant thin -film processor. The experimental data were used to select an appropriate linear fluid flow model for the process. The model parameters were evaluated over this range using frequency response techniques. These models were subsequently incorporated into a numerical heat transfer simulation of the thin -film processor. Careful matching of the pilot plant transient temperature responses to those predicted by the simulation yielded the sought after intrinsic (dispersion corrected) heat transfer film coefficients for the processor.