Comparison of DPF and TIS Models

The TIS model is relatively simple mathematically and hence easy to use. The DPF or axial dispersion model is mathematically more complex and yields significantly different results for different choices of boundary conditions, if the extent of backmixing is large (small Pe,). On this basis, the TIS model may be favored. 

Nevertheless, we may compare the two models more quantitatively by means of the two methods already used for estimating values of N and Pe, from tracer data (1) matching E(6) for the two models and (2) matching variances, aj. 

For Pe, - small, the results of the matching to obtain N from Pe, give increasingly different values, as already illustrated for j2e in Table 19.8. 

The consequences of the differences in these and other mixing models for reactor performance are explored in Chapter 20. 

19-1 Stimulus-response experiments were used to evaluate the operation of a 1.465L laboratory stirred-tank reactor as a CSTR. The response curves were obtained (a) by using acetic acid (A, ca = 0.85 mol L-1) as a tracer chasing water in step-change experiments, and (b) by using a small pulse of glacial acetic acid (density = 1.05 g cm-3, M = 60 g mol-1) on a 

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