ISSN:
0001-1541
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
An exact analytical theory of the local behavior of finite slugs which are dispersed in three-dimensional velocity fields is developed. It is shown that the dispersion coefficient enters the problem as an eigenvalue. For the important special case of fully developed straight pipe flow, considered first by Taylor and later generalized by Aris, the dispersion coefficient can be found very easily by the present method, which also provides the basis for studying a large class of more complicated problems.A detailed numerical analysis is carried out to determine the limits of applicability of the analytical theory. Fortunately, it is found that dispersion of slug stimuli in fully developed laminar tube flow is described by Equation (15) when τ exceeds certain minimum values which depend only weakly on Peclet number and are independent of slug length in the region considered here. Since peak mean concentrations are predicated accurately by Equation (19) for X 〉 0.1, this is a convenient quantity to use to determine dispersion coefficients experimentally.On comparing the numerical and analytical results for local point concentrations, good agreement is found, provided the average concentration is predicted accurately by Equation (15). This is significant because it implies that a broad class of difficult transient heat and mass transfer problems, with aperiodic inlet disturbances, can be solved by using superposition in conjunction with the present approach.
Additional Material:
10 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/aic.690130439
